Objective C's va_list struct is parsed inconsistently

[liamappelbe]

va_list is being parsed differently on different Mac machines.

--- a/test/native_objc_test/native_objc_test_bindings.dart
+++ b/test/native_objc_test/native_objc_test_bindings.dart
@@ -158,7 +158,7 @@ class NativeObjCLibrary {
 
   void NSLogv(
     ffi.Pointer<ObjCObject> format,
-    ffi.Pointer<__va_list_tag> args,
+    va_list args,
   ) {
     return _NSLogv(
       format,
@@ -168,10 +168,9 @@ class NativeObjCLibrary {
 
   late final _NSLogvPtr = _lookup<
       ffi.NativeFunction<
-          ffi.Void Function(
-              ffi.Pointer<ObjCObject>, ffi.Pointer<__va_list_tag>)>>('NSLogv');
-  late final _NSLogv = _NSLogvPtr.asFunction<
-      void Function(ffi.Pointer<ObjCObject>, ffi.Pointer<__va_list_tag>)>();
+          ffi.Void Function(ffi.Pointer<ObjCObject>, va_list)>>('NSLogv');
+  late final _NSLogv =
+      _NSLogvPtr.asFunction<void Function(ffi.Pointer<ObjCObject>, va_list)>();
 
   late final ffi.Pointer<NSInteger> _NSNotFound =
       _lookup<NSInteger>('NSNotFound');
@@ -4615,18 +4614,8 @@ class ObjCObject extends ffi.Opaque {}
 class ObjCSel extends ffi.Opaque {}
 
 typedef NSUInteger = pkg_ffi.UnsignedLong;
-
-class __va_list_tag extends ffi.Struct {
-  @pkg_ffi.UnsignedInt()
-  external int gp_offset;
-
-  @pkg_ffi.UnsignedInt()
-  external int fp_offset;
-
-  external ffi.Pointer<ffi.Void> overflow_arg_area;
-
-  external ffi.Pointer<ffi.Void> reg_save_area;
-}
+typedef va_list = __builtin_va_list;
+typedef __builtin_va_list = ffi.Pointer<pkg_ffi.Char>;
 
 abstract class NSComparisonResult {
   static const int NSOrderedAscending = -1;

[liamappelbe]

cc @brianquinlan

[liamappelbe]

Actually this inconsistency only matters for our test infrastructure. It's not like the BOOL inconsistency, which was much more fundamental. I'm just going to exclude this irrelevant stuff from the test.

[dcharkes]

Less unused generated stuff in the tests is better. 👍

dart:ffi does not support the valist calling conventions from C. Did I reverse engineer from the diff correctly that one just passes a pointer in ObjectiveC for valists?

[liamappelbe]

Yep, one of the internal headers defines the va_list struct (in a way that differs depending on the user's setup), and then that struct is passed around by pointer.