fix: fix resolveNamedType cannot resolve type parameter in contextual element

Author: HerrCai0907

src/program.ts

@@ -2841,6 +2841,10 @@ export abstract class Element {
     return this.parent.lookup(name, isType);
   }
 
+  lookupGenericType(name: string): Type | null {
+    return this.parent.lookupGenericType(name);
+  }
+
   /** Adds an element as a member of this one. Reports and returns `false` if a duplicate. */
   add(name: string, element: DeclaredElement, localIdentifierIfImport: IdentifierExpression | null = null): bool {
     var originalDeclaration = element.declaration;
@@ -3124,6 +3128,10 @@ export class File extends Element {
     return this.program.lookup(name); // has no meaningful parent
   }
 
+  override lookupGenericType(name: string): Type | null {
+    return null;
+  }
+
   /** Ensures that an element is an export of this file. */
   ensureExport(name: string, element: DeclaredElement): void {
     var exports = this.exports;
@@ -3687,6 +3695,14 @@ export class Function extends TypedElement {
     registerConcreteElement(program, this);
   }
 
+  override lookupGenericType(name: string): Type | null {
+    let contextualTypeArguments = this.contextualTypeArguments;
+    if (contextualTypeArguments && contextualTypeArguments.has(name)) {
+      return assert(contextualTypeArguments.get(name));
+    }
+    return this.parent.lookupGenericType(name);
+  }
+
   /** Gets the name of the parameter at the specified index. */
   getParameterName(index: i32): string {
     var parameters = (<FunctionDeclaration>this.declaration).signature.parameters;
@@ -4297,6 +4313,14 @@ export class Class extends TypedElement {
     registerConcreteElement(program, this);
   }
 
+  override lookupGenericType(name: string): Type | null {
+    let contextualTypeArguments = this.contextualTypeArguments;
+    if (contextualTypeArguments && contextualTypeArguments.has(name)) {
+      return assert(contextualTypeArguments.get(name));
+    }
+    return this.parent.lookupGenericType(name);
+  }
+
   /** Sets the base class. */
   setBase(base: Class): void {
     assert(!this.base);

src/resolver.ts

@@ -188,8 +188,13 @@ export class Resolver extends DiagnosticEmitter {
     // Look up in contextual types if a simple type
     if (isSimpleType) {
       let simpleName = nameNode.identifier.text;
+      let type: Type | null = null;
       if (ctxTypes && ctxTypes.has(simpleName)) {
-        let type = assert(ctxTypes.get(simpleName));
+        type = assert(ctxTypes.get(simpleName));
+      } else {
+        type = ctxElement.lookupGenericType(simpleName);
+      }
+      if (type) {
         if (typeArgumentNodes && typeArgumentNodes.length > 0) {
           if (reportMode == ReportMode.REPORT) {
             this.error(
@@ -763,7 +768,7 @@ export class Resolver extends DiagnosticEmitter {
           }
           let defaultType = typeParameterNode.defaultType;
           if (defaultType) {
-            let resolvedDefaultType = this.resolveType(defaultType, ctxFlow.actualFunction, contextualTypeArguments, reportMode);
+            let resolvedDefaultType = this.resolveType(defaultType, prototype, contextualTypeArguments, reportMode);
             if (!resolvedDefaultType) return null;
             resolvedTypeArguments[i] = resolvedDefaultType;
             continue;