- always format blocks with closing } on a new line, even if empty

- at the moment this also affects single-line function declarations
  because we have disabled them at the moment (but not single-line
  function literals)

R=rsc
http://go/go-review/1016040

src/pkg/go/printer/nodes.go

@@ -614,13 +614,11 @@ func (p *printer) stmtList(list []ast.Stmt, _indent int) {
 }
 
 
-// Sets multiLine to true if the block spans multiple lines.
-func (p *printer) block(s *ast.BlockStmt, indent int, multiLine *bool) {
+// block prints an *ast.BlockStmt; it always spans at least two lines.
+func (p *printer) block(s *ast.BlockStmt, indent int) {
 	p.print(s.Pos(), token.LBRACE);
-	if len(s.List) > 0 || p.commentBefore(s.Rbrace) {
 	p.stmtList(s.List, indent);
 	p.linebreak(s.Rbrace.Line, 1, maxStmtNewlines, ignore, true);
-	}
 	p.print(s.Rbrace, token.RBRACE);
 }
 
@@ -731,24 +729,25 @@ func (p *printer) stmt(stmt ast.Stmt, multiLine *bool) (optSemi bool) {
 		}
 
 	case *ast.BlockStmt:
-		p.block(s, 1, multiLine);
+		p.block(s, 1);
+		*multiLine = true;
 		optSemi = true;
 
 	case *ast.IfStmt:
 		p.print(token.IF);
 		p.controlClause(false, s.Init, s.Cond, nil);
-		p.block(s.Body, 1, multiLine);
+		p.block(s.Body, 1);
+		*multiLine = true;
 		optSemi = true;
 		if s.Else != nil {
 			p.print(blank, token.ELSE, blank);
 			switch s.Else.(type) {
 			case *ast.BlockStmt, *ast.IfStmt:
-				optSemi = p.stmt(s.Else, multiLine);
+				optSemi = p.stmt(s.Else, ignoreMultiLine);
 			default:
 				p.print(token.LBRACE, indent, formfeed);
 				p.stmt(s.Else, ignoreMultiLine);
 				p.print(unindent, formfeed, token.RBRACE);
-				*multiLine = true;
 			}
 		}
 
@@ -766,7 +765,8 @@ func (p *printer) stmt(stmt ast.Stmt, multiLine *bool) (optSemi bool) {
 	case *ast.SwitchStmt:
 		p.print(token.SWITCH);
 		p.controlClause(false, s.Init, s.Tag, nil);
-		p.block(s.Body, 0, multiLine);
+		p.block(s.Body, 0);
+		*multiLine = true;
 		optSemi = true;
 
 	case *ast.TypeCaseClause:
@@ -784,13 +784,14 @@ func (p *printer) stmt(stmt ast.Stmt, multiLine *bool) (optSemi bool) {
 		p.print(token.SWITCH);
 		if s.Init != nil {
 			p.print(blank);
-			p.stmt(s.Init, multiLine);
+			p.stmt(s.Init, ignoreMultiLine);
 			p.print(token.SEMICOLON);
 		}
 		p.print(blank);
-		p.stmt(s.Assign, multiLine);
+		p.stmt(s.Assign, ignoreMultiLine);
 		p.print(blank);
-		p.block(s.Body, 0, multiLine);
+		p.block(s.Body, 0);
+		*multiLine = true;
 		optSemi = true;
 
 	case *ast.CommClause:
@@ -810,13 +811,15 @@ func (p *printer) stmt(stmt ast.Stmt, multiLine *bool) (optSemi bool) {
 
 	case *ast.SelectStmt:
 		p.print(token.SELECT, blank);
-		p.block(s.Body, 0, multiLine);
+		p.block(s.Body, 0);
+		*multiLine = true;
 		optSemi = true;
 
 	case *ast.ForStmt:
 		p.print(token.FOR);
 		p.controlClause(true, s.Init, s.Cond, s.Post);
-		p.block(s.Body, 1, multiLine);
+		p.block(s.Body, 1);
+		*multiLine = true;
 		optSemi = true;
 
 	case *ast.RangeStmt:
@@ -829,7 +832,8 @@ func (p *printer) stmt(stmt ast.Stmt, multiLine *bool) (optSemi bool) {
 		p.print(blank, s.TokPos, s.Tok, blank, token.RANGE, blank);
 		p.expr(s.X, multiLine);
 		p.print(blank);
-		p.block(s.Body, 1, multiLine);
+		p.block(s.Body, 1);
+		*multiLine = true;
 		optSemi = true;
 
 	default:
@@ -963,9 +967,11 @@ func (p *printer) genDecl(d *ast.GenDecl, context declContext, multiLine *bool)
 
 
 func (p *printer) isOneLiner(b *ast.BlockStmt) bool {
-	if len(b.List) != 1 || p.commentBefore(b.Rbrace) {
-		// too many statements or there is a comment - all bets are off
-		return false;
+	switch {
+	case len(b.List) > 1 || p.commentBefore(b.Rbrace):
+		return false;  // too many statements or there is a comment - all bets are off
+	case len(b.List) == 0:
+		return true;  // empty block and no comments
 	}
 
