Simplify assignTypeToParameterAndFixTypeParameters (microsoft#17706)

Andy · web-flow · commit 2c4361aadf40 · 2017-08-10T06:51:50.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -16586,14 +16586,14 @@ namespace ts {
 
         // When contextual typing assigns a type to a parameter that contains a binding pattern, we also need to push
         // the destructured type into the contained binding elements.
-        function assignBindingElementTypes(node: VariableLikeDeclaration) {
-            if (isBindingPattern(node.name)) {
-                for (const element of node.name.elements) {
-                    if (!isOmittedExpression(element)) {
-                        if (element.name.kind === SyntaxKind.Identifier) {
-                            getSymbolLinks(getSymbolOfNode(element)).type = getTypeForBindingElement(element);
-                        }
-                        assignBindingElementTypes(element);
+        function assignBindingElementTypes(pattern: BindingPattern) {
+            for (const element of pattern.elements) {
+                if (!isOmittedExpression(element)) {
+                    if (element.name.kind === SyntaxKind.Identifier) {
+                        getSymbolLinks(getSymbolOfNode(element)).type = getTypeForBindingElement(element);
+                    }
+                    else {
+                        assignBindingElementTypes(element.name);
                     }
                 }
             }
@@ -16603,13 +16603,14 @@ namespace ts {
             const links = getSymbolLinks(parameter);
             if (!links.type) {
                 links.type = contextualType;
-                const name = getNameOfDeclaration(parameter.valueDeclaration);
-                // if inference didn't come up with anything but {}, fall back to the binding pattern if present.
-                if (links.type === emptyObjectType &&
-                    (name.kind === SyntaxKind.ObjectBindingPattern || name.kind === SyntaxKind.ArrayBindingPattern)) {
-                    links.type = getTypeFromBindingPattern(<BindingPattern>name);
+                const decl = parameter.valueDeclaration as ParameterDeclaration;
+                if (decl.name.kind !== SyntaxKind.Identifier) {
+                    // if inference didn't come up with anything but {}, fall back to the binding pattern if present.
+                    if (links.type === emptyObjectType) {
+                        links.type = getTypeFromBindingPattern(decl.name);
+                    }
+                    assignBindingElementTypes(decl.name);
                 }
-                assignBindingElementTypes(<ParameterDeclaration>parameter.valueDeclaration);
             }
         }
 
