Source file src/cmd/compile/internal/types2/api_test.go

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package types2_test
     6  
     7  import (
     8  	"cmd/compile/internal/syntax"
     9  	"errors"
    10  	"fmt"
    11  	"internal/goversion"
    12  	"internal/testenv"
    13  	"slices"
    14  	"strings"
    15  	"sync"
    16  	"testing"
    17  
    18  	. "cmd/compile/internal/types2"
    19  )
    20  
    21  // nopos indicates an unknown position
    22  var nopos syntax.Pos
    23  
    24  func mustParse(src string) *syntax.File {
    25  	f, err := syntax.Parse(syntax.NewFileBase(pkgName(src)), strings.NewReader(src), nil, nil, 0)
    26  	if err != nil {
    27  		panic(err) // so we don't need to pass *testing.T
    28  	}
    29  	return f
    30  }
    31  
    32  func typecheck(src string, conf *Config, info *Info) (*Package, error) {
    33  	f := mustParse(src)
    34  	if conf == nil {
    35  		conf = &Config{
    36  			Error:    func(err error) {}, // collect all errors
    37  			Importer: defaultImporter(),
    38  		}
    39  	}
    40  	return conf.Check(f.PkgName.Value, []*syntax.File{f}, info)
    41  }
    42  
    43  func mustTypecheck(src string, conf *Config, info *Info) *Package {
    44  	pkg, err := typecheck(src, conf, info)
    45  	if err != nil {
    46  		panic(err) // so we don't need to pass *testing.T
    47  	}
    48  	return pkg
    49  }
    50  
    51  // pkgName extracts the package name from src, which must contain a package header.
    52  func pkgName(src string) string {
    53  	const kw = "package "
    54  	if i := strings.Index(src, kw); i >= 0 {
    55  		after := src[i+len(kw):]
    56  		n := len(after)
    57  		if i := strings.IndexAny(after, "\n\t ;/"); i >= 0 {
    58  			n = i
    59  		}
    60  		return after[:n]
    61  	}
    62  	panic("missing package header: " + src)
    63  }
    64  
    65  func TestValuesInfo(t *testing.T) {
    66  	var tests = []struct {
    67  		src  string
    68  		expr string // constant expression
    69  		typ  string // constant type
    70  		val  string // constant value
    71  	}{
    72  		{`package a0; const _ = false`, `false`, `untyped bool`, `false`},
    73  		{`package a1; const _ = 0`, `0`, `untyped int`, `0`},
    74  		{`package a2; const _ = 'A'`, `'A'`, `untyped rune`, `65`},
    75  		{`package a3; const _ = 0.`, `0.`, `untyped float`, `0`},
    76  		{`package a4; const _ = 0i`, `0i`, `untyped complex`, `(0 + 0i)`},
    77  		{`package a5; const _ = "foo"`, `"foo"`, `untyped string`, `"foo"`},
    78  
    79  		{`package b0; var _ = false`, `false`, `bool`, `false`},
    80  		{`package b1; var _ = 0`, `0`, `int`, `0`},
    81  		{`package b2; var _ = 'A'`, `'A'`, `rune`, `65`},
    82  		{`package b3; var _ = 0.`, `0.`, `float64`, `0`},
    83  		{`package b4; var _ = 0i`, `0i`, `complex128`, `(0 + 0i)`},
    84  		{`package b5; var _ = "foo"`, `"foo"`, `string`, `"foo"`},
    85  
    86  		{`package c0a; var _ = bool(false)`, `false`, `bool`, `false`},
    87  		{`package c0b; var _ = bool(false)`, `bool(false)`, `bool`, `false`},
    88  		{`package c0c; type T bool; var _ = T(false)`, `T(false)`, `c0c.T`, `false`},
    89  
    90  		{`package c1a; var _ = int(0)`, `0`, `int`, `0`},
    91  		{`package c1b; var _ = int(0)`, `int(0)`, `int`, `0`},
    92  		{`package c1c; type T int; var _ = T(0)`, `T(0)`, `c1c.T`, `0`},
    93  
    94  		{`package c2a; var _ = rune('A')`, `'A'`, `rune`, `65`},
    95  		{`package c2b; var _ = rune('A')`, `rune('A')`, `rune`, `65`},
    96  		{`package c2c; type T rune; var _ = T('A')`, `T('A')`, `c2c.T`, `65`},
    97  
    98  		{`package c3a; var _ = float32(0.)`, `0.`, `float32`, `0`},
    99  		{`package c3b; var _ = float32(0.)`, `float32(0.)`, `float32`, `0`},
   100  		{`package c3c; type T float32; var _ = T(0.)`, `T(0.)`, `c3c.T`, `0`},
   101  
   102  		{`package c4a; var _ = complex64(0i)`, `0i`, `complex64`, `(0 + 0i)`},
   103  		{`package c4b; var _ = complex64(0i)`, `complex64(0i)`, `complex64`, `(0 + 0i)`},
   104  		{`package c4c; type T complex64; var _ = T(0i)`, `T(0i)`, `c4c.T`, `(0 + 0i)`},
   105  
   106  		{`package c5a; var _ = string("foo")`, `"foo"`, `string`, `"foo"`},
   107  		{`package c5b; var _ = string("foo")`, `string("foo")`, `string`, `"foo"`},
   108  		{`package c5c; type T string; var _ = T("foo")`, `T("foo")`, `c5c.T`, `"foo"`},
   109  		{`package c5d; var _ = string(65)`, `65`, `untyped int`, `65`},
   110  		{`package c5e; var _ = string('A')`, `'A'`, `untyped rune`, `65`},
   111  		{`package c5f; type T string; var _ = T('A')`, `'A'`, `untyped rune`, `65`},
   112  
   113  		{`package d0; var _ = []byte("foo")`, `"foo"`, `string`, `"foo"`},
   114  		{`package d1; var _ = []byte(string("foo"))`, `"foo"`, `string`, `"foo"`},
   115  		{`package d2; var _ = []byte(string("foo"))`, `string("foo")`, `string`, `"foo"`},
   116  		{`package d3; type T []byte; var _ = T("foo")`, `"foo"`, `string`, `"foo"`},
   117  
   118  		{`package e0; const _ = float32( 1e-200)`, `float32(1e-200)`, `float32`, `0`},
   119  		{`package e1; const _ = float32(-1e-200)`, `float32(-1e-200)`, `float32`, `0`},
   120  		{`package e2; const _ = float64( 1e-2000)`, `float64(1e-2000)`, `float64`, `0`},
   121  		{`package e3; const _ = float64(-1e-2000)`, `float64(-1e-2000)`, `float64`, `0`},
   122  		{`package e4; const _ = complex64( 1e-200)`, `complex64(1e-200)`, `complex64`, `(0 + 0i)`},
   123  		{`package e5; const _ = complex64(-1e-200)`, `complex64(-1e-200)`, `complex64`, `(0 + 0i)`},
   124  		{`package e6; const _ = complex128( 1e-2000)`, `complex128(1e-2000)`, `complex128`, `(0 + 0i)`},
   125  		{`package e7; const _ = complex128(-1e-2000)`, `complex128(-1e-2000)`, `complex128`, `(0 + 0i)`},
   126  
   127  		{`package f0 ; var _ float32 =  1e-200`, `1e-200`, `float32`, `0`},
   128  		{`package f1 ; var _ float32 = -1e-200`, `-1e-200`, `float32`, `0`},
   129  		{`package f2a; var _ float64 =  1e-2000`, `1e-2000`, `float64`, `0`},
   130  		{`package f3a; var _ float64 = -1e-2000`, `-1e-2000`, `float64`, `0`},
   131  		{`package f2b; var _         =  1e-2000`, `1e-2000`, `float64`, `0`},
   132  		{`package f3b; var _         = -1e-2000`, `-1e-2000`, `float64`, `0`},
   133  		{`package f4 ; var _ complex64  =  1e-200 `, `1e-200`, `complex64`, `(0 + 0i)`},
   134  		{`package f5 ; var _ complex64  = -1e-200 `, `-1e-200`, `complex64`, `(0 + 0i)`},
   135  		{`package f6a; var _ complex128 =  1e-2000i`, `1e-2000i`, `complex128`, `(0 + 0i)`},
   136  		{`package f7a; var _ complex128 = -1e-2000i`, `-1e-2000i`, `complex128`, `(0 + 0i)`},
   137  		{`package f6b; var _            =  1e-2000i`, `1e-2000i`, `complex128`, `(0 + 0i)`},
   138  		{`package f7b; var _            = -1e-2000i`, `-1e-2000i`, `complex128`, `(0 + 0i)`},
   139  
   140  		{`package g0; const (a = len([iota]int{}); b; c); const _ = c`, `c`, `int`, `2`}, // go.dev/issue/22341
   141  		{`package g1; var(j int32; s int; n = 1.0<<s == j)`, `1.0`, `int32`, `1`},        // go.dev/issue/48422
   142  	}
   143  
   144  	for _, test := range tests {
   145  		info := Info{
   146  			Types: make(map[syntax.Expr]TypeAndValue),
   147  		}
   148  		name := mustTypecheck(test.src, nil, &info).Name()
   149  
   150  		// look for expression
   151  		var expr syntax.Expr
   152  		for e := range info.Types {
   153  			if ExprString(e) == test.expr {
   154  				expr = e
   155  				break
   156  			}
   157  		}
   158  		if expr == nil {
   159  			t.Errorf("package %s: no expression found for %s", name, test.expr)
   160  			continue
   161  		}
   162  		tv := info.Types[expr]
   163  
   164  		// check that type is correct
   165  		if got := tv.Type.String(); got != test.typ {
   166  			t.Errorf("package %s: got type %s; want %s", name, got, test.typ)
   167  			continue
   168  		}
   169  
   170  		// if we have a constant, check that value is correct
   171  		if tv.Value != nil {
   172  			if got := tv.Value.ExactString(); got != test.val {
   173  				t.Errorf("package %s: got value %s; want %s", name, got, test.val)
   174  			}
   175  		} else {
   176  			if test.val != "" {
   177  				t.Errorf("package %s: no constant found; want %s", name, test.val)
   178  			}
   179  		}
   180  	}
   181  }
   182  
   183  func TestTypesInfo(t *testing.T) {
   184  	// Test sources that are not expected to typecheck must start with the broken prefix.
   185  	const brokenPkg = "package broken_"
   186  
   187  	var tests = []struct {
   188  		src  string
   189  		expr string // expression
   190  		typ  string // value type
   191  	}{
   192  		// single-valued expressions of untyped constants
   193  		{`package b0; var x interface{} = false`, `false`, `bool`},
   194  		{`package b1; var x interface{} = 0`, `0`, `int`},
   195  		{`package b2; var x interface{} = 0.`, `0.`, `float64`},
   196  		{`package b3; var x interface{} = 0i`, `0i`, `complex128`},
   197  		{`package b4; var x interface{} = "foo"`, `"foo"`, `string`},
   198  
   199  		// uses of nil
   200  		{`package n0; var _ *int = nil`, `nil`, `*int`},
   201  		{`package n1; var _ func() = nil`, `nil`, `func()`},
   202  		{`package n2; var _ []byte = nil`, `nil`, `[]byte`},
   203  		{`package n3; var _ map[int]int = nil`, `nil`, `map[int]int`},
   204  		{`package n4; var _ chan int = nil`, `nil`, `chan int`},
   205  		{`package n5a; var _ interface{} = (*int)(nil)`, `nil`, `*int`},
   206  		{`package n5b; var _ interface{m()} = nil`, `nil`, `interface{m()}`},
   207  		{`package n6; import "unsafe"; var _ unsafe.Pointer = nil`, `nil`, `unsafe.Pointer`},
   208  
   209  		{`package n10; var (x *int; _ = x == nil)`, `nil`, `*int`},
   210  		{`package n11; var (x func(); _ = x == nil)`, `nil`, `func()`},
   211  		{`package n12; var (x []byte; _ = x == nil)`, `nil`, `[]byte`},
   212  		{`package n13; var (x map[int]int; _ = x == nil)`, `nil`, `map[int]int`},
   213  		{`package n14; var (x chan int; _ = x == nil)`, `nil`, `chan int`},
   214  		{`package n15a; var (x interface{}; _ = x == (*int)(nil))`, `nil`, `*int`},
   215  		{`package n15b; var (x interface{m()}; _ = x == nil)`, `nil`, `interface{m()}`},
   216  		{`package n15; import "unsafe"; var (x unsafe.Pointer; _ = x == nil)`, `nil`, `unsafe.Pointer`},
   217  
   218  		{`package n20; var _ = (*int)(nil)`, `nil`, `*int`},
   219  		{`package n21; var _ = (func())(nil)`, `nil`, `func()`},
   220  		{`package n22; var _ = ([]byte)(nil)`, `nil`, `[]byte`},
   221  		{`package n23; var _ = (map[int]int)(nil)`, `nil`, `map[int]int`},
   222  		{`package n24; var _ = (chan int)(nil)`, `nil`, `chan int`},
   223  		{`package n25a; var _ = (interface{})((*int)(nil))`, `nil`, `*int`},
   224  		{`package n25b; var _ = (interface{m()})(nil)`, `nil`, `interface{m()}`},
   225  		{`package n26; import "unsafe"; var _ = unsafe.Pointer(nil)`, `nil`, `unsafe.Pointer`},
   226  
   227  		{`package n30; func f(*int) { f(nil) }`, `nil`, `*int`},
   228  		{`package n31; func f(func()) { f(nil) }`, `nil`, `func()`},
   229  		{`package n32; func f([]byte) { f(nil) }`, `nil`, `[]byte`},
   230  		{`package n33; func f(map[int]int) { f(nil) }`, `nil`, `map[int]int`},
   231  		{`package n34; func f(chan int) { f(nil) }`, `nil`, `chan int`},
   232  		{`package n35a; func f(interface{}) { f((*int)(nil)) }`, `nil`, `*int`},
   233  		{`package n35b; func f(interface{m()}) { f(nil) }`, `nil`, `interface{m()}`},
   234  		{`package n35; import "unsafe"; func f(unsafe.Pointer) { f(nil) }`, `nil`, `unsafe.Pointer`},
   235  
   236  		// comma-ok expressions
   237  		{`package p0; var x interface{}; var _, _ = x.(int)`,
   238  			`x.(int)`,
   239  			`(int, bool)`,
   240  		},
   241  		{`package p1; var x interface{}; func _() { _, _ = x.(int) }`,
   242  			`x.(int)`,
   243  			`(int, bool)`,
   244  		},
   245  		{`package p2a; type mybool bool; var m map[string]complex128; var b mybool; func _() { _, b = m["foo"] }`,
   246  			`m["foo"]`,
   247  			`(complex128, p2a.mybool)`,
   248  		},
   249  		{`package p2b; var m map[string]complex128; var b bool; func _() { _, b = m["foo"] }`,
   250  			`m["foo"]`,
   251  			`(complex128, bool)`,
   252  		},
   253  		{`package p3; var c chan string; var _, _ = <-c`,
   254  			`<-c`,
   255  			`(string, bool)`,
   256  		},
   257  
   258  		// go.dev/issue/6796
   259  		{`package issue6796_a; var x interface{}; var _, _ = (x.(int))`,
   260  			`x.(int)`,
   261  			`(int, bool)`,
   262  		},
   263  		{`package issue6796_b; var c chan string; var _, _ = (<-c)`,
   264  			`(<-c)`,
   265  			`(string, bool)`,
   266  		},
   267  		{`package issue6796_c; var c chan string; var _, _ = (<-c)`,
   268  			`<-c`,
   269  			`(string, bool)`,
   270  		},
   271  		{`package issue6796_d; var c chan string; var _, _ = ((<-c))`,
   272  			`(<-c)`,
   273  			`(string, bool)`,
   274  		},
   275  		{`package issue6796_e; func f(c chan string) { _, _ = ((<-c)) }`,
   276  			`(<-c)`,
   277  			`(string, bool)`,
   278  		},
   279  
   280  		// go.dev/issue/7060
   281  		{`package issue7060_a; var ( m map[int]string; x, ok = m[0] )`,
   282  			`m[0]`,
   283  			`(string, bool)`,
   284  		},
   285  		{`package issue7060_b; var ( m map[int]string; x, ok interface{} = m[0] )`,
   286  			`m[0]`,
   287  			`(string, bool)`,
   288  		},
   289  		{`package issue7060_c; func f(x interface{}, ok bool, m map[int]string) { x, ok = m[0] }`,
   290  			`m[0]`,
   291  			`(string, bool)`,
   292  		},
   293  		{`package issue7060_d; var ( ch chan string; x, ok = <-ch )`,
   294  			`<-ch`,
   295  			`(string, bool)`,
   296  		},
   297  		{`package issue7060_e; var ( ch chan string; x, ok interface{} = <-ch )`,
   298  			`<-ch`,
   299  			`(string, bool)`,
   300  		},
   301  		{`package issue7060_f; func f(x interface{}, ok bool, ch chan string) { x, ok = <-ch }`,
   302  			`<-ch`,
   303  			`(string, bool)`,
   304  		},
   305  
   306  		// go.dev/issue/28277
   307  		{`package issue28277_a; func f(...int)`,
   308  			`...int`,
   309  			`[]int`,
   310  		},
   311  		{`package issue28277_b; func f(a, b int, c ...[]struct{})`,
   312  			`...[]struct{}`,
   313  			`[][]struct{}`,
   314  		},
   315  
   316  		// go.dev/issue/47243
   317  		{`package issue47243_a; var x int32; var _ = x << 3`, `3`, `untyped int`},
   318  		{`package issue47243_b; var x int32; var _ = x << 3.`, `3.`, `untyped float`},
   319  		{`package issue47243_c; var x int32; var _ = 1 << x`, `1 << x`, `int`},
   320  		{`package issue47243_d; var x int32; var _ = 1 << x`, `1`, `int`},
   321  		{`package issue47243_e; var x int32; var _ = 1 << 2`, `1`, `untyped int`},
   322  		{`package issue47243_f; var x int32; var _ = 1 << 2`, `2`, `untyped int`},
   323  		{`package issue47243_g; var x int32; var _ = int(1) << 2`, `2`, `untyped int`},
   324  		{`package issue47243_h; var x int32; var _ = 1 << (2 << x)`, `1`, `int`},
   325  		{`package issue47243_i; var x int32; var _ = 1 << (2 << x)`, `(2 << x)`, `untyped int`},
   326  		{`package issue47243_j; var x int32; var _ = 1 << (2 << x)`, `2`, `untyped int`},
   327  
   328  		// tests for broken code that doesn't type-check
   329  		{brokenPkg + `x0; func _() { var x struct {f string}; x.f := 0 }`, `x.f`, `string`},
   330  		{brokenPkg + `x1; func _() { var z string; type x struct {f string}; y := &x{q: z}}`, `z`, `string`},
   331  		{brokenPkg + `x2; func _() { var a, b string; type x struct {f string}; z := &x{f: a, f: b,}}`, `b`, `string`},
   332  		{brokenPkg + `x3; var x = panic("");`, `panic`, `func(interface{})`},
   333  		{`package x4; func _() { panic("") }`, `panic`, `func(interface{})`},
   334  		{brokenPkg + `x5; func _() { var x map[string][...]int; x = map[string][...]int{"": {1,2,3}} }`, `x`, `map[string]invalid type`},
   335  
   336  		// parameterized functions
   337  		{`package p0; func f[T any](T) {}; var _ = f[int]`, `f`, `func[T any](T)`},
