Expose getTypeOfArrayLiteralOrObjectLiteralDestructuringAssignment with better name (#31564)

Author: rbuckton

src/compiler/checker.ts

@@ -182,6 +182,10 @@ namespace ts {
                 node = getParseTreeNode(node);
                 return node ? getTypeOfNode(node) : errorType;
             },
+            getTypeOfAssignmentPattern: nodeIn => {
+                const node = getParseTreeNode(nodeIn, isAssignmentPattern);
+                return node && getTypeOfAssignmentPattern(node) || errorType;
+            },
             getPropertySymbolOfDestructuringAssignment: locationIn => {
                 const location = getParseTreeNode(locationIn, isIdentifier);
                 return location ? getPropertySymbolOfDestructuringAssignment(location) : undefined;
@@ -29982,7 +29986,7 @@ namespace ts {
         //     }
         // [ a ] from
         //     [a] = [ some array ...]
-        function getTypeOfArrayLiteralOrObjectLiteralDestructuringAssignment(expr: Expression): Type {
+        function getTypeOfAssignmentPattern(expr: AssignmentPattern): Type | undefined {
             Debug.assert(expr.kind === SyntaxKind.ObjectLiteralExpression || expr.kind === SyntaxKind.ArrayLiteralExpression);
             // If this is from "for of"
             //     for ( { a } of elems) {
@@ -30001,17 +30005,16 @@ namespace ts {
             //     for ({ skills: { primary, secondary } } = multiRobot, i = 0; i < 1; i++) {
             if (expr.parent.kind === SyntaxKind.PropertyAssignment) {
                 const node = cast(expr.parent.parent, isObjectLiteralExpression);
-                const typeOfParentObjectLiteral = getTypeOfArrayLiteralOrObjectLiteralDestructuringAssignment(node);
+                const typeOfParentObjectLiteral = getTypeOfAssignmentPattern(node) || errorType;
                 const propertyIndex = indexOfNode(node.properties, expr.parent);
-                return checkObjectLiteralDestructuringPropertyAssignment(node, typeOfParentObjectLiteral || errorType, propertyIndex)!; // TODO: GH#18217
+                return checkObjectLiteralDestructuringPropertyAssignment(node, typeOfParentObjectLiteral, propertyIndex);
             }
             // Array literal assignment - array destructuring pattern
-            Debug.assert(expr.parent.kind === SyntaxKind.ArrayLiteralExpression);
+            const node = cast(expr.parent, isArrayLiteralExpression);
             //    [{ property1: p1, property2 }] = elems;
-            const typeOfArrayLiteral = getTypeOfArrayLiteralOrObjectLiteralDestructuringAssignment(<Expression>expr.parent);
-            const elementType = checkIteratedTypeOrElementType(typeOfArrayLiteral || errorType, expr.parent, /*allowStringInput*/ false, /*allowAsyncIterables*/ false) || errorType;
-            return checkArrayLiteralDestructuringElementAssignment(<ArrayLiteralExpression>expr.parent, typeOfArrayLiteral,
-                (<ArrayLiteralExpression>expr.parent).elements.indexOf(expr), elementType || errorType)!; // TODO: GH#18217
+            const typeOfArrayLiteral = getTypeOfAssignmentPattern(node) || errorType;
+            const elementType = checkIteratedTypeOrElementType(typeOfArrayLiteral, expr.parent, /*allowStringInput*/ false, /*allowAsyncIterables*/ false) || errorType;
+            return checkArrayLiteralDestructuringElementAssignment(node, typeOfArrayLiteral, node.elements.indexOf(expr), elementType);
         }
 
         // Gets the property symbol corresponding to the property in destructuring assignment
@@ -30022,7 +30025,7 @@ namespace ts {
         //     [a] = [ property1, property2 ]
         function getPropertySymbolOfDestructuringAssignment(location: Identifier) {
             // Get the type of the object or array literal and then look for property of given name in the type
-            const typeOfObjectLiteral = getTypeOfArrayLiteralOrObjectLiteralDestructuringAssignment(<Expression>location.parent.parent);
+            const typeOfObjectLiteral = getTypeOfAssignmentPattern(cast(location.parent.parent, isAssignmentPattern));
             return typeOfObjectLiteral && getPropertyOfType(typeOfObjectLiteral, location.escapedText);
         }
 

src/compiler/types.ts

@@ -3154,6 +3154,7 @@ namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
+        getTypeOfAssignmentPattern(pattern: AssignmentPattern): Type;
         getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
 

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -1969,6 +1969,7 @@ declare namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
+        getTypeOfAssignmentPattern(pattern: AssignmentPattern): Type;
         getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
         signatureToString(signature: Signature, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): string;

tests/baselines/reference/api/typescript.d.ts

@@ -1969,6 +1969,7 @@ declare namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
+        getTypeOfAssignmentPattern(pattern: AssignmentPattern): Type;
         getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
         signatureToString(signature: Signature, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): string;