object.go

     1  // Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.
     2  // Source: ../../cmd/compile/internal/types2/object.go
     3  
     4  // Copyright 2013 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  package types
     9  
    10  import (
    11  	"bytes"
    12  	"fmt"
    13  	"go/constant"
    14  	"go/token"
    15  	"strings"
    16  	"unicode"
    17  	"unicode/utf8"
    18  )
    19  
    20  // An Object is a named language entity.
    21  // An Object may be a constant ([Const]), type name ([TypeName]),
    22  // variable or struct field ([Var]), function or method ([Func]),
    23  // imported package ([PkgName]), label ([Label]),
    24  // built-in function ([Builtin]),
    25  // or the predeclared identifier 'nil' ([Nil]).
    26  //
    27  // The environment, which is structured as a tree of Scopes,
    28  // maps each name to the unique Object that it denotes.
    29  type Object interface {
    30  	Parent() *Scope // scope in which this object is declared; nil for methods and struct fields
    31  	Pos() token.Pos // position of object identifier in declaration
    32  	Pkg() *Package  // package to which this object belongs; nil for labels and objects in the Universe scope
    33  	Name() string   // package local object name
    34  	Type() Type     // object type
    35  	Exported() bool // reports whether the name starts with a capital letter
    36  	Id() string     // object name if exported, qualified name if not exported (see func Id)
    37  
    38  	// String returns a human-readable string of the object.
    39  	// Use [ObjectString] to control how package names are formatted in the string.
    40  	String() string
    41  
    42  	// order reflects a package-level object's source order: if object
    43  	// a is before object b in the source, then a.order() < b.order().
    44  	// order returns a value > 0 for package-level objects; it returns
    45  	// 0 for all other objects (including objects in file scopes).
    46  	order() uint32
    47  
    48  	// setType sets the type of the object.
    49  	setType(Type)
    50  
    51  	// setOrder sets the order number of the object. It must be > 0.
    52  	setOrder(uint32)
    53  
    54  	// setParent sets the parent scope of the object.
    55  	setParent(*Scope)
    56  
    57  	// sameId reports whether obj.Id() and Id(pkg, name) are the same.
    58  	// If foldCase is true, names are considered equal if they are equal with case folding
    59  	// and their packages are ignored (e.g., pkg1.m, pkg1.M, pkg2.m, and pkg2.M are all equal).
    60  	sameId(pkg *Package, name string, foldCase bool) bool
    61  
    62  	// scopePos returns the start position of the scope of this Object
    63  	scopePos() token.Pos
    64  
    65  	// setScopePos sets the start position of the scope for this Object.
    66  	setScopePos(pos token.Pos)
    67  }
    68  
    69  func isExported(name string) bool {
    70  	ch, _ := utf8.DecodeRuneInString(name)
    71  	return unicode.IsUpper(ch)
    72  }
    73  
    74  // Id returns name if it is exported, otherwise it
    75  // returns the name qualified with the package path.
    76  func Id(pkg *Package, name string) string {
    77  	if isExported(name) {
    78  		return name
    79  	}
    80  	// unexported names need the package path for differentiation
    81  	// (if there's no package, make sure we don't start with '.'
    82  	// as that may change the order of methods between a setup
    83  	// inside a package and outside a package - which breaks some
    84  	// tests)
    85  	path := "_"
    86  	// pkg is nil for objects in Universe scope and possibly types
    87  	// introduced via Eval (see also comment in object.sameId)
    88  	if pkg != nil && pkg.path != "" {
    89  		path = pkg.path
    90  	}
    91  	return path + "." + name
    92  }
    93  
    94  // An object implements the common parts of an Object.
    95  type object struct {
    96  	parent    *Scope
    97  	pos       token.Pos
    98  	pkg       *Package
    99  	name      string
   100  	typ       Type
   101  	order_    uint32
   102  	scopePos_ token.Pos
   103  }
   104  
   105  // Parent returns the scope in which the object is declared.
   106  // The result is nil for methods and struct fields.
   107  func (obj *object) Parent() *Scope { return obj.parent }
   108  
   109  // Pos returns the declaration position of the object's identifier.