   338  		{`package p1; func f[T any](T) {}; var _ = f[int]`, `f[int]`, `func(int)`},
   339  		{`package p2; func f[T any](T) {}; func _() { f(42) }`, `f`, `func(int)`},
   340  		{`package p3; func f[T any](T) {}; func _() { f[int](42) }`, `f[int]`, `func(int)`},
   341  		{`package p4; func f[T any](T) {}; func _() { f[int](42) }`, `f`, `func[T any](T)`},
   342  		{`package p5; func f[T any](T) {}; func _() { f(42) }`, `f(42)`, `()`},
   343  
   344  		// type parameters
   345  		{`package t0; type t[] int; var _ t`, `t`, `t0.t`}, // t[] is a syntax error that is ignored in this test in favor of t
   346  		{`package t1; type t[P any] int; var _ t[int]`, `t`, `t1.t[P any]`},
   347  		{`package t2; type t[P interface{}] int; var _ t[int]`, `t`, `t2.t[P interface{}]`},
   348  		{`package t3; type t[P, Q interface{}] int; var _ t[int, int]`, `t`, `t3.t[P, Q interface{}]`},
   349  		{brokenPkg + `t4; type t[P, Q interface{ m() }] int; var _ t[int, int]`, `t`, `broken_t4.t[P, Q interface{m()}]`},
   350  
   351  		// instantiated types must be sanitized
   352  		{`package g0; type t[P any] int; var x struct{ f t[int] }; var _ = x.f`, `x.f`, `g0.t[int]`},
   353  
   354  		// go.dev/issue/45096
   355  		{`package issue45096; func _[T interface{ ~int8 | ~int16 | ~int32 }](x T) { _ = x < 0 }`, `0`, `T`},
   356  
   357  		// go.dev/issue/47895
   358  		{`package p; import "unsafe"; type S struct { f int }; var s S; var _ = unsafe.Offsetof(s.f)`, `s.f`, `int`},
   359  
   360  		// go.dev/issue/50093
   361  		{`package u0a; func _[_ interface{int}]() {}`, `int`, `int`},
   362  		{`package u1a; func _[_ interface{~int}]() {}`, `~int`, `~int`},
   363  		{`package u2a; func _[_ interface{int | string}]() {}`, `int | string`, `int | string`},
   364  		{`package u3a; func _[_ interface{int | string | ~bool}]() {}`, `int | string | ~bool`, `int | string | ~bool`},
   365  		{`package u3a; func _[_ interface{int | string | ~bool}]() {}`, `int | string`, `int | string`},
   366  		{`package u3a; func _[_ interface{int | string | ~bool}]() {}`, `~bool`, `~bool`},
   367  		{`package u3a; func _[_ interface{int | string | ~float64|~bool}]() {}`, `int | string | ~float64`, `int | string | ~float64`},
   368  
   369  		{`package u0b; func _[_ int]() {}`, `int`, `int`},
   370  		{`package u1b; func _[_ ~int]() {}`, `~int`, `~int`},
   371  		{`package u2b; func _[_ int | string]() {}`, `int | string`, `int | string`},
   372  		{`package u3b; func _[_ int | string | ~bool]() {}`, `int | string | ~bool`, `int | string | ~bool`},
   373  		{`package u3b; func _[_ int | string | ~bool]() {}`, `int | string`, `int | string`},
   374  		{`package u3b; func _[_ int | string | ~bool]() {}`, `~bool`, `~bool`},
   375  		{`package u3b; func _[_ int | string | ~float64|~bool]() {}`, `int | string | ~float64`, `int | string | ~float64`},
   376  
   377  		{`package u0c; type _ interface{int}`, `int`, `int`},
   378  		{`package u1c; type _ interface{~int}`, `~int`, `~int`},
   379  		{`package u2c; type _ interface{int | string}`, `int | string`, `int | string`},
   380  		{`package u3c; type _ interface{int | string | ~bool}`, `int | string | ~bool`, `int | string | ~bool`},
   381  		{`package u3c; type _ interface{int | string | ~bool}`, `int | string`, `int | string`},
   382  		{`package u3c; type _ interface{int | string | ~bool}`, `~bool`, `~bool`},
   383  		{`package u3c; type _ interface{int | string | ~float64|~bool}`, `int | string | ~float64`, `int | string | ~float64`},
   384  
   385  		// reverse type inference
   386  		{`package r1; var _ func(int) = g; func g[P any](P) {}`, `g`, `func(int)`},
   387  		{`package r2; var _ func(int) = g[int]; func g[P any](P) {}`, `g`, `func[P any](P)`}, // go.dev/issues/60212
   388  		{`package r3; var _ func(int) = g[int]; func g[P any](P) {}`, `g[int]`, `func(int)`},
   389  		{`package r4; var _ func(int, string) = g; func g[P, Q any](P, Q) {}`, `g`, `func(int, string)`},
   390  		{`package r5; var _ func(int, string) = g[int]; func g[P, Q any](P, Q) {}`, `g`, `func[P, Q any](P, Q)`}, // go.dev/issues/60212
   391  		{`package r6; var _ func(int, string) = g[int]; func g[P, Q any](P, Q) {}`, `g[int]`, `func(int, string)`},
   392  
   393  		{`package s1; func _() { f(g) }; func f(func(int)) {}; func g[P any](P) {}`, `g`, `func(int)`},
   394  		{`package s2; func _() { f(g[int]) }; func f(func(int)) {}; func g[P any](P) {}`, `g`, `func[P any](P)`}, // go.dev/issues/60212
   395  		{`package s3; func _() { f(g[int]) }; func f(func(int)) {}; func g[P any](P) {}`, `g[int]`, `func(int)`},
   396  		{`package s4; func _() { f(g) }; func f(func(int, string)) {}; func g[P, Q any](P, Q) {}`, `g`, `func(int, string)`},
   397  		{`package s5; func _() { f(g[int]) }; func f(func(int, string)) {}; func g[P, Q any](P, Q) {}`, `g`, `func[P, Q any](P, Q)`}, // go.dev/issues/60212
   398  		{`package s6; func _() { f(g[int]) }; func f(func(int, string)) {}; func g[P, Q any](P, Q) {}`, `g[int]`, `func(int, string)`},
   399  
   400  		{`package s7; func _() { f(g, h) }; func f[P any](func(int, P), func(P, string)) {}; func g[P any](P, P) {}; func h[P, Q any](P, Q) {}`, `g`, `func(int, int)`},
   401  		{`package s8; func _() { f(g, h) }; func f[P any](func(int, P), func(P, string)) {}; func g[P any](P, P) {}; func h[P, Q any](P, Q) {}`, `h`, `func(int, string)`},
   402  		{`package s9; func _() { f(g, h[int]) }; func f[P any](func(int, P), func(P, string)) {}; func g[P any](P, P) {}; func h[P, Q any](P, Q) {}`, `h`, `func[P, Q any](P, Q)`}, // go.dev/issues/60212
   403  		{`package s10; func _() { f(g, h[int]) }; func f[P any](func(int, P), func(P, string)) {}; func g[P any](P, P) {}; func h[P, Q any](P, Q) {}`, `h[int]`, `func(int, string)`},
   404  
   405  		// go.dev/issue/68639
   406  		// parenthesized and pointer type expressions in various positions
   407  		// (note that the syntax parser doesn't record unnecessary parentheses
   408  		// around types, tests that fail because of that are commented out below)
   409  		// - as variable type, not generic
   410  		{`package qa1; type T int; var x T`, `T`, `qa1.T`},
   411  		{`package qa2; type T int; var x (T)`, `T`, `qa2.T`},
   412  		// {`package qa3; type T int; var x (T)`, `(T)`, `qa3.T`}, // parser doesn't record parens
   413  		{`package qa4; type T int; var x ((T))`, `T`, `qa4.T`},
   414  		// {`package qa5; type T int; var x ((T))`, `(T)`, `qa5.T`}, // parser doesn't record parens
   415  		// {`package qa6; type T int; var x ((T))`, `((T))`, `qa6.T`}, // parser doesn't record parens
   416  		{`package qa7; type T int; var x *T`, `T`, `qa7.T`},
   417  		{`package qa8; type T int; var x *T`, `*T`, `*qa8.T`},
   418  		{`package qa9; type T int; var x (*T)`, `T`, `qa9.T`},
   419  		{`package qa10; type T int; var x (*T)`, `*T`, `*qa10.T`},
   420  		{`package qa11; type T int; var x *(T)`, `T`, `qa11.T`},
   421  		// {`package qa12; type T int; var x *(T)`, `(T)`, `qa12.T`}, // parser doesn't record parens
   422  		// {`package qa13; type T int; var x *(T)`, `*(T)`, `*qa13.T`}, // parser doesn't record parens
   423  		// {`package qa14; type T int; var x (*(T))`, `(T)`, `qa14.T`}, // parser doesn't record parens
   424  		// {`package qa15; type T int; var x (*(T))`, `*(T)`, `*qa15.T`}, // parser doesn't record parens
   425  		// {`package qa16; type T int; var x (*(T))`, `(*(T))`, `*qa16.T`}, // parser doesn't record parens
   426  
   427  		// - as ordinary function parameter, not generic
   428  		{`package qb1; type T int; func _(T)`, `T`, `qb1.T`},
   429  		{`package qb2; type T int; func _((T))`, `T`, `qb2.T`},
   430  		// {`package qb3; type T int; func _((T))`, `(T)`, `qb3.T`}, // parser doesn't record parens
   431  		{`package qb4; type T int; func _(((T)))`, `T`, `qb4.T`},
   432  		// {`package qb5; type T int; func _(((T)))`, `(T)`, `qb5.T`}, // parser doesn't record parens
   433  		// {`package qb6; type T int; func _(((T)))`, `((T))`, `qb6.T`}, // parser doesn't record parens
   434  		{`package qb7; type T int; func _(*T)`, `T`, `qb7.T`},
   435  		{`package qb8; type T int; func _(*T)`, `*T`, `*qb8.T`},
   436  		{`package qb9; type T int; func _((*T))`, `T`, `qb9.T`},
   437  		{`package qb10; type T int; func _((*T))`, `*T`, `*qb10.T`},
   438  		{`package qb11; type T int; func _(*(T))`, `T`, `qb11.T`},
   439  		// {`package qb12; type T int; func _(*(T))`, `(T)`, `qb12.T`}, // parser doesn't record parens
   440  		// {`package qb13; type T int; func _(*(T))`, `*(T)`, `*qb13.T`}, // parser doesn't record parens
   441  		// {`package qb14; type T int; func _((*(T)))`, `(T)`, `qb14.T`}, // parser doesn't record parens
   442  		// {`package qb15; type T int; func _((*(T)))`, `*(T)`, `*qb15.T`}, // parser doesn't record parens
   443  		// {`package qb16; type T int; func _((*(T)))`, `(*(T))`, `*qb16.T`}, // parser doesn't record parens
   444  
   445  		// - as method receiver, not generic
   446  		{`package qc1; type T int; func (T) _() {}`, `T`, `qc1.T`},
   447  		{`package qc2; type T int; func ((T)) _() {}`, `T`, `qc2.T`},
   448  		// {`package qc3; type T int; func ((T)) _() {}`, `(T)`, `qc3.T`}, // parser doesn't record parens
   449  		{`package qc4; type T int; func (((T))) _() {}`, `T`, `qc4.T`},
   450  		// {`package qc5; type T int; func (((T))) _() {}`, `(T)`, `qc5.T`}, // parser doesn't record parens
   451  		// {`package qc6; type T int; func (((T))) _() {}`, `((T))`, `qc6.T`}, // parser doesn't record parens
   452  		{`package qc7; type T int; func (*T) _() {}`, `T`, `qc7.T`},
   453  		{`package qc8; type T int; func (*T) _() {}`, `*T`, `*qc8.T`},
   454  		{`package qc9; type T int; func ((*T)) _() {}`, `T`, `qc9.T`},
   455  		{`package qc10; type T int; func ((*T)) _() {}`, `*T`, `*qc10.T`},
   456  		{`package qc11; type T int; func (*(T)) _() {}`, `T`, `qc11.T`},
   457  		// {`package qc12; type T int; func (*(T)) _() {}`, `(T)`, `qc12.T`}, // parser doesn't record parens
   458  		// {`package qc13; type T int; func (*(T)) _() {}`, `*(T)`, `*qc13.T`}, // parser doesn't record parens
   459  		// {`package qc14; type T int; func ((*(T))) _() {}`, `(T)`, `qc14.T`}, // parser doesn't record parens
   460  		// {`package qc15; type T int; func ((*(T))) _() {}`, `*(T)`, `*qc15.T`}, // parser doesn't record parens
   461  		// {`package qc16; type T int; func ((*(T))) _() {}`, `(*(T))`, `*qc16.T`}, // parser doesn't record parens
   462  
   463  		// - as variable type, generic
   464  		{`package qd1; type T[_ any] int; var x T[int]`, `T`, `qd1.T[_ any]`},
   465  		{`package qd2; type T[_ any] int; var x (T[int])`, `T[int]`, `qd2.T[int]`},
   466  		// {`package qd3; type T[_ any] int; var x (T[int])`, `(T[int])`, `qd3.T[int]`}, // parser doesn't record parens
   467  		{`package qd4; type T[_ any] int; var x ((T[int]))`, `T`, `qd4.T[_ any]`},
   468  		// {`package qd5; type T[_ any] int; var x ((T[int]))`, `(T[int])`, `qd5.T[int]`}, // parser doesn't record parens
   469  		// {`package qd6; type T[_ any] int; var x ((T[int]))`, `((T[int]))`, `qd6.T[int]`}, // parser doesn't record parens
   470  		{`package qd7; type T[_ any] int; var x *T[int]`, `T`, `qd7.T[_ any]`},
   471  		{`package qd8; type T[_ any] int; var x *T[int]`, `*T[int]`, `*qd8.T[int]`},
   472  		{`package qd9; type T[_ any] int; var x (*T[int])`, `T`, `qd9.T[_ any]`},
   473  		{`package qd10; type T[_ any] int; var x (*T[int])`, `*T[int]`, `*qd10.T[int]`},
   474  		{`package qd11; type T[_ any] int; var x *(T[int])`, `T[int]`, `qd11.T[int]`},
   475  		// {`package qd12; type T[_ any] int; var x *(T[int])`, `(T[int])`, `qd12.T[int]`}, // parser doesn't record parens
   476  		// {`package qd13; type T[_ any] int; var x *(T[int])`, `*(T[int])`, `*qd13.T[int]`}, // parser doesn't record parens
   477  		// {`package qd14; type T[_ any] int; var x (*(T[int]))`, `(T[int])`, `qd14.T[int]`}, // parser doesn't record parens
   478  		// {`package qd15; type T[_ any] int; var x (*(T[int]))`, `*(T[int])`, `*qd15.T[int]`}, // parser doesn't record parens
   479  		// {`package qd16; type T[_ any] int; var x (*(T[int]))`, `(*(T[int]))`, `*qd16.T[int]`}, // parser doesn't record parens
   480  
   481  		// - as ordinary function parameter, generic
   482  		{`package qe1; type T[_ any] int; func _(T[int])`, `T`, `qe1.T[_ any]`},
   483  		{`package qe2; type T[_ any] int; func _((T[int]))`, `T[int]`, `qe2.T[int]`},
   484  		// {`package qe3; type T[_ any] int; func _((T[int]))`, `(T[int])`, `qe3.T[int]`}, // parser doesn't record parens
   485  		{`package qe4; type T[_ any] int; func _(((T[int])))`, `T`, `qe4.T[_ any]`},
   486  		// {`package qe5; type T[_ any] int; func _(((T[int])))`, `(T[int])`, `qe5.T[int]`}, // parser doesn't record parens
   487  		// {`package qe6; type T[_ any] int; func _(((T[int])))`, `((T[int]))`, `qe6.T[int]`}, // parser doesn't record parens
   488  		{`package qe7; type T[_ any] int; func _(*T[int])`, `T`, `qe7.T[_ any]`},
   489  		{`package qe8; type T[_ any] int; func _(*T[int])`, `*T[int]`, `*qe8.T[int]`},
   490  		{`package qe9; type T[_ any] int; func _((*T[int]))`, `T`, `qe9.T[_ any]`},
   491  		{`package qe10; type T[_ any] int; func _((*T[int]))`, `*T[int]`, `*qe10.T[int]`},
   492  		{`package qe11; type T[_ any] int; func _(*(T[int]))`, `T[int]`, `qe11.T[int]`},
   493  		// {`package qe12; type T[_ any] int; func _(*(T[int]))`, `(T[int])`, `qe12.T[int]`}, // parser doesn't record parens
   494  		// {`package qe13; type T[_ any] int; func _(*(T[int]))`, `*(T[int])`, `*qe13.T[int]`}, // parser doesn't record parens
   495  		// {`package qe14; type T[_ any] int; func _((*(T[int])))`, `(T[int])`, `qe14.T[int]`}, // parser doesn't record parens
   496  		// {`package qe15; type T[_ any] int; func _((*(T[int])))`, `*(T[int])`, `*qe15.T[int]`}, // parser doesn't record parens
   497  		// {`package qe16; type T[_ any] int; func _((*(T[int])))`, `(*(T[int]))`, `*qe16.T[int]`}, // parser doesn't record parens
   498  
   499  		// - as method receiver, generic
   500  		{`package qf1; type T[_ any] int; func (T[_]) _() {}`, `T`, `qf1.T[_ any]`},
   501  		{`package qf2; type T[_ any] int; func ((T[_])) _() {}`, `T[_]`, `qf2.T[_]`},
   502  		// {`package qf3; type T[_ any] int; func ((T[_])) _() {}`, `(T[_])`, `qf3.T[_]`}, // parser doesn't record parens
   503  		{`package qf4; type T[_ any] int; func (((T[_]))) _() {}`, `T`, `qf4.T[_ any]`},
   504  		// {`package qf5; type T[_ any] int; func (((T[_]))) _() {}`, `(T[_])`, `qf5.T[_]`}, // parser doesn't record parens
   505  		// {`package qf6; type T[_ any] int; func (((T[_]))) _() {}`, `((T[_]))`, `qf6.T[_]`}, // parser doesn't record parens
   506  		{`package qf7; type T[_ any] int; func (*T[_]) _() {}`, `T`, `qf7.T[_ any]`},
   507  		{`package qf8; type T[_ any] int; func (*T[_]) _() {}`, `*T[_]`, `*qf8.T[_]`},
   508  		{`package qf9; type T[_ any] int; func ((*T[_])) _() {}`, `T`, `qf9.T[_ any]`},
   509  		{`package qf10; type T[_ any] int; func ((*T[_])) _() {}`, `*T[_]`, `*qf10.T[_]`},
   510  		{`package qf11; type T[_ any] int; func (*(T[_])) _() {}`, `T[_]`, `qf11.T[_]`},
   511  		// {`package qf12; type T[_ any] int; func (*(T[_])) _() {}`, `(T[_])`, `qf12.T[_]`}, // parser doesn't record parens
   512  		// {`package qf13; type T[_ any] int; func (*(T[_])) _() {}`, `*(T[_])`, `*qf13.T[_]`}, // parser doesn't record parens
   513  		// {`package qf14; type T[_ any] int; func ((*(T[_]))) _() {}`, `(T[_])`, `qf14.T[_]`}, // parser doesn't record parens
   514  		// {`package qf15; type T[_ any] int; func ((*(T[_]))) _() {}`, `*(T[_])`, `*qf15.T[_]`}, // parser doesn't record parens
   515  		// {`package qf16; type T[_ any] int; func ((*(T[_]))) _() {}`, `(*(T[_]))`, `*qf16.T[_]`}, // parser doesn't record parens
   516  
   517  		// For historic reasons, type parameters in receiver type expressions
   518  		// are considered both definitions and uses and thus also show up in
   519  		// the Info.Types map (see go.dev/issue/68670).
