Fixed an issue with quickInfo crashing on a function property returned from generic function (#49049)

Author: Andarist

src/compiler/checker.ts

@@ -11340,7 +11340,18 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     // The outer type parameters are those defined by enclosing generic classes, methods, or functions.
     function getOuterTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined {
-        const declaration = symbol.flags & SymbolFlags.Class ? symbol.valueDeclaration : getDeclarationOfKind(symbol, SyntaxKind.InterfaceDeclaration)!;
+        const declaration = (symbol.flags & SymbolFlags.Class || symbol.flags & SymbolFlags.Function)
+            ? symbol.valueDeclaration
+            : symbol.declarations?.find(decl => {
+                if (decl.kind === SyntaxKind.InterfaceDeclaration) {
+                    return true;
+                }
+                if (decl.kind !== SyntaxKind.VariableDeclaration) {
+                    return false;
+                }
+                const initializer = (decl as VariableDeclaration).initializer;
+                return !!initializer && (initializer.kind === SyntaxKind.FunctionExpression || initializer.kind === SyntaxKind.ArrowFunction);
+            })!;
         Debug.assert(!!declaration, "Class was missing valueDeclaration -OR- non-class had no interface declarations");
         return getOuterTypeParameters(declaration);
     }

tests/cases/fourslash/quickInfoOnFunctionPropertyReturnedFromGenericFunction1.ts

@@ -0,0 +1,13 @@
+/// <reference path="fourslash.ts" />
+
+//// function createProps<T>(t: T) {
+////   function getProps() {}
+////   function createVariants() {}
+////
+////   getProps.createVariants = createVariants;
+////   return getProps;
+//// }
+////
+//// createProps({})./**/createVariants();
+
+verify.quickInfoAt("", "(property) getProps<{}>.createVariants: () => void");

tests/cases/fourslash/quickInfoOnFunctionPropertyReturnedFromGenericFunction2.ts

@@ -0,0 +1,13 @@
+/// <reference path="fourslash.ts" />
+
+//// function createProps<T>(t: T) {
+////   const getProps = function() {}
+////   const createVariants = function() {}
+////
+////   getProps.createVariants = createVariants;
+////   return getProps;
+//// }
+////
+//// createProps({})./**/createVariants();
+
+verify.quickInfoAt("", "(property) getProps<{}>.createVariants: () => void");

tests/cases/fourslash/quickInfoOnFunctionPropertyReturnedFromGenericFunction3.ts

@@ -0,0 +1,13 @@
+/// <reference path="fourslash.ts" />
+
+//// function createProps<T>(t: T) {
+////   const getProps = () => {}
+////   const createVariants = () => {}
+////
+////   getProps.createVariants = createVariants;
+////   return getProps;
+//// }
+////
+//// createProps({})./**/createVariants();
+
+verify.quickInfoAt("", "(property) getProps<{}>.createVariants: () => void");