   110  func (obj *object) Pos() token.Pos { return obj.pos }
   111  
   112  // Pkg returns the package to which the object belongs.
   113  // The result is nil for labels and objects in the Universe scope.
   114  func (obj *object) Pkg() *Package { return obj.pkg }
   115  
   116  // Name returns the object's (package-local, unqualified) name.
   117  func (obj *object) Name() string { return obj.name }
   118  
   119  // Type returns the object's type.
   120  func (obj *object) Type() Type { return obj.typ }
   121  
   122  // Exported reports whether the object is exported (starts with a capital letter).
   123  // It doesn't take into account whether the object is in a local (function) scope
   124  // or not.
   125  func (obj *object) Exported() bool { return isExported(obj.name) }
   126  
   127  // Id is a wrapper for Id(obj.Pkg(), obj.Name()).
   128  func (obj *object) Id() string { return Id(obj.pkg, obj.name) }
   129  
   130  func (obj *object) String() string      { panic("abstract") }
   131  func (obj *object) order() uint32       { return obj.order_ }
   132  func (obj *object) scopePos() token.Pos { return obj.scopePos_ }
   133  
   134  func (obj *object) setParent(parent *Scope)   { obj.parent = parent }
   135  func (obj *object) setType(typ Type)          { obj.typ = typ }
   136  func (obj *object) setOrder(order uint32)     { assert(order > 0); obj.order_ = order }
   137  func (obj *object) setScopePos(pos token.Pos) { obj.scopePos_ = pos }
   138  
   139  func (obj *object) sameId(pkg *Package, name string, foldCase bool) bool {
   140  	// If we don't care about capitalization, we also ignore packages.
   141  	if foldCase && strings.EqualFold(obj.name, name) {
   142  		return true
   143  	}
   144  	// spec:
   145  	// "Two identifiers are different if they are spelled differently,
   146  	// or if they appear in different packages and are not exported.
   147  	// Otherwise, they are the same."
   148  	if obj.name != name {
   149  		return false
   150  	}
   151  	// obj.Name == name
   152  	if obj.Exported() {
   153  		return true
   154  	}
   155  	// not exported, so packages must be the same
   156  	return samePkg(obj.pkg, pkg)
   157  }
   158  
   159  // cmp reports whether object a is ordered before object b.
   160  // cmp returns:
   161  //
   162  //	-1 if a is before b
   163  //	 0 if a is equivalent to b
   164  //	+1 if a is behind b
   165  //
   166  // Objects are ordered nil before non-nil, exported before
   167  // non-exported, then by name, and finally (for non-exported
   168  // functions) by package path.
   169  func (a *object) cmp(b *object) int {
   170  	if a == b {
   171  		return 0
   172  	}
   173  
   174  	// Nil before non-nil.
   175  	if a == nil {
   176  		return -1
   177  	}
   178  	if b == nil {
   179  		return +1
   180  	}
   181  
   182  	// Exported functions before non-exported.
   183  	ea := isExported(a.name)
   184  	eb := isExported(b.name)
   185  	if ea != eb {
   186  		if ea {
   187  			return -1
   188  		}
   189  		return +1
   190  	}
   191  
   192  	// Order by name and then (for non-exported names) by package.
   193  	if a.name != b.name {
   194  		return strings.Compare(a.name, b.name)
   195  	}
   196  	if !ea {
   197  		return strings.Compare(a.pkg.path, b.pkg.path)
   198  	}
   199  
   200  	return 0
   201  }
   202  
   203  // A PkgName represents an imported Go package.
   204  // PkgNames don't have a type.
   205  type PkgName struct {
   206  	object
   207  	imported *Package
   208  }
   209  
   210  // NewPkgName returns a new PkgName object representing an imported package.
   211  // The remaining arguments set the attributes found with all Objects.
   212  func NewPkgName(pos token.Pos, pkg *Package, name string, imported *Package) *PkgName {
   213  	return &PkgName{object{nil, pos, pkg, name, Typ[Invalid], 0, nopos}, imported}
   214  }
   215  
   216  // Imported returns the package that was imported.
