Fix review

Author: Changqing-JING

src/compiler.ts

@@ -1575,6 +1575,7 @@ export class Compiler extends DiagnosticEmitter {
     forceStdAlternative: bool = false
   ): bool {
     if (instance.is(CommonFlags.Compiled)) return !instance.is(CommonFlags.Errored);
+    if (instance.is(CommonFlags.Errored)) return false;
 
     if (!forceStdAlternative) {
       if (instance.hasDecorator(DecoratorFlags.Builtin)) return true;
@@ -7186,21 +7187,6 @@ export class Compiler extends DiagnosticEmitter {
     let sourceFunction = flow.sourceFunction;
     let isNamed = declaration.name.text.length > 0;
     let isSemanticallyAnonymous = !isNamed || contextualType != Type.void;
-
-    // Check for duplicate named function declarations before creating the
-    // prototype, since registering a concrete element with a duplicate
-    // internalName would trigger an assertion error.
-    if (!isSemanticallyAnonymous) {
-      let existingLocal = flow.getScopedLocal(declaration.name.text);
-      if (existingLocal) {
-        this.error(
-          DiagnosticCode.Duplicate_function_implementation,
-          declaration.name.range
-        );
-        return this.module.unreachable();
-      }
-    }
-
     let prototype = new FunctionPrototype(
       isSemanticallyAnonymous
         ? `${isNamed ? declaration.name.text : "anonymous"}|${sourceFunction.nextAnonymousId++}`

src/program.ts

@@ -3850,7 +3850,15 @@ export class Function extends TypedElement {
         flow.setLocalFlag(local.index, LocalFlags.Initialized);
       }
     }
-    registerConcreteElement(program, this);
+    if (program.instancesByName.has(this.internalName)) {
+      program.error(
+        DiagnosticCode.Duplicate_function_implementation,
+        prototype.declaration.name.range
+      );
+      this.set(CommonFlags.Errored);
+    } else {
+      registerConcreteElement(program, this);
+    }
   }
 
   /** Gets the types of additional locals that are not parameters. */

tests/compiler/duplicate-function-in-scope.json

@@ -2,6 +2,7 @@
   "asc_flags": [],
   "stderr": [
     "EOF",
+    "TS2300: Duplicate identifier 'inner'.",
     "TS2393: Duplicate function implementation."
   ]
 }

tests/compiler/duplicate-function-in-scope.ts

@@ -1,6 +1,12 @@
 // Duplicate named function declarations in the same scope should
 // produce a diagnostic instead of crashing the compiler.
 
+export function testMixed1(): void {
+  const inner = function (): void {};
+  function inner(): void {}
+  inner();
+}
+
 export function test(): void {
   function inner(): void {}
   function inner(): void {}