Weak type errors on signature-only types

src/compiler/checker.ts

@@ -8938,7 +8938,9 @@ namespace ts {
                     !(target.flags & TypeFlags.Union) &&
                     !isIntersectionConstituent &&
                     source !== globalObjectType &&
-                    getPropertiesOfType(source).length > 0 &&
+                    (getPropertiesOfType(source).length > 0 ||
+                     getSignaturesOfType(source, SignatureKind.Call).length > 0 ||
+                     getSignaturesOfType(source, SignatureKind.Construct).length > 0) &&
                     isWeakType(target) &&
                     !hasCommonProperties(source, target)) {
                     if (reportErrors) {

tests/baselines/reference/weakType.errors.txt

@@ -1,14 +1,17 @@
-tests/cases/compiler/weakType.ts(16,13): error TS2559: Type '12' has no properties in common with type 'Settings'.
-tests/cases/compiler/weakType.ts(17,13): error TS2559: Type '"completely wrong"' has no properties in common with type 'Settings'.
-tests/cases/compiler/weakType.ts(18,13): error TS2559: Type 'false' has no properties in common with type 'Settings'.
-tests/cases/compiler/weakType.ts(35,18): error TS2559: Type '{ error?: number; }' has no properties in common with type 'ChangeOptions'.
-tests/cases/compiler/weakType.ts(60,5): error TS2322: Type '{ properties: { wrong: string; }; }' is not assignable to type 'Weak & Spoiler'.
+tests/cases/compiler/weakType.ts(15,13): error TS2559: Type '() => { timeout: number; }' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(16,13): error TS2559: Type '() => void' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(17,13): error TS2559: Type 'CtorOnly' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(18,13): error TS2559: Type '12' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(19,13): error TS2559: Type '"completely wrong"' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(20,13): error TS2559: Type 'false' has no properties in common with type 'Settings'.
+tests/cases/compiler/weakType.ts(37,18): error TS2559: Type '{ error?: number; }' has no properties in common with type 'ChangeOptions'.
+tests/cases/compiler/weakType.ts(62,5): error TS2322: Type '{ properties: { wrong: string; }; }' is not assignable to type 'Weak & Spoiler'.
   Type '{ properties: { wrong: string; }; }' is not assignable to type 'Weak'.
     Types of property 'properties' are incompatible.
       Type '{ wrong: string; }' has no properties in common with type '{ b?: number; }'.
 
 
-==== tests/cases/compiler/weakType.ts (5 errors) ====
+==== tests/cases/compiler/weakType.ts (8 errors) ====
     interface Settings {
         timeout?: number;
         onError?(): void;
@@ -17,13 +20,21 @@ tests/cases/compiler/weakType.ts(60,5): error TS2322: Type '{ properties: { wron
     function getDefaultSettings() {
         return { timeout: 1000 };
     }
+    interface CtorOnly {
+        new(s: string): string
+    }
 
     function doSomething(settings: Settings) { /* ... */ }
     // forgot to call `getDefaultSettings`
-    // but it is not caught because we don't check for call signatures
     doSomething(getDefaultSettings);
-    // same for arrow expressions:
+                ~~~~~~~~~~~~~~~~~~
+!!! error TS2559: Type '() => { timeout: number; }' has no properties in common with type 'Settings'.
     doSomething(() => { });
+                ~~~~~~~~~
+!!! error TS2559: Type '() => void' has no properties in common with type 'Settings'.
+    doSomething(null as CtorOnly);
+                ~~~~~~~~~~~~~~~~
+!!! error TS2559: Type 'CtorOnly' has no properties in common with type 'Settings'.
     doSomething(12);
                 ~~
 !!! error TS2559: Type '12' has no properties in common with type 'Settings'.
@@ -82,4 +93,5 @@ tests/cases/compiler/weakType.ts(60,5): error TS2322: Type '{ properties: { wron
 !!! error TS2322:   Type '{ properties: { wrong: string; }; }' is not assignable to type 'Weak'.
 !!! error TS2322:     Types of property 'properties' are incompatible.
 !!! error TS2322:       Type '{ wrong: string; }' has no properties in common with type '{ b?: number; }'.
+
 

tests/baselines/reference/weakType.js

@@ -7,13 +7,15 @@ interface Settings {
 function getDefaultSettings() {
     return { timeout: 1000 };
 }
+interface CtorOnly {
+    new(s: string): string
+}
 
 function doSomething(settings: Settings) { /* ... */ }
 // forgot to call `getDefaultSettings`
-// but it is not caught because we don't check for call signatures
 doSomething(getDefaultSettings);
-// same for arrow expressions:
 doSomething(() => { });
+doSomething(null as CtorOnly);
 doSomething(12);
 doSomething('completely wrong');
 doSomething(false);
@@ -59,6 +61,7 @@ declare let unknown: {
     }
 }
 let weak: Weak & Spoiler = unknown
+
 
 
 //// [weakType.js]
@@ -67,10 +70,9 @@ function getDefaultSettings() {
 }
 function doSomething(settings) { }
 // forgot to call `getDefaultSettings`
-// but it is not caught because we don't check for call signatures
 doSomething(getDefaultSettings);
-// same for arrow expressions:
 doSomething(function () { });
+doSomething(null);
 doSomething(12);
 doSomething('completely wrong');
 doSomething(false);

tests/cases/compiler/weakType.ts

@@ -6,13 +6,15 @@ interface Settings {
 function getDefaultSettings() {
     return { timeout: 1000 };
 }
+interface CtorOnly {
+    new(s: string): string
+}
 
 function doSomething(settings: Settings) { /* ... */ }
 // forgot to call `getDefaultSettings`
-// but it is not caught because we don't check for call signatures
 doSomething(getDefaultSettings);
-// same for arrow expressions:
 doSomething(() => { });
+doSomething(null as CtorOnly);
 doSomething(12);
 doSomething('completely wrong');
 doSomething(false);
@@ -58,3 +60,4 @@ declare let unknown: {
     }
 }
 let weak: Weak & Spoiler = unknown
+