narrowTypeByInstanceof understands ctor funcs (microsoft#27551)

* narrowTypeByInstanceof understands ctor funcs

* Rename test filename

* Fix whitespace lint

Author: sandersn

src/compiler/checker.ts

@@ -15391,9 +15391,12 @@ namespace ts {
                 }
 
                 if (!targetType) {
-                    const constructSignatures = getSignaturesOfType(rightType, SignatureKind.Construct);
-                    targetType = constructSignatures && constructSignatures.length ?
-                        getUnionType(map(constructSignatures, signature => getReturnTypeOfSignature(getErasedSignature(signature)))) :
+                    let constructSignatures = getSignaturesOfType(rightType, SignatureKind.Construct);
+                    if (constructSignatures.length === 0) {
+                        constructSignatures = filter(getSignaturesOfType(rightType, SignatureKind.Call), sig => isJSConstructor(sig.declaration));
+                    }
+                    targetType = constructSignatures.length ?
+                        getUnionType(map(constructSignatures, signature => isJSConstructor(signature.declaration) && getJSClassType(getSymbolOfNode(signature.declaration!)) || getReturnTypeOfSignature(getErasedSignature(signature)))) :
                         emptyObjectType;
                 }
 

tests/baselines/reference/controlFlowInstanceof.js

@@ -247,3 +247,28 @@ if (x instanceof ctor) {
 >x : Symbol(x, Decl(controlFlowInstanceof.ts, 100, 13))
 }
 
+// Repro from #27550 (based on uglify code)
+=== tests/cases/compiler/uglify.js ===
+/** @constructor */
+function AtTop(val) { this.val = val }
+>AtTop : Symbol(AtTop, Decl(uglify.js, 0, 0))
+>val : Symbol(val, Decl(uglify.js, 1, 15))
+>this.val : Symbol(AtTop.val, Decl(uglify.js, 1, 21))
+>this : Symbol(AtTop, Decl(uglify.js, 0, 0))
+>val : Symbol(AtTop.val, Decl(uglify.js, 1, 21))
+>val : Symbol(val, Decl(uglify.js, 1, 15))
+
+/** @type {*} */
+var v = 1;
+>v : Symbol(v, Decl(uglify.js, 3, 3))
+
+if (v instanceof AtTop) {
+>v : Symbol(v, Decl(uglify.js, 3, 3))
+>AtTop : Symbol(AtTop, Decl(uglify.js, 0, 0))
+
+    v.val
+>v.val : Symbol(AtTop.val, Decl(uglify.js, 1, 21))
+>v : Symbol(v, Decl(uglify.js, 3, 3))
+>val : Symbol(AtTop.val, Decl(uglify.js, 1, 21))
+}
+

tests/baselines/reference/controlFlowInstanceof.symbols

@@ -261,3 +261,31 @@ if (x instanceof ctor) {
 >x : () => void
 }
 
+// Repro from #27550 (based on uglify code)
+=== tests/cases/compiler/uglify.js ===
+/** @constructor */
+function AtTop(val) { this.val = val }
+>AtTop : typeof AtTop
+>val : any
+>this.val = val : any
+>this.val : any
+>this : AtTop
+>val : any
+>val : any
+
+/** @type {*} */
+var v = 1;
+>v : any
+>1 : 1
+
+if (v instanceof AtTop) {
+>v instanceof AtTop : boolean
+>v : any
+>AtTop : typeof AtTop
+
+    v.val
+>v.val : any
+>v : AtTop
+>val : any
+}
+

tests/baselines/reference/controlFlowInstanceof.types

@@ -1,6 +1,10 @@
 // @target: es6
+// @noEmit: true
+// @allowJs: true
+// @checkJs: true
 // @strictNullChecks: true
 
+// @Filename: controlFlowInstanceof.ts
 // Repros from #10167
 
 function f1(s: Set<string> | Set<number>) {
@@ -107,3 +111,13 @@ declare const ctor: Function;
 if (x instanceof ctor) {
     x();
 }
+
+// Repro from #27550 (based on uglify code)
+// @Filename: uglify.js
+/** @constructor */
+function AtTop(val) { this.val = val }
+/** @type {*} */
+var v = 1;
+if (v instanceof AtTop) {
+    v.val
+}