 	// test-print the statement and see if it would fit
@@ -1001,14 +1007,19 @@ func (p *printer) funcBody(b *ast.BlockStmt, isLit bool, multiLine *bool) {
 		if isLit {
 			sep = blank;
 		}
+		if len(b.List) > 0 {
 			p.print(sep, b.Pos(), token.LBRACE, blank);
 			p.stmt(b.List[0], ignoreMultiLine);
 			p.print(blank, b.Rbrace, token.RBRACE);
+		} else {
+			p.print(sep, b.Pos(), token.LBRACE, b.Rbrace, token.RBRACE);
+		}
 		return;
 	}
 
 	p.print(blank);
-	p.block(b, 1, multiLine);
+	p.block(b, 1);
+	*multiLine = true;
 }
 
 

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

@@ -111,9 +111,11 @@ func typeswitch(x interface{}) {
 	default:
 	}
 
-	switch x.(type) {}
+	switch x.(type) {
+	}
 
-	switch v0, ok := x.(int); v := x.(type) {}
+	switch v0, ok := x.(int); v := x.(type) {
+	}
 
 	switch v0, ok := x.(int); x.(type) {
 	case bool, int, float:

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

@@ -445,13 +445,19 @@ func _() {
 
 
 // formatting of consecutive single-line functions
-func _() {}
-func _() {}
-func _() {}
+func _() {
+}
+func _() {
+}
+func _() {
+}
 
-func _() {}	// an empty line before this function
-func _() {}
-func _() {}
+func _() {
+}	// an empty line before this function
+func _() {
+}
+func _() {
+}
 
 func _() {
 	f(1, 2, 3);

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

@@ -6,16 +6,23 @@ package statements
 
 var expr bool
 
-func use(x interface{}) {}
+func use(x interface{}) {
+}
 
 // Formatting of if-statement headers.
 func _() {
-	if {}
-	if {}	// no semicolon printed
-	if expr {}
-	if expr {}	// no semicolon printed
-	if expr {}	// no parens printed
-	if expr {}	// no semicolon and parens printed
+	if {
+	}
+	if {
+	}	// no semicolon printed
+	if expr {
+	}
+	if expr {
+	}	// no semicolon printed
+	if expr {
+	}	// no parens printed
+	if expr {
+	}	// no semicolon and parens printed
 	if x := expr; {
 		use(x);
 	}
@@ -27,12 +34,18 @@ func _() {
 
 // Formatting of switch-statement headers.
 func _() {
-	switch {}
-	switch {}	// no semicolon printed
-	switch expr {}
-	switch expr {}	// no semicolon printed
-	switch expr {}	// no parens printed
-	switch expr {}	// no semicolon and parens printed
+	switch {
+	}
+	switch {
+	}	// no semicolon printed
+	switch expr {
+	}
+	switch expr {
+	}	// no semicolon printed
+	switch expr {
+	}	// no parens printed
+	switch expr {
+	}	// no semicolon and parens printed
 	switch x := expr; {
 	default:
 		use(
@@ -47,7 +60,8 @@ func _() {
 
 // Formatting of switch statement bodies.
 func _() {
-	switch {}
+	switch {
+	}
 
 	switch x := 0; x {
 	case 1:
@@ -100,23 +114,31 @@ func _() {
 
 // Formatting of for-statement headers.
 func _() {
-	for {}
-	for expr {}
-	for expr {}	// no parens printed
-	for {}		// no semicolons printed
+	for {
+	}
+	for expr {
+	}
+	for expr {
+	}	// no parens printed
+	for {
+	}	// no semicolons printed
 	for x := expr; ; {
 		use(x);
 	}
-	for expr {}	// no semicolons printed
-	for expr {}	// no semicolons and parens printed
-	for ; ; expr = false {}
+	for expr {
+	}	// no semicolons printed
+	for expr {
+	}	// no semicolons and parens printed
+	for ; ; expr = false {
+	}
 	for x := expr; expr; {
 		use(x);
 	}
 	for x := expr; ; expr = false {
 		use(x);
 	}
-	for ; expr; expr = false {}
+	for ; expr; expr = false {
+	}
 	for x := expr; expr; expr = false {
 		use(x);
 	}