   520  		{`package t1; type T[_ any] int; func (T[P]) _() {}`, `P`, `P`},
   521  		{`package t2; type T[_, _ any] int; func (T[P, Q]) _() {}`, `P`, `P`},
   522  		{`package t3; type T[_, _ any] int; func (T[P, Q]) _() {}`, `Q`, `Q`},
   523  	}
   524  
   525  	for _, test := range tests {
   526  		info := Info{Types: make(map[syntax.Expr]TypeAndValue)}
   527  		var name string
   528  		if strings.HasPrefix(test.src, brokenPkg) {
   529  			pkg, err := typecheck(test.src, nil, &info)
   530  			if err == nil {
   531  				t.Errorf("package %s: expected to fail but passed", pkg.Name())
   532  				continue
   533  			}
   534  			if pkg != nil {
   535  				name = pkg.Name()
   536  			}
   537  		} else {
   538  			name = mustTypecheck(test.src, nil, &info).Name()
   539  		}
   540  
   541  		// look for expression type
   542  		var typ Type
   543  		for e, tv := range info.Types {
   544  			if ExprString(e) == test.expr {
   545  				typ = tv.Type
   546  				break
   547  			}
   548  		}
   549  		if typ == nil {
   550  			t.Errorf("package %s: no type found for %s", name, test.expr)
   551  			continue
   552  		}
   553  
   554  		// check that type is correct
   555  		if got := typ.String(); got != test.typ {
   556  			t.Errorf("package %s: expr = %s: got %s; want %s", name, test.expr, got, test.typ)
   557  		}
   558  	}
   559  }
   560  
   561  func TestInstanceInfo(t *testing.T) {
   562  	const lib = `package lib
   563  
   564  func F[P any](P) {}
   565  
   566  type T[P any] []P
   567  `
   568  
   569  	type testInst struct {
   570  		name  string
   571  		targs []string
   572  		typ   string
   573  	}
   574  
   575  	var tests = []struct {
   576  		src       string
   577  		instances []testInst // recorded instances in source order
   578  	}{
   579  		{`package p0; func f[T any](T) {}; func _() { f(42) }`,
   580  			[]testInst{{`f`, []string{`int`}, `func(int)`}},
   581  		},
   582  		{`package p1; func f[T any](T) T { panic(0) }; func _() { f('@') }`,
   583  			[]testInst{{`f`, []string{`rune`}, `func(rune) rune`}},
   584  		},
   585  		{`package p2; func f[T any](...T) T { panic(0) }; func _() { f(0i) }`,
   586  			[]testInst{{`f`, []string{`complex128`}, `func(...complex128) complex128`}},
   587  		},
   588  		{`package p3; func f[A, B, C any](A, *B, []C) {}; func _() { f(1.2, new(string), []byte{}) }`,
   589  			[]testInst{{`f`, []string{`float64`, `string`, `byte`}, `func(float64, *string, []byte)`}},
   590  		},
   591  		{`package p4; func f[A, B any](A, *B, ...[]B) {}; func _() { f(1.2, new(byte)) }`,
   592  			[]testInst{{`f`, []string{`float64`, `byte`}, `func(float64, *byte, ...[]byte)`}},
   593  		},
   594  
   595  		{`package s1; func f[T any, P interface{*T}](x T) {}; func _(x string) { f(x) }`,
   596  			[]testInst{{`f`, []string{`string`, `*string`}, `func(x string)`}},
   597  		},
   598  		{`package s2; func f[T any, P interface{*T}](x []T) {}; func _(x []int) { f(x) }`,
   599  			[]testInst{{`f`, []string{`int`, `*int`}, `func(x []int)`}},
   600  		},
   601  		{`package s3; type C[T any] interface{chan<- T}; func f[T any, P C[T]](x []T) {}; func _(x []int) { f(x) }`,
   602  			[]testInst{
   603  				{`C`, []string{`T`}, `interface{chan<- T}`},
   604  				{`f`, []string{`int`, `chan<- int`}, `func(x []int)`},
   605  			},
   606  		},
   607  		{`package s4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]](x []T) {}; func _(x []int) { f(x) }`,
   608  			[]testInst{
   609  				{`C`, []string{`T`}, `interface{chan<- T}`},
   610  				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
   611  				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func(x []int)`},
   612  			},
   613  		},
   614  
   615  		{`package t1; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = f[string] }`,
   616  			[]testInst{{`f`, []string{`string`, `*string`}, `func() string`}},
   617  		},
   618  		{`package t2; func f[T any, P interface{*T}]() T { panic(0) }; func _() { _ = (f[string]) }`,
   619  			[]testInst{{`f`, []string{`string`, `*string`}, `func() string`}},
   620  		},
   621  		{`package t3; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = f[int] }`,
   622  			[]testInst{
   623  				{`C`, []string{`T`}, `interface{chan<- T}`},
   624  				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
   625  				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func() []int`},
   626  			},
   627  		},
   628  		{`package t4; type C[T any] interface{chan<- T}; func f[T any, P C[T], Q C[[]*P]]() []T { return nil }; func _() { _ = (f[int]) }`,
   629  			[]testInst{
   630  				{`C`, []string{`T`}, `interface{chan<- T}`},
   631  				{`C`, []string{`[]*P`}, `interface{chan<- []*P}`},
   632  				{`f`, []string{`int`, `chan<- int`, `chan<- []*chan<- int`}, `func() []int`},
   633  			},
   634  		},
   635  		{`package i0; import "lib"; func _() { lib.F(42) }`,
   636  			[]testInst{{`F`, []string{`int`}, `func(int)`}},
   637  		},
   638  
   639  		{`package duplfunc0; func f[T any](T) {}; func _() { f(42); f("foo"); f[int](3) }`,
   640  			[]testInst{
   641  				{`f`, []string{`int`}, `func(int)`},
   642  				{`f`, []string{`string`}, `func(string)`},
   643  				{`f`, []string{`int`}, `func(int)`},
   644  			},
   645  		},
   646  		{`package duplfunc1; import "lib"; func _() { lib.F(42); lib.F("foo"); lib.F(3) }`,
   647  			[]testInst{
   648  				{`F`, []string{`int`}, `func(int)`},
   649  				{`F`, []string{`string`}, `func(string)`},
   650  				{`F`, []string{`int`}, `func(int)`},
   651  			},
   652  		},
   653  
   654  		{`package type0; type T[P interface{~int}] struct{ x P }; var _ T[int]`,
   655  			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
   656  		},
   657  		{`package type1; type T[P interface{~int}] struct{ x P }; var _ (T[int])`,
   658  			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
   659  		},
   660  		{`package type2; type T[P interface{~int}] struct{ x P }; var _ T[(int)]`,
   661  			[]testInst{{`T`, []string{`int`}, `struct{x int}`}},
   662  		},
   663  		{`package type3; type T[P1 interface{~[]P2}, P2 any] struct{ x P1; y P2 }; var _ T[[]int, int]`,
   664  			[]testInst{{`T`, []string{`[]int`, `int`}, `struct{x []int; y int}`}},
   665  		},
   666  		{`package type4; import "lib"; var _ lib.T[int]`,
   667  			[]testInst{{`T`, []string{`int`}, `[]int`}},
   668  		},
   669  
   670  		{`package dupltype0; type T[P interface{~int}] struct{ x P }; var x T[int]; var y T[int]`,
   671  			[]testInst{
   672  				{`T`, []string{`int`}, `struct{x int}`},
   673  				{`T`, []string{`int`}, `struct{x int}`},
   674  			},
   675  		},
   676  		{`package dupltype1; type T[P ~int] struct{ x P }; func (r *T[Q]) add(z T[Q]) { r.x += z.x }`,
   677  			[]testInst{
   678  				{`T`, []string{`Q`}, `struct{x Q}`},
   679  				{`T`, []string{`Q`}, `struct{x Q}`},
   680  			},
   681  		},
   682  		{`package dupltype1; import "lib"; var x lib.T[int]; var y lib.T[int]; var z lib.T[string]`,
   683  			[]testInst{
   684  				{`T`, []string{`int`}, `[]int`},
   685  				{`T`, []string{`int`}, `[]int`},
   686  				{`T`, []string{`string`}, `[]string`},
   687  			},
   688  		},
   689  		{`package issue51803; func foo[T any](T) {}; func _() { foo[int]( /* leave arg away on purpose */ ) }`,
   690  			[]testInst{{`foo`, []string{`int`}, `func(int)`}},
   691  		},
   692  
   693  		// reverse type inference
   694  		{`package reverse1a; var f func(int) = g; func g[P any](P) {}`,
   695  			[]testInst{{`g`, []string{`int`}, `func(int)`}},
   696  		},
   697  		{`package reverse1b; func f(func(int)) {}; func g[P any](P) {}; func _() { f(g) }`,
   698  			[]testInst{{`g`, []string{`int`}, `func(int)`}},
   699  		},
   700  		{`package reverse2a; var f func(int, string) = g; func g[P, Q any](P, Q) {}`,
   701  			[]testInst{{`g`, []string{`int`, `string`}, `func(int, string)`}},
   702  		},
   703  		{`package reverse2b; func f(func(int, string)) {}; func g[P, Q any](P, Q) {}; func _() { f(g) }`,
   704  			[]testInst{{`g`, []string{`int`, `string`}, `func(int, string)`}},
   705  		},
   706  		{`package reverse2c; func f(func(int, string)) {}; func g[P, Q any](P, Q) {}; func _() { f(g[int]) }`,
   707  			[]testInst{{`g`, []string{`int`, `string`}, `func(int, string)`}},
   708  		},
   709  		// reverse3a not possible (cannot assign to generic function outside of argument passing)
   710  		{`package reverse3b; func f[R any](func(int) R) {}; func g[P any](P) string { return "" }; func _() { f(g) }`,
   711  			[]testInst{
   712  				{`f`, []string{`string`}, `func(func(int) string)`},
   713  				{`g`, []string{`int`}, `func(int) string`},
   714  			},
   715  		},
   716  		{`package reverse4a; var _, _ func([]int, *float32) = g, h; func g[P, Q any]([]P, *Q) {}; func h[R any]([]R, *float32) {}`,
   717  			[]testInst{
   718  				{`g`, []string{`int`, `float32`}, `func([]int, *float32)`},
   719  				{`h`, []string{`int`}, `func([]int, *float32)`},
   720  			},
   721  		},
   722  		{`package reverse4b; func f(_, _ func([]int, *float32)) {}; func g[P, Q any]([]P, *Q) {}; func h[R any]([]R, *float32) {}; func _() { f(g, h) }`,
   723  			[]testInst{
   724  				{`g`, []string{`int`, `float32`}, `func([]int, *float32)`},
   725  				{`h`, []string{`int`}, `func([]int, *float32)`},
   726  			},
   727  		},
   728  		{`package issue59956; func f(func(int), func(string), func(bool)) {}; func g[P any](P) {}; func _() { f(g, g, g) }`,
   729  			[]testInst{
   730  				{`g`, []string{`int`}, `func(int)`},
   731  				{`g`, []string{`string`}, `func(string)`},
   732  				{`g`, []string{`bool`}, `func(bool)`},
   733  			},
   734  		},
   735  	}
   736  
   737  	for _, test := range tests {
   738  		imports := make(testImporter)
   739  		conf := Config{Importer: imports}
   740  		instMap := make(map[*syntax.Name]Instance)
   741  		useMap := make(map[*syntax.Name]Object)
   742  		makePkg := func(src string) *Package {
   743  			pkg, err := typecheck(src, &conf, &Info{Instances: instMap, Uses: useMap})
   744  			// allow error for issue51803
   745  			if err != nil && (pkg == nil || pkg.Name() != "issue51803") {
   746  				t.Fatal(err)
   747  			}
   748  			imports[pkg.Name()] = pkg
   749  			return pkg
   750  		}
   751  		makePkg(lib)
   752  		pkg := makePkg(test.src)
   753  
   754  		t.Run(pkg.Name(), func(t *testing.T) {
   755  			// Sort instances in source order for stability.
   756  			instances := sortedInstances(instMap)
   757  			if got, want := len(instances), len(test.instances); got != want {
   758  				t.Fatalf("got %d instances, want %d", got, want)
   759  			}
   760  
   761  			// Pairwise compare with the expected instances.
   762  			for ii, inst := range instances {
   763  				var targs []Type
   764  				for i := 0; i < inst.Inst.TypeArgs.Len(); i++ {
   765  					targs = append(targs, inst.Inst.TypeArgs.At(i))
   766  				}
   767  				typ := inst.Inst.Type
   768  
   769  				testInst := test.instances[ii]
   770  				if got := inst.Name.Value; got != testInst.name {
   771  					t.Fatalf("got name %s, want %s", got, testInst.name)
   772  				}
   773  
   774  				if len(targs) != len(testInst.targs) {
   775  					t.Fatalf("got %d type arguments; want %d", len(targs), len(testInst.targs))
   776  				}
   777  				for i, targ := range targs {
   778  					if got := targ.String(); got != testInst.targs[i] {
   779  						t.Errorf("type argument %d: got %s; want %s", i, got, testInst.targs[i])
   780  					}
   781  				}
   782  				if got := typ.Underlying().String(); got != testInst.typ {
   783  					t.Errorf("package %s: got %s; want %s", pkg.Name(), got, testInst.typ)
   784  				}
   785  
   786  				// Verify the invariant that re-instantiating the corresponding generic
   787  				// type with TypeArgs results in an identical instance.
   788  				ptype := useMap[inst.Name].Type()
   789  				lister, _ := ptype.(interface{ TypeParams() *TypeParamList })
   790  				if lister == nil || lister.TypeParams().Len() == 0 {
   791  					t.Fatalf("info.Types[%v] = %v, want parameterized type", inst.Name, ptype)
   792  				}
   793  				inst2, err := Instantiate(nil, ptype, targs, true)
   794  				if err != nil {
   795  					t.Errorf("Instantiate(%v, %v) failed: %v", ptype, targs, err)
   796  				}
   797  				if !Identical(inst.Inst.Type, inst2) {
   798  					t.Errorf("%v and %v are not identical", inst.Inst.Type, inst2)
   799  				}
   800  			}
   801  		})
   802  	}
   803  }
   804  
   805  type recordedInstance struct {
   806  	Name *syntax.Name
   807  	Inst Instance
   808  }
   809  
   810  func sortedInstances(m map[*syntax.Name]Instance) (instances []recordedInstance) {
   811  	for id, inst := range m {
   812  		instances = append(instances, recordedInstance{id, inst})
   813  	}
   814  	slices.SortFunc(instances, func(a, b recordedInstance) int {
   815  		return CmpPos(a.Name.Pos(), b.Name.Pos())
   816  	})
   817  	return instances
   818  }
   819  
   820  func TestDefsInfo(t *testing.T) {
   821  	var tests = []struct {
   822  		src  string
   823  		obj  string
   824  		want string
   825  	}{
   826  		{`package p0; const x = 42`, `x`, `const p0.x untyped int`},
   827  		{`package p1; const x int = 42`, `x`, `const p1.x int`},
   828  		{`package p2; var x int`, `x`, `var p2.x int`},
   829  		{`package p3; type x int`, `x`, `type p3.x int`},
   830  		{`package p4; func f()`, `f`, `func p4.f()`},
   831  		{`package p5; func f() int { x, _ := 1, 2; return x }`, `_`, `var _ int`},
   832  
   833  		// Tests using generics.
   834  		{`package g0; type x[T any] int`, `x`, `type g0.x[T any] int`},
   835  		{`package g1; func f[T any]() {}`, `f`, `func g1.f[T any]()`},
   836  		{`package g2; type x[T any] int; func (*x[_]) m() {}`, `m`, `func (*g2.x[_]).m()`},
   837  
   838  		// Type parameters in receiver type expressions are definitions.
   839  		{`package r0; type T[_ any] int; func (T[P]) _() {}`, `P`, `type parameter P any`},
   840  		{`package r1; type T[_, _ any] int; func (T[P, Q]) _() {}`, `P`, `type parameter P any`},
   841  		{`package r2; type T[_, _ any] int; func (T[P, Q]) _() {}`, `Q`, `type parameter Q any`},
   842  	}
   843  
   844  	for _, test := range tests {
   845  		info := Info{
   846  			Defs: make(map[*syntax.Name]Object),
   847  		}
   848  		name := mustTypecheck(test.src, nil, &info).Name()
   849  
   850  		// find object
   851  		var def Object
   852  		for id, obj := range info.Defs {
   853  			if id.Value == test.obj {
   854  				def = obj
   855  				break
   856  			}
   857  		}
   858  		if def == nil {
   859  			t.Errorf("package %s: %s not found", name, test.obj)
   860  			continue
   861  		}
   862  
   863  		if got := def.String(); got != test.want {
   864  			t.Errorf("package %s: got %s; want %s", name, got, test.want)
   865  		}
   866  	}
   867  }
   868  
   869  func TestUsesInfo(t *testing.T) {
   870  	var tests = []struct {
   871  		src  string
   872  		obj  string
   873  		want string
   874  	}{
   875  		{`package p0; func _() { _ = x }; const x = 42`, `x`, `const p0.x untyped int`},
   876  		{`package p1; func _() { _ = x }; const x int = 42`, `x`, `const p1.x int`},
   877  		{`package p2; func _() { _ = x }; var x int`, `x`, `var p2.x int`},
   878  		{`package p3; func _() { type _ x }; type x int`, `x`, `type p3.x int`},
   879  		{`package p4; func _() { _ = f }; func f()`, `f`, `func p4.f()`},
   880  
   881  		// Tests using generics.
   882  		{`package g0; func _[T any]() { _ = x }; const x = 42`, `x`, `const g0.x untyped int`},
   883  		{`package g1; func _[T any](x T) { }`, `T`, `type parameter T any`},
   884  		{`package g2; type N[A any] int; var _ N[int]`, `N`, `type g2.N[A any] int`},
   885  		{`package g3; type N[A any] int; func (N[_]) m() {}`, `N`, `type g3.N[A any] int`},
   886  
   887  		// Uses of fields are instantiated.
   888  		{`package s1; type N[A any] struct{ a A }; var f = N[int]{}.a`, `a`, `field a int`},
   889  		{`package s2; type N[A any] struct{ a A }; func (r N[B]) m(b B) { r.a = b }`, `a`, `field a B`},
   890  
   891  		// Uses of methods are uses of the instantiated method.
