go/types: adopt spec terminology, use 'embedded' rather then 'anonyous' field

Commit f8b41236 (https://go-review.googlesource.com/35108) adjusted
the spec to uniformly use 'embedded' rather than 'anonymous' for struct
embedded fields. Adjust go/types' internal terminology.

Provide an additional accessor Var.IsEmbedded().

This is essentially a rename of an internal field and adjustments of
documentation.

Change-Id: Icd07aa192bc5df7a2ee103185fa7e9c55e8f1ac3
Reviewed-on: https://go-review.googlesource.com/112716
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

src/go/types/api.go

@@ -161,14 +161,14 @@ type Info struct {
 	// in package clauses, or symbolic variables t in t := x.(type) of
 	// type switch headers), the corresponding objects are nil.
 	//
-	// For an anonymous field, Defs returns the field *Var it defines.
+	// For an embedded field, Defs returns the field *Var it defines.
 	//
 	// Invariant: Defs[id] == nil || Defs[id].Pos() == id.Pos()
 	Defs map[*ast.Ident]Object
 
 	// Uses maps identifiers to the objects they denote.
 	//
-	// For an anonymous field, Uses returns the *TypeName it denotes.
+	// For an embedded field, Uses returns the *TypeName it denotes.
 	//
 	// Invariant: Uses[id].Pos() != id.Pos()
 	Uses map[*ast.Ident]Object
@@ -239,7 +239,7 @@ func (info *Info) TypeOf(e ast.Expr) Type {
 // ObjectOf returns the object denoted by the specified id,
 // or nil if not found.
 //
-// If id is an anonymous struct field, ObjectOf returns the field (*Var)
+// If id is an embedded struct field, ObjectOf returns the field (*Var)
 // it uses, not the type (*TypeName) it defines.
 //
 // Precondition: the Uses and Defs maps are populated.

src/go/types/lookup.go

@@ -19,7 +19,7 @@ package types
 //	2) the list of all methods (method set) of an interface type; or
 //	3) the list of fields of a struct type.
 //
-// The earlier index entries are the indices of the anonymous struct fields
+// The earlier index entries are the indices of the embedded struct fields
 // traversed to get to the found entry, starting at depth 0.
 //
 // If no entry is found, a nil object is returned. In this case, the returned
@@ -149,7 +149,7 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 					// T is a type name. If e.typ appeared multiple times at
 					// this depth, f.typ appears multiple times at the next
 					// depth.
-					if obj == nil && f.anonymous {
+					if obj == nil && f.embedded {
 						typ, isPtr := deref(f.typ)
 						// TODO(gri) optimization: ignore types that can't
 						// have fields or methods (only Named, Struct, and

src/go/types/methodset.go

@@ -132,7 +132,7 @@ func NewMethodSet(T Type) *MethodSet {
 					// T is a type name. If typ appeared multiple times at
 					// this depth, f.Type appears multiple times at the next
 					// depth.
-					if f.anonymous {
+					if f.embedded {
 						typ, isPtr := deref(f.typ)
 						// TODO(gri) optimization: ignore types that can't
 						// have fields or methods (only Named, Struct, and

src/go/types/object.go

@@ -215,10 +215,10 @@ func (obj *TypeName) IsAlias() bool {
 // A Variable represents a declared variable (including function parameters and results, and struct fields).
 type Var struct {
 	object
-	anonymous bool // if set, the variable is an anonymous struct field, and name is the type name
-	visited   bool // for initialization cycle detection
-	isField   bool // var is struct field
-	used      bool // set if the variable was used
+	embedded bool // if set, the variable is an embedded struct field, and name is the type name
+	visited  bool // for initialization cycle detection
+	isField  bool // var is struct field
+	used     bool // set if the variable was used
 }
 
 // NewVar returns a new variable.
@@ -233,14 +233,18 @@ func NewParam(pos token.Pos, pkg *Package, name string, typ Type) *Var {
 }
 
 // NewField returns a new variable representing a struct field.
-// For anonymous (embedded) fields, the name is the unqualified
-// type name under which the field is accessible.
-func NewField(pos token.Pos, pkg *Package, name string, typ Type, anonymous bool) *Var {
-	return &Var{object: object{nil, pos, pkg, name, typ, 0, token.NoPos}, anonymous: anonymous, isField: true}
+// For embedded fields, the name is the unqualified type name
+/// under which the field is accessible.
+func NewField(pos token.Pos, pkg *Package, name string, typ Type, embedded bool) *Var {
+	return &Var{object: object{nil, pos, pkg, name, typ, 0, token.NoPos}, embedded: embedded, isField: true}
 }
 
-// Anonymous reports whether the variable is an anonymous field.
-func (obj *Var) Anonymous() bool { return obj.anonymous }
+// Anonymous reports whether the variable is an embedded field.
+// Same as Embedded; only present for backward-compatibility.
+func (obj *Var) Anonymous() bool { return obj.embedded }
+
+// Embedded reports whether the variable is an embedded field.
+func (obj *Var) Embedded() bool { return obj.embedded }
 
 // IsField reports whether the variable is a struct field.
 func (obj *Var) IsField() bool { return obj.isField }

src/go/types/predicates.go

@@ -164,13 +164,13 @@ func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
 	case *Struct:
 		// Two struct types are identical if they have the same sequence of fields,
 		// and if corresponding fields have the same names, and identical types,
-		// and identical tags. Two anonymous fields are considered to have the same
+		// and identical tags. Two embedded fields are considered to have the same
 		// name. Lower-case field names from different packages are always different.
 		if y, ok := y.(*Struct); ok {
 			if x.NumFields() == y.NumFields() {
 				for i, f := range x.fields {
 					g := y.fields[i]
-					if f.anonymous != g.anonymous ||
+					if f.embedded != g.embedded ||
 						cmpTags && x.Tag(i) != y.Tag(i) ||
 						!f.sameId(g.pkg, g.name) ||
 						!identical(f.typ, g.typ, cmpTags, p) {

src/go/types/testdata/decls0.src

@@ -97,7 +97,7 @@ type (
 		u, v, a /* ERROR "redeclared" */ float32
 	}
 	S2 struct {
-		S0 // anonymous field
+		S0 // embedded field
 		S0 /* ERROR "redeclared" */ int
 	}
 	S3 struct {

src/go/types/type.go

@@ -141,7 +141,7 @@ func NewStruct(fields []*Var, tags []string) *Struct {
 	return &Struct{fields: fields, tags: tags}
 }
 
-// NumFields returns the number of fields in the struct (including blank and anonymous fields).
+// NumFields returns the number of fields in the struct (including blank and embedded fields).
 func (s *Struct) NumFields() int { return len(s.fields) }
 
 // Field returns the i'th field for 0 <= i < NumFields().

src/go/types/typestring.go

@@ -121,7 +121,7 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 			if i > 0 {
 				buf.WriteString("; ")
 			}
-			if !f.anonymous {
+			if !f.embedded {
 				buf.WriteString(f.name)
 				buf.WriteByte(' ')
 			}
@@ -146,7 +146,7 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 	case *Interface:
 		// We write the source-level methods and embedded types rather
 		// than the actual method set since resolved method signatures
-		// may have non-printable cycles if parameters have anonymous
+		// may have non-printable cycles if parameters have embedded
 		// interface types that (directly or indirectly) embed the
 		// current interface. For instance, consider the result type
 		// of m:

src/go/types/typexpr.go

@@ -658,7 +658,7 @@ func (check *Checker) structType(styp *Struct, e *ast.StructType, path []*TypeNa
 	// current field typ and tag
 	var typ Type
 	var tag string
-	add := func(ident *ast.Ident, anonymous bool, pos token.Pos) {
+	add := func(ident *ast.Ident, embedded bool, pos token.Pos) {
 		if tag != "" && tags == nil {
 			tags = make([]string, len(fields))
 		}
@@ -667,7 +667,7 @@ func (check *Checker) structType(styp *Struct, e *ast.StructType, path []*TypeNa
 		}
 
 		name := ident.Name
-		fld := NewField(pos, check.pkg, name, typ, anonymous)
+		fld := NewField(pos, check.pkg, name, typ, embedded)
 		// spec: "Within a struct, non-blank field names must be unique."
 		if name == "_" || check.declareInSet(&fset, pos, fld) {
 			fields = append(fields, fld)
@@ -684,13 +684,13 @@ func (check *Checker) structType(styp *Struct, e *ast.StructType, path []*TypeNa
 				add(name, false, name.Pos())
 			}
 		} else {
-			// anonymous field
+			// embedded field
 			// spec: "An embedded type must be specified as a type name T or as a pointer
 			// to a non-interface type name *T, and T itself may not be a pointer type."
 			pos := f.Type.Pos()
-			name := anonymousFieldIdent(f.Type)
+			name := embeddedFieldIdent(f.Type)
 			if name == nil {
-				check.invalidAST(pos, "anonymous field type %s has no name", f.Type)
+				check.invalidAST(pos, "embedded field type %s has no name", f.Type)
 				continue
 			}
 			t, isPtr := deref(typ)
@@ -705,17 +705,17 @@ func (check *Checker) structType(styp *Struct, e *ast.StructType, path []*TypeNa
 
 				// unsafe.Pointer is treated like a regular pointer
 				if t.kind == UnsafePointer {
-					check.errorf(pos, "anonymous field type cannot be unsafe.Pointer")
+					check.errorf(pos, "embedded field type cannot be unsafe.Pointer")
 					continue
 				}
 
 			case *Pointer:
-				check.errorf(pos, "anonymous field type cannot be a pointer")
+				check.errorf(pos, "embedded field type cannot be a pointer")
 				continue
 
 			case *Interface:
 				if isPtr {
-					check.errorf(pos, "anonymous field type cannot be a pointer to an interface")
+					check.errorf(pos, "embedded field type cannot be a pointer to an interface")
 					continue
 				}
 			}
@@ -727,17 +727,17 @@ func (check *Checker) structType(styp *Struct, e *ast.StructType, path []*TypeNa
 	styp.tags = tags
 }
 
-func anonymousFieldIdent(e ast.Expr) *ast.Ident {
+func embeddedFieldIdent(e ast.Expr) *ast.Ident {
 	switch e := e.(type) {
 	case *ast.Ident:
 		return e
 	case *ast.StarExpr:
 		// *T is valid, but **T is not
 		if _, ok := e.X.(*ast.StarExpr); !ok {
-			return anonymousFieldIdent(e.X)
+			return embeddedFieldIdent(e.X)
 		}
 	case *ast.SelectorExpr:
 		return e.Sel
 	}
-	return nil // invalid anonymous field
+	return nil // invalid embedded field
 }