literals.go

     1  // Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.
     2  // Source: ../../cmd/compile/internal/types2/literals.go
     3  
     4  // Copyright 2024 The Go Authors. All rights reserved.
     5  // Use of this source code is governed by a BSD-style
     6  // license that can be found in the LICENSE file.
     7  
     8  // This file implements typechecking of literals.
     9  
    10  package types
    11  
    12  import (
    13  	"go/ast"
    14  	"go/token"
    15  	. "internal/types/errors"
    16  	"strings"
    17  )
    18  
    19  // langCompat reports an error if the representation of a numeric
    20  // literal is not compatible with the current language version.
    21  func (check *Checker) langCompat(lit *ast.BasicLit) {
    22  	s := lit.Value
    23  	if len(s) <= 2 || check.allowVersion(go1_13) {
    24  		return
    25  	}
    26  	// len(s) > 2
    27  	if strings.Contains(s, "_") {
    28  		check.versionErrorf(lit, go1_13, "underscore in numeric literal")
    29  		return
    30  	}
    31  	if s[0] != '0' {
    32  		return
    33  	}
    34  	radix := s[1]
    35  	if radix == 'b' || radix == 'B' {
    36  		check.versionErrorf(lit, go1_13, "binary literal")
    37  		return
    38  	}
    39  	if radix == 'o' || radix == 'O' {
    40  		check.versionErrorf(lit, go1_13, "0o/0O-style octal literal")
    41  		return
    42  	}
    43  	if lit.Kind != token.INT && (radix == 'x' || radix == 'X') {
    44  		check.versionErrorf(lit, go1_13, "hexadecimal floating-point literal")
    45  	}
    46  }
    47  
    48  func (check *Checker) basicLit(x *operand, e *ast.BasicLit) {
    49  	switch e.Kind {
    50  	case token.INT, token.FLOAT, token.IMAG:
    51  		check.langCompat(e)
    52  		// The max. mantissa precision for untyped numeric values
    53  		// is 512 bits, or 4048 bits for each of the two integer
    54  		// parts of a fraction for floating-point numbers that are
    55  		// represented accurately in the go/constant package.
    56  		// Constant literals that are longer than this many bits
    57  		// are not meaningful; and excessively long constants may
    58  		// consume a lot of space and time for a useless conversion.
    59  		// Cap constant length with a generous upper limit that also
    60  		// allows for separators between all digits.
    61  		const limit = 10000
    62  		if len(e.Value) > limit {
    63  			check.errorf(e, InvalidConstVal, "excessively long constant: %s... (%d chars)", e.Value[:10], len(e.Value))
    64  			x.mode = invalid
    65  			return
    66  		}
    67  	}
    68  	x.setConst(e.Kind, e.Value)
    69  	if x.mode == invalid {
    70  		// The parser already establishes syntactic correctness.
    71  		// If we reach here it's because of number under-/overflow.
    72  		// TODO(gri) setConst (and in turn the go/constant package)
    73  		// should return an error describing the issue.
    74  		check.errorf(e, InvalidConstVal, "malformed constant: %s", e.Value)
    75  		x.mode = invalid
    76  		return
    77  	}
    78  	// Ensure that integer values don't overflow (go.dev/issue/54280).
    79  	x.expr = e // make sure that check.overflow below has an error position
    80  	check.overflow(x, opPos(x.expr))
    81  }
    82  
    83  func (check *Checker) funcLit(x *operand, e *ast.FuncLit) {
    84  	if sig, ok := check.typ(e.Type).(*Signature); ok {
    85  		// Set the Scope's extent to the complete "func (...) {...}"
    86  		// so that Scope.Innermost works correctly.
    87  		sig.scope.pos = e.Pos()
    88  		sig.scope.end = endPos(e)
    89  		if !check.conf.IgnoreFuncBodies && e.Body != nil {
    90  			// Anonymous functions are considered part of the
    91  			// init expression/func declaration which contains
    92  			// them: use existing package-level declaration info.
