refactor narrowTypeByInstanceof

Author: mhegazy

src/compiler/checker.ts

@@ -5384,38 +5384,42 @@ module ts {
                 if (!isTypeSubtypeOf(rightType, globalFunctionType)) {
                     return type;
                 }
-                // Target type is type of prototype property
+
+                let targetType: Type;
                 let prototypeProperty = getPropertyOfType(rightType, "prototype");
                 if (prototypeProperty) {
-                    let targetType = getTypeOfSymbol(prototypeProperty);
-                    if (targetType !== anyType) {
-                        // Narrow to the target type if it's a subtype of the current type
-                        if (isTypeSubtypeOf(targetType, type)) {
-                            return targetType;
-                        }
-                        // If the current type is a union type, remove all constituents that aren't subtypes of the target.
-                        if (type.flags & TypeFlags.Union) {
-                            return getUnionType(filter((<UnionType>type).types, t => isTypeSubtypeOf(t, targetType)));
-                        }
+                    // Target type is type of the protoype property
+                    let prototypePropertyType = getTypeOfSymbol(prototypeProperty);
+                    if (prototypePropertyType !== anyType) {
+                        targetType = prototypePropertyType;
                     }
                 }
-                // Target type is type of construct signature
-                let constructSignatures: Signature[];
-                if (rightType.flags & TypeFlags.Interface) {
-                    constructSignatures = resolveDeclaredMembers(<InterfaceType>rightType).declaredConstructSignatures;
-                }
-                else if (rightType.flags & TypeFlags.Anonymous) {
-                    constructSignatures = getSignaturesOfType(rightType, SignatureKind.Construct);
+
+                if (!targetType) {
+                    // Target type is type of construct signature
+                    let constructSignatures: Signature[];
+                    if (rightType.flags & TypeFlags.Interface) {
+                        constructSignatures = resolveDeclaredMembers(<InterfaceType>rightType).declaredConstructSignatures;
+                    }
+                    else if (rightType.flags & TypeFlags.Anonymous) {
+                        constructSignatures = getSignaturesOfType(rightType, SignatureKind.Construct);
+                    }
+                    if (constructSignatures && constructSignatures.length) {
+                        targetType = getUnionType(map(constructSignatures, signature => getReturnTypeOfSignature(getErasedSignature(signature))));
+                    }
                 }
 
-                if (constructSignatures && constructSignatures.length !== 0) {
-                    let instanceType = getUnionType(map(constructSignatures, signature => getReturnTypeOfSignature(getErasedSignature(signature))));
-                    // Pickup type from union types
+                if (targetType) {
+                    // Narrow to the target type if it's a subtype of the current type
+                    if (isTypeSubtypeOf(targetType, type)) {
+                        return targetType;
+                    }
+                    // If the current type is a union type, remove all constituents that aren't subtypes of the target.
                     if (type.flags & TypeFlags.Union) {
-                        return getUnionType(filter((<UnionType>type).types, t => isTypeSubtypeOf(t, instanceType)));
+                        return getUnionType(filter((<UnionType>type).types, t => isTypeSubtypeOf(t, targetType)));
                     }
-                    return instanceType;
                 }
+
                 return type;
             }
 

tests/baselines/reference/typeGuardsWithInstanceOfByConstructorSignature.errors.txt

@@ -1,16 +1,18 @@
 tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(12,10): error TS2339: Property 'bar' does not exist on type 'A'.
 tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(33,5): error TS2322: Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(34,10): error TS2339: Property 'bar' does not exist on type 'B<number>'.
-tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(63,10): error TS2339: Property 'bar2' does not exist on type 'C1'.
+tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(62,10): error TS2339: Property 'bar1' does not exist on type 'C1 | C2'.
+tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(63,10): error TS2339: Property 'bar2' does not exist on type 'C1 | C2'.
 tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(82,10): error TS2339: Property 'bar' does not exist on type 'D'.
-tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(109,10): error TS2339: Property 'bar2' does not exist on type 'E1'.
+tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(108,10): error TS2339: Property 'bar1' does not exist on type 'E1 | E2'.
+tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(109,10): error TS2339: Property 'bar2' does not exist on type 'E1 | E2'.
 tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(131,11): error TS2339: Property 'foo' does not exist on type 'string | F'.
 tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(132,11): error TS2339: Property 'bar' does not exist on type 'string | F'.
 tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(157,11): error TS2339: Property 'foo2' does not exist on type 'G1'.
 tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(179,11): error TS2339: Property 'bar' does not exist on type 'H'.
 
 
-==== tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts (10 errors) ====
+==== tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts (12 errors) ====
     interface AConstructor {
         new (): A;
     }
@@ -79,9 +81,11 @@ tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstru
     if (obj5 instanceof C) { // narrowed to C1.
         obj5.foo;
         obj5.bar1;
+             ~~~~
+!!! error TS2339: Property 'bar1' does not exist on type 'C1 | C2'.
         obj5.bar2;
              ~~~~
-!!! error TS2339: Property 'bar2' does not exist on type 'C1'.
+!!! error TS2339: Property 'bar2' does not exist on type 'C1 | C2'.
     }
 
     var obj6: any;
@@ -129,9 +133,11 @@ tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstru
     if (obj9 instanceof E) { // narrowed to E1.
         obj9.foo;
         obj9.bar1;
+             ~~~~
+!!! error TS2339: Property 'bar1' does not exist on type 'E1 | E2'.
         obj9.bar2;
              ~~~~
-!!! error TS2339: Property 'bar2' does not exist on type 'E1'.
+!!! error TS2339: Property 'bar2' does not exist on type 'E1 | E2'.
     }
 
     var obj10: any;