Find first callable/constructable type in union when appropriate

src/compiler/checker.ts

@@ -11395,7 +11395,8 @@ namespace ts {
                     const bestMatchingType =
                         findMatchingDiscriminantType(source, target) ||
                         findMatchingTypeReferenceOrTypeAliasReference(source, target) ||
-                        findBestTypeForObjectLiteral(source, target);
+                        findBestTypeForObjectLiteral(source, target) ||
+                        findBestTypeForInvokable(source, target);
 
                     isRelatedTo(source, bestMatchingType || targetTypes[targetTypes.length - 1], /*reportErrors*/ true);
                 }
@@ -11426,6 +11427,15 @@ namespace ts {
                 }
             }
 
+            function findBestTypeForInvokable(source: Type, unionTarget: UnionOrIntersectionType) {
+                let signatureKind = SignatureKind.Call;
+                const hasSignatures = getSignaturesOfType(source, signatureKind).length > 0 ||
+                    (signatureKind = SignatureKind.Construct, getSignaturesOfType(source, signatureKind).length > 0);
+                if (hasSignatures) {
+                    return find(unionTarget.types, t => getSignaturesOfType(t, signatureKind).length > 0);
+                }
+            }
+
             // Keep this up-to-date with the same logic within `getApparentTypeOfContextualType`, since they should behave similarly
             function findMatchingDiscriminantType(source: Type, target: UnionOrIntersectionType) {
                 let match: Type | undefined;

tests/baselines/reference/contextualTypeWithUnionTypeObjectLiteral.errors.txt

@@ -22,9 +22,9 @@ tests/cases/conformance/types/union/contextualTypeWithUnionTypeObjectLiteral.ts(
       Type 'string | number' is not assignable to type 'number'.
         Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/union/contextualTypeWithUnionTypeObjectLiteral.ts(58,5): error TS2322: Type '(a: string, b: number) => string | number' is not assignable to type '((a: string, b: number) => string) | ((a: string, b: number) => number)'.
-  Type '(a: string, b: number) => string | number' is not assignable to type '(a: string, b: number) => number'.
-    Type 'string | number' is not assignable to type 'number'.
-      Type 'string' is not assignable to type 'number'.
+  Type '(a: string, b: number) => string | number' is not assignable to type '(a: string, b: number) => string'.
+    Type 'string | number' is not assignable to type 'string'.
+      Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/union/contextualTypeWithUnionTypeObjectLiteral.ts (6 errors) ====
@@ -116,8 +116,8 @@ tests/cases/conformance/types/union/contextualTypeWithUnionTypeObjectLiteral.ts(
         commonMethodDifferentReturnType: (a, b) => strOrNumber,
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2322: Type '(a: string, b: number) => string | number' is not assignable to type '((a: string, b: number) => string) | ((a: string, b: number) => number)'.
-!!! error TS2322:   Type '(a: string, b: number) => string | number' is not assignable to type '(a: string, b: number) => number'.
-!!! error TS2322:     Type 'string | number' is not assignable to type 'number'.
-!!! error TS2322:       Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Type '(a: string, b: number) => string | number' is not assignable to type '(a: string, b: number) => string'.
+!!! error TS2322:     Type 'string | number' is not assignable to type 'string'.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
 !!! related TS6500 tests/cases/conformance/types/union/contextualTypeWithUnionTypeObjectLiteral.ts:35:5: The expected type comes from property 'commonMethodDifferentReturnType' which is declared here on type 'I11 | I21'
     };

