go/types: propagate *ast.LabeledStmt in blockBranches properly

Fixes #70974

Change-Id: I330c0ae53dcbcdb173ab514ee94f2ca53944df09
GitHub-Last-Rev: 7c2b740
GitHub-Pull-Request: #70976
Reviewed-on: https://go-review.googlesource.com/c/go/+/638257
Reviewed-by: Michael Knyszek <[email protected]>
Auto-Submit: Alan Donovan <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Commit-Queue: Alan Donovan <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

src/cmd/compile/internal/types2/labels.go

@@ -112,8 +112,8 @@ func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *syntax.Lab
 		return varDeclPos.IsKnown() && slices.Contains(badJumps, jmp)
 	}
 
-	var stmtBranches func(syntax.Stmt)
-	stmtBranches = func(s syntax.Stmt) {
+	var stmtBranches func(*syntax.LabeledStmt, syntax.Stmt)
+	stmtBranches = func(lstmt *syntax.LabeledStmt, s syntax.Stmt) {
 		switch s := s.(type) {
 		case *syntax.DeclStmt:
 			for _, d := range s.DeclList {
@@ -163,7 +163,7 @@ func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *syntax.Lab
 				fwdJumps = fwdJumps[:i]
 				lstmt = s
 			}
-			stmtBranches(s.Stmt)
+			stmtBranches(lstmt, s.Stmt)
 
 		case *syntax.BranchStmt:
 			if s.Label == nil {
@@ -232,9 +232,9 @@ func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *syntax.Lab
 			fwdJumps = append(fwdJumps, check.blockBranches(all, b, lstmt, s.List)...)
 
 		case *syntax.IfStmt:
-			stmtBranches(s.Then)
+			stmtBranches(lstmt, s.Then)
 			if s.Else != nil {
-				stmtBranches(s.Else)
+				stmtBranches(lstmt, s.Else)
 			}
 
 		case *syntax.SwitchStmt:
@@ -250,12 +250,12 @@ func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *syntax.Lab
 			}
 
 		case *syntax.ForStmt:
-			stmtBranches(s.Body)
+			stmtBranches(lstmt, s.Body)
 		}
 	}
 
 	for _, s := range list {
-		stmtBranches(s)
+		stmtBranches(nil, s)
 	}
 
 	return fwdJumps

src/go/types/labels.go

@@ -119,8 +119,8 @@ func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *ast.Labele
 		fwdJumps = append(fwdJumps, check.blockBranches(all, b, lstmt, list)...)
 	}
 
-	var stmtBranches func(ast.Stmt)
-	stmtBranches = func(s ast.Stmt) {
+	var stmtBranches func(*ast.LabeledStmt, ast.Stmt)
+	stmtBranches = func(lstmt *ast.LabeledStmt, s ast.Stmt) {
 		switch s := s.(type) {
 		case *ast.DeclStmt:
 			if d, _ := s.Decl.(*ast.GenDecl); d != nil && d.Tok == token.VAR {
@@ -168,7 +168,7 @@ func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *ast.Labele
 				fwdJumps = fwdJumps[:i]
 				lstmt = s
 			}
-			stmtBranches(s.Stmt)
+			stmtBranches(lstmt, s.Stmt)
 
 		case *ast.BranchStmt:
 			if s.Label == nil {
@@ -235,36 +235,36 @@ func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *ast.Labele
 			blockBranches(lstmt, s.List)
 
 		case *ast.IfStmt:
-			stmtBranches(s.Body)
+			stmtBranches(lstmt, s.Body)
 			if s.Else != nil {
-				stmtBranches(s.Else)
+				stmtBranches(lstmt, s.Else)
 			}
 
 		case *ast.CaseClause:
 			blockBranches(nil, s.Body)
 
 		case *ast.SwitchStmt:
-			stmtBranches(s.Body)
+			stmtBranches(lstmt, s.Body)
 
 		case *ast.TypeSwitchStmt:
-			stmtBranches(s.Body)
+			stmtBranches(lstmt, s.Body)
 
 		case *ast.CommClause:
 			blockBranches(nil, s.Body)
 
 		case *ast.SelectStmt:
-			stmtBranches(s.Body)
+			stmtBranches(lstmt, s.Body)
 
 		case *ast.ForStmt:
-			stmtBranches(s.Body)
+			stmtBranches(lstmt, s.Body)
 
 		case *ast.RangeStmt:
-			stmtBranches(s.Body)
+			stmtBranches(lstmt, s.Body)
 		}
 	}
 
 	for _, s := range list {
-		stmtBranches(s)
+		stmtBranches(nil, s)
 	}
 
 	return fwdJumps

src/internal/types/testdata/check/doubled_labels.go

@@ -0,0 +1,26 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func _() {
+outer:
+inner:
+	for {
+		continue inner
+		break inner
+	}
+	goto outer
+}
+
+func _() {
+outer:
+inner:
+	for {
+		continue inner
+		continue outer /* ERROR "invalid continue label outer" */
+		break outer    /* ERROR "invalid break label outer" */
+	}
+	goto outer
+}

src/internal/types/testdata/check/issue70974.go

@@ -0,0 +1,27 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func _() {
+outer:
+	for {
+		break outer
+	}
+
+	for {
+		break outer /* ERROR "invalid break label outer" */
+	}
+}
+
+func _() {
+outer:
+	for {
+		continue outer
+	}
+
+	for {
+		continue outer /* ERROR "invalid continue label outer" */
+	}
+}