]> git.ipfire.org Git - thirdparty/gcc.git/commitdiff
libstdc++: Fix std::move_only_function for incomplete parameter types
authorJonathan Wakely <jwakely@redhat.com>
Tue, 18 Oct 2022 19:49:42 +0000 (20:49 +0100)
committerJonathan Wakely <jwakely@redhat.com>
Fri, 21 Oct 2022 09:40:40 +0000 (10:40 +0100)
The std::move_only_function::__param_t alias template attempts to
optimize argument passing for the invoker, by passing by rvalue
reference for types that are non-trivial or large. However, the
precondition for is_trivally_copyable makes it unsuitable for using
here, and can cause ODR violations. Just use is_scalar instead, and pass
all class types (even small, trivial ones) by value.

libstdc++-v3/ChangeLog:

* include/bits/mofunc_impl.h (move_only_function::__param_t):
Use __is_scalar instead of is_trivially_copyable.
* testsuite/20_util/move_only_function/call.cc: Check parameters
involving incomplete types.

libstdc++-v3/include/bits/mofunc_impl.h
libstdc++-v3/testsuite/20_util/move_only_function/call.cc

index 405c4054642d4811d2f5868c0469799c15399aba..47e1e5063069c51518e0162ffe5506d8ad38e91d 100644 (file)
@@ -205,10 +205,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     private:
       template<typename _Tp>
-       using __param_t
-         = __conditional_t<is_trivially_copyable_v<_Tp>
-                             && sizeof(_Tp) <= sizeof(long),
-                           _Tp, _Tp&&>;
+       using __param_t = __conditional_t<is_scalar_v<_Tp>, _Tp, _Tp&&>;
 
       using _Invoker = _Res (*)(_Mofunc_base _GLIBCXX_MOF_CV*,
                                __param_t<_ArgTypes>...) noexcept(_Noex);
index 68aa20568ebcf75bd9650b892175f37b452ebf20..3e15983641216a98018c7fe421f4174a09e0255c 100644 (file)
@@ -191,10 +191,21 @@ test04()
   VERIFY( std::move(std::as_const(f5))() == 3 );
 }
 
+struct Incomplete;
+
+void
+test_params()
+{
+  std::move_only_function<void(Incomplete)> f1;
+  std::move_only_function<void(Incomplete&)> f2;
+  std::move_only_function<void(Incomplete&&)> f3;
+}
+
 int main()
 {
   test01();
   test02();
   test03();
   test04();
+  test_params();
 }