[ffigen] Remove Writer.usedEnumCTypes (#2521)

Author: liamappelbe

pkgs/ffigen/lib/src/code_generator/enum_class.dart

@@ -264,10 +264,7 @@ class EnumClass extends BindingType {
   }
 
   @override
-  String getCType(Writer w) {
-    w.usedEnumCTypes.add(this);
-    return nativeType.getCType(w);
-  }
+  String getCType(Writer w) => nativeType.getCType(w);
 
   @override
   String getFfiDartType(Writer w) => nativeType.getFfiDartType(w);

pkgs/ffigen/lib/src/code_generator/writer.dart

@@ -7,6 +7,7 @@ import 'package:path/path.dart' as p;
 import '../code_generator.dart';
 import '../context.dart';
 import '../strings.dart' as strings;
+import '../visitor/visitor.dart';
 import 'unique_namer.dart';
 import 'utils.dart';
 
@@ -39,10 +40,6 @@ class Writer {
 
   final List<String> nativeEntryPoints;
 
-  /// Tracks the enums for which enumType.getCType is called. Reset everytime
-  /// [generate] is called.
-  final usedEnumCTypes = <EnumClass>{};
-
   String? _ffiLibraryPrefix;
   String get ffiLibraryPrefix {
     if (_ffiLibraryPrefix != null) {
@@ -228,9 +225,6 @@ class Writer {
     // Reset unique namers to initial state.
     _resetUniqueNamers();
 
-    // Reset [usedEnumCTypes].
-    usedEnumCTypes.clear();
-
     // Write file header (if any).
     if (header != null) {
       result.writeln(header);
@@ -325,17 +319,23 @@ class Writer {
     result.write(s);
 
     // Warn about Enum usage in API surface.
-    if (!silenceEnumWarning && usedEnumCTypes.isNotEmpty) {
-      final names = usedEnumCTypes.map((e) => e.originalName).toList()..sort();
-      context.logger.severe(
-        'The integer type used for enums is '
-        'implementation-defined. FFIgen tries to mimic the integer sizes '
-        'chosen by the most common compilers for the various OS and '
-        'architecture combinations. To prevent any crashes, remove the '
-        'enums from your API surface. To rely on the (unsafe!) mimicking, '
-        'you can silence this warning by adding silence-enum-warning: true '
-        'to the FFIgen config. Affected enums:\n\t${names.join('\n\t')}',
+    if (!silenceEnumWarning) {
+      final notEnums = _allBindings.where(
+        (b) => b is! Type || (b as Type).typealiasType is! EnumClass,
       );
+      final usedEnums = visit(context, _FindEnumsVisitation(), notEnums).enums;
+      if (usedEnums.isNotEmpty) {
+        final names = usedEnums.map((e) => e.originalName).toList()..sort();
+        context.logger.severe(
+          'The integer type used for enums is '
+          'implementation-defined. FFIgen tries to mimic the integer sizes '
+          'chosen by the most common compilers for the various OS and '
+          'architecture combinations. To prevent any crashes, remove the '
+          'enums from your API surface. To rely on the (unsafe!) mimicking, '
+          'you can silence this warning by adding silence-enum-warning: true '
+          'to the FFIgen config. Affected enums:\n\t${names.join('\n\t')}',
+        );
+      }
     }
 
     _canGenerateSymbolOutput = true;
@@ -583,3 +583,13 @@ class _SymbolAddressUnit {
 
   _SymbolAddressUnit(this.type, this.name, this.ptrName, this.native);
 }
+
+class _FindEnumsVisitation extends Visitation {
+  final enums = <EnumClass>{};
+
+  @override
+  void visitEnumClass(EnumClass node) {
+    node.visitChildren(visitor);
+    enums.add(node);
+  }
+}

pkgs/ffigen/test/large_integration_tests/large_test.dart

@@ -24,8 +24,10 @@ void main() {
         'libclang',
         'include',
       );
+      final logArr = <String>[];
+      final logger = logToArray(logArr, Level.SEVERE);
       final config = FfiGen(
-        Logger.root,
+        logger,
         wrapperName: 'LibClang',
         wrapperDocComment: 'Bindings to LibClang.',
         output: Uri.file('unused'),
@@ -75,6 +77,44 @@ void main() {
         codeNormalizer: (code) =>
             code.replaceAll(RegExp('[^\n]*///[^\n]*@[^\n]*\n'), ''),
       );
+
+      const expectedEnumWarnings = [
+        'CXAvailabilityKind',
+        'CXCallingConv',
+        'CXChildVisitResult',
+        'CXCompletionChunkKind',
+        'CXCursorKind',
+        'CXDiagnosticSeverity',
+        'CXErrorCode',
+        'CXEvalResultKind',
+        'CXIdxAttrKind',
+        'CXIdxEntityCXXTemplateKind',
+        'CXIdxEntityKind',
+        'CXIdxEntityLanguage',
+        'CXIdxEntityRefKind',
+        'CXIdxObjCContainerKind',
+        'CXLanguageKind',
+        'CXLinkageKind',
+        'CXLoadDiag_Error',
+        'CXPrintingPolicyProperty',
+        'CXRefQualifierKind',
+        'CXResult',
+        'CXSymbolRole',
+        'CXTLSKind',
+        'CXTUResourceUsageKind',
+        'CXTemplateArgumentKind',
+        'CXTokenKind',
+        'CXTypeKind',
+        'CXTypeNullabilityKind',
+        'CXVisibilityKind',
+        'CXVisitorResult',
+        'CX_CXXAccessSpecifier',
+        'CX_StorageClass',
+      ];
+      final actualLogs = logArr.join('\n');
+      for (final e in expectedEnumWarnings) {
+        expect(actualLogs, contains(e));
+      }
     });
 
     test('CJSON test', () {