Ensure call-less references to builtin functions in namespaces error

src/compiler.ts

@@ -9035,10 +9035,29 @@ export class Compiler extends DiagnosticEmitter {
       }
       case ElementKind.FunctionPrototype: {
         let functionPrototype = <FunctionPrototype>target;
+        let typeParameterNodes = functionPrototype.typeParameterNodes;
+
+        if (typeParameterNodes && typeParameterNodes.length != 0) {
+          this.error(
+            DiagnosticCode.Type_argument_expected,
+            expression.range
+          );
+          break; // also diagnose 'not a value at runtime'
+        }
+
         let functionInstance = this.resolver.resolveFunction(functionPrototype, null);
         if (!functionInstance) return module.unreachable();
         if (!this.compileFunction(functionInstance)) return module.unreachable();
         this.currentType = functionInstance.type;
+
+        if (functionInstance.hasDecorator(DecoratorFlags.Builtin)) {
+          this.error(
+            DiagnosticCode.Not_implemented_0,
+            expression.range, "First-class built-ins"
+          );
+          return module.unreachable();
+        }
+
         let offset = this.ensureRuntimeFunction(functionInstance);
         return this.options.isWasm64
           ? module.i64(i64_low(offset), i64_high(offset))

tests/compiler/issues/2737.json

@@ -0,0 +1,15 @@
+{
+  "stderr": [
+    "TS1140: Type argument expected.",
+    "foo.bar;",
+    "AS234: Expression does not compile to a value at runtime.",
+    "foo.bar;",
+    "TS1140: Type argument expected.",
+    "memory.data;",
+    "AS234: Expression does not compile to a value at runtime.",
+    "memory.data;",
+    "AS100: Not implemented: First-class built-ins",
+    "atomic.fence;",
+    "EOF"
+  ]
+}

tests/compiler/issues/2737.ts

@@ -0,0 +1,12 @@
+namespace foo {
+    export function bar<T>(): void {}
+}
+
+// Should error from missing type arguments:
+foo.bar;
+memory.data;
+
+// Should error from lacking first-class builtins:
+atomic.fence;
+
+ERROR("EOF");