   892  		{`package m0; type N[A any] int; func (r N[B]) m() { r.n() }; func (N[C]) n() {}`, `n`, `func (m0.N[B]).n()`},
   893  		{`package m1; type N[A any] int; func (r N[B]) m() { }; var f = N[int].m`, `m`, `func (m1.N[int]).m()`},
   894  		{`package m2; func _[A any](v interface{ m() A }) { v.m() }`, `m`, `func (interface).m() A`},
   895  		{`package m3; func f[A any]() interface{ m() A } { return nil }; var _ = f[int]().m()`, `m`, `func (interface).m() int`},
   896  		{`package m4; type T[A any] func() interface{ m() A }; var x T[int]; var y = x().m`, `m`, `func (interface).m() int`},
   897  		{`package m5; type T[A any] interface{ m() A }; func _[B any](t T[B]) { t.m() }`, `m`, `func (m5.T[B]).m() B`},
   898  		{`package m6; type T[A any] interface{ m() }; func _[B any](t T[B]) { t.m() }`, `m`, `func (m6.T[B]).m()`},
   899  		{`package m7; type T[A any] interface{ m() A }; func _(t T[int]) { t.m() }`, `m`, `func (m7.T[int]).m() int`},
   900  		{`package m8; type T[A any] interface{ m() }; func _(t T[int]) { t.m() }`, `m`, `func (m8.T[int]).m()`},
   901  		{`package m9; type T[A any] interface{ m() }; func _(t T[int]) { _ = t.m }`, `m`, `func (m9.T[int]).m()`},
   902  		{
   903  			`package m10; type E[A any] interface{ m() }; type T[B any] interface{ E[B]; n() }; func _(t T[int]) { t.m() }`,
   904  			`m`,
   905  			`func (m10.E[int]).m()`,
   906  		},
   907  
   908  		// For historic reasons, type parameters in receiver type expressions
   909  		// are considered both definitions and uses (see go.dev/issue/68670).
   910  		{`package r0; type T[_ any] int; func (T[P]) _() {}`, `P`, `type parameter P any`},
   911  		{`package r1; type T[_, _ any] int; func (T[P, Q]) _() {}`, `P`, `type parameter P any`},
   912  		{`package r2; type T[_, _ any] int; func (T[P, Q]) _() {}`, `Q`, `type parameter Q any`},
   913  	}
   914  
   915  	for _, test := range tests {
   916  		info := Info{
   917  			Uses: make(map[*syntax.Name]Object),
   918  		}
   919  		name := mustTypecheck(test.src, nil, &info).Name()
   920  
   921  		// find object
   922  		var use Object
   923  		for id, obj := range info.Uses {
   924  			if id.Value == test.obj {
   925  				if use != nil {
   926  					panic(fmt.Sprintf("multiple uses of %q", id.Value))
   927  				}
   928  				use = obj
   929  			}
   930  		}
   931  		if use == nil {
   932  			t.Errorf("package %s: %s not found", name, test.obj)
   933  			continue
   934  		}
   935  
   936  		if got := use.String(); got != test.want {
   937  			t.Errorf("package %s: got %s; want %s", name, got, test.want)
   938  		}
   939  	}
   940  }
   941  
   942  func TestGenericMethodInfo(t *testing.T) {
   943  	src := `package p
   944  
   945  type N[A any] int
   946  
   947  func (r N[B]) m() { r.m(); r.n() }
   948  
   949  func (r *N[C]) n() {  }
   950  `
   951  	f := mustParse(src)
   952  	info := Info{
   953  		Defs:       make(map[*syntax.Name]Object),
   954  		Uses:       make(map[*syntax.Name]Object),
   955  		Selections: make(map[*syntax.SelectorExpr]*Selection),
   956  	}
   957  	var conf Config
   958  	pkg, err := conf.Check("p", []*syntax.File{f}, &info)
   959  	if err != nil {
   960  		t.Fatal(err)
   961  	}
   962  
   963  	N := pkg.Scope().Lookup("N").Type().(*Named)
   964  
   965  	// Find the generic methods stored on N.
   966  	gm, gn := N.Method(0), N.Method(1)
   967  	if gm.Name() == "n" {
   968  		gm, gn = gn, gm
   969  	}
   970  
   971  	// Collect objects from info.
   972  	var dm, dn *Func   // the declared methods
   973  	var dmm, dmn *Func // the methods used in the body of m
   974  	for _, decl := range f.DeclList {
   975  		fdecl, ok := decl.(*syntax.FuncDecl)
   976  		if !ok {
   977  			continue
   978  		}
   979  		def := info.Defs[fdecl.Name].(*Func)
   980  		switch fdecl.Name.Value {
   981  		case "m":
   982  			dm = def
   983  			syntax.Inspect(fdecl.Body, func(n syntax.Node) bool {
   984  				if call, ok := n.(*syntax.CallExpr); ok {
   985  					sel := call.Fun.(*syntax.SelectorExpr)
   986  					use := info.Uses[sel.Sel].(*Func)
   987  					selection := info.Selections[sel]
   988  					if selection.Kind() != MethodVal {
   989  						t.Errorf("Selection kind = %v, want %v", selection.Kind(), MethodVal)
   990  					}
   991  					if selection.Obj() != use {
   992  						t.Errorf("info.Selections contains %v, want %v", selection.Obj(), use)
   993  					}
   994  					switch sel.Sel.Value {
   995  					case "m":
   996  						dmm = use
   997  					case "n":
   998  						dmn = use
   999  					}
  1000  				}
  1001  				return true
  1002  			})
  1003  		case "n":
  1004  			dn = def
  1005  		}
  1006  	}
  1007  
  1008  	if gm != dm {
  1009  		t.Errorf(`N.Method(...) returns %v for "m", but Info.Defs has %v`, gm, dm)
  1010  	}
  1011  	if gn != dn {
  1012  		t.Errorf(`N.Method(...) returns %v for "m", but Info.Defs has %v`, gm, dm)
  1013  	}
  1014  	if dmm != dm {
  1015  		t.Errorf(`Inside "m", r.m uses %v, want the defined func %v`, dmm, dm)
  1016  	}
  1017  	if dmn == dn {
  1018  		t.Errorf(`Inside "m", r.n uses %v, want a func distinct from %v`, dmm, dm)
  1019  	}
  1020  }
  1021  
  1022  func TestImplicitsInfo(t *testing.T) {
  1023  	testenv.MustHaveGoBuild(t)
  1024  
  1025  	var tests = []struct {
  1026  		src  string
  1027  		want string
  1028  	}{
  1029  		{`package p2; import . "fmt"; var _ = Println`, ""},           // no Implicits entry
  1030  		{`package p0; import local "fmt"; var _ = local.Println`, ""}, // no Implicits entry
  1031  		{`package p1; import "fmt"; var _ = fmt.Println`, "importSpec: package fmt"},
  1032  
  1033  		{`package p3; func f(x interface{}) { switch x.(type) { case int: } }`, ""}, // no Implicits entry
  1034  		{`package p4; func f(x interface{}) { switch t := x.(type) { case int: _ = t } }`, "caseClause: var t int"},
  1035  		{`package p5; func f(x interface{}) { switch t := x.(type) { case int, uint: _ = t } }`, "caseClause: var t interface{}"},
  1036  		{`package p6; func f(x interface{}) { switch t := x.(type) { default: _ = t } }`, "caseClause: var t interface{}"},
  1037  
  1038  		{`package p7; func f(x int) {}`, ""}, // no Implicits entry
  1039  		{`package p8; func f(int) {}`, "field: var  int"},
  1040  		{`package p9; func f() (complex64) { return 0 }`, "field: var  complex64"},
  1041  		{`package p10; type T struct{}; func (*T) f() {}`, "field: var  *p10.T"},
  1042  
  1043  		// Tests using generics.
  1044  		{`package f0; func f[T any](x int) {}`, ""}, // no Implicits entry
  1045  		{`package f1; func f[T any](int) {}`, "field: var  int"},
  1046  		{`package f2; func f[T any](T) {}`, "field: var  T"},
  1047  		{`package f3; func f[T any]() (complex64) { return 0 }`, "field: var  complex64"},
  1048  		{`package f4; func f[T any](t T) (T) { return t }`, "field: var  T"},
  1049  		{`package t0; type T[A any] struct{}; func (*T[_]) f() {}`, "field: var  *t0.T[_]"},
  1050  		{`package t1; type T[A any] struct{}; func _(x interface{}) { switch t := x.(type) { case T[int]: _ = t } }`, "caseClause: var t t1.T[int]"},
  1051  		{`package t2; type T[A any] struct{}; func _[P any](x interface{}) { switch t := x.(type) { case T[P]: _ = t } }`, "caseClause: var t t2.T[P]"},
  1052  		{`package t3; func _[P any](x interface{}) { switch t := x.(type) { case P: _ = t } }`, "caseClause: var t P"},
  1053  	}
  1054  
  1055  	for _, test := range tests {
  1056  		info := Info{
  1057  			Implicits: make(map[syntax.Node]Object),
  1058  		}
  1059  		name := mustTypecheck(test.src, nil, &info).Name()
  1060  
  1061  		// the test cases expect at most one Implicits entry
  1062  		if len(info.Implicits) > 1 {
  1063  			t.Errorf("package %s: %d Implicits entries found", name, len(info.Implicits))
  1064  			continue
  1065  		}
  1066  
  1067  		// extract Implicits entry, if any
  1068  		var got string
  1069  		for n, obj := range info.Implicits {
  1070  			switch x := n.(type) {
  1071  			case *syntax.ImportDecl:
  1072  				got = "importSpec"
  1073  			case *syntax.CaseClause:
  1074  				got = "caseClause"
  1075  			case *syntax.Field:
  1076  				got = "field"
  1077  			default:
  1078  				t.Fatalf("package %s: unexpected %T", name, x)
  1079  			}
  1080  			got += ": " + obj.String()
  1081  		}
  1082  
  1083  		// verify entry
  1084  		if got != test.want {
  1085  			t.Errorf("package %s: got %q; want %q", name, got, test.want)
  1086  		}
  1087  	}
  1088  }
  1089  
  1090  func TestPkgNameOf(t *testing.T) {
  1091  	testenv.MustHaveGoBuild(t)
  1092  
  1093  	const src = `
  1094  package p
  1095  
  1096  import (
  1097  	. "os"
  1098  	_ "io"
  1099  	"math"
  1100  	"path/filepath"
  1101  	snort "sort"
  1102  )
  1103  
  1104  // avoid imported and not used errors
  1105  var (
  1106  	_ = Open // os.Open
  1107  	_ = math.Sin
  1108  	_ = filepath.Abs
  1109  	_ = snort.Ints
  1110  )
  1111  `
  1112  
  1113  	var tests = []struct {
  1114  		path string // path string enclosed in "'s
  1115  		want string
  1116  	}{
  1117  		{`"os"`, "."},
  1118  		{`"io"`, "_"},
  1119  		{`"math"`, "math"},
  1120  		{`"path/filepath"`, "filepath"},
  1121  		{`"sort"`, "snort"},
  1122  	}
  1123  
  1124  	f := mustParse(src)
  1125  	info := Info{
  1126  		Defs:      make(map[*syntax.Name]Object),
  1127  		Implicits: make(map[syntax.Node]Object),
  1128  	}
  1129  	var conf Config
  1130  	conf.Importer = defaultImporter()
  1131  	_, err := conf.Check("p", []*syntax.File{f}, &info)
  1132  	if err != nil {
  1133  		t.Fatal(err)
  1134  	}
  1135  
  1136  	// map import paths to importDecl
  1137  	imports := make(map[string]*syntax.ImportDecl)
  1138  	for _, d := range f.DeclList {
  1139  		if imp, _ := d.(*syntax.ImportDecl); imp != nil {
  1140  			imports[imp.Path.Value] = imp
  1141  		}
  1142  	}
  1143  
  1144  	for _, test := range tests {
  1145  		imp := imports[test.path]
  1146  		if imp == nil {
  1147  			t.Fatalf("invalid test case: import path %s not found", test.path)
  1148  		}
  1149  		got := info.PkgNameOf(imp)
  1150  		if got == nil {
  1151  			t.Fatalf("import %s: package name not found", test.path)
  1152  		}
  1153  		if got.Name() != test.want {
  1154  			t.Errorf("import %s: got %s; want %s", test.path, got.Name(), test.want)
  1155  		}
  1156  	}
  1157  
  1158  	// test non-existing importDecl
  1159  	if got := info.PkgNameOf(new(syntax.ImportDecl)); got != nil {
  1160  		t.Errorf("got %s for non-existing import declaration", got.Name())
  1161  	}
  1162  }
  1163  
  1164  func predString(tv TypeAndValue) string {
  1165  	var buf strings.Builder
  1166  	pred := func(b bool, s string) {
  1167  		if b {
  1168  			if buf.Len() > 0 {
  1169  				buf.WriteString(", ")
  1170  			}
  1171  			buf.WriteString(s)
  1172  		}
  1173  	}
  1174  
  1175  	pred(tv.IsVoid(), "void")
  1176  	pred(tv.IsType(), "type")
  1177  	pred(tv.IsBuiltin(), "builtin")
  1178  	pred(tv.IsValue() && tv.Value != nil, "const")
  1179  	pred(tv.IsValue() && tv.Value == nil, "value")
  1180  	pred(tv.IsNil(), "nil")
  1181  	pred(tv.Addressable(), "addressable")
  1182  	pred(tv.Assignable(), "assignable")
  1183  	pred(tv.HasOk(), "hasOk")
  1184  
  1185  	if buf.Len() == 0 {
  1186  		return "invalid"
  1187  	}
  1188  	return buf.String()
  1189  }
  1190  
  1191  func TestPredicatesInfo(t *testing.T) {
  1192  	testenv.MustHaveGoBuild(t)
  1193  
  1194  	var tests = []struct {
  1195  		src  string
  1196  		expr string
  1197  		pred string
  1198  	}{
  1199  		// void
  1200  		{`package n0; func f() { f() }`, `f()`, `void`},
  1201  
  1202  		// types
  1203  		{`package t0; type _ int`, `int`, `type`},
  1204  		{`package t1; type _ []int`, `[]int`, `type`},
  1205  		{`package t2; type _ func()`, `func()`, `type`},
  1206  		{`package t3; type _ func(int)`, `int`, `type`},
  1207  		{`package t3; type _ func(...int)`, `...int`, `type`},
  1208  
  1209  		// built-ins
  1210  		{`package b0; var _ = len("")`, `len`, `builtin`},
  1211  		{`package b1; var _ = (len)("")`, `(len)`, `builtin`},
  1212  
  1213  		// constants
  1214  		{`package c0; var _ = 42`, `42`, `const`},
  1215  		{`package c1; var _ = "foo" + "bar"`, `"foo" + "bar"`, `const`},
  1216  		{`package c2; const (i = 1i; _ = i)`, `i`, `const`},
  1217  
  1218  		// values
  1219  		{`package v0; var (a, b int; _ = a + b)`, `a + b`, `value`},
  1220  		{`package v1; var _ = &[]int{1}`, `[]int{…}`, `value`},
  1221  		{`package v2; var _ = func(){}`, `func() {}`, `value`},
  1222  		{`package v4; func f() { _ = f }`, `f`, `value`},
  1223  		{`package v3; var _ *int = nil`, `nil`, `value, nil`},
  1224  		{`package v3; var _ *int = (nil)`, `(nil)`, `value, nil`},
  1225  
  1226  		// addressable (and thus assignable) operands
  1227  		{`package a0; var (x int; _ = x)`, `x`, `value, addressable, assignable`},
  1228  		{`package a1; var (p *int; _ = *p)`, `*p`, `value, addressable, assignable`},
  1229  		{`package a2; var (s []int; _ = s[0])`, `s[0]`, `value, addressable, assignable`},
  1230  		{`package a3; var (s struct{f int}; _ = s.f)`, `s.f`, `value, addressable, assignable`},
  1231  		{`package a4; var (a [10]int; _ = a[0])`, `a[0]`, `value, addressable, assignable`},
  1232  		{`package a5; func _(x int) { _ = x }`, `x`, `value, addressable, assignable`},
  1233  		{`package a6; func _()(x int) { _ = x; return }`, `x`, `value, addressable, assignable`},
  1234  		{`package a7; type T int; func (x T) _() { _ = x }`, `x`, `value, addressable, assignable`},
  1235  		// composite literals are not addressable
  1236  
  1237  		// assignable but not addressable values
  1238  		{`package s0; var (m map[int]int; _ = m[0])`, `m[0]`, `value, assignable, hasOk`},
  1239  		{`package s1; var (m map[int]int; _, _ = m[0])`, `m[0]`, `value, assignable, hasOk`},
  1240  
  1241  		// hasOk expressions
  1242  		{`package k0; var (ch chan int; _ = <-ch)`, `<-ch`, `value, hasOk`},
  1243  		{`package k1; var (ch chan int; _, _ = <-ch)`, `<-ch`, `value, hasOk`},
  1244  
  1245  		// missing entries
  1246  		// - package names are collected in the Uses map
  1247  		// - identifiers being declared are collected in the Defs map
  1248  		{`package m0; import "os"; func _() { _ = os.Stdout }`, `os`, `<missing>`},
  1249  		{`package m1; import p "os"; func _() { _ = p.Stdout }`, `p`, `<missing>`},
  1250  		{`package m2; const c = 0`, `c`, `<missing>`},
  1251  		{`package m3; type T int`, `T`, `<missing>`},
  1252  		{`package m4; var v int`, `v`, `<missing>`},
  1253  		{`package m5; func f() {}`, `f`, `<missing>`},
  1254  		{`package m6; func _(x int) {}`, `x`, `<missing>`},
  1255  		{`package m6; func _()(x int) { return }`, `x`, `<missing>`},
  1256  		{`package m6; type T int; func (x T) _() {}`, `x`, `<missing>`},
  1257  	}
  1258  
  1259  	for _, test := range tests {
  1260  		info := Info{Types: make(map[syntax.Expr]TypeAndValue)}
  1261  		name := mustTypecheck(test.src, nil, &info).Name()
  1262  
  1263  		// look for expression predicates
  1264  		got := "<missing>"
  1265  		for e, tv := range info.Types {
  1266  			//println(name, ExprString(e))
  1267  			if ExprString(e) == test.expr {
  1268  				got = predString(tv)
  1269  				break
  1270  			}
  1271  		}
  1272  
  1273  		if got != test.pred {
  1274  			t.Errorf("package %s: got %s; want %s", name, got, test.pred)
  1275  		}
  1276  	}
  1277  }
  1278  
  1279  func TestScopesInfo(t *testing.T) {
  1280  	testenv.MustHaveGoBuild(t)
  1281  
  1282  	var tests = []struct {
  1283  		src    string
  1284  		scopes []string // list of scope descriptors of the form kind:varlist
  1285  	}{
