From: Jonathan Wakely <jwakely@redhat.com>
To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: [committed] libstdc++: Fix link failure in _OutputIteratorConcept
Date: Wed, 2 Feb 2022 17:38:27 +0000 [thread overview]
Message-ID: <20220202173827.2339108-1-jwakely@redhat.com> (raw)
Tested x86_64-linux and by building x86_64-w64-mingw, pushed to trunk.
The C++98-style concept check for output iterators causes a link
failure on mingw-w64, because the __val() member function isn't defined.
Change it to use a function pointer instead. That pointer is never set
to anything meaningful, but it doesn't matter as the __constraints()
function only has to be instantiated, it's never called.
We could refactor all of these to use unevaluated contexts (e.g. sizeof
of __decltype) so that we only check the expressions are well-formed,
without any codegen at all. Any improvements to these are very low
priority though.
libstdc++-v3/ChangeLog:
* include/bits/boost_concept_check.h (_OutputIteratorConcept):
Change member function to data member of function pointer type.
---
libstdc++-v3/include/bits/boost_concept_check.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/bits/boost_concept_check.h b/libstdc++-v3/include/bits/boost_concept_check.h
index 23dba067693..3d884eb440f 100644
--- a/libstdc++-v3/include/bits/boost_concept_check.h
+++ b/libstdc++-v3/include/bits/boost_concept_check.h
@@ -483,7 +483,9 @@ struct _Aux_require_same<_Tp,_Tp> { typedef _Tp _Type; };
*__i++ = __val(); // require postincrement and assignment
}
_Tp __i;
- _ValueT __val() const;
+