permit only one method name per method signature in interface types

(in sync with spec CL 35047)

R=rsc
DELTA=44  (4 added, 8 deleted, 32 changed)
OCL=35048
CL=35054

src/pkg/go/parser/parser.go

@@ -305,16 +305,13 @@ func (p *parser) parseIdent() *ast.Ident {
 }
 
 
-func (p *parser) parseIdentList(x ast.Expr) []*ast.Ident {
+func (p *parser) parseIdentList() []*ast.Ident {
 	if p.trace {
 		defer un(trace(p, "IdentList"));
 	}
 
 	list := vector.New(0);
-	if x == nil {
-		x = p.parseIdent();
-	}
-	list.Push(x);
+	list.Push(p.parseIdent());
 	for p.tok == token.COMMA {
 		p.next();
 		list.Push(p.parseIdent());
@@ -587,7 +584,7 @@ func (p *parser) parseParameterList(ellipsisOk bool) []*ast.Field {
 
 		for p.tok == token.COMMA {
 			p.next();
-			idents := p.parseIdentList(nil);
+			idents := p.parseIdentList();
 			typ := p.parseParameterType(ellipsisOk);
 			list.Push(&ast.Field{nil, idents, typ, nil, nil});
 		}
@@ -679,9 +676,9 @@ func (p *parser) parseMethodSpec() *ast.Field {
 	var idents []*ast.Ident;
 	var typ ast.Expr;
 	x := p.parseQualifiedIdent();
-	if _, isIdent := x.(*ast.Ident); isIdent && (p.tok == token.COMMA || p.tok == token.LPAREN) {
-		// methods
-		idents = p.parseIdentList(x);
+	if ident, isIdent := x.(*ast.Ident); isIdent && p.tok == token.LPAREN {
+		// method
+		idents = []*ast.Ident{ident};
 		params, results := p.parseSignature();
 		typ = &ast.FuncType{noPos, params, results};
 	} else {
@@ -1748,7 +1745,7 @@ func parseConstSpec(p *parser, doc *ast.CommentGroup, getSemi bool) (spec ast.Sp
 		defer un(trace(p, "ConstSpec"));
 	}
 
-	idents := p.parseIdentList(nil);
+	idents := p.parseIdentList();
 	typ := p.tryType();
 	var values []ast.Expr;
 	if typ != nil || p.tok == token.ASSIGN {
@@ -1779,7 +1776,7 @@ func parseVarSpec(p *parser, doc *ast.CommentGroup, getSemi bool) (spec ast.Spec
 		defer un(trace(p, "VarSpec"));
 	}
 
-	idents := p.parseIdentList(nil);
+	idents := p.parseIdentList();
 	typ := p.tryType();
 	var values []ast.Expr;
 	if typ == nil || p.tok == token.ASSIGN {

src/pkg/go/printer/printer.go

@@ -610,12 +610,9 @@ func (p *printer) fieldList(lbrace token.Position, list []*ast.Field, rbrace tok
 	} else { // interface
 		for i, f := range list {
 			p.leadComment(f.Doc);
-			p.identList(f.Names);
-			if len(f.Names) > 1 {
-				p.print(blank);
-			}
 			if ftyp, isFtyp := f.Type.(*ast.FuncType); isFtyp {
-				// method(s)
+				// method
+				p.expr(f.Names[0]);  // exactly one name
 				p.signature(ftyp.Params, ftyp.Results);
 			} else {
 				// embedded interface

src/pkg/go/printer/testdata/comments.go

@@ -42,20 +42,21 @@ type SZ interface {}
 
 // The I0 interface; no method is exported.
 type I0 interface {
-	f, g (x int) int;  // 2 unexported methods
+	f(x int) int;  // unexported method
 }
 
 // The I1 interface; some methods are not exported.
 type I1 interface {
 	I0;
-	F, G (x float) float;  // 2 exported methods
-	H, g (x int) int;  // 1 unexported method
+	F(x float) float;  // exported methods
+	g(x int) int;  // unexported method
 }
 
 // The I2 interface; all methods are exported.
 type I1 interface {
 	I0;
-	F, G (x float) float;  // 2 exported methods
+	F(x float) float;  // exported method
+	G(x float) float;  // exported method
 }
 
 // This comment group should be separated

src/pkg/go/printer/testdata/comments.golden

@@ -42,20 +42,21 @@ type SZ interface{}
 
 // The I0 interface; no method is exported.
 type I0 interface {
-	f, g (x int) int;	// 2 unexported methods
+	f(x int) int;	// unexported method
 }
 
 // The I1 interface; some methods are not exported.
 type I1 interface {
 	I0;
-	F, G (x float) float;	// 2 exported methods
-	H, g (x int) int;		// 1 unexported method
+	F(x float) float;	// exported methods
+	g(x int) int;		// unexported method
 }
 
 // The I2 interface; all methods are exported.
 type I1 interface {
 	I0;
-	F, G (x float) float;	// 2 exported methods
+	F(x float) float;	// exported method
+	G(x float) float;	// exported method
 }
 
 // This comment group should be separated

src/pkg/go/printer/testdata/comments.x

@@ -35,13 +35,13 @@ type I0 interface {
 // The I1 interface; some methods are not exported.
 type I1 interface {
 	I0;
-	F, G (x float) float;
-	H(x int) int;
+	F(x float) float;
 	// contains unexported methods
 }
 
 // The I2 interface; all methods are exported.
 type I1 interface {
 	I0;
-	F, G (x float) float;
+	F(x float) float;
+	G(x float) float;
 }

src/pkg/go/printer/testdata/declarations.go

@@ -215,18 +215,18 @@ type _ interface {
 
 type _ interface {
 	f();
-	fffff, g ();
+	fffff();
 }
 
 type _ interface {
 	EI;
 	f();
-	fffff, g ();
+	fffffg();
 }
 
 type _ interface {  // this comment must not change indentation
 	EI;  // here's a comment
-	f();  // no blank between f and ()
-	fffff, g ();  // blank between identifiers and ()
-	gggggggggggg, hhhhhhhhhhhhhh (x, y, z int) ();  // hurray
+	f();  // no blank between identifier and ()
+	fffff();  // no blank between identifier and ()
+	gggggggggggg(x, y, z int) ();  // hurray
 }

src/pkg/go/printer/testdata/declarations.golden

@@ -209,18 +209,18 @@ type _ interface {
 
 type _ interface {
 	f();
-	fffff, g ();
+	fffff();
 }
 
 type _ interface {
 	EI;
 	f();
-	fffff, g ();
+	fffffg();
 }
 
 type _ interface {	// this comment must not change indentation
 	EI;							// here's a comment
-	f();										// no blank between f and ()
-	fffff, g ();								// blank between identifiers and ()
-	gggggggggggg, hhhhhhhhhhhhhh (x, y, z int);	// hurray
+	f();						// no blank between identifier and ()
+	fffff();					// no blank between identifier and ()
+	gggggggggggg(x, y, z int);	// hurray
 }