  1286  		{`package p0`, []string{
  1287  			"file:",
  1288  		}},
  1289  		{`package p1; import ( "fmt"; m "math"; _ "os" ); var ( _ = fmt.Println; _ = m.Pi )`, []string{
  1290  			"file:fmt m",
  1291  		}},
  1292  		{`package p2; func _() {}`, []string{
  1293  			"file:", "func:",
  1294  		}},
  1295  		{`package p3; func _(x, y int) {}`, []string{
  1296  			"file:", "func:x y",
  1297  		}},
  1298  		{`package p4; func _(x, y int) { x, z := 1, 2; _ = z }`, []string{
  1299  			"file:", "func:x y z", // redeclaration of x
  1300  		}},
  1301  		{`package p5; func _(x, y int) (u, _ int) { return }`, []string{
  1302  			"file:", "func:u x y",
  1303  		}},
  1304  		{`package p6; func _() { { var x int; _ = x } }`, []string{
  1305  			"file:", "func:", "block:x",
  1306  		}},
  1307  		{`package p7; func _() { if true {} }`, []string{
  1308  			"file:", "func:", "if:", "block:",
  1309  		}},
  1310  		{`package p8; func _() { if x := 0; x < 0 { y := x; _ = y } }`, []string{
  1311  			"file:", "func:", "if:x", "block:y",
  1312  		}},
  1313  		{`package p9; func _() { switch x := 0; x {} }`, []string{
  1314  			"file:", "func:", "switch:x",
  1315  		}},
  1316  		{`package p10; func _() { switch x := 0; x { case 1: y := x; _ = y; default: }}`, []string{
  1317  			"file:", "func:", "switch:x", "case:y", "case:",
  1318  		}},
  1319  		{`package p11; func _(t interface{}) { switch t.(type) {} }`, []string{
  1320  			"file:", "func:t", "switch:",
  1321  		}},
  1322  		{`package p12; func _(t interface{}) { switch t := t; t.(type) {} }`, []string{
  1323  			"file:", "func:t", "switch:t",
  1324  		}},
  1325  		{`package p13; func _(t interface{}) { switch x := t.(type) { case int: _ = x } }`, []string{
  1326  			"file:", "func:t", "switch:", "case:x", // x implicitly declared
  1327  		}},
  1328  		{`package p14; func _() { select{} }`, []string{
  1329  			"file:", "func:",
  1330  		}},
  1331  		{`package p15; func _(c chan int) { select{ case <-c: } }`, []string{
  1332  			"file:", "func:c", "comm:",
  1333  		}},
  1334  		{`package p16; func _(c chan int) { select{ case i := <-c: x := i; _ = x} }`, []string{
  1335  			"file:", "func:c", "comm:i x",
  1336  		}},
  1337  		{`package p17; func _() { for{} }`, []string{
  1338  			"file:", "func:", "for:", "block:",
  1339  		}},
  1340  		{`package p18; func _(n int) { for i := 0; i < n; i++ { _ = i } }`, []string{
  1341  			"file:", "func:n", "for:i", "block:",
  1342  		}},
  1343  		{`package p19; func _(a []int) { for i := range a { _ = i} }`, []string{
  1344  			"file:", "func:a", "for:i", "block:",
  1345  		}},
  1346  		{`package p20; var s int; func _(a []int) { for i, x := range a { s += x; _ = i } }`, []string{
  1347  			"file:", "func:a", "for:i x", "block:",
  1348  		}},
  1349  	}
  1350  
  1351  	for _, test := range tests {
  1352  		info := Info{Scopes: make(map[syntax.Node]*Scope)}
  1353  		name := mustTypecheck(test.src, nil, &info).Name()
  1354  
  1355  		// number of scopes must match
  1356  		if len(info.Scopes) != len(test.scopes) {
  1357  			t.Errorf("package %s: got %d scopes; want %d", name, len(info.Scopes), len(test.scopes))
  1358  		}
  1359  
  1360  		// scope descriptions must match
  1361  		for node, scope := range info.Scopes {
  1362  			var kind string
  1363  			switch node.(type) {
  1364  			case *syntax.File:
  1365  				kind = "file"
  1366  			case *syntax.FuncType:
  1367  				kind = "func"
  1368  			case *syntax.BlockStmt:
  1369  				kind = "block"
  1370  			case *syntax.IfStmt:
  1371  				kind = "if"
  1372  			case *syntax.SwitchStmt:
  1373  				kind = "switch"
  1374  			case *syntax.SelectStmt:
  1375  				kind = "select"
  1376  			case *syntax.CaseClause:
  1377  				kind = "case"
  1378  			case *syntax.CommClause:
  1379  				kind = "comm"
  1380  			case *syntax.ForStmt:
  1381  				kind = "for"
  1382  			default:
  1383  				kind = fmt.Sprintf("%T", node)
  1384  			}
  1385  
  1386  			// look for matching scope description
  1387  			desc := kind + ":" + strings.Join(scope.Names(), " ")
  1388  			if !slices.Contains(test.scopes, desc) {
  1389  				t.Errorf("package %s: no matching scope found for %s", name, desc)
  1390  			}
  1391  		}
  1392  	}
  1393  }
  1394  
  1395  func TestInitOrderInfo(t *testing.T) {
  1396  	var tests = []struct {
  1397  		src   string
  1398  		inits []string
  1399  	}{
  1400  		{`package p0; var (x = 1; y = x)`, []string{
  1401  			"x = 1", "y = x",
  1402  		}},
  1403  		{`package p1; var (a = 1; b = 2; c = 3)`, []string{
  1404  			"a = 1", "b = 2", "c = 3",
  1405  		}},
  1406  		{`package p2; var (a, b, c = 1, 2, 3)`, []string{
  1407  			"a = 1", "b = 2", "c = 3",
  1408  		}},
  1409  		{`package p3; var _ = f(); func f() int { return 1 }`, []string{
  1410  			"_ = f()", // blank var
  1411  		}},
  1412  		{`package p4; var (a = 0; x = y; y = z; z = 0)`, []string{
  1413  			"a = 0", "z = 0", "y = z", "x = y",
  1414  		}},
  1415  		{`package p5; var (a, _ = m[0]; m map[int]string)`, []string{
  1416  			"a, _ = m[0]", // blank var
  1417  		}},
  1418  		{`package p6; var a, b = f(); func f() (_, _ int) { return z, z }; var z = 0`, []string{
  1419  			"z = 0", "a, b = f()",
  1420  		}},
  1421  		{`package p7; var (a = func() int { return b }(); b = 1)`, []string{
  1422  			"b = 1", "a = func() int {…}()",
  1423  		}},
  1424  		{`package p8; var (a, b = func() (_, _ int) { return c, c }(); c = 1)`, []string{
  1425  			"c = 1", "a, b = func() (_, _ int) {…}()",
  1426  		}},
  1427  		{`package p9; type T struct{}; func (T) m() int { _ = y; return 0 }; var x, y = T.m, 1`, []string{
  1428  			"y = 1", "x = T.m",
  1429  		}},
  1430  		{`package p10; var (d = c + b; a = 0; b = 0; c = 0)`, []string{
  1431  			"a = 0", "b = 0", "c = 0", "d = c + b",
  1432  		}},
  1433  		{`package p11; var (a = e + c; b = d + c; c = 0; d = 0; e = 0)`, []string{
  1434  			"c = 0", "d = 0", "b = d + c", "e = 0", "a = e + c",
  1435  		}},
  1436  		// emit an initializer for n:1 initializations only once (not for each node
  1437  		// on the lhs which may appear in different order in the dependency graph)
  1438  		{`package p12; var (a = x; b = 0; x, y = m[0]; m map[int]int)`, []string{
  1439  			"b = 0", "x, y = m[0]", "a = x",
  1440  		}},
  1441  		// test case from spec section on package initialization
  1442  		{`package p12
  1443  
  1444  		var (
  1445  			a = c + b
  1446  			b = f()
  1447  			c = f()
  1448  			d = 3
  1449  		)
  1450  
  1451  		func f() int {
  1452  			d++
  1453  			return d
  1454  		}`, []string{
  1455  			"d = 3", "b = f()", "c = f()", "a = c + b",
  1456  		}},
  1457  		// test case for go.dev/issue/7131
  1458  		{`package main
  1459  
  1460  		var counter int
  1461  		func next() int { counter++; return counter }
  1462  
  1463  		var _ = makeOrder()
  1464  		func makeOrder() []int { return []int{f, b, d, e, c, a} }
  1465  
  1466  		var a       = next()
  1467  		var b, c    = next(), next()
  1468  		var d, e, f = next(), next(), next()
  1469  		`, []string{
  1470  			"a = next()", "b = next()", "c = next()", "d = next()", "e = next()", "f = next()", "_ = makeOrder()",
  1471  		}},
  1472  		// test case for go.dev/issue/10709
  1473  		{`package p13
  1474  
  1475  		var (
  1476  		    v = t.m()
  1477  		    t = makeT(0)
  1478  		)
  1479  
  1480  		type T struct{}
  1481  
  1482  		func (T) m() int { return 0 }
  1483  
  1484  		func makeT(n int) T {
  1485  		    if n > 0 {
  1486  		        return makeT(n-1)
  1487  		    }
  1488  		    return T{}
  1489  		}`, []string{
  1490  			"t = makeT(0)", "v = t.m()",
  1491  		}},
  1492  		// test case for go.dev/issue/10709: same as test before, but variable decls swapped
  1493  		{`package p14
  1494  
  1495  		var (
  1496  		    t = makeT(0)
  1497  		    v = t.m()
  1498  		)
  1499  
  1500  		type T struct{}
  1501  
  1502  		func (T) m() int { return 0 }
  1503  
  1504  		func makeT(n int) T {
  1505  		    if n > 0 {
  1506  		        return makeT(n-1)
  1507  		    }
  1508  		    return T{}
  1509  		}`, []string{
  1510  			"t = makeT(0)", "v = t.m()",
  1511  		}},
  1512  		// another candidate possibly causing problems with go.dev/issue/10709
  1513  		{`package p15
  1514  
  1515  		var y1 = f1()
  1516  
  1517  		func f1() int { return g1() }
  1518  		func g1() int { f1(); return x1 }
  1519  
  1520  		var x1 = 0
  1521  
  1522  		var y2 = f2()
  1523  
  1524  		func f2() int { return g2() }
  1525  		func g2() int { return x2 }
  1526  
  1527  		var x2 = 0`, []string{
  1528  			"x1 = 0", "y1 = f1()", "x2 = 0", "y2 = f2()",
  1529  		}},
  1530  	}
  1531  
  1532  	for _, test := range tests {
  1533  		info := Info{}
  1534  		name := mustTypecheck(test.src, nil, &info).Name()
  1535  
  1536  		// number of initializers must match
  1537  		if len(info.InitOrder) != len(test.inits) {
  1538  			t.Errorf("package %s: got %d initializers; want %d", name, len(info.InitOrder), len(test.inits))
  1539  			continue
  1540  		}
  1541  
  1542  		// initializers must match
  1543  		for i, want := range test.inits {
  1544  			got := info.InitOrder[i].String()
  1545  			if got != want {
  1546  				t.Errorf("package %s, init %d: got %s; want %s", name, i, got, want)
  1547  				continue
  1548  			}
  1549  		}
  1550  	}
  1551  }
  1552  
  1553  func TestMultiFileInitOrder(t *testing.T) {
  1554  	fileA := mustParse(`package main; var a = 1`)
  1555  	fileB := mustParse(`package main; var b = 2`)
  1556  
  1557  	// The initialization order must not depend on the parse
  1558  	// order of the files, only on the presentation order to
  1559  	// the type-checker.
  1560  	for _, test := range []struct {
  1561  		files []*syntax.File
  1562  		want  string
  1563  	}{
  1564  		{[]*syntax.File{fileA, fileB}, "[a = 1 b = 2]"},
  1565  		{[]*syntax.File{fileB, fileA}, "[b = 2 a = 1]"},
  1566  	} {
  1567  		var info Info
  1568  		if _, err := new(Config).Check("main", test.files, &info); err != nil {
  1569  			t.Fatal(err)
  1570  		}
  1571  		if got := fmt.Sprint(info.InitOrder); got != test.want {
  1572  			t.Fatalf("got %s; want %s", got, test.want)
  1573  		}
  1574  	}
  1575  }
  1576  
  1577  func TestFiles(t *testing.T) {
  1578  	var sources = []string{
  1579  		"package p; type T struct{}; func (T) m1() {}",
  1580  		"package p; func (T) m2() {}; var x interface{ m1(); m2() } = T{}",
  1581  		"package p; func (T) m3() {}; var y interface{ m1(); m2(); m3() } = T{}",
  1582  		"package p",
  1583  	}
  1584  
  1585  	var conf Config
  1586  	pkg := NewPackage("p", "p")
  1587  	var info Info
  1588  	check := NewChecker(&conf, pkg, &info)
  1589  
  1590  	for _, src := range sources {
  1591  		if err := check.Files([]*syntax.File{mustParse(src)}); err != nil {
  1592  			t.Error(err)
  1593  		}
  1594  	}
  1595  
  1596  	// check InitOrder is [x y]
  1597  	var vars []string
  1598  	for _, init := range info.InitOrder {
  1599  		for _, v := range init.Lhs {
  1600  			vars = append(vars, v.Name())
  1601  		}
  1602  	}
  1603  	if got, want := fmt.Sprint(vars), "[x y]"; got != want {
  1604  		t.Errorf("InitOrder == %s, want %s", got, want)
  1605  	}
  1606  }
  1607  
  1608  type testImporter map[string]*Package
  1609  
  1610  func (m testImporter) Import(path string) (*Package, error) {
  1611  	if pkg := m[path]; pkg != nil {
  1612  		return pkg, nil
  1613  	}
  1614  	return nil, fmt.Errorf("package %q not found", path)
  1615  }
  1616  
  1617  func TestSelection(t *testing.T) {
  1618  	selections := make(map[*syntax.SelectorExpr]*Selection)
  1619  
  1620  	imports := make(testImporter)
  1621  	conf := Config{Importer: imports}
  1622  	makePkg := func(path, src string) {
  1623  		pkg := mustTypecheck(src, &conf, &Info{Selections: selections})
  1624  		imports[path] = pkg
  1625  	}
  1626  
  1627  	const libSrc = `
  1628  package lib
  1629  type T float64
  1630  const C T = 3
  1631  var V T
  1632  func F() {}
  1633  func (T) M() {}
  1634  `
  1635  	const mainSrc = `
  1636  package main
  1637  import "lib"
  1638  
  1639  type A struct {
  1640  	*B
  1641  	C
  1642  }
  1643  
  1644  type B struct {
  1645  	b int
  1646  }
  1647  
  1648  func (B) f(int)
  1649  
  1650  type C struct {
  1651  	c int
  1652  }
  1653  
  1654  type G[P any] struct {
  1655  	p P
  1656  }
  1657  
  1658  func (G[P]) m(P) {}
  1659  
  1660  var Inst G[int]
  1661  
  1662  func (C) g()
  1663  func (*C) h()
  1664  
  1665  func main() {
  1666  	// qualified identifiers
  1667  	var _ lib.T
  1668  	_ = lib.C
  1669  	_ = lib.F
  1670  	_ = lib.V
  1671  	_ = lib.T.M
  1672  
  1673  	// fields
  1674  	_ = A{}.B
  1675  	_ = new(A).B
  1676  
  1677  	_ = A{}.C
  1678  	_ = new(A).C
  1679  
  1680  	_ = A{}.b
  1681  	_ = new(A).b
  1682  
  1683  	_ = A{}.c
  1684  	_ = new(A).c
  1685  
  1686  	_ = Inst.p
  1687  	_ = G[string]{}.p
  1688  
  1689  	// methods
  1690  	_ = A{}.f
  1691  	_ = new(A).f
  1692  	_ = A{}.g
  1693  	_ = new(A).g
  1694  	_ = new(A).h
  1695  
  1696  	_ = B{}.f
  1697  	_ = new(B).f
  1698  
  1699  	_ = C{}.g
  1700  	_ = new(C).g
  1701  	_ = new(C).h
  1702  	_ = Inst.m
  1703  
  1704  	// method expressions
  1705  	_ = A.f
  1706  	_ = (*A).f
  1707  	_ = B.f
  1708  	_ = (*B).f
  1709  	_ = G[string].m
  1710  }`
  1711  
  1712  	wantOut := map[string][2]string{
  1713  		"lib.T.M": {"method expr (lib.T) M(lib.T)", ".[0]"},
  1714  
  1715  		"A{}.B":    {"field (main.A) B *main.B", ".[0]"},
  1716  		"new(A).B": {"field (*main.A) B *main.B", "->[0]"},
  1717  		"A{}.C":    {"field (main.A) C main.C", ".[1]"},
  1718  		"new(A).C": {"field (*main.A) C main.C", "->[1]"},
  1719  		"A{}.b":    {"field (main.A) b int", "->[0 0]"},
  1720  		"new(A).b": {"field (*main.A) b int", "->[0 0]"},
  1721  		"A{}.c":    {"field (main.A) c int", ".[1 0]"},
  1722  		"new(A).c": {"field (*main.A) c int", "->[1 0]"},
  1723  		"Inst.p":   {"field (main.G[int]) p int", ".[0]"},
  1724  
  1725  		"A{}.f":    {"method (main.A) f(int)", "->[0 0]"},
  1726  		"new(A).f": {"method (*main.A) f(int)", "->[0 0]"},
  1727  		"A{}.g":    {"method (main.A) g()", ".[1 0]"},
  1728  		"new(A).g": {"method (*main.A) g()", "->[1 0]"},
  1729  		"new(A).h": {"method (*main.A) h()", "->[1 1]"}, // TODO(gri) should this report .[1 1] ?
  1730  		"B{}.f":    {"method (main.B) f(int)", ".[0]"},
  1731  		"new(B).f": {"method (*main.B) f(int)", "->[0]"},
  1732  		"C{}.g":    {"method (main.C) g()", ".[0]"},
  1733  		"new(C).g": {"method (*main.C) g()", "->[0]"},
  1734  		"new(C).h": {"method (*main.C) h()", "->[1]"}, // TODO(gri) should this report .[1] ?
  1735  		"Inst.m":   {"method (main.G[int]) m(int)", ".[0]"},
  1736  
  1737  		"A.f":           {"method expr (main.A) f(main.A, int)", "->[0 0]"},
  1738  		"(*A).f":        {"method expr (*main.A) f(*main.A, int)", "->[0 0]"},
  1739  		"B.f":           {"method expr (main.B) f(main.B, int)", ".[0]"},
  1740  		"(*B).f":        {"method expr (*main.B) f(*main.B, int)", "->[0]"},
  1741  		"G[string].m":   {"method expr (main.G[string]) m(main.G[string], string)", ".[0]"},
  1742  		"G[string]{}.p": {"field (main.G[string]) p string", ".[0]"},
  1743  	}
  1744  
  1745  	makePkg("lib", libSrc)
  1746  	makePkg("main", mainSrc)
  1747  
  1748  	for e, sel := range selections {
  1749  		_ = sel.String() // assertion: must not panic
  1750  
  1751  		start := indexFor(mainSrc, syntax.StartPos(e))
  1752  		end := indexFor(mainSrc, syntax.EndPos(e))
  1753  		segment := mainSrc[start:end] // (all SelectorExprs are in main, not lib)
  1754  
  1755  		direct := "."
