Remove DestructuringAssignment and Generator flags

Author: rbuckton

src/compiler/binder.ts

@@ -3189,7 +3189,6 @@ namespace ts {
         let transformFlags = subtreeFlags;
         const expression = node.expression;
         const expressionKind = expression.kind;
-        const expressionTransformFlags = expression.transformFlags;
 
         // If the node is synthesized, it means the emitter put the parentheses there,
         // not the user. If we didn't want them, the emitter would not have put them
@@ -3199,12 +3198,6 @@ namespace ts {
             transformFlags |= TransformFlags.AssertTypeScript;
         }
 
-        // If the expression of a ParenthesizedExpression is a destructuring assignment,
-        // then the ParenthesizedExpression is a destructuring assignment.
-        if (expressionTransformFlags & TransformFlags.DestructuringAssignment) {
-            transformFlags |= TransformFlags.DestructuringAssignment;
-        }
-
         node.transformFlags = transformFlags | TransformFlags.HasComputedFlags;
         return transformFlags & ~TransformFlags.OuterExpressionExcludes;
     }
@@ -3585,15 +3578,7 @@ namespace ts {
     }
 
     function computeExpressionStatement(node: ExpressionStatement, subtreeFlags: TransformFlags) {
-        let transformFlags = subtreeFlags;
-
-        // If the expression of an expression statement is a destructuring assignment,
-        // then we treat the statement as ES6 so that we can indicate that we do not
-        // need to hold on to the right-hand side.
-        if (node.expression.transformFlags & TransformFlags.DestructuringAssignment) {
-            transformFlags |= TransformFlags.AssertES2015;
-        }
-
+        const transformFlags = subtreeFlags;
         node.transformFlags = transformFlags | TransformFlags.HasComputedFlags;
         return transformFlags & ~TransformFlags.NodeExcludes;
     }

src/compiler/transformers/generators.ts

@@ -316,7 +316,7 @@ namespace ts {
             else if (inGeneratorFunctionBody) {
                 return visitJavaScriptInGeneratorFunctionBody(node);
             }
-            else if (transformFlags & TransformFlags.Generator) {
+            else if (isFunctionLikeDeclaration(node) && node.asteriskToken) {
                 return visitGenerator(node);
             }
             else if (transformFlags & TransformFlags.ContainsGenerator) {

src/compiler/transformers/module/module.ts

@@ -537,8 +537,8 @@ namespace ts {
             if (isImportCall(node)) {
                 return visitImportCallExpression(node);
             }
-            else if (node.transformFlags & TransformFlags.DestructuringAssignment && isBinaryExpression(node)) {
-                return visitDestructuringAssignment(node as DestructuringAssignment);
+            else if (isDestructuringAssignment(node)) {
+                return visitDestructuringAssignment(node);
             }
             else {
                 return visitEachChild(node, moduleExpressionElementVisitor, context);

src/compiler/transformers/module/system.ts

@@ -1463,9 +1463,8 @@ namespace ts {
          * @param node The node to visit.
          */
         function destructuringAndImportCallVisitor(node: Node): VisitResult<Node> {
-            if (node.transformFlags & TransformFlags.DestructuringAssignment
-                && node.kind === SyntaxKind.BinaryExpression) {
-                return visitDestructuringAssignment(<DestructuringAssignment>node);
+            if (isDestructuringAssignment(node)) {
+                return visitDestructuringAssignment(node);
             }
             else if (isImportCall(node)) {
                 return visitImportCallExpression(node);

src/compiler/types.ts

@@ -5049,21 +5049,20 @@ namespace ts {
         ContainsES2016 = 1 << 5,
         ContainsES2015 = 1 << 6,
         ContainsGenerator = 1 << 7,
-        DestructuringAssignment = 1 << 8,
-        ContainsDestructuringAssignment = 1 << 9,
+        ContainsDestructuringAssignment = 1 << 8,
 
         // Markers
         // - Flags used to indicate that a subtree contains a specific transformation.
-        ContainsTypeScriptClassSyntax = 1 << 10,                // Decorators, Property Initializers, Parameter Property Initializers
-        ContainsLexicalThis = 1 << 11,
-        ContainsRestOrSpread = 1 << 12,
-        ContainsObjectRestOrSpread = 1 << 13,
-        ContainsComputedPropertyName = 1 << 14,
-        ContainsBlockScopedBinding = 1 << 15,
-        ContainsBindingPattern = 1 << 16,
-        ContainsYield = 1 << 17,
-        ContainsHoistedDeclarationOrCompletion = 1 << 18,
-        ContainsDynamicImport = 1 << 19,
+        ContainsTypeScriptClassSyntax = 1 << 9,                // Decorators, Property Initializers, Parameter Property Initializers
+        ContainsLexicalThis = 1 << 10,
+        ContainsRestOrSpread = 1 << 11,
+        ContainsObjectRestOrSpread = 1 << 12,
+        ContainsComputedPropertyName = 1 << 13,
+        ContainsBlockScopedBinding = 1 << 14,
+        ContainsBindingPattern = 1 << 15,
+        ContainsYield = 1 << 16,
+        ContainsHoistedDeclarationOrCompletion = 1 << 17,
+        ContainsDynamicImport = 1 << 18,
 
         // Please leave this as 1 << 29.
         // It is the maximum bit we can set before we outgrow the size of a v8 small integer (SMI) on an x86 system.
@@ -5080,12 +5079,12 @@ namespace ts {
         AssertES2016 = ContainsES2016,
         AssertES2015 = ContainsES2015,
         AssertGenerator = ContainsGenerator,
-        AssertDestructuringAssignment = DestructuringAssignment | ContainsDestructuringAssignment,
+        AssertDestructuringAssignment = ContainsDestructuringAssignment,
 
         // Scope Exclusions
         // - Bitmasks that exclude flags from propagating out of a specific context
         //   into the subtree flags of their container.
-        OuterExpressionExcludes = DestructuringAssignment | HasComputedFlags,
+        OuterExpressionExcludes = HasComputedFlags,
         PropertyAccessExcludes = OuterExpressionExcludes,
         NodeExcludes = PropertyAccessExcludes,
         ArrowFunctionExcludes = NodeExcludes | ContainsTypeScriptClassSyntax | ContainsBlockScopedBinding | ContainsYield | ContainsHoistedDeclarationOrCompletion | ContainsBindingPattern | ContainsObjectRestOrSpread,