   217  // It is distinct from Pkg(), which is the package containing the import statement.
   218  func (obj *PkgName) Imported() *Package { return obj.imported }
   219  
   220  // A Const represents a declared constant.
   221  type Const struct {
   222  	object
   223  	val constant.Value
   224  }
   225  
   226  // NewConst returns a new constant with value val.
   227  // The remaining arguments set the attributes found with all Objects.
   228  func NewConst(pos token.Pos, pkg *Package, name string, typ Type, val constant.Value) *Const {
   229  	return &Const{object{nil, pos, pkg, name, typ, 0, nopos}, val}
   230  }
   231  
   232  // Val returns the constant's value.
   233  func (obj *Const) Val() constant.Value { return obj.val }
   234  
   235  func (*Const) isDependency() {} // a constant may be a dependency of an initialization expression
   236  
   237  // A TypeName is an [Object] that represents a type with a name:
   238  // a defined type ([Named]),
   239  // an alias type ([Alias]),
   240  // a type parameter ([TypeParam]),
   241  // or a predeclared type such as int or error.
   242  type TypeName struct {
   243  	object
   244  }
   245  
   246  // NewTypeName returns a new type name denoting the given typ.
   247  // The remaining arguments set the attributes found with all Objects.
   248  //
   249  // The typ argument may be a defined (Named) type or an alias type.
   250  // It may also be nil such that the returned TypeName can be used as
   251  // argument for NewNamed, which will set the TypeName's type as a side-
   252  // effect.
   253  func NewTypeName(pos token.Pos, pkg *Package, name string, typ Type) *TypeName {
   254  	return &TypeName{object{nil, pos, pkg, name, typ, 0, nopos}}
   255  }
   256  
   257  // NewTypeNameLazy returns a new defined type like NewTypeName, but it
   258  // lazily calls unpack to finish constructing the Named object.
   259  func _NewTypeNameLazy(pos token.Pos, pkg *Package, name string, load func(*Named) ([]*TypeParam, Type, []*Func, []func())) *TypeName {
   260  	obj := NewTypeName(pos, pkg, name, nil)
   261  	n := (*Checker)(nil).newNamed(obj, nil, nil)
   262  	n.loader = load
   263  	return obj
   264  }
   265  
   266  // IsAlias reports whether obj is an alias name for a type.
   267  func (obj *TypeName) IsAlias() bool {
   268  	switch t := obj.typ.(type) {
   269  	case nil:
   270  		return false
   271  	// case *Alias:
   272  	//	handled by default case
   273  	case *Basic:
   274  		// unsafe.Pointer is not an alias.
   275  		if obj.pkg == Unsafe {
   276  			return false
   277  		}
   278  		// Any user-defined type name for a basic type is an alias for a
   279  		// basic type (because basic types are pre-declared in the Universe
   280  		// scope, outside any package scope), and so is any type name with
   281  		// a different name than the name of the basic type it refers to.
   282  		// Additionally, we need to look for "byte" and "rune" because they
   283  		// are aliases but have the same names (for better error messages).
   284  		return obj.pkg != nil || t.name != obj.name || t == universeByte || t == universeRune
   285  	case *Named:
   286  		return obj != t.obj
   287  	case *TypeParam:
   288  		return obj != t.obj
   289  	default:
   290  		return true
   291  	}
   292  }
   293  
   294  // A Var represents a declared variable (including function parameters and results, and struct fields).
   295  type Var struct {
   296  	object
   297  	origin   *Var // if non-nil, the Var from which this one was instantiated
   298  	kind     VarKind
   299  	embedded bool // if set, the variable is an embedded struct field, and name is the type name
   300  }
   301  
   302  // A VarKind discriminates the various kinds of variables.