  1756  		if sel.Indirect() {
  1757  			direct = "->"
  1758  		}
  1759  		got := [2]string{
  1760  			sel.String(),
  1761  			fmt.Sprintf("%s%v", direct, sel.Index()),
  1762  		}
  1763  		want := wantOut[segment]
  1764  		if want != got {
  1765  			t.Errorf("%s: got %q; want %q", segment, got, want)
  1766  		}
  1767  		delete(wantOut, segment)
  1768  
  1769  		// We must explicitly assert properties of the
  1770  		// Signature's receiver since it doesn't participate
  1771  		// in Identical() or String().
  1772  		sig, _ := sel.Type().(*Signature)
  1773  		if sel.Kind() == MethodVal {
  1774  			got := sig.Recv().Type()
  1775  			want := sel.Recv()
  1776  			if !Identical(got, want) {
  1777  				t.Errorf("%s: Recv() = %s, want %s", segment, got, want)
  1778  			}
  1779  		} else if sig != nil && sig.Recv() != nil {
  1780  			t.Errorf("%s: signature has receiver %s", sig, sig.Recv().Type())
  1781  		}
  1782  	}
  1783  	// Assert that all wantOut entries were used exactly once.
  1784  	for segment := range wantOut {
  1785  		t.Errorf("no syntax.Selection found with syntax %q", segment)
  1786  	}
  1787  }
  1788  
  1789  // indexFor returns the index into s corresponding to the position pos.
  1790  func indexFor(s string, pos syntax.Pos) int {
  1791  	i, line := 0, 1 // string index and corresponding line
  1792  	target := int(pos.Line())
  1793  	for line < target && i < len(s) {
  1794  		if s[i] == '\n' {
  1795  			line++
  1796  		}
  1797  		i++
  1798  	}
  1799  	return i + int(pos.Col()-1) // columns are 1-based
  1800  }
  1801  
  1802  func TestIssue8518(t *testing.T) {
  1803  	imports := make(testImporter)
  1804  	conf := Config{
  1805  		Error:    func(err error) { t.Log(err) }, // don't exit after first error
  1806  		Importer: imports,
  1807  	}
  1808  	makePkg := func(path, src string) {
  1809  		imports[path], _ = conf.Check(path, []*syntax.File{mustParse(src)}, nil) // errors logged via conf.Error
  1810  	}
  1811  
  1812  	const libSrc = `
  1813  package a
  1814  import "missing"
  1815  const C1 = foo
  1816  const C2 = missing.C
  1817  `
  1818  
  1819  	const mainSrc = `
  1820  package main
  1821  import "a"
  1822  var _ = a.C1
  1823  var _ = a.C2
  1824  `
  1825  
  1826  	makePkg("a", libSrc)
  1827  	makePkg("main", mainSrc) // don't crash when type-checking this package
  1828  }
  1829  
  1830  func TestIssue59603(t *testing.T) {
  1831  	imports := make(testImporter)
  1832  	conf := Config{
  1833  		Error:    func(err error) { t.Log(err) }, // don't exit after first error
  1834  		Importer: imports,
  1835  	}
  1836  	makePkg := func(path, src string) {
  1837  		imports[path], _ = conf.Check(path, []*syntax.File{mustParse(src)}, nil) // errors logged via conf.Error
  1838  	}
  1839  
  1840  	const libSrc = `
  1841  package a
  1842  const C = foo
  1843  `
  1844  
  1845  	const mainSrc = `
  1846  package main
  1847  import "a"
  1848  const _ = a.C
  1849  `
  1850  
  1851  	makePkg("a", libSrc)
  1852  	makePkg("main", mainSrc) // don't crash when type-checking this package
  1853  }
  1854  
  1855  func TestLookupFieldOrMethodOnNil(t *testing.T) {
  1856  	// LookupFieldOrMethod on a nil type is expected to produce a run-time panic.
  1857  	defer func() {
  1858  		const want = "LookupFieldOrMethod on nil type"
  1859  		p := recover()
  1860  		if s, ok := p.(string); !ok || s != want {
  1861  			t.Fatalf("got %v, want %s", p, want)
  1862  		}
  1863  	}()
  1864  	LookupFieldOrMethod(nil, false, nil, "")
  1865  }
  1866  
  1867  func TestLookupFieldOrMethod(t *testing.T) {
  1868  	// Test cases assume a lookup of the form a.f or x.f, where a stands for an
  1869  	// addressable value, and x for a non-addressable value (even though a variable
  1870  	// for ease of test case writing).
  1871  	var tests = []struct {
  1872  		src      string
  1873  		found    bool
  1874  		index    []int
  1875  		indirect bool
  1876  	}{
  1877  		// field lookups
  1878  		{"var x T; type T struct{}", false, nil, false},
  1879  		{"var x T; type T struct{ f int }", true, []int{0}, false},
  1880  		{"var x T; type T struct{ a, b, f, c int }", true, []int{2}, false},
  1881  
  1882  		// field lookups on a generic type
  1883  		{"var x T[int]; type T[P any] struct{}", false, nil, false},
  1884  		{"var x T[int]; type T[P any] struct{ f P }", true, []int{0}, false},
  1885  		{"var x T[int]; type T[P any] struct{ a, b, f, c P }", true, []int{2}, false},
  1886  
  1887  		// method lookups
  1888  		{"var a T; type T struct{}; func (T) f() {}", true, []int{0}, false},
  1889  		{"var a *T; type T struct{}; func (T) f() {}", true, []int{0}, true},
  1890  		{"var a T; type T struct{}; func (*T) f() {}", true, []int{0}, false},
  1891  		{"var a *T; type T struct{}; func (*T) f() {}", true, []int{0}, true}, // TODO(gri) should this report indirect = false?
  1892  
  1893  		// method lookups on a generic type
  1894  		{"var a T[int]; type T[P any] struct{}; func (T[P]) f() {}", true, []int{0}, false},
  1895  		{"var a *T[int]; type T[P any] struct{}; func (T[P]) f() {}", true, []int{0}, true},
  1896  		{"var a T[int]; type T[P any] struct{}; func (*T[P]) f() {}", true, []int{0}, false},
  1897  		{"var a *T[int]; type T[P any] struct{}; func (*T[P]) f() {}", true, []int{0}, true}, // TODO(gri) should this report indirect = false?
  1898  
  1899  		// collisions
  1900  		{"type ( E1 struct{ f int }; E2 struct{ f int }; x struct{ E1; *E2 })", false, []int{1, 0}, false},
  1901  		{"type ( E1 struct{ f int }; E2 struct{}; x struct{ E1; *E2 }); func (E2) f() {}", false, []int{1, 0}, false},
  1902  
  1903  		// collisions on a generic type
  1904  		{"type ( E1[P any] struct{ f P }; E2[P any] struct{ f P }; x struct{ E1[int]; *E2[int] })", false, []int{1, 0}, false},
  1905  		{"type ( E1[P any] struct{ f P }; E2[P any] struct{}; x struct{ E1[int]; *E2[int] }); func (E2[P]) f() {}", false, []int{1, 0}, false},
  1906  
  1907  		// outside methodset
  1908  		// (*T).f method exists, but value of type T is not addressable
  1909  		{"var x T; type T struct{}; func (*T) f() {}", false, nil, true},
  1910  
  1911  		// outside method set of a generic type
  1912  		{"var x T[int]; type T[P any] struct{}; func (*T[P]) f() {}", false, nil, true},
  1913  
  1914  		// recursive generic types; see go.dev/issue/52715
  1915  		{"var a T[int]; type ( T[P any] struct { *N[P] }; N[P any] struct { *T[P] } ); func (N[P]) f() {}", true, []int{0, 0}, true},
  1916  		{"var a T[int]; type ( T[P any] struct { *N[P] }; N[P any] struct { *T[P] } ); func (T[P]) f() {}", true, []int{0}, false},
  1917  	}
  1918  
  1919  	for _, test := range tests {
  1920  		pkg := mustTypecheck("package p;"+test.src, nil, nil)
  1921  
  1922  		obj := pkg.Scope().Lookup("a")
  1923  		if obj == nil {
  1924  			if obj = pkg.Scope().Lookup("x"); obj == nil {
  1925  				t.Errorf("%s: incorrect test case - no object a or x", test.src)
  1926  				continue
  1927  			}
  1928  		}
  1929  
  1930  		f, index, indirect := LookupFieldOrMethod(obj.Type(), obj.Name() == "a", pkg, "f")
  1931  		if (f != nil) != test.found {
  1932  			if f == nil {
  1933  				t.Errorf("%s: got no object; want one", test.src)
  1934  			} else {
  1935  				t.Errorf("%s: got object = %v; want none", test.src, f)
  1936  			}
  1937  		}
  1938  		if !slices.Equal(index, test.index) {
  1939  			t.Errorf("%s: got index = %v; want %v", test.src, index, test.index)
  1940  		}
  1941  		if indirect != test.indirect {
  1942  			t.Errorf("%s: got indirect = %v; want %v", test.src, indirect, test.indirect)
  1943  		}
  1944  	}
  1945  }
  1946  
  1947  // Test for go.dev/issue/52715
  1948  func TestLookupFieldOrMethod_RecursiveGeneric(t *testing.T) {
  1949  	const src = `
  1950  package pkg
  1951  
  1952  type Tree[T any] struct {
  1953  	*Node[T]
  1954  }
  1955  
  1956  func (*Tree[R]) N(r R) R { return r }
  1957  
  1958  type Node[T any] struct {
  1959  	*Tree[T]
  1960  }
  1961  
  1962  type Instance = *Tree[int]
  1963  `
  1964  
  1965  	f := mustParse(src)
  1966  	pkg := NewPackage("pkg", f.PkgName.Value)
  1967  	if err := NewChecker(nil, pkg, nil).Files([]*syntax.File{f}); err != nil {
  1968  		panic(err)
  1969  	}
  1970  
  1971  	T := pkg.Scope().Lookup("Instance").Type()
  1972  	_, _, _ = LookupFieldOrMethod(T, false, pkg, "M") // verify that LookupFieldOrMethod terminates
  1973  }
  1974  
  1975  // newDefined creates a new defined type named T with the given underlying type.
  1976  func newDefined(underlying Type) *Named {
  1977  	tname := NewTypeName(nopos, nil, "T", nil)
  1978  	return NewNamed(tname, underlying, nil)
  1979  }
  1980  
  1981  func TestConvertibleTo(t *testing.T) {
  1982  	for _, test := range []struct {
  1983  		v, t Type
  1984  		want bool
  1985  	}{
  1986  		{Typ[Int], Typ[Int], true},
  1987  		{Typ[Int], Typ[Float32], true},
  1988  		{Typ[Int], Typ[String], true},
  1989  		{newDefined(Typ[Int]), Typ[Int], true},
  1990  		{newDefined(new(Struct)), new(Struct), true},
  1991  		{newDefined(Typ[Int]), new(Struct), false},
  1992  		{Typ[UntypedInt], Typ[Int], true},
  1993  		{NewSlice(Typ[Int]), NewArray(Typ[Int], 10), true},
  1994  		{NewSlice(Typ[Int]), NewArray(Typ[Uint], 10), false},
  1995  		{NewSlice(Typ[Int]), NewPointer(NewArray(Typ[Int], 10)), true},
  1996  		{NewSlice(Typ[Int]), NewPointer(NewArray(Typ[Uint], 10)), false},
  1997  		// Untyped string values are not permitted by the spec, so the behavior below is undefined.
  1998  		{Typ[UntypedString], Typ[String], true},
  1999  	} {
  2000  		if got := ConvertibleTo(test.v, test.t); got != test.want {
  2001  			t.Errorf("ConvertibleTo(%v, %v) = %t, want %t", test.v, test.t, got, test.want)
  2002  		}
  2003  	}
  2004  }
  2005  
  2006  func TestAssignableTo(t *testing.T) {
  2007  	for _, test := range []struct {
  2008  		v, t Type
  2009  		want bool
  2010  	}{
  2011  		{Typ[Int], Typ[Int], true},
  2012  		{Typ[Int], Typ[Float32], false},
  2013  		{newDefined(Typ[Int]), Typ[Int], false},
  2014  		{newDefined(new(Struct)), new(Struct), true},
  2015  		{Typ[UntypedBool], Typ[Bool], true},
  2016  		{Typ[UntypedString], Typ[Bool], false},
  2017  		// Neither untyped string nor untyped numeric assignments arise during
  2018  		// normal type checking, so the below behavior is technically undefined by
  2019  		// the spec.
  2020  		{Typ[UntypedString], Typ[String], true},
  2021  		{Typ[UntypedInt], Typ[Int], true},
  2022  	} {
  2023  		if got := AssignableTo(test.v, test.t); got != test.want {
  2024  			t.Errorf("AssignableTo(%v, %v) = %t, want %t", test.v, test.t, got, test.want)
  2025  		}
  2026  	}
  2027  }
  2028  
  2029  func TestIdentical(t *testing.T) {
  2030  	// For each test, we compare the types of objects X and Y in the source.
  2031  	tests := []struct {
  2032  		src  string
  2033  		want bool
  2034  	}{
  2035  		// Basic types.
  2036  		{"var X int; var Y int", true},
  2037  		{"var X int; var Y string", false},
  2038  
  2039  		// TODO: add more tests for complex types.
  2040  
  2041  		// Named types.
  2042  		{"type X int; type Y int", false},
  2043  
  2044  		// Aliases.
  2045  		{"type X = int; type Y = int", true},
  2046  
  2047  		// Functions.
  2048  		{`func X(int) string { return "" }; func Y(int) string { return "" }`, true},
  2049  		{`func X() string { return "" }; func Y(int) string { return "" }`, false},
  2050  		{`func X(int) string { return "" }; func Y(int) {}`, false},
  2051  
  2052  		// Generic functions. Type parameters should be considered identical modulo
  2053  		// renaming. See also go.dev/issue/49722.
  2054  		{`func X[P ~int](){}; func Y[Q ~int]() {}`, true},
  2055  		{`func X[P1 any, P2 ~*P1](){}; func Y[Q1 any, Q2 ~*Q1]() {}`, true},
  2056  		{`func X[P1 any, P2 ~[]P1](){}; func Y[Q1 any, Q2 ~*Q1]() {}`, false},
  2057  		{`func X[P ~int](P){}; func Y[Q ~int](Q) {}`, true},
  2058  		{`func X[P ~string](P){}; func Y[Q ~int](Q) {}`, false},
  2059  		{`func X[P ~int]([]P){}; func Y[Q ~int]([]Q) {}`, true},
  2060  	}
  2061  
  2062  	for _, test := range tests {
  2063  		pkg := mustTypecheck("package p;"+test.src, nil, nil)
  2064  		X := pkg.Scope().Lookup("X")
  2065  		Y := pkg.Scope().Lookup("Y")
  2066  		if X == nil || Y == nil {
  2067  			t.Fatal("test must declare both X and Y")
  2068  		}
  2069  		if got := Identical(X.Type(), Y.Type()); got != test.want {
  2070  			t.Errorf("Identical(%s, %s) = %t, want %t", X.Type(), Y.Type(), got, test.want)
  2071  		}
  2072  	}
  2073  }
  2074  
  2075  func TestIdentical_issue15173(t *testing.T) {
  2076  	// Identical should allow nil arguments and be symmetric.
  2077  	for _, test := range []struct {
  2078  		x, y Type
  2079  		want bool
  2080  	}{
  2081  		{Typ[Int], Typ[Int], true},
  2082  		{Typ[Int], nil, false},
  2083  		{nil, Typ[Int], false},
  2084  		{nil, nil, true},
  2085  	} {
  2086  		if got := Identical(test.x, test.y); got != test.want {
  2087  			t.Errorf("Identical(%v, %v) = %t", test.x, test.y, got)
  2088  		}
  2089  	}
  2090  }
  2091  
  2092  func TestIdenticalUnions(t *testing.T) {
  2093  	tname := NewTypeName(nopos, nil, "myInt", nil)
  2094  	myInt := NewNamed(tname, Typ[Int], nil)
  2095  	tmap := map[string]*Term{
  2096  		"int":     NewTerm(false, Typ[Int]),
  2097  		"~int":    NewTerm(true, Typ[Int]),
  2098  		"string":  NewTerm(false, Typ[String]),
  2099  		"~string": NewTerm(true, Typ[String]),
  2100  		"myInt":   NewTerm(false, myInt),
  2101  	}
  2102  	makeUnion := func(s string) *Union {
  2103  		parts := strings.Split(s, "|")
  2104  		var terms []*Term
  2105  		for _, p := range parts {
  2106  			term := tmap[p]
  2107  			if term == nil {
  2108  				t.Fatalf("missing term %q", p)
  2109  			}
  2110  			terms = append(terms, term)
  2111  		}
  2112  		return NewUnion(terms)
  2113  	}
  2114  	for _, test := range []struct {
  2115  		x, y string
  2116  		want bool
  2117  	}{
  2118  		// These tests are just sanity checks. The tests for type sets and
  2119  		// interfaces provide much more test coverage.
  2120  		{"int|~int", "~int", true},
  2121  		{"myInt|~int", "~int", true},
  2122  		{"int|string", "string|int", true},
  2123  		{"int|int|string", "string|int", true},
  2124  		{"myInt|string", "int|string", false},
  2125  	} {
  2126  		x := makeUnion(test.x)
  2127  		y := makeUnion(test.y)
  2128  		if got := Identical(x, y); got != test.want {
  2129  			t.Errorf("Identical(%v, %v) = %t", test.x, test.y, got)
  2130  		}
  2131  	}
  2132  }
  2133  
  2134  func TestIssue61737(t *testing.T) {
  2135  	// This test verifies that it is possible to construct invalid interfaces
  2136  	// containing duplicate methods using the go/types API.
  2137  	//
  2138  	// It must be possible for importers to construct such invalid interfaces.
  2139  	// Previously, this panicked.
  2140  
  2141  	sig1 := NewSignatureType(nil, nil, nil, NewTuple(NewParam(nopos, nil, "", Typ[Int])), nil, false)
  2142  	sig2 := NewSignatureType(nil, nil, nil, NewTuple(NewParam(nopos, nil, "", Typ[String])), nil, false)
  2143  
  2144  	methods := []*Func{
  2145  		NewFunc(nopos, nil, "M", sig1),
  2146  		NewFunc(nopos, nil, "M", sig2),
  2147  	}
  2148  
  2149  	embeddedMethods := []*Func{
  2150  		NewFunc(nopos, nil, "M", sig2),
  2151  	}
  2152  	embedded := NewInterfaceType(embeddedMethods, nil)
  2153  	iface := NewInterfaceType(methods, []Type{embedded})
  2154  	iface.NumMethods() // unlike go/types, there is no Complete() method, so we complete implicitly
  2155  }
  2156  
  2157  func TestNewAlias_Issue65455(t *testing.T) {
  2158  	obj := NewTypeName(nopos, nil, "A", nil)
  2159  	alias := NewAlias(obj, Typ[Int])
  2160  	alias.Underlying() // must not panic
  2161  }
  2162  
  2163  func TestIssue15305(t *testing.T) {
  2164  	const src = "package p; func f() int16; var _ = f(undef)"
  2165  	f := mustParse(src)
  2166  	conf := Config{
  2167  		Error: func(err error) {}, // allow errors
  2168  	}
  2169  	info := &Info{
  2170  		Types: make(map[syntax.Expr]TypeAndValue),
  2171  	}
  2172  	conf.Check("p", []*syntax.File{f}, info) // ignore result
  2173  	for e, tv := range info.Types {
  2174  		if _, ok := e.(*syntax.CallExpr); ok {
  2175  			if tv.Type != Typ[Int16] {
  2176  				t.Errorf("CallExpr has type %v, want int16", tv.Type)
  2177  			}
  2178  			return
  2179  		}
  2180  	}
  2181  	t.Errorf("CallExpr has no type")
  2182  }
  2183  
  2184  // TestCompositeLitTypes verifies that Info.Types registers the correct
  2185  // types for composite literal expressions and composite literal type
  2186  // expressions.