tests/baselines/reference/errorsWithInvokablesInUnions01.errors.txt

@@ -0,0 +1,40 @@
+tests/cases/compiler/errorsWithInvokablesInUnions01.ts(14,12): error TS2322: Type '(x: string) => void' is not assignable to type 'ConstructableA | IDirectiveLinkFn<number> | IDirectivePrePost<number>'.
+  Type '(x: string) => void' is not assignable to type 'IDirectiveLinkFn<number>'.
+    Types of parameters 'x' and 'scope' are incompatible.
+      Type 'number' is not assignable to type 'string'.
+tests/cases/compiler/errorsWithInvokablesInUnions01.ts(16,12): error TS2322: Type 'typeof ctor' is not assignable to type 'ConstructableA | IDirectiveLinkFn<number> | IDirectivePrePost<number>'.
+  Type 'typeof ctor' is not assignable to type 'ConstructableA'.
+    Type 'ctor' is not assignable to type '{ somePropA: any; }'.
+      Property 'somePropA' is missing in type 'ctor'.
+
+
+==== tests/cases/compiler/errorsWithInvokablesInUnions01.ts (2 errors) ====
+    interface ConstructableA {
+      new(): { somePropA: any };
+    }
+
+    interface IDirectiveLinkFn<TScope> {
+        (scope: TScope): void;
+    }
+
+    interface IDirectivePrePost<TScope> {
+        pre?: IDirectiveLinkFn<TScope>;
+        post?: IDirectiveLinkFn<TScope>;
+    }
+
+    export let blah: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = (x: string) => {}
+               ~~~~
+!!! error TS2322: Type '(x: string) => void' is not assignable to type 'ConstructableA | IDirectiveLinkFn<number> | IDirectivePrePost<number>'.
+!!! error TS2322:   Type '(x: string) => void' is not assignable to type 'IDirectiveLinkFn<number>'.
+!!! error TS2322:     Types of parameters 'x' and 'scope' are incompatible.
+!!! error TS2322:       Type 'number' is not assignable to type 'string'.
+
+    export let ctor: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = class {
+               ~~~~
+!!! error TS2322: Type 'typeof ctor' is not assignable to type 'ConstructableA | IDirectiveLinkFn<number> | IDirectivePrePost<number>'.
+!!! error TS2322:   Type 'typeof ctor' is not assignable to type 'ConstructableA'.
+!!! error TS2322:     Type 'ctor' is not assignable to type '{ somePropA: any; }'.
+!!! error TS2322:       Property 'somePropA' is missing in type 'ctor'.
+        someUnaccountedProp: any;
+    }
+

tests/baselines/reference/errorsWithInvokablesInUnions01.js

@@ -0,0 +1,30 @@
+//// [errorsWithInvokablesInUnions01.ts]
+interface ConstructableA {
+  new(): { somePropA: any };
+}
+
+interface IDirectiveLinkFn<TScope> {
+    (scope: TScope): void;
+}
+
+interface IDirectivePrePost<TScope> {
+    pre?: IDirectiveLinkFn<TScope>;
+    post?: IDirectiveLinkFn<TScope>;
+}
+
+export let blah: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = (x: string) => {}
+
+export let ctor: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = class {
+    someUnaccountedProp: any;
+}
+
+
+//// [errorsWithInvokablesInUnions01.js]
+"use strict";
+exports.__esModule = true;
+exports.blah = function (x) { };
+exports.ctor = /** @class */ (function () {
+    function class_1() {
+    }
+    return class_1;
+}());

tests/baselines/reference/errorsWithInvokablesInUnions01.symbols

@@ -0,0 +1,49 @@
+=== tests/cases/compiler/errorsWithInvokablesInUnions01.ts ===
+interface ConstructableA {
+>ConstructableA : Symbol(ConstructableA, Decl(errorsWithInvokablesInUnions01.ts, 0, 0))
+
+  new(): { somePropA: any };
+>somePropA : Symbol(somePropA, Decl(errorsWithInvokablesInUnions01.ts, 1, 10))
+}
+
+interface IDirectiveLinkFn<TScope> {
+>IDirectiveLinkFn : Symbol(IDirectiveLinkFn, Decl(errorsWithInvokablesInUnions01.ts, 2, 1))
+>TScope : Symbol(TScope, Decl(errorsWithInvokablesInUnions01.ts, 4, 27))
+
+    (scope: TScope): void;
+>scope : Symbol(scope, Decl(errorsWithInvokablesInUnions01.ts, 5, 5))
+>TScope : Symbol(TScope, Decl(errorsWithInvokablesInUnions01.ts, 4, 27))
+}
+
+interface IDirectivePrePost<TScope> {
+>IDirectivePrePost : Symbol(IDirectivePrePost, Decl(errorsWithInvokablesInUnions01.ts, 6, 1))
+>TScope : Symbol(TScope, Decl(errorsWithInvokablesInUnions01.ts, 8, 28))
+
+    pre?: IDirectiveLinkFn<TScope>;
+>pre : Symbol(IDirectivePrePost.pre, Decl(errorsWithInvokablesInUnions01.ts, 8, 37))
+>IDirectiveLinkFn : Symbol(IDirectiveLinkFn, Decl(errorsWithInvokablesInUnions01.ts, 2, 1))
+>TScope : Symbol(TScope, Decl(errorsWithInvokablesInUnions01.ts, 8, 28))
+
+    post?: IDirectiveLinkFn<TScope>;
+>post : Symbol(IDirectivePrePost.post, Decl(errorsWithInvokablesInUnions01.ts, 9, 35))
+>IDirectiveLinkFn : Symbol(IDirectiveLinkFn, Decl(errorsWithInvokablesInUnions01.ts, 2, 1))
+>TScope : Symbol(TScope, Decl(errorsWithInvokablesInUnions01.ts, 8, 28))
+}
+
+export let blah: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = (x: string) => {}
+>blah : Symbol(blah, Decl(errorsWithInvokablesInUnions01.ts, 13, 10))
+>IDirectiveLinkFn : Symbol(IDirectiveLinkFn, Decl(errorsWithInvokablesInUnions01.ts, 2, 1))
+>ConstructableA : Symbol(ConstructableA, Decl(errorsWithInvokablesInUnions01.ts, 0, 0))
+>IDirectivePrePost : Symbol(IDirectivePrePost, Decl(errorsWithInvokablesInUnions01.ts, 6, 1))
+>x : Symbol(x, Decl(errorsWithInvokablesInUnions01.ts, 13, 90))
+
+export let ctor: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = class {
+>ctor : Symbol(ctor, Decl(errorsWithInvokablesInUnions01.ts, 15, 10))
+>IDirectiveLinkFn : Symbol(IDirectiveLinkFn, Decl(errorsWithInvokablesInUnions01.ts, 2, 1))
+>ConstructableA : Symbol(ConstructableA, Decl(errorsWithInvokablesInUnions01.ts, 0, 0))
+>IDirectivePrePost : Symbol(IDirectivePrePost, Decl(errorsWithInvokablesInUnions01.ts, 6, 1))
+
+    someUnaccountedProp: any;
+>someUnaccountedProp : Symbol(ctor.someUnaccountedProp, Decl(errorsWithInvokablesInUnions01.ts, 15, 96))
+}
+

