| Message ID | CAG4ZjNkSk3z9Mg5-kTD=su+gRCJihwAQwD=NFDfN20Lg_BgM0Q@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On 14/02/17 13:59 -0800, Tim Shen via libstdc++ wrote: >This is an obvious missing std::forward. :) I was about to look into it, I assumed it would be something simple! >diff --git a/libstdc++-v3/testsuite/20_util/variant/compile.cc b/libstdc++-v3/testsuite/20_util/variant/compile.cc >index 65f4326c397..d40a4ccb784 100644 >--- a/libstdc++-v3/testsuite/20_util/variant/compile.cc >+++ b/libstdc++-v3/testsuite/20_util/variant/compile.cc >@@ -291,6 +291,13 @@ void test_visit() > }; > static_assert(visit(Visitor(), variant<int, nonliteral>(0)), ""); > } >+ // PR libstdc++/79513 >+ { >+ std::variant<int> v(5); >+ std::visit([](int&){}, v); >+ std::visit([](int&&){}, std::move(v)); >+ (void)v; Is this to suppress an unused variable warning? If it is, please use an attribute instead, as it's more reliable: std::variant<int> v __attribute__((unused)) (5); OK for trunk if testing passes, thanks.
On Tue, Feb 14, 2017 at 2:49 PM, Jonathan Wakely <jwakely@redhat.com> wrote: > On 14/02/17 13:59 -0800, Tim Shen via libstdc++ wrote: >> >> This is an obvious missing std::forward. :) > > > I was about to look into it, I assumed it would be something simple! > >> diff --git a/libstdc++-v3/testsuite/20_util/variant/compile.cc >> b/libstdc++-v3/testsuite/20_util/variant/compile.cc >> index 65f4326c397..d40a4ccb784 100644 >> --- a/libstdc++-v3/testsuite/20_util/variant/compile.cc >> +++ b/libstdc++-v3/testsuite/20_util/variant/compile.cc >> @@ -291,6 +291,13 @@ void test_visit() >> }; >> static_assert(visit(Visitor(), variant<int, nonliteral>(0)), ""); >> } >> + // PR libstdc++/79513 >> + { >> + std::variant<int> v(5); >> + std::visit([](int&){}, v); >> + std::visit([](int&&){}, std::move(v)); >> + (void)v; > > > Is this to suppress an unused variable warning? > > If it is, please use an attribute instead, as it's more reliable: > > std::variant<int> v __attribute__((unused)) (5); Even better, I used the shiny new [[gnu::unused]]. :) > > OK for trunk if testing passes, thanks. > Tested and committed.
commit 08235141a7e06db2b604b5869c9d8e4aaf8fa29b
Author: Tim Shen <timshen@google.com>
Date: Tue Feb 14 13:55:18 2017 -0800
2017-02-14 Tim Shen <timshen@google.com>
PR libstdc++/79513
* include/std/variant (visit()): Forward variant types to the return
type detection code.
* testsuite/20_util/variant/compile.cc: Add test cases.
diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index c5138e56803..866c4c40a61 100644
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -1263,7 +1263,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__throw_bad_variant_access("Unexpected index");
using _Result_type =
- decltype(std::forward<_Visitor>(__visitor)(get<0>(__variants)...));
+ decltype(std::forward<_Visitor>(__visitor)(
+ get<0>(std::forward<_Variants>(__variants))...));
constexpr auto& __vtable = __detail::__variant::__gen_vtable<
_Result_type, _Visitor&&, _Variants&&...>::_S_vtable;
diff --git a/libstdc++-v3/testsuite/20_util/variant/compile.cc b/libstdc++-v3/testsuite/20_util/variant/compile.cc
index 65f4326c397..d40a4ccb784 100644
--- a/libstdc++-v3/testsuite/20_util/variant/compile.cc
+++ b/libstdc++-v3/testsuite/20_util/variant/compile.cc
@@ -291,6 +291,13 @@ void test_visit()
};
static_assert(visit(Visitor(), variant<int, nonliteral>(0)), "");
}
+ // PR libstdc++/79513
+ {
+ std::variant<int> v(5);
+ std::visit([](int&){}, v);
+ std::visit([](int&&){}, std::move(v));
+ (void)v;
+ }
}
void test_constexpr()