  2187  func TestCompositeLitTypes(t *testing.T) {
  2188  	for i, test := range []struct {
  2189  		lit, typ string
  2190  	}{
  2191  		{`[16]byte{}`, `[16]byte`},
  2192  		{`[...]byte{}`, `[0]byte`},                // test for go.dev/issue/14092
  2193  		{`[...]int{1, 2, 3}`, `[3]int`},           // test for go.dev/issue/14092
  2194  		{`[...]int{90: 0, 98: 1, 2}`, `[100]int`}, // test for go.dev/issue/14092
  2195  		{`[]int{}`, `[]int`},
  2196  		{`map[string]bool{"foo": true}`, `map[string]bool`},
  2197  		{`struct{}{}`, `struct{}`},
  2198  		{`struct{x, y int; z complex128}{}`, `struct{x int; y int; z complex128}`},
  2199  	} {
  2200  		f := mustParse(fmt.Sprintf("package p%d; var _ = %s", i, test.lit))
  2201  		types := make(map[syntax.Expr]TypeAndValue)
  2202  		if _, err := new(Config).Check("p", []*syntax.File{f}, &Info{Types: types}); err != nil {
  2203  			t.Fatalf("%s: %v", test.lit, err)
  2204  		}
  2205  
  2206  		cmptype := func(x syntax.Expr, want string) {
  2207  			tv, ok := types[x]
  2208  			if !ok {
  2209  				t.Errorf("%s: no Types entry found", test.lit)
  2210  				return
  2211  			}
  2212  			if tv.Type == nil {
  2213  				t.Errorf("%s: type is nil", test.lit)
  2214  				return
  2215  			}
  2216  			if got := tv.Type.String(); got != want {
  2217  				t.Errorf("%s: got %v, want %s", test.lit, got, want)
  2218  			}
  2219  		}
  2220  
  2221  		// test type of composite literal expression
  2222  		rhs := f.DeclList[0].(*syntax.VarDecl).Values
  2223  		cmptype(rhs, test.typ)
  2224  
  2225  		// test type of composite literal type expression
  2226  		cmptype(rhs.(*syntax.CompositeLit).Type, test.typ)
  2227  	}
  2228  }
  2229  
  2230  // TestObjectParents verifies that objects have parent scopes or not
  2231  // as specified by the Object interface.
  2232  func TestObjectParents(t *testing.T) {
  2233  	const src = `
  2234  package p
  2235  
  2236  const C = 0
  2237  
  2238  type T1 struct {
  2239  	a, b int
  2240  	T2
  2241  }
  2242  
  2243  type T2 interface {
  2244  	im1()
  2245  	im2()
  2246  }
  2247  
  2248  func (T1) m1() {}
  2249  func (*T1) m2() {}
  2250  
  2251  func f(x int) { y := x; print(y) }
  2252  `
  2253  
  2254  	f := mustParse(src)
  2255  
  2256  	info := &Info{
  2257  		Defs: make(map[*syntax.Name]Object),
  2258  	}
  2259  	if _, err := new(Config).Check("p", []*syntax.File{f}, info); err != nil {
  2260  		t.Fatal(err)
  2261  	}
  2262  
  2263  	for ident, obj := range info.Defs {
  2264  		if obj == nil {
  2265  			// only package names and implicit vars have a nil object
  2266  			// (in this test we only need to handle the package name)
  2267  			if ident.Value != "p" {
  2268  				t.Errorf("%v has nil object", ident)
  2269  			}
  2270  			continue
  2271  		}
  2272  
  2273  		// struct fields, type-associated and interface methods
  2274  		// have no parent scope
  2275  		wantParent := true
  2276  		switch obj := obj.(type) {
  2277  		case *Var:
  2278  			if obj.IsField() {
  2279  				wantParent = false
  2280  			}
  2281  		case *Func:
  2282  			if obj.Type().(*Signature).Recv() != nil { // method
  2283  				wantParent = false
  2284  			}
  2285  		}
  2286  
  2287  		gotParent := obj.Parent() != nil
  2288  		switch {
  2289  		case gotParent && !wantParent:
  2290  			t.Errorf("%v: want no parent, got %s", ident, obj.Parent())
  2291  		case !gotParent && wantParent:
  2292  			t.Errorf("%v: no parent found", ident)
  2293  		}
  2294  	}
  2295  }
  2296  
  2297  // TestFailedImport tests that we don't get follow-on errors
  2298  // elsewhere in a package due to failing to import a package.
  2299  func TestFailedImport(t *testing.T) {
  2300  	testenv.MustHaveGoBuild(t)
  2301  
  2302  	const src = `
  2303  package p
  2304  
  2305  import foo "go/types/thisdirectorymustnotexistotherwisethistestmayfail/foo" // should only see an error here
  2306  
  2307  const c = foo.C
  2308  type T = foo.T
  2309  var v T = c
  2310  func f(x T) T { return foo.F(x) }
  2311  `
  2312  	f := mustParse(src)
  2313  	files := []*syntax.File{f}
  2314  
  2315  	// type-check using all possible importers
  2316  	for _, compiler := range []string{"gc", "gccgo", "source"} {
  2317  		errcount := 0
  2318  		conf := Config{
  2319  			Error: func(err error) {
  2320  				// we should only see the import error
  2321  				if errcount > 0 || !strings.Contains(err.Error(), "could not import") {
  2322  					t.Errorf("for %s importer, got unexpected error: %v", compiler, err)
  2323  				}
  2324  				errcount++
  2325  			},
  2326  			//Importer: importer.For(compiler, nil),
  2327  		}
  2328  
  2329  		info := &Info{
  2330  			Uses: make(map[*syntax.Name]Object),
  2331  		}
  2332  		pkg, _ := conf.Check("p", files, info)
  2333  		if pkg == nil {
  2334  			t.Errorf("for %s importer, type-checking failed to return a package", compiler)
  2335  			continue
  2336  		}
  2337  
  2338  		imports := pkg.Imports()
  2339  		if len(imports) != 1 {
  2340  			t.Errorf("for %s importer, got %d imports, want 1", compiler, len(imports))
  2341  			continue
  2342  		}
  2343  		imp := imports[0]
  2344  		if imp.Name() != "foo" {
  2345  			t.Errorf(`for %s importer, got %q, want "foo"`, compiler, imp.Name())
  2346  			continue
  2347  		}
  2348  
  2349  		// verify that all uses of foo refer to the imported package foo (imp)
  2350  		for ident, obj := range info.Uses {
  2351  			if ident.Value == "foo" {
  2352  				if obj, ok := obj.(*PkgName); ok {
  2353  					if obj.Imported() != imp {
  2354  						t.Errorf("%s resolved to %v; want %v", ident.Value, obj.Imported(), imp)
  2355  					}
  2356  				} else {
  2357  					t.Errorf("%s resolved to %v; want package name", ident.Value, obj)
  2358  				}
  2359  			}
  2360  		}
  2361  	}
  2362  }
  2363  
  2364  func TestInstantiate(t *testing.T) {
  2365  	// eventually we like more tests but this is a start
  2366  	const src = "package p; type T[P any] *T[P]"
  2367  	pkg := mustTypecheck(src, nil, nil)
  2368  
  2369  	// type T should have one type parameter
  2370  	T := pkg.Scope().Lookup("T").Type().(*Named)
  2371  	if n := T.TypeParams().Len(); n != 1 {
  2372  		t.Fatalf("expected 1 type parameter; found %d", n)
  2373  	}
  2374  
  2375  	// instantiation should succeed (no endless recursion)
  2376  	// even with a nil *Checker
  2377  	res, err := Instantiate(nil, T, []Type{Typ[Int]}, false)
  2378  	if err != nil {
  2379  		t.Fatal(err)
  2380  	}
  2381  
  2382  	// instantiated type should point to itself
  2383  	if p := res.Underlying().(*Pointer).Elem(); p != res {
  2384  		t.Fatalf("unexpected result type: %s points to %s", res, p)
  2385  	}
  2386  }
  2387  
  2388  func TestInstantiateConcurrent(t *testing.T) {
  2389  	const src = `package p
  2390  
  2391  type I[P any] interface {
  2392  	m(P)
  2393  	n() P
  2394  }
  2395  
  2396  type J = I[int]
  2397  
  2398  type Nested[P any] *interface{b(P)}
  2399  
  2400  type K = Nested[string]
  2401  `
  2402  	pkg := mustTypecheck(src, nil, nil)
  2403  
  2404  	insts := []*Interface{
  2405  		pkg.Scope().Lookup("J").Type().Underlying().(*Interface),
  2406  		pkg.Scope().Lookup("K").Type().Underlying().(*Pointer).Elem().(*Interface),
  2407  	}
  2408  
  2409  	// Use the interface instances concurrently.
  2410  	for _, inst := range insts {
  2411  		var (
  2412  			counts  [2]int      // method counts
  2413  			methods [2][]string // method strings
  2414  		)
  2415  		var wg sync.WaitGroup
  2416  		for i := 0; i < 2; i++ {
  2417  			i := i
  2418  			wg.Add(1)
  2419  			go func() {
  2420  				defer wg.Done()
  2421  
  2422  				counts[i] = inst.NumMethods()
  2423  				for mi := 0; mi < counts[i]; mi++ {
  2424  					methods[i] = append(methods[i], inst.Method(mi).String())
  2425  				}
  2426  			}()
  2427  		}
  2428  		wg.Wait()
  2429  
  2430  		if counts[0] != counts[1] {
  2431  			t.Errorf("mismatching method counts for %s: %d vs %d", inst, counts[0], counts[1])
  2432  			continue
  2433  		}
  2434  		for i := 0; i < counts[0]; i++ {
  2435  			if m0, m1 := methods[0][i], methods[1][i]; m0 != m1 {
  2436  				t.Errorf("mismatching methods for %s: %s vs %s", inst, m0, m1)
  2437  			}
  2438  		}
  2439  	}
  2440  }
  2441  
  2442  func TestInstantiateErrors(t *testing.T) {
  2443  	tests := []struct {
  2444  		src    string // by convention, T must be the type being instantiated
  2445  		targs  []Type
  2446  		wantAt int // -1 indicates no error
  2447  	}{
  2448  		{"type T[P interface{~string}] int", []Type{Typ[Int]}, 0},
  2449  		{"type T[P1 interface{int}, P2 interface{~string}] int", []Type{Typ[Int], Typ[Int]}, 1},
  2450  		{"type T[P1 any, P2 interface{~[]P1}] int", []Type{Typ[Int], NewSlice(Typ[String])}, 1},
  2451  		{"type T[P1 interface{~[]P2}, P2 any] int", []Type{NewSlice(Typ[String]), Typ[Int]}, 0},
  2452  	}
  2453  
  2454  	for _, test := range tests {
  2455  		src := "package p; " + test.src
  2456  		pkg := mustTypecheck(src, nil, nil)
  2457  
  2458  		T := pkg.Scope().Lookup("T").Type().(*Named)
  2459  
  2460  		_, err := Instantiate(nil, T, test.targs, true)
  2461  		if err == nil {
  2462  			t.Fatalf("Instantiate(%v, %v) returned nil error, want non-nil", T, test.targs)
  2463  		}
  2464  
  2465  		var argErr *ArgumentError
  2466  		if !errors.As(err, &argErr) {
  2467  			t.Fatalf("Instantiate(%v, %v): error is not an *ArgumentError", T, test.targs)
  2468  		}
  2469  
  2470  		if argErr.Index != test.wantAt {
  2471  			t.Errorf("Instantiate(%v, %v): error at index %d, want index %d", T, test.targs, argErr.Index, test.wantAt)
  2472  		}
  2473  	}
  2474  }
  2475  
  2476  func TestArgumentErrorUnwrapping(t *testing.T) {
  2477  	var err error = &ArgumentError{
  2478  		Index: 1,
  2479  		Err:   Error{Msg: "test"},
  2480  	}
  2481  	var e Error
  2482  	if !errors.As(err, &e) {
  2483  		t.Fatalf("error %v does not wrap types.Error", err)
  2484  	}
  2485  	if e.Msg != "test" {
  2486  		t.Errorf("e.Msg = %q, want %q", e.Msg, "test")
  2487  	}
  2488  }
  2489  
  2490  func TestInstanceIdentity(t *testing.T) {
  2491  	imports := make(testImporter)
  2492  	conf := Config{Importer: imports}
  2493  	makePkg := func(src string) {
  2494  		f := mustParse(src)
  2495  		name := f.PkgName.Value
  2496  		pkg, err := conf.Check(name, []*syntax.File{f}, nil)
  2497  		if err != nil {
  2498  			t.Fatal(err)
  2499  		}
  2500  		imports[name] = pkg
  2501  	}
  2502  	makePkg(`package lib; type T[P any] struct{}`)
  2503  	makePkg(`package a; import "lib"; var A lib.T[int]`)
  2504  	makePkg(`package b; import "lib"; var B lib.T[int]`)
  2505  	a := imports["a"].Scope().Lookup("A")
  2506  	b := imports["b"].Scope().Lookup("B")
  2507  	if !Identical(a.Type(), b.Type()) {
  2508  		t.Errorf("mismatching types: a.A: %s, b.B: %s", a.Type(), b.Type())
  2509  	}
  2510  }
  2511  
  2512  // TestInstantiatedObjects verifies properties of instantiated objects.
  2513  func TestInstantiatedObjects(t *testing.T) {
  2514  	const src = `
  2515  package p
  2516  
  2517  type T[P any] struct {
  2518  	field P
  2519  }
  2520  
  2521  func (recv *T[Q]) concreteMethod(mParam Q) (mResult Q) { return }
  2522  
  2523  type FT[P any] func(ftParam P) (ftResult P)
  2524  
  2525  func F[P any](fParam P) (fResult P){ return }
  2526  
  2527  type I[P any] interface {
  2528  	interfaceMethod(P)
  2529  }
  2530  
  2531  type R[P any] T[P]
  2532  
  2533  func (R[P]) m() {} // having a method triggers expansion of R
  2534  
  2535  var (
  2536  	t T[int]
  2537  	ft FT[int]
  2538  	f = F[int]
  2539  	i I[int]
  2540  )
  2541  
  2542  func fn() {
  2543  	var r R[int]
  2544  	_ = r
  2545  }
  2546  `
  2547  	info := &Info{
  2548  		Defs: make(map[*syntax.Name]Object),
  2549  	}
  2550  	f := mustParse(src)
  2551  	conf := Config{}
  2552  	pkg, err := conf.Check(f.PkgName.Value, []*syntax.File{f}, info)
  2553  	if err != nil {
  2554  		t.Fatal(err)
  2555  	}
  2556  
  2557  	lookup := func(name string) Type { return pkg.Scope().Lookup(name).Type() }
  2558  	fnScope := pkg.Scope().Lookup("fn").(*Func).Scope()
  2559  
  2560  	tests := []struct {
  2561  		name string
  2562  		obj  Object
  2563  	}{
  2564  		// Struct fields
  2565  		{"field", lookup("t").Underlying().(*Struct).Field(0)},
  2566  		{"field", fnScope.Lookup("r").Type().Underlying().(*Struct).Field(0)},
  2567  
  2568  		// Methods and method fields
  2569  		{"concreteMethod", lookup("t").(*Named).Method(0)},
  2570  		{"recv", lookup("t").(*Named).Method(0).Type().(*Signature).Recv()},
  2571  		{"mParam", lookup("t").(*Named).Method(0).Type().(*Signature).Params().At(0)},
  2572  		{"mResult", lookup("t").(*Named).Method(0).Type().(*Signature).Results().At(0)},
  2573  
  2574  		// Interface methods
  2575  		{"interfaceMethod", lookup("i").Underlying().(*Interface).Method(0)},
  2576  
  2577  		// Function type fields
  2578  		{"ftParam", lookup("ft").Underlying().(*Signature).Params().At(0)},
  2579  		{"ftResult", lookup("ft").Underlying().(*Signature).Results().At(0)},
  2580  
  2581  		// Function fields
  2582  		{"fParam", lookup("f").(*Signature).Params().At(0)},
  2583  		{"fResult", lookup("f").(*Signature).Results().At(0)},
  2584  	}
  2585  
  2586  	// Collect all identifiers by name.
  2587  	idents := make(map[string][]*syntax.Name)
  2588  	syntax.Inspect(f, func(n syntax.Node) bool {
  2589  		if id, ok := n.(*syntax.Name); ok {
  2590  			idents[id.Value] = append(idents[id.Value], id)
  2591  		}
  2592  		return true
  2593  	})
  2594  
  2595  	for _, test := range tests {
  2596  		test := test
  2597  		t.Run(test.name, func(t *testing.T) {
  2598  			if got := len(idents[test.name]); got != 1 {
  2599  				t.Fatalf("found %d identifiers named %s, want 1", got, test.name)
  2600  			}
  2601  			ident := idents[test.name][0]
  2602  			def := info.Defs[ident]
  2603  			if def == test.obj {
  2604  				t.Fatalf("info.Defs[%s] contains the test object", test.name)
  2605  			}
  2606  			if orig := originObject(test.obj); def != orig {
  2607  				t.Errorf("info.Defs[%s] does not match obj.Origin()", test.name)
  2608  			}
  2609  			if def.Pkg() != test.obj.Pkg() {
  2610  				t.Errorf("Pkg() = %v, want %v", def.Pkg(), test.obj.Pkg())
  2611  			}
  2612  			if def.Name() != test.obj.Name() {
  2613  				t.Errorf("Name() = %v, want %v", def.Name(), test.obj.Name())
  2614  			}
  2615  			if def.Pos() != test.obj.Pos() {
  2616  				t.Errorf("Pos() = %v, want %v", def.Pos(), test.obj.Pos())
  2617  			}
  2618  			if def.Parent() != test.obj.Parent() {
  2619  				t.Fatalf("Parent() = %v, want %v", def.Parent(), test.obj.Parent())
  2620  			}
  2621  			if def.Exported() != test.obj.Exported() {
  2622  				t.Fatalf("Exported() = %v, want %v", def.Exported(), test.obj.Exported())
  2623  			}
  2624  			if def.Id() != test.obj.Id() {
  2625  				t.Fatalf("Id() = %v, want %v", def.Id(), test.obj.Id())
  2626  			}
  2627  			// String and Type are expected to differ.