tests/baselines/reference/errorsWithInvokablesInUnions01.types

@@ -0,0 +1,32 @@
+=== tests/cases/compiler/errorsWithInvokablesInUnions01.ts ===
+interface ConstructableA {
+  new(): { somePropA: any };
+>somePropA : any
+}
+
+interface IDirectiveLinkFn<TScope> {
+    (scope: TScope): void;
+>scope : TScope
+}
+
+interface IDirectivePrePost<TScope> {
+    pre?: IDirectiveLinkFn<TScope>;
+>pre : IDirectiveLinkFn<TScope>
+
+    post?: IDirectiveLinkFn<TScope>;
+>post : IDirectiveLinkFn<TScope>
+}
+
+export let blah: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = (x: string) => {}
+>blah : ConstructableA | IDirectiveLinkFn<number> | IDirectivePrePost<number>
+>(x: string) => {} : (x: string) => void
+>x : string
+
+export let ctor: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = class {
+>ctor : ConstructableA | IDirectiveLinkFn<number> | IDirectivePrePost<number>
+>class {    someUnaccountedProp: any;} : typeof ctor
+
+    someUnaccountedProp: any;
+>someUnaccountedProp : any
+}
+

tests/baselines/reference/functionExpressionContextualTyping2.errors.txt

@@ -1,6 +1,6 @@
 tests/cases/conformance/expressions/contextualTyping/functionExpressionContextualTyping2.ts(11,1): error TS2322: Type '(foo: number, bar: string) => boolean' is not assignable to type '((n: number, s: string) => number) | ((n: number, s: string) => string)'.
-  Type '(foo: number, bar: string) => boolean' is not assignable to type '(n: number, s: string) => string'.
-    Type 'boolean' is not assignable to type 'string'.
+  Type '(foo: number, bar: string) => boolean' is not assignable to type '(n: number, s: string) => number'.
+    Type 'boolean' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/expressions/contextualTyping/functionExpressionContextualTyping2.ts (1 errors) ====
@@ -17,5 +17,5 @@ tests/cases/conformance/expressions/contextualTyping/functionExpressionContextua
     a1 = (foo, bar) => { return true; }  // Error
     ~~
 !!! error TS2322: Type '(foo: number, bar: string) => boolean' is not assignable to type '((n: number, s: string) => number) | ((n: number, s: string) => string)'.
-!!! error TS2322:   Type '(foo: number, bar: string) => boolean' is not assignable to type '(n: number, s: string) => string'.
-!!! error TS2322:     Type 'boolean' is not assignable to type 'string'.
+!!! error TS2322:   Type '(foo: number, bar: string) => boolean' is not assignable to type '(n: number, s: string) => number'.
+!!! error TS2322:     Type 'boolean' is not assignable to type 'number'.

tests/cases/compiler/errorsWithInvokablesInUnions01.ts

@@ -0,0 +1,18 @@
+interface ConstructableA {
+  new(): { somePropA: any };
+}
+
+interface IDirectiveLinkFn<TScope> {
+    (scope: TScope): void;
+}
+
+interface IDirectivePrePost<TScope> {
+    pre?: IDirectiveLinkFn<TScope>;
+    post?: IDirectiveLinkFn<TScope>;
+}
+
+export let blah: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = (x: string) => {}
+
+export let ctor: IDirectiveLinkFn<number> | ConstructableA | IDirectivePrePost<number> = class {
+    someUnaccountedProp: any;
+}