   303  type VarKind uint8
   304  
   305  const (
   306  	_          VarKind = iota // (not meaningful)
   307  	PackageVar                // a package-level variable
   308  	LocalVar                  // a local variable
   309  	RecvVar                   // a method receiver variable
   310  	ParamVar                  // a function parameter variable
   311  	ResultVar                 // a function result variable
   312  	FieldVar                  // a struct field
   313  )
   314  
   315  var varKindNames = [...]string{
   316  	0:          "VarKind(0)",
   317  	PackageVar: "PackageVar",
   318  	LocalVar:   "LocalVar",
   319  	RecvVar:    "RecvVar",
   320  	ParamVar:   "ParamVar",
   321  	ResultVar:  "ResultVar",
   322  	FieldVar:   "FieldVar",
   323  }
   324  
   325  func (kind VarKind) String() string {
   326  	if 0 <= kind && int(kind) < len(varKindNames) {
   327  		return varKindNames[kind]
   328  	}
   329  	return fmt.Sprintf("VarKind(%d)", kind)
   330  }
   331  
   332  // Kind reports what kind of variable v is.
   333  func (v *Var) Kind() VarKind { return v.kind }
   334  
   335  // SetKind sets the kind of the variable.
   336  // It should be used only immediately after [NewVar] or [NewParam].
   337  func (v *Var) SetKind(kind VarKind) { v.kind = kind }
   338  
   339  // NewVar returns a new variable.
   340  // The arguments set the attributes found with all Objects.
   341  //
   342  // The caller must subsequently call [Var.SetKind]
   343  // if the desired Var is not of kind [PackageVar].
   344  func NewVar(pos token.Pos, pkg *Package, name string, typ Type) *Var {
   345  	return newVar(PackageVar, pos, pkg, name, typ)
   346  }
   347  
   348  // NewParam returns a new variable representing a function parameter.
   349  //
   350  // The caller must subsequently call [Var.SetKind] if the desired Var
   351  // is not of kind [ParamVar]: for example, [RecvVar] or [ResultVar].
   352  func NewParam(pos token.Pos, pkg *Package, name string, typ Type) *Var {
   353  	return newVar(ParamVar, pos, pkg, name, typ)
   354  }
   355  
   356  // NewField returns a new variable representing a struct field.
   357  // For embedded fields, the name is the unqualified type name
   358  // under which the field is accessible.
   359  func NewField(pos token.Pos, pkg *Package, name string, typ Type, embedded bool) *Var {
   360  	v := newVar(FieldVar, pos, pkg, name, typ)
   361  	v.embedded = embedded
   362  	return v
   363  }
   364  
   365  // newVar returns a new variable.
   366  // The arguments set the attributes found with all Objects.
   367  func newVar(kind VarKind, pos token.Pos, pkg *Package, name string, typ Type) *Var {
   368  	return &Var{object: object{nil, pos, pkg, name, typ, 0, nopos}, kind: kind}
   369  }
   370  
   371  // Anonymous reports whether the variable is an embedded field.
   372  // Same as Embedded; only present for backward-compatibility.
   373  func (obj *Var) Anonymous() bool { return obj.embedded }
   374  
   375  // Embedded reports whether the variable is an embedded field.
   376  func (obj *Var) Embedded() bool { return obj.embedded }
   377  
   378  // IsField reports whether the variable is a struct field.
   379  func (obj *Var) IsField() bool { return obj.kind == FieldVar }
   380  
   381  // Origin returns the canonical Var for its receiver, i.e. the Var object
   382  // recorded in Info.Defs.
   383  //
   384  // For synthetic Vars created during instantiation (such as struct fields or
   385  // function parameters that depend on type arguments), this will be the
   386  // corresponding Var on the generic (uninstantiated) type. For all other Vars
   387  // Origin returns the receiver.
   388  func (obj *Var) Origin() *Var {
   389  	if obj.origin != nil {
   390  		return obj.origin
   391  	}
   392  	return obj
   393  }
   394  
   395  func (*Var) isDependency() {} // a variable may be a dependency of an initialization expression
   396  
   397  // A Func represents a declared function, concrete method, or abstract
   398  // (interface) method. Its Type() is always a *Signature.
   399  // An abstract method may belong to many interfaces due to embedding.
