Merge pull request #20814 from Microsoft/fixUnionSignatures

Fix union signatures

Author: ahejlsberg

src/compiler/checker.ts

@@ -5936,7 +5936,7 @@ namespace ts {
                             if (unionSignatures.length > 1) {
                                 let thisParameter = signature.thisParameter;
                                 if (forEach(unionSignatures, sig => sig.thisParameter)) {
-                                    const thisType = getUnionType(map(unionSignatures, sig => getTypeOfSymbol(sig.thisParameter) || anyType), UnionReduction.Subtype);
+                                    const thisType = getUnionType(map(unionSignatures, sig => sig.thisParameter ? getTypeOfSymbol(sig.thisParameter) : anyType), UnionReduction.Subtype);
                                     thisParameter = createSymbolWithType(signature.thisParameter, thisType);
                                 }
                                 s = cloneSignature(signature);

tests/baselines/reference/unionSignaturesWithThisParameter.js

@@ -0,0 +1,20 @@
+//// [unionSignaturesWithThisParameter.ts]
+// Repro from #20802
+
+function x<T>(ctor: {
+    (this: {}, v: T): void;
+    new(v: T): void;
+} | {
+    (v: T): void;
+    new(v: T): void;
+}, t: T) {
+    new ctor(t);
+}
+
+
+//// [unionSignaturesWithThisParameter.js]
+"use strict";
+// Repro from #20802
+function x(ctor, t) {
+    new ctor(t);
+}

tests/baselines/reference/unionSignaturesWithThisParameter.symbols

@@ -0,0 +1,35 @@
+=== tests/cases/compiler/unionSignaturesWithThisParameter.ts ===
+// Repro from #20802
+
+function x<T>(ctor: {
+>x : Symbol(x, Decl(unionSignaturesWithThisParameter.ts, 0, 0))
+>T : Symbol(T, Decl(unionSignaturesWithThisParameter.ts, 2, 11))
+>ctor : Symbol(ctor, Decl(unionSignaturesWithThisParameter.ts, 2, 14))
+
+    (this: {}, v: T): void;
+>this : Symbol(this, Decl(unionSignaturesWithThisParameter.ts, 3, 5))
+>v : Symbol(v, Decl(unionSignaturesWithThisParameter.ts, 3, 14))
+>T : Symbol(T, Decl(unionSignaturesWithThisParameter.ts, 2, 11))
+
+    new(v: T): void;
+>v : Symbol(v, Decl(unionSignaturesWithThisParameter.ts, 4, 8))
+>T : Symbol(T, Decl(unionSignaturesWithThisParameter.ts, 2, 11))
+
+} | {
+    (v: T): void;
+>v : Symbol(v, Decl(unionSignaturesWithThisParameter.ts, 6, 5))
+>T : Symbol(T, Decl(unionSignaturesWithThisParameter.ts, 2, 11))
+
+    new(v: T): void;
+>v : Symbol(v, Decl(unionSignaturesWithThisParameter.ts, 7, 8))
+>T : Symbol(T, Decl(unionSignaturesWithThisParameter.ts, 2, 11))
+
+}, t: T) {
+>t : Symbol(t, Decl(unionSignaturesWithThisParameter.ts, 8, 2))
+>T : Symbol(T, Decl(unionSignaturesWithThisParameter.ts, 2, 11))
+
+    new ctor(t);
+>ctor : Symbol(ctor, Decl(unionSignaturesWithThisParameter.ts, 2, 14))
+>t : Symbol(t, Decl(unionSignaturesWithThisParameter.ts, 8, 2))
+}
+

tests/baselines/reference/unionSignaturesWithThisParameter.types

@@ -0,0 +1,36 @@
+=== tests/cases/compiler/unionSignaturesWithThisParameter.ts ===
+// Repro from #20802
+
+function x<T>(ctor: {
+>x : <T>(ctor: { (this: {}, v: T): void; new (v: T): void; } | { (v: T): void; new (v: T): void; }, t: T) => void
+>T : T
+>ctor : { (this: {}, v: T): void; new (v: T): void; } | { (v: T): void; new (v: T): void; }
+
+    (this: {}, v: T): void;
+>this : {}
+>v : T
+>T : T
+
+    new(v: T): void;
+>v : T
+>T : T
+
+} | {
+    (v: T): void;
+>v : T
+>T : T
+
+    new(v: T): void;
+>v : T
+>T : T
+
+}, t: T) {
+>t : T
+>T : T
+
+    new ctor(t);
+>new ctor(t) : void
+>ctor : { (this: {}, v: T): void; new (v: T): void; } | { (v: T): void; new (v: T): void; }
+>t : T
+}
+

tests/cases/compiler/unionSignaturesWithThisParameter.ts

@@ -0,0 +1,13 @@
+// @strict: true
+
+// Repro from #20802
+
+function x<T>(ctor: {
+    (this: {}, v: T): void;
+    new(v: T): void;
+} | {
+    (v: T): void;
+    new(v: T): void;
+}, t: T) {
+    new ctor(t);
+}