[analyzer/ffi] Error on missing type argument to @Native

Also, update error messages to mention `Native` rather than
`FfiNative`, as `FfiNative` syntax is deprecated.

TEST=tests/ffi/regress_51913_test.dart

Closes: #51913
Change-Id: I0830a360bfdd9faffb04761d1ce2da33b380341d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/293687
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

pkg/analyzer/lib/src/generated/ffi_verifier.dart

@@ -318,8 +318,10 @@ class FfiVerifier extends RecursiveAstVisitor<void> {
 
       final typeArguments = annotation.typeArguments?.arguments;
       final arguments = annotation.arguments?.arguments;
-      if (typeArguments == null || arguments == null) {
-        continue;
+      if (typeArguments == null) {
+        _errorReporter.reportErrorForNode(
+            FfiCode.MUST_BE_A_NATIVE_FUNCTION_TYPE, errorNode, ['T', 'Native']);
+        return;
       }
 
       final ffiSignature = typeArguments[0].type! as FunctionType;
@@ -400,13 +402,13 @@ class FfiVerifier extends RecursiveAstVisitor<void> {
         _errorReporter.reportErrorForNode(
             FfiCode.MUST_BE_A_NATIVE_FUNCTION_TYPE,
             errorNode,
-            [nativeType, 'FfiNative']);
+            [nativeType, 'Native']);
         return;
       }
       if (!_validateCompatibleFunctionTypes(dartType, nativeType,
           nativeFieldWrappersAsPointer: true, allowStricterReturn: true)) {
         _errorReporter.reportErrorForNode(FfiCode.MUST_BE_A_SUBTYPE, errorNode,
-            [nativeType, dartType, 'FfiNative']);
+            [nativeType, dartType, 'Native']);
         return;
       }
     }
@@ -926,8 +928,8 @@ class FfiVerifier extends RecursiveAstVisitor<void> {
   }
 
   void _validateFfiLeafCallUsesNoHandles(
-      NodeList<Expression> args, DartType nativeType, AstNode errorNode) {
-    if (args.isEmpty) {
+      NodeList<Expression>? args, DartType nativeType, AstNode errorNode) {
+    if (args == null || args.isEmpty) {
       return;
     }
     for (final arg in args) {

pkg/analyzer/test/src/diagnostics/ffi_native_test.dart

@@ -41,6 +41,7 @@ import 'dart:ffi';
 external int foo();
 ''', [
       error(CompileTimeErrorCode.NO_ANNOTATION_CONSTRUCTOR_ARGUMENTS, 20, 10),
+      error(FfiCode.MUST_BE_A_NATIVE_FUNCTION_TYPE, 20, 30),
     ]);
   }
 
@@ -51,6 +52,7 @@ import 'dart:ffi';
 @FfiNative()
 external int foo();
 ''', [
+      error(FfiCode.MUST_BE_A_NATIVE_FUNCTION_TYPE, 20, 32),
       error(CompileTimeErrorCode.NOT_ENOUGH_POSITIONAL_ARGUMENTS_NAME_SINGULAR,
           31, 1),
     ]);
@@ -210,6 +212,7 @@ import 'dart:ffi';
 external int foo();
 ''', [
       error(CompileTimeErrorCode.NO_ANNOTATION_CONSTRUCTOR_ARGUMENTS, 20, 7),
+      error(FfiCode.MUST_BE_A_NATIVE_FUNCTION_TYPE, 20, 27),
     ]);
   }