  2628  		})
  2629  	}
  2630  }
  2631  
  2632  func originObject(obj Object) Object {
  2633  	switch obj := obj.(type) {
  2634  	case *Var:
  2635  		return obj.Origin()
  2636  	case *Func:
  2637  		return obj.Origin()
  2638  	}
  2639  	return obj
  2640  }
  2641  
  2642  func TestImplements(t *testing.T) {
  2643  	const src = `
  2644  package p
  2645  
  2646  type EmptyIface interface{}
  2647  
  2648  type I interface {
  2649  	m()
  2650  }
  2651  
  2652  type C interface {
  2653  	m()
  2654  	~int
  2655  }
  2656  
  2657  type Integer interface{
  2658  	int8 | int16 | int32 | int64
  2659  }
  2660  
  2661  type EmptyTypeSet interface{
  2662  	Integer
  2663  	~string
  2664  }
  2665  
  2666  type N1 int
  2667  func (N1) m() {}
  2668  
  2669  type N2 int
  2670  func (*N2) m() {}
  2671  
  2672  type N3 int
  2673  func (N3) m(int) {}
  2674  
  2675  type N4 string
  2676  func (N4) m()
  2677  
  2678  type Bad Bad // invalid type
  2679  `
  2680  
  2681  	f := mustParse(src)
  2682  	conf := Config{Error: func(error) {}}
  2683  	pkg, _ := conf.Check(f.PkgName.Value, []*syntax.File{f}, nil)
  2684  
  2685  	lookup := func(tname string) Type { return pkg.Scope().Lookup(tname).Type() }
  2686  	var (
  2687  		EmptyIface   = lookup("EmptyIface").Underlying().(*Interface)
  2688  		I            = lookup("I").(*Named)
  2689  		II           = I.Underlying().(*Interface)
  2690  		C            = lookup("C").(*Named)
  2691  		CI           = C.Underlying().(*Interface)
  2692  		Integer      = lookup("Integer").Underlying().(*Interface)
  2693  		EmptyTypeSet = lookup("EmptyTypeSet").Underlying().(*Interface)
  2694  		N1           = lookup("N1")
  2695  		N1p          = NewPointer(N1)
  2696  		N2           = lookup("N2")
  2697  		N2p          = NewPointer(N2)
  2698  		N3           = lookup("N3")
  2699  		N4           = lookup("N4")
  2700  		Bad          = lookup("Bad")
  2701  	)
  2702  
  2703  	tests := []struct {
  2704  		V    Type
  2705  		T    *Interface
  2706  		want bool
  2707  	}{
  2708  		{I, II, true},
  2709  		{I, CI, false},
  2710  		{C, II, true},
  2711  		{C, CI, true},
  2712  		{Typ[Int8], Integer, true},
  2713  		{Typ[Int64], Integer, true},
  2714  		{Typ[String], Integer, false},
  2715  		{EmptyTypeSet, II, true},
  2716  		{EmptyTypeSet, EmptyTypeSet, true},
  2717  		{Typ[Int], EmptyTypeSet, false},
  2718  		{N1, II, true},
  2719  		{N1, CI, true},
  2720  		{N1p, II, true},
  2721  		{N1p, CI, false},
  2722  		{N2, II, false},
  2723  		{N2, CI, false},
  2724  		{N2p, II, true},
  2725  		{N2p, CI, false},
  2726  		{N3, II, false},
  2727  		{N3, CI, false},
  2728  		{N4, II, true},
  2729  		{N4, CI, false},
  2730  		{Bad, II, false},
  2731  		{Bad, CI, false},
  2732  		{Bad, EmptyIface, true},
  2733  	}
  2734  
  2735  	for _, test := range tests {
  2736  		if got := Implements(test.V, test.T); got != test.want {
  2737  			t.Errorf("Implements(%s, %s) = %t, want %t", test.V, test.T, got, test.want)
  2738  		}
  2739  
  2740  		// The type assertion x.(T) is valid if T is an interface or if T implements the type of x.
  2741  		// The assertion is never valid if T is a bad type.
  2742  		V := test.T
  2743  		T := test.V
  2744  		want := false
  2745  		if _, ok := T.Underlying().(*Interface); (ok || Implements(T, V)) && T != Bad {
  2746  			want = true
  2747  		}
  2748  		if got := AssertableTo(V, T); got != want {
  2749  			t.Errorf("AssertableTo(%s, %s) = %t, want %t", V, T, got, want)
  2750  		}
  2751  	}
  2752  }
  2753  
  2754  func TestMissingMethodAlternative(t *testing.T) {
  2755  	const src = `
  2756  package p
  2757  type T interface {
  2758  	m()
  2759  }
  2760  
  2761  type V0 struct{}
  2762  func (V0) m() {}
  2763  
  2764  type V1 struct{}
  2765  
  2766  type V2 struct{}
  2767  func (V2) m() int
  2768  
  2769  type V3 struct{}
  2770  func (*V3) m()
  2771  
  2772  type V4 struct{}
  2773  func (V4) M()
  2774  `
  2775  
  2776  	pkg := mustTypecheck(src, nil, nil)
  2777  
  2778  	T := pkg.Scope().Lookup("T").Type().Underlying().(*Interface)
  2779  	lookup := func(name string) (*Func, bool) {
  2780  		return MissingMethod(pkg.Scope().Lookup(name).Type(), T, true)
  2781  	}
  2782  
  2783  	// V0 has method m with correct signature. Should not report wrongType.
  2784  	method, wrongType := lookup("V0")
  2785  	if method != nil || wrongType {
  2786  		t.Fatalf("V0: got method = %v, wrongType = %v", method, wrongType)
  2787  	}
  2788  
  2789  	checkMissingMethod := func(tname string, reportWrongType bool) {
  2790  		method, wrongType := lookup(tname)
  2791  		if method == nil || method.Name() != "m" || wrongType != reportWrongType {
  2792  			t.Fatalf("%s: got method = %v, wrongType = %v", tname, method, wrongType)
  2793  		}
  2794  	}
  2795  
  2796  	// V1 has no method m. Should not report wrongType.
  2797  	checkMissingMethod("V1", false)
  2798  
  2799  	// V2 has method m with wrong signature type (ignoring receiver). Should report wrongType.
  2800  	checkMissingMethod("V2", true)
  2801  
  2802  	// V3 has no method m but it exists on *V3. Should report wrongType.
  2803  	checkMissingMethod("V3", true)
  2804  
  2805  	// V4 has no method m but has M. Should not report wrongType.
  2806  	checkMissingMethod("V4", false)
  2807  }
  2808  
  2809  func TestErrorURL(t *testing.T) {
  2810  	conf := Config{ErrorURL: " [go.dev/e/%s]"}
  2811  
  2812  	// test case for a one-line error
  2813  	const src1 = `
  2814  package p
  2815  var _ T
  2816  `
  2817  	_, err := typecheck(src1, &conf, nil)
  2818  	if err == nil || !strings.HasSuffix(err.Error(), " [go.dev/e/UndeclaredName]") {
  2819  		t.Errorf("src1: unexpected error: got %v", err)
  2820  	}
  2821  
  2822  	// test case for a multi-line error
  2823  	const src2 = `
  2824  package p
  2825  func f() int { return 0 }
  2826  var _ = f(1, 2)
  2827  `
  2828  	_, err = typecheck(src2, &conf, nil)
  2829  	if err == nil || !strings.Contains(err.Error(), " [go.dev/e/WrongArgCount]\n") {
  2830  		t.Errorf("src1: unexpected error: got %v", err)
  2831  	}
  2832  }
  2833  
  2834  func TestModuleVersion(t *testing.T) {
  2835  	// version go1.dd must be able to typecheck go1.dd.0, go1.dd.1, etc.
  2836  	goversion := fmt.Sprintf("go1.%d", goversion.Version)
  2837  	for _, v := range []string{
  2838  		goversion,
  2839  		goversion + ".0",
  2840  		goversion + ".1",
  2841  		goversion + ".rc",
  2842  	} {
  2843  		conf := Config{GoVersion: v}
  2844  		pkg := mustTypecheck("package p", &conf, nil)
  2845  		if pkg.GoVersion() != conf.GoVersion {
  2846  			t.Errorf("got %s; want %s", pkg.GoVersion(), conf.GoVersion)
  2847  		}
  2848  	}
  2849  }
  2850  
  2851  func TestFileVersions(t *testing.T) {
  2852  	for _, test := range []struct {
  2853  		goVersion   string
  2854  		fileVersion string
  2855  		wantVersion string
  2856  	}{
  2857  		{"", "", ""},                    // no versions specified
  2858  		{"go1.19", "", "go1.19"},        // module version specified
  2859  		{"", "go1.20", "go1.21"},        // file version specified below minimum of 1.21
  2860  		{"go1", "", "go1"},              // no file version specified
  2861  		{"go1", "goo1.22", "go1"},       // invalid file version specified
  2862  		{"go1", "go1.19", "go1.21"},     // file version specified below minimum of 1.21
  2863  		{"go1", "go1.20", "go1.21"},     // file version specified below minimum of 1.21
  2864  		{"go1", "go1.21", "go1.21"},     // file version specified at 1.21
  2865  		{"go1", "go1.22", "go1.22"},     // file version specified above 1.21
  2866  		{"go1.19", "", "go1.19"},        // no file version specified
  2867  		{"go1.19", "goo1.22", "go1.19"}, // invalid file version specified
  2868  		{"go1.19", "go1.20", "go1.21"},  // file version specified below minimum of 1.21
  2869  		{"go1.19", "go1.21", "go1.21"},  // file version specified at 1.21
  2870  		{"go1.19", "go1.22", "go1.22"},  // file version specified above 1.21
  2871  		{"go1.20", "", "go1.20"},        // no file version specified
  2872  		{"go1.20", "goo1.22", "go1.20"}, // invalid file version specified
  2873  		{"go1.20", "go1.19", "go1.21"},  // file version specified below minimum of 1.21
  2874  		{"go1.20", "go1.20", "go1.21"},  // file version specified below minimum of 1.21
  2875  		{"go1.20", "go1.21", "go1.21"},  // file version specified at 1.21
  2876  		{"go1.20", "go1.22", "go1.22"},  // file version specified above 1.21
  2877  		{"go1.21", "", "go1.21"},        // no file version specified
  2878  		{"go1.21", "goo1.22", "go1.21"}, // invalid file version specified
  2879  		{"go1.21", "go1.19", "go1.21"},  // file version specified below minimum of 1.21
  2880  		{"go1.21", "go1.20", "go1.21"},  // file version specified below minimum of 1.21
  2881  		{"go1.21", "go1.21", "go1.21"},  // file version specified at 1.21
  2882  		{"go1.21", "go1.22", "go1.22"},  // file version specified above 1.21
  2883  		{"go1.22", "", "go1.22"},        // no file version specified
  2884  		{"go1.22", "goo1.22", "go1.22"}, // invalid file version specified
  2885  		{"go1.22", "go1.19", "go1.21"},  // file version specified below minimum of 1.21
  2886  		{"go1.22", "go1.20", "go1.21"},  // file version specified below minimum of 1.21
  2887  		{"go1.22", "go1.21", "go1.21"},  // file version specified at 1.21
  2888  		{"go1.22", "go1.22", "go1.22"},  // file version specified above 1.21
  2889  
  2890  		// versions containing release numbers
  2891  		// (file versions containing release numbers are considered invalid)
  2892  		{"go1.19.0", "", "go1.19.0"},         // no file version specified
  2893  		{"go1.20.1", "go1.19.1", "go1.20.1"}, // invalid file version
  2894  		{"go1.20.1", "go1.21.1", "go1.20.1"}, // invalid file version
  2895  		{"go1.21.1", "go1.19.1", "go1.21.1"}, // invalid file version
  2896  		{"go1.21.1", "go1.21.1", "go1.21.1"}, // invalid file version
  2897  		{"go1.22.1", "go1.19.1", "go1.22.1"}, // invalid file version
  2898  		{"go1.22.1", "go1.21.1", "go1.22.1"}, // invalid file version
  2899  	} {
  2900  		var src string
  2901  		if test.fileVersion != "" {
  2902  			src = "//go:build " + test.fileVersion + "\n"
  2903  		}
  2904  		src += "package p"
  2905  
  2906  		conf := Config{GoVersion: test.goVersion}
  2907  		versions := make(map[*syntax.PosBase]string)
  2908  		var info Info
  2909  		info.FileVersions = versions
  2910  		mustTypecheck(src, &conf, &info)
  2911  
  2912  		n := 0
  2913  		for _, v := range info.FileVersions {
  2914  			want := test.wantVersion
  2915  			if v != want {
  2916  				t.Errorf("%q: unexpected file version: got %v, want %v", src, v, want)
  2917  			}
  2918  			n++
  2919  		}
  2920  		if n != 1 {
  2921  			t.Errorf("%q: incorrect number of map entries: got %d", src, n)
  2922  		}
  2923  	}
  2924  }
  2925  
  2926  // TestTooNew ensures that "too new" errors are emitted when the file
  2927  // or module is tagged with a newer version of Go than this go/types.
  2928  func TestTooNew(t *testing.T) {
  2929  	for _, test := range []struct {
  2930  		goVersion   string // package's Go version (as if derived from go.mod file)
  2931  		fileVersion string // file's Go version (becomes a build tag)
  2932  		wantErr     string // expected substring of concatenation of all errors
  2933  	}{
  2934  		{"go1.98", "", "package requires newer Go version go1.98"},
  2935  		{"", "go1.99", "p:2:9: file requires newer Go version go1.99"},
  2936  		{"go1.98", "go1.99", "package requires newer Go version go1.98"}, // (two
  2937  		{"go1.98", "go1.99", "file requires newer Go version go1.99"},    // errors)
  2938  	} {
  2939  		var src string
  2940  		if test.fileVersion != "" {
  2941  			src = "//go:build " + test.fileVersion + "\n"
  2942  		}
  2943  		src += "package p; func f()"
  2944  
  2945  		var errs []error
  2946  		conf := Config{
  2947  			GoVersion: test.goVersion,
  2948  			Error:     func(err error) { errs = append(errs, err) },
  2949  		}
  2950  		info := &Info{Defs: make(map[*syntax.Name]Object)}
  2951  		typecheck(src, &conf, info)
  2952  		got := fmt.Sprint(errs)
  2953  		if !strings.Contains(got, test.wantErr) {
  2954  			t.Errorf("%q: unexpected error: got %q, want substring %q",
  2955  				src, got, test.wantErr)
  2956  		}
  2957  
  2958  		// Assert that declarations were type checked nonetheless.
  2959  		var gotObjs []string
  2960  		for id, obj := range info.Defs {
  2961  			if obj != nil {
  2962  				objStr := strings.ReplaceAll(fmt.Sprintf("%s:%T", id.Value, obj), "types2", "types")
  2963  				gotObjs = append(gotObjs, objStr)
  2964  			}
  2965  		}
  2966  		wantObjs := "f:*types.Func"
  2967  		if !strings.Contains(fmt.Sprint(gotObjs), wantObjs) {
  2968  			t.Errorf("%q: got %s, want substring %q",
  2969  				src, gotObjs, wantObjs)
  2970  		}
  2971  	}
  2972  }
  2973  
  2974  // This is a regression test for #66704.
  2975  func TestUnaliasTooSoonInCycle(t *testing.T) {
  2976  	t.Setenv("GODEBUG", "gotypesalias=1")
  2977  	const src = `package a
  2978  
  2979  var x T[B] // this appears to cause Unalias to be called on B while still Invalid
  2980  
  2981  type T[_ any] struct{}
  2982  type A T[B]
  2983  type B = T[A]
  2984  `
  2985  	pkg := mustTypecheck(src, nil, nil)
  2986  	B := pkg.Scope().Lookup("B")
  2987  
  2988  	got, want := Unalias(B.Type()).String(), "a.T[a.A]"
  2989  	if got != want {
  2990  		t.Errorf("Unalias(type B = T[A]) = %q, want %q", got, want)
  2991  	}
  2992  }
  2993  
  2994  func TestAlias_Rhs(t *testing.T) {
  2995  	const src = `package p
  2996  
  2997  type A = B
  2998  type B = C
  2999  type C = int
  3000  `
  3001  
  3002  	pkg := mustTypecheck(src, &Config{EnableAlias: true}, nil)
  3003  	A := pkg.Scope().Lookup("A")
  3004  
  3005  	got, want := A.Type().(*Alias).Rhs().String(), "p.B"
  3006  	if got != want {
  3007  		t.Errorf("A.Rhs = %s, want %s", got, want)
  3008  	}
  3009  }
  3010  
  3011  // Test the hijacking described of "any" described in golang/go#66921, for
  3012  // (concurrent) type checking.
  3013  func TestAnyHijacking_Check(t *testing.T) {
  3014  	for _, enableAlias := range []bool{false, true} {
  3015  		t.Run(fmt.Sprintf("EnableAlias=%t", enableAlias), func(t *testing.T) {
  3016  			var wg sync.WaitGroup
  3017  			for i := 0; i < 10; i++ {
  3018  				wg.Add(1)
  3019  				go func() {
  3020  					defer wg.Done()
  3021  					pkg := mustTypecheck("package p; var x any", &Config{EnableAlias: enableAlias}, nil)
  3022  					x := pkg.Scope().Lookup("x")
  3023  					if _, gotAlias := x.Type().(*Alias); gotAlias != enableAlias {
  3024  						t.Errorf(`Lookup("x").Type() is %T: got Alias: %t, want %t`, x.Type(), gotAlias, enableAlias)
  3025  					}
  3026  				}()
  3027  			}
  3028  			wg.Wait()
  3029  		})
  3030  	}
  3031  }
  3032  
  3033  // This test function only exists for go/types.
  3034  // func TestVersionIssue69477(t *testing.T)
  3035  
  3036  // TestVersionWithoutPos is a regression test for issue #69477,
  3037  // in which the type checker would use position information
  3038  // to compute which file it is "in" based on syntax position.
  3039  //
  3040  // As a rule the type checker should not depend on position
  3041  // information for correctness, only for error messages and
  3042  // Object.Pos. (Scope.LookupParent was a mistake.)
  3043  //
  3044  // The Checker now holds the effective version in a state variable.
  3045  func TestVersionWithoutPos(t *testing.T) {
  3046  	f := mustParse("//go:build go1.22\n\npackage p; var _ int")
  3047  
  3048  	// Splice in a decl from another file. Its pos will be wrong.
  3049  	f.DeclList[0] = mustParse("package q; func _(s func(func() bool)) { for range s {} }").DeclList[0]
  3050  
  3051  	// Type check. The checker will consult the effective
  3052  	// version (1.22) for the for-range stmt to know whether
  3053  	// range-over-func are permitted: they are not.
  3054  	// (Previously, no error was reported.)
  3055  	pkg := NewPackage("p", "p")
  3056  	check := NewChecker(&Config{}, pkg, nil)
  3057  	err := check.Files([]*syntax.File{f})
  3058  	got := fmt.Sprint(err)
  3059  	want := "range over s (variable of type func(func() bool)): requires go1.23"
  3060  	if !strings.Contains(got, want) {
  3061  		t.Errorf("check error was %q, want substring %q", got, want)
  3062  	}
  3063  }
  3064  

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