Fix crash due to unchecked cast in addImplementationSuccessElaboration

src/compiler/checker.ts

@@ -27335,7 +27335,7 @@ namespace ts {
 
                 const declCount = length(failed.declaration?.symbol.declarations);
                 const isOverload = declCount > 1;
-                const implDecl = isOverload ? find(failed.declaration?.symbol.declarations || emptyArray, d => nodeIsPresent((d as FunctionLikeDeclaration).body)) : undefined;
+                const implDecl = isOverload ? find(failed.declaration?.symbol.declarations || emptyArray, d => isFunctionLikeDeclaration(d) && nodeIsPresent(d.body)) : undefined;
                 if (implDecl) {
                     const candidate = getSignatureFromDeclaration(implDecl as FunctionLikeDeclaration);
                     const isSingleNonGenericCandidate = !candidate.typeParameters;

tests/baselines/reference/namespaceMergedWithFunctionWithOverloadsUsage.errors.txt

@@ -0,0 +1,28 @@
+tests/cases/compiler/index.ts(3,3): error TS2769: No overload matches this call.
+  Overload 1 of 2, '(opts?: Whatever): void', gave the following error.
+    Argument of type 'number' is not assignable to parameter of type 'Whatever'.
+  Overload 2 of 2, '(cb: Function, opts?: Whatever): void', gave the following error.
+    Argument of type 'number' is not assignable to parameter of type 'Function'.
+
+
+==== tests/cases/compiler/index.ts (1 errors) ====
+    import X = require("./file");
+
+    X(0); // shouldn't cause a crash
+      ~
+!!! error TS2769: No overload matches this call.
+!!! error TS2769:   Overload 1 of 2, '(opts?: Whatever): void', gave the following error.
+!!! error TS2769:     Argument of type 'number' is not assignable to parameter of type 'Whatever'.
+!!! error TS2769:   Overload 2 of 2, '(cb: Function, opts?: Whatever): void', gave the following error.
+!!! error TS2769:     Argument of type 'number' is not assignable to parameter of type 'Function'.
+==== tests/cases/compiler/file.d.ts (0 errors) ====
+    declare namespace Foo {
+        interface Whatever {
+            prop: any;
+        }
+    }
+
+    declare function Foo(opts?: Foo.Whatever): void;
+    declare function Foo(cb: Function, opts?: Foo.Whatever): void;
+
+    export = Foo;

tests/baselines/reference/namespaceMergedWithFunctionWithOverloadsUsage.js

@@ -0,0 +1,23 @@
+//// [tests/cases/compiler/namespaceMergedWithFunctionWithOverloadsUsage.ts] ////
+
+//// [file.d.ts]
+declare namespace Foo {
+    interface Whatever {
+        prop: any;
+    }
+}
+
+declare function Foo(opts?: Foo.Whatever): void;
+declare function Foo(cb: Function, opts?: Foo.Whatever): void;
+
+export = Foo;
+//// [index.ts]
+import X = require("./file");
+
+X(0); // shouldn't cause a crash
+
+//// [index.js]
+"use strict";
+exports.__esModule = true;
+var X = require("./file");
+X(0); // shouldn't cause a crash

tests/baselines/reference/namespaceMergedWithFunctionWithOverloadsUsage.symbols

@@ -0,0 +1,36 @@
+=== tests/cases/compiler/index.ts ===
+import X = require("./file");
+>X : Symbol(X, Decl(index.ts, 0, 0))
+
+X(0); // shouldn't cause a crash
+>X : Symbol(X, Decl(index.ts, 0, 0))
+
+=== tests/cases/compiler/file.d.ts ===
+declare namespace Foo {
+>Foo : Symbol(Foo, Decl(file.d.ts, 4, 1), Decl(file.d.ts, 6, 48), Decl(file.d.ts, 0, 0))
+
+    interface Whatever {
+>Whatever : Symbol(Whatever, Decl(file.d.ts, 0, 23))
+
+        prop: any;
+>prop : Symbol(Whatever.prop, Decl(file.d.ts, 1, 24))
+    }
+}
+
+declare function Foo(opts?: Foo.Whatever): void;
+>Foo : Symbol(Foo, Decl(file.d.ts, 4, 1), Decl(file.d.ts, 6, 48), Decl(file.d.ts, 0, 0))
+>opts : Symbol(opts, Decl(file.d.ts, 6, 21))
+>Foo : Symbol(Foo, Decl(file.d.ts, 4, 1), Decl(file.d.ts, 6, 48), Decl(file.d.ts, 0, 0))
+>Whatever : Symbol(Foo.Whatever, Decl(file.d.ts, 0, 23))
+
+declare function Foo(cb: Function, opts?: Foo.Whatever): void;
+>Foo : Symbol(Foo, Decl(file.d.ts, 4, 1), Decl(file.d.ts, 6, 48), Decl(file.d.ts, 0, 0))
+>cb : Symbol(cb, Decl(file.d.ts, 7, 21))
+>Function : Symbol(Function, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>opts : Symbol(opts, Decl(file.d.ts, 7, 34))
+>Foo : Symbol(Foo, Decl(file.d.ts, 4, 1), Decl(file.d.ts, 6, 48), Decl(file.d.ts, 0, 0))
+>Whatever : Symbol(Foo.Whatever, Decl(file.d.ts, 0, 23))
+
+export = Foo;
+>Foo : Symbol(Foo, Decl(file.d.ts, 4, 1), Decl(file.d.ts, 6, 48), Decl(file.d.ts, 0, 0))
+

tests/baselines/reference/namespaceMergedWithFunctionWithOverloadsUsage.types

@@ -0,0 +1,31 @@
+=== tests/cases/compiler/index.ts ===
+import X = require("./file");
+>X : { (opts?: X.Whatever): void; (cb: Function, opts?: X.Whatever): void; }
+
+X(0); // shouldn't cause a crash
+>X(0) : void
+>X : { (opts?: X.Whatever): void; (cb: Function, opts?: X.Whatever): void; }
+>0 : 0
+
+=== tests/cases/compiler/file.d.ts ===
+declare namespace Foo {
+    interface Whatever {
+        prop: any;
+>prop : any
+    }
+}
+
+declare function Foo(opts?: Foo.Whatever): void;
+>Foo : { (opts?: Foo.Whatever): void; (cb: Function, opts?: Foo.Whatever): void; }
+>opts : Foo.Whatever
+>Foo : any
+
+declare function Foo(cb: Function, opts?: Foo.Whatever): void;
+>Foo : { (opts?: Foo.Whatever): void; (cb: Function, opts?: Foo.Whatever): void; }
+>cb : Function
+>opts : Foo.Whatever
+>Foo : any
+
+export = Foo;
+>Foo : { (opts?: Foo.Whatever): void; (cb: Function, opts?: Foo.Whatever): void; }
+

tests/cases/compiler/namespaceMergedWithFunctionWithOverloadsUsage.ts

@@ -0,0 +1,15 @@
+// @filename: file.d.ts
+declare namespace Foo {
+    interface Whatever {
+        prop: any;
+    }
+}
+
+declare function Foo(opts?: Foo.Whatever): void;
+declare function Foo(cb: Function, opts?: Foo.Whatever): void;
+
+export = Foo;
+// @filename: index.ts
+import X = require("./file");
+
+X(0); // shouldn't cause a crash