    93  			decl := check.decl // capture for use in closure below
    94  			iota := check.iota // capture for use in closure below (go.dev/issue/22345)
    95  			// Don't type-check right away because the function may
    96  			// be part of a type definition to which the function
    97  			// body refers. Instead, type-check as soon as possible,
    98  			// but before the enclosing scope contents changes (go.dev/issue/22992).
    99  			check.later(func() {
   100  				check.funcBody(decl, "<function literal>", sig, e.Body, iota)
   101  			}).describef(e, "func literal")
   102  		}
   103  		x.mode = value
   104  		x.typ = sig
   105  	} else {
   106  		check.errorf(e, InvalidSyntaxTree, "invalid function literal %v", e)
   107  		x.mode = invalid
   108  	}
   109  }
   110  
   111  func (check *Checker) compositeLit(x *operand, e *ast.CompositeLit, hint Type) {
   112  	var typ, base Type
   113  	var isElem bool // true if composite literal is an element of an enclosing composite literal
   114  
   115  	switch {
   116  	case e.Type != nil:
   117  		// composite literal type present - use it
   118  		// [...]T array types may only appear with composite literals.
   119  		// Check for them here so we don't have to handle ... in general.
   120  		if atyp, _ := e.Type.(*ast.ArrayType); atyp != nil && isdddArray(atyp) {
   121  			// We have an "open" [...]T array type.
   122  			// Create a new ArrayType with unknown length (-1)
   123  			// and finish setting it up after analyzing the literal.
   124  			typ = &Array{len: -1, elem: check.varType(atyp.Elt)}
   125  			base = typ
   126  			break
   127  		}
   128  		typ = check.typ(e.Type)
   129  		base = typ
   130  
   131  	case hint != nil:
   132  		// no composite literal type present - use hint (element type of enclosing type)
   133  		typ = hint
   134  		base = typ
   135  		// *T implies &T{}
   136  		u, _ := commonUnder(base, nil)
   137  		if b, ok := deref(u); ok {
   138  			base = b
   139  		}
   140  		isElem = true
   141  
   142  	default:
   143  		// TODO(gri) provide better error messages depending on context
   144  		check.error(e, UntypedLit, "missing type in composite literal")
   145  		// continue with invalid type so that elements are "used" (go.dev/issue/69092)
   146  		typ = Typ[Invalid]
   147  		base = typ
   148  	}
   149  
   150  	switch u, _ := commonUnder(base, nil); utyp := u.(type) {
   151  	case *Struct:
   152  		// Prevent crash if the struct referred to is not yet set up.
   153  		// See analogous comment for *Array.
   154  		if utyp.fields == nil {
   155  			check.error(e, InvalidTypeCycle, "invalid recursive type")
   156  			x.mode = invalid
   157  			return
   158  		}
   159  		if len(e.Elts) == 0 {
   160  			break
   161  		}
   162  		// Convention for error messages on invalid struct literals:
   163  		// we mention the struct type only if it clarifies the error
   164  		// (e.g., a duplicate field error doesn't need the struct type).
   165  		fields := utyp.fields
   166  		if _, ok := e.Elts[0].(*ast.KeyValueExpr); ok {
   167  			// all elements must have keys
   168  			visited := make([]bool, len(fields))
   169  			for _, e := range e.Elts {
   170  				kv, _ := e.(*ast.KeyValueExpr)
   171  				if kv == nil {
   172  					check.error(e, MixedStructLit, "mixture of field:value and value elements in struct literal")
   173  					continue
   174  				}
   175  				key, _ := kv.Key.(*ast.Ident)
   176  				// do all possible checks early (before exiting due to errors)
   177  				// so we don't drop information on the floor
   178  				check.expr(nil, x, kv.Value)
   179  				if key == nil {
   180  					check.errorf(kv, InvalidLitField, "invalid field name %s in struct literal", kv.Key)
   181  					continue
   182  				}
   183  				i := fieldIndex(fields, check.pkg, key.Name, false)
   184  				if i < 0 {
   185  					var alt Object
   186  					if j := fieldIndex(fields, check.pkg, key.Name, true); j >= 0 {
   187  						alt = fields[j]
   188  					}
   189  					msg := check.lookupError(base, key.Name, alt, true)
