Revise return control flow graph construction logic

ahejlsberg · ahejlsberg · commit 041d04577ef7 · 2017-11-17T09:05:46.000-08:00
diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
@@ -506,16 +506,14 @@ namespace ts {
                 const isIIFE = containerFlags & ContainerFlags.IsFunctionExpression && !hasModifier(node, ModifierFlags.Async) && !!getImmediatelyInvokedFunctionExpression(node);
                 // A non-async IIFE is considered part of the containing control flow. Return statements behave
                 // similarly to break statements that exit to a label just past the statement body.
-                if (isIIFE) {
-                    currentReturnTarget = createBranchLabel();
-                }
-                else {
+                if (!isIIFE) {
                     currentFlow = { flags: FlowFlags.Start };
                     if (containerFlags & (ContainerFlags.IsFunctionExpression | ContainerFlags.IsObjectLiteralOrClassExpressionMethod)) {
                         (<FlowStart>currentFlow).container = <FunctionExpression | ArrowFunction | MethodDeclaration>node;
                     }
-                    currentReturnTarget = node.kind === SyntaxKind.Constructor ? createBranchLabel() : undefined;
                 }
+                // We create a return control flow graph for IIFEs and constructors. For constructors
+                // we use the return control flow graph in strict property intialization checks.
                 currentReturnTarget = isIIFE || node.kind === SyntaxKind.Constructor ? createBranchLabel() : undefined;
                 currentBreakTarget = undefined;
                 currentContinueTarget = undefined;
@@ -531,15 +529,14 @@ namespace ts {
                 if (node.kind === SyntaxKind.SourceFile) {
                     node.flags |= emitFlags;
                 }
-                if (isIIFE) {
+                if (currentReturnTarget) {
                     addAntecedent(currentReturnTarget, currentFlow);
                     currentFlow = finishFlowLabel(currentReturnTarget);
-                }
-                else {
                     if (node.kind === SyntaxKind.Constructor) {
-                        addAntecedent(currentReturnTarget, currentFlow);
                         (<ConstructorDeclaration>node).returnFlowNode = currentFlow;
                     }
+                }
+                if (!isIIFE) {
                     currentFlow = saveCurrentFlow;
                 }
                 currentBreakTarget = saveBreakTarget;