   400  type Func struct {
   401  	object
   402  	origin      *Func // if non-nil, the Func from which this one was instantiated
   403  	hasPtrRecv_ bool  // only valid for methods that don't have a type yet; use hasPtrRecv() to read
   404  	nointerface bool
   405  }
   406  
   407  // NewFunc returns a new function with the given signature, representing
   408  // the function's type.
   409  func NewFunc(pos token.Pos, pkg *Package, name string, sig *Signature) *Func {
   410  	var typ Type
   411  	if sig != nil {
   412  		typ = sig
   413  	} else {
   414  		// Don't store a (typed) nil *Signature.
   415  		// We can't simply replace it with new(Signature) either,
   416  		// as this would violate object.{Type,color} invariants.
   417  		// TODO(adonovan): propose to disallow NewFunc with nil *Signature.
   418  	}
   419  	return &Func{object{nil, pos, pkg, name, typ, 0, nopos}, nil, false, false}
   420  }
   421  
   422  // Signature returns the signature (type) of the function or method.
   423  func (obj *Func) Signature() *Signature {
   424  	if obj.typ != nil {
   425  		return obj.typ.(*Signature) // normal case
   426  	}
   427  	// No signature: Signature was called either:
   428  	// - within go/types, before a FuncDecl's initially
   429  	//   nil Func.Type was lazily populated, indicating
   430  	//   a types bug; or
   431  	// - by a client after NewFunc(..., nil),
   432  	//   which is arguably a client bug, but we need a
   433  	//   proposal to tighten NewFunc's precondition.
   434  	// For now, return a trivial signature.
   435  	return new(Signature)
   436  }
   437  
   438  // FullName returns the package- or receiver-type-qualified name of
   439  // function or method obj.
   440  func (obj *Func) FullName() string {
   441  	var buf bytes.Buffer
   442  	writeFuncName(&buf, obj, nil)
   443  	return buf.String()
   444  }
   445  
   446  // Scope returns the scope of the function's body block.
   447  // The result is nil for imported or instantiated functions and methods
   448  // (but there is also no mechanism to get to an instantiated function).
   449  func (obj *Func) Scope() *Scope { return obj.typ.(*Signature).scope }
   450  
   451  // Origin returns the canonical Func for its receiver, i.e. the Func object
   452  // recorded in Info.Defs.
   453  //
   454  // For synthetic functions created during instantiation (such as methods on an
   455  // instantiated Named type or interface methods that depend on type arguments),
   456  // this will be the corresponding Func on the generic (uninstantiated) type.
   457  // For all other Funcs Origin returns the receiver.
   458  func (obj *Func) Origin() *Func {
   459  	if obj.origin != nil {
   460  		return obj.origin
   461  	}
   462  	return obj
   463  }
   464  
   465  // Pkg returns the package to which the function belongs.
   466  //
   467  // The result is nil for methods of types in the Universe scope,
   468  // like method Error of the error built-in interface type.
   469  func (obj *Func) Pkg() *Package { return obj.object.Pkg() }
   470  
   471  // hasPtrRecv reports whether the receiver is of the form *T for the given method obj.
   472  func (obj *Func) hasPtrRecv() bool {
   473  	// If a method's receiver type is set, use that as the source of truth for the receiver.
   474  	// Caution: Checker.funcDecl (decl.go) marks a function by setting its type to an empty
   475  	// signature. We may reach here before the signature is fully set up: we must explicitly
   476  	// check if the receiver is set (we cannot just look for non-nil obj.typ).
   477  	if sig, _ := obj.typ.(*Signature); sig != nil && sig.recv != nil {
   478  		_, isPtr := deref(sig.recv.typ)
   479  		return isPtr
   480  	}
   481  
   482  	// If a method's type is not set it may be a method/function that is:
   483  	// 1) client-supplied (via NewFunc with no signature), or
   484  	// 2) internally created but not yet type-checked.
   485  	// For case 1) we can't do anything; the client must know what they are doing.
   486  	// For case 2) we can use the information gathered by the resolver.
   487  	return obj.hasPtrRecv_
   488  }
   489  
   490  func (*Func) isDependency() {} // a function may be a dependency of an initialization expression
   491  
   492  // A Label represents a declared label.
   493  // Labels don't have a type.
   494  type Label struct {
   495  	object
   496  	used bool // set if the label was used
   497  }
   498  
   499  // NewLabel returns a new label.
   500  func NewLabel(pos token.Pos, pkg *Package, name string) *Label {
   501  	return &Label{object{pos: pos, pkg: pkg, name: name, typ: Typ[Invalid]}, false}
   502  }
   503  
   504  // A Builtin represents a built-in function.
   505  // Builtins don't have a valid type.
   506  type Builtin struct {
   507  	object
   508  	id builtinId
   509  }
   510  
   511  func newBuiltin(id builtinId) *Builtin {
   512  	return &Builtin{object{name: predeclaredFuncs[id].name, typ: Typ[Invalid]}, id}
   513  }
   514  
   515  // Nil represents the predeclared value nil.
   516  type Nil struct {
   517  	object
   518  }
   519  
   520  func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
   521  	var tname *TypeName
   522  	typ := obj.Type()
   523  
   524  	switch obj := obj.(type) {
   525  	case *PkgName:
   526  		fmt.Fprintf(buf, "package %s", obj.Name())
   527  		if path := obj.imported.path; path != "" && path != obj.name {
   528  			fmt.Fprintf(buf, " (%q)", path)
   529  		}
   530  		return
   531  
   532  	case *Const:
   533  		buf.WriteString("const")
   534  
   535  	case *TypeName:
   536  		tname = obj
   537  		buf.WriteString("type")
   538  		if isTypeParam(typ) {
   539  			buf.WriteString(" parameter")
   540  		}
   541  
   542  	case *Var:
   543  		if obj.IsField() {
   544  			buf.WriteString("field")
   545  		} else {
   546  			buf.WriteString("var")
   547  		}
   548  
   549  	case *Func:
   550  		buf.WriteString("func ")
   551  		writeFuncName(buf, obj, qf)
   552  		if typ != nil {
   553  			WriteSignature(buf, typ.(*Signature), qf)
   554  		}
   555  		return
   556  
   557  	case *Label:
   558  		buf.WriteString("label")
   559  		typ = nil
   560  
   561  	case *Builtin:
   562  		buf.WriteString("builtin")
   563  		typ = nil
   564  
   565  	case *Nil:
   566  		buf.WriteString("nil")
   567  		return
   568  
   569  	default:
   570  		panic(fmt.Sprintf("writeObject(%T)", obj))
   571  	}
   572  
   573  	buf.WriteByte(' ')
   574  
   575  	// For package-level objects, qualify the name.
   576  	if obj.Pkg() != nil && obj.Pkg().scope.Lookup(obj.Name()) == obj {
   577  		buf.WriteString(packagePrefix(obj.Pkg(), qf))
   578  	}
   579  	buf.WriteString(obj.Name())
   580  
   581  	if typ == nil {
   582  		return
   583  	}
   584  
   585  	if tname != nil {
   586  		switch t := typ.(type) {
   587  		case *Basic:
   588  			// Don't print anything more for basic types since there's
   589  			// no more information.
   590  			return
   591  		case genericType:
   592  			if t.TypeParams().Len() > 0 {
   593  				newTypeWriter(buf, qf).tParamList(t.TypeParams().list())
   594  			}
   595  		}
   596  		if tname.IsAlias() {
   597  			buf.WriteString(" =")
   598  			if alias, ok := typ.(*Alias); ok { // materialized? TODO(gri) Do we still need this (e.g. for byte, rune)?
   599  				typ = alias.fromRHS
   600  			}
   601  		} else if t, _ := typ.(*TypeParam); t != nil {
   602  			typ = t.bound
   603  		} else {
   604  			// TODO(gri) should this be fromRHS for *Named?
   605  			// (See discussion in #66559.)
   606  			typ = typ.Underlying()
   607  		}
   608  	}
   609  
   610  	// Special handling for any: because WriteType will format 'any' as 'any',
   611  	// resulting in the object string `type any = any` rather than `type any =
   612  	// interface{}`. To avoid this, swap in a different empty interface.
   613  	if obj.Name() == "any" && obj.Parent() == Universe {
   614  		assert(Identical(typ, &emptyInterface))
   615  		typ = &emptyInterface
   616  	}
   617  
   618  	buf.WriteByte(' ')
   619  	WriteType(buf, typ, qf)
   620  }
   621  
   622  func packagePrefix(pkg *Package, qf Qualifier) string {
   623  	if pkg == nil {
   624  		return ""
   625  	}
   626  	var s string
   627  	if qf != nil {
   628  		s = qf(pkg)
   629  	} else {
   630  		s = pkg.Path()
   631  	}
   632  	if s != "" {
   633  		s += "."
   634  	}
   635  	return s
   636  }
   637  
   638  // ObjectString returns the string form of obj.
   639  // The Qualifier controls the printing of
   640  // package-level objects, and may be nil.
   641  func ObjectString(obj Object, qf Qualifier) string {
   642  	var buf bytes.Buffer
   643  	writeObject(&buf, obj, qf)
   644  	return buf.String()
   645  }
   646  
   647  func (obj *PkgName) String() string  { return ObjectString(obj, nil) }
   648  func (obj *Const) String() string    { return ObjectString(obj, nil) }
   649  func (obj *TypeName) String() string { return ObjectString(obj, nil) }
   650  func (obj *Var) String() string      { return ObjectString(obj, nil) }
   651  func (obj *Func) String() string     { return ObjectString(obj, nil) }
   652  func (obj *Label) String() string    { return ObjectString(obj, nil) }
   653  func (obj *Builtin) String() string  { return ObjectString(obj, nil) }
   654  func (obj *Nil) String() string      { return ObjectString(obj, nil) }
   655  
   656  func writeFuncName(buf *bytes.Buffer, f *Func, qf Qualifier) {
   657  	if f.typ != nil {
   658  		sig := f.typ.(*Signature)
   659  		if recv := sig.Recv(); recv != nil {
   660  			buf.WriteByte('(')
   661  			if _, ok := recv.Type().(*Interface); ok {
   662  				// gcimporter creates abstract methods of
   663  				// named interfaces using the interface type
   664  				// (not the named type) as the receiver.
   665  				// Don't print it in full.
   666  				buf.WriteString("interface")
   667  			} else {
   668  				WriteType(buf, recv.Type(), qf)
   669  			}
   670  			buf.WriteByte(')')
   671  			buf.WriteByte('.')
   672  		} else if f.pkg != nil {
   673  			buf.WriteString(packagePrefix(f.pkg, qf))
   674  		}
   675  	}
   676  	buf.WriteString(f.name)
   677  }
   678  
   679  // objectKind returns a description of the object's kind.
   680  func objectKind(obj Object) string {
   681  	switch obj := obj.(type) {
   682  	case *PkgName:
   683  		return "package name"
   684  	case *Const:
   685  		return "constant"
   686  	case *TypeName:
   687  		if obj.IsAlias() {
   688  			return "type alias"
   689  		} else if _, ok := obj.Type().(*TypeParam); ok {
   690  			return "type parameter"
   691  		} else {
   692  			return "defined type"
   693  		}
   694  	case *Var:
   695  		switch obj.Kind() {
   696  		case PackageVar:
   697  			return "package-level variable"
   698  		case LocalVar:
   699  			return "local variable"
   700  		case RecvVar:
   701  			return "receiver"
   702  		case ParamVar:
   703  			return "parameter"
   704  		case ResultVar:
   705  			return "result variable"
   706  		case FieldVar:
   707  			return "struct field"
   708  		}
   709  	case *Func:
   710  		if obj.Signature().Recv() != nil {
   711  			return "method"
   712  		} else {
   713  			return "function"
   714  		}
   715  	case *Label:
   716  		return "label"
   717  	case *Builtin:
   718  		return "built-in function"
   719  	case *Nil:
   720  		return "untyped nil"
   721  	}
   722  	if debug {
   723  		panic(fmt.Sprintf("unknown symbol (%T)", obj))
   724  	}
   725  	return "unknown symbol"
   726  }
   727
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