   190  					check.error(kv.Key, MissingLitField, msg)
   191  					continue
   192  				}
   193  				fld := fields[i]
   194  				check.recordUse(key, fld)
   195  				etyp := fld.typ
   196  				check.assignment(x, etyp, "struct literal")
   197  				// 0 <= i < len(fields)
   198  				if visited[i] {
   199  					check.errorf(kv, DuplicateLitField, "duplicate field name %s in struct literal", key.Name)
   200  					continue
   201  				}
   202  				visited[i] = true
   203  			}
   204  		} else {
   205  			// no element must have a key
   206  			for i, e := range e.Elts {
   207  				if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
   208  					check.error(kv, MixedStructLit, "mixture of field:value and value elements in struct literal")
   209  					continue
   210  				}
   211  				check.expr(nil, x, e)
   212  				if i >= len(fields) {
   213  					check.errorf(x, InvalidStructLit, "too many values in struct literal of type %s", base)
   214  					break // cannot continue
   215  				}
   216  				// i < len(fields)
   217  				fld := fields[i]
   218  				if !fld.Exported() && fld.pkg != check.pkg {
   219  					check.errorf(x, UnexportedLitField, "implicit assignment to unexported field %s in struct literal of type %s", fld.name, base)
   220  					continue
   221  				}
   222  				etyp := fld.typ
   223  				check.assignment(x, etyp, "struct literal")
   224  			}
   225  			if len(e.Elts) < len(fields) {
   226  				check.errorf(inNode(e, e.Rbrace), InvalidStructLit, "too few values in struct literal of type %s", base)
   227  				// ok to continue
   228  			}
   229  		}
   230  
   231  	case *Array:
   232  		// Prevent crash if the array referred to is not yet set up. Was go.dev/issue/18643.
   233  		// This is a stop-gap solution. Should use Checker.objPath to report entire
   234  		// path starting with earliest declaration in the source. TODO(gri) fix this.
   235  		if utyp.elem == nil {
   236  			check.error(e, InvalidTypeCycle, "invalid recursive type")
   237  			x.mode = invalid
   238  			return
   239  		}
   240  		n := check.indexedElts(e.Elts, utyp.elem, utyp.len)
   241  		// If we have an array of unknown length (usually [...]T arrays, but also
   242  		// arrays [n]T where n is invalid) set the length now that we know it and
   243  		// record the type for the array (usually done by check.typ which is not
   244  		// called for [...]T). We handle [...]T arrays and arrays with invalid
   245  		// length the same here because it makes sense to "guess" the length for
   246  		// the latter if we have a composite literal; e.g. for [n]int{1, 2, 3}
   247  		// where n is invalid for some reason, it seems fair to assume it should
   248  		// be 3 (see also Checked.arrayLength and go.dev/issue/27346).
   249  		if utyp.len < 0 {
   250  			utyp.len = n
   251  			// e.Type is missing if we have a composite literal element
   252  			// that is itself a composite literal with omitted type. In
   253  			// that case there is nothing to record (there is no type in
   254  			// the source at that point).
   255  			if e.Type != nil {
   256  				check.recordTypeAndValue(e.Type, typexpr, utyp, nil)
   257  			}
   258  		}
   259  
   260  	case *Slice:
   261  		// Prevent crash if the slice referred to is not yet set up.
   262  		// See analogous comment for *Array.
   263  		if utyp.elem == nil {
   264  			check.error(e, InvalidTypeCycle, "invalid recursive type")
   265  			x.mode = invalid
   266  			return
   267  		}
   268  		check.indexedElts(e.Elts, utyp.elem, -1)
   269  
   270  	case *Map:
   271  		// Prevent crash if the map referred to is not yet set up.
   272  		// See analogous comment for *Array.
   273  		if utyp.key == nil || utyp.elem == nil {
   274  			check.error(e, InvalidTypeCycle, "invalid recursive type")
   275  			x.mode = invalid
   276  			return
   277  		}
   278  		// If the map key type is an interface (but not a type parameter),
   279  		// the type of a constant key must be considered when checking for
   280  		// duplicates.
   281  		keyIsInterface := isNonTypeParamInterface(utyp.key)
   282  		visited := make(map[any][]Type, len(e.Elts))
   283  		for _, e := range e.Elts {
   284  			kv, _ := e.(*ast.KeyValueExpr)
   285  			if kv == nil {
   286  				check.error(e, MissingLitKey, "missing key in map literal")
   287  				continue
   288  			}
   289  			check.exprWithHint(x, kv.Key, utyp.key)
   290  			check.assignment(x, utyp.key, "map literal")
   291  			if x.mode == invalid {
   292  				continue
   293  			}
   294  			if x.mode == constant_ {
   295  				duplicate := false
   296  				xkey := keyVal(x.val)
   297  				if keyIsInterface {
   298  					for _, vtyp := range visited[xkey] {
   299  						if Identical(vtyp, x.typ) {
   300  							duplicate = true
   301  							break
   302  						}
   303  					}
   304  					visited[xkey] = append(visited[xkey], x.typ)
   305  				} else {
   306  					_, duplicate = visited[xkey]
   307  					visited[xkey] = nil
   308  				}
   309  				if duplicate {
   310  					check.errorf(x, DuplicateLitKey, "duplicate key %s in map literal", x.val)
   311  					continue
   312  				}
   313  			}
   314  			check.exprWithHint(x, kv.Value, utyp.elem)
   315  			check.assignment(x, utyp.elem, "map literal")
   316  		}
   317  
   318  	default:
   319  		// when "using" all elements unpack KeyValueExpr
   320  		// explicitly because check.use doesn't accept them
   321  		for _, e := range e.Elts {
   322  			if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
   323  				// Ideally, we should also "use" kv.Key but we can't know
   324  				// if it's an externally defined struct key or not. Going
   325  				// forward anyway can lead to other errors. Give up instead.
   326  				e = kv.Value
   327  			}
   328  			check.use(e)
   329  		}
   330  		// if utyp is invalid, an error was reported before
   331  		if isValid(utyp) {
   332  			var qualifier string
   333  			if isElem {
   334  				qualifier = " element"
   335  			}
   336  			var cause string
   337  			if utyp == nil {
   338  				cause = " (no common underlying type)"
   339  			}
   340  			check.errorf(e, InvalidLit, "invalid composite literal%s type %s%s", qualifier, typ, cause)
   341  			x.mode = invalid
   342  			return
   343  		}
   344  	}
   345  
   346  	x.mode = value
   347  	x.typ = typ
   348  }
   349  
   350  // indexedElts checks the elements (elts) of an array or slice composite literal
   351  // against the literal's element type (typ), and the element indices against
   352  // the literal length if known (length >= 0). It returns the length of the
   353  // literal (maximum index value + 1).
   354  func (check *Checker) indexedElts(elts []ast.Expr, typ Type, length int64) int64 {
   355  	visited := make(map[int64]bool, len(elts))
   356  	var index, max int64
   357  	for _, e := range elts {
   358  		// determine and check index
   359  		validIndex := false
   360  		eval := e
   361  		if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
   362  			if typ, i := check.index(kv.Key, length); isValid(typ) {
   363  				if i >= 0 {
   364  					index = i
   365  					validIndex = true
   366  				} else {
   367  					check.errorf(e, InvalidLitIndex, "index %s must be integer constant", kv.Key)
   368  				}
   369  			}
   370  			eval = kv.Value
   371  		} else if length >= 0 && index >= length {
   372  			check.errorf(e, OversizeArrayLit, "index %d is out of bounds (>= %d)", index, length)
   373  		} else {
   374  			validIndex = true
   375  		}
   376  
   377  		// if we have a valid index, check for duplicate entries
   378  		if validIndex {
   379  			if visited[index] {
   380  				check.errorf(e, DuplicateLitKey, "duplicate index %d in array or slice literal", index)
   381  			}
   382  			visited[index] = true
   383  		}
   384  		index++
   385  		if index > max {
   386  			max = index
   387  		}
   388  
   389  		// check element against composite literal element type
   390  		var x operand
   391  		check.exprWithHint(&x, eval, typ)
   392  		check.assignment(&x, typ, "array or slice literal")
   393  	}
   394  	return max
   395  }
   396
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