type 指令支持冒号分隔符

internal/ast/ast.go

@@ -798,11 +798,12 @@ type (
 
 	// A TypeSpec node represents a type declaration (TypeSpec production).
 	TypeSpec struct {
-		Doc     *CommentGroup // associated documentation; or nil
-		Name    *Ident        // type name
-		Assign  token.Pos     // position of '=', if any
-		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
-		Comment *CommentGroup // line comments; or nil
+		Doc      *CommentGroup // associated documentation; or nil
+		Name     *Ident        // type name
+		ColonPos token.Pos     // position of ":" operator (token.NoPos if there is no ":")
+		Assign   token.Pos     // position of '=', if any
+		Type     Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
+		Comment  *CommentGroup // line comments; or nil
 	}
 )
 

internal/parser/parser.go

@@ -2297,7 +2297,10 @@ func (p *parser) parseTypeSpec(doc *ast.CommentGroup, _ token.Token, _ int) ast.
 	// (Global identifiers are resolved in a separate phase after parsing.)
 	spec := &ast.TypeSpec{Doc: doc, Name: ident}
 	p.declare(spec, nil, p.topScope, ast.Typ, ident)
-	if p.tok == token.ASSIGN {
+	if p.tok == token.COLON {
+		spec.ColonPos = p.pos
+		p.next()
+	} else if p.tok == token.ASSIGN {
 		spec.Assign = p.pos
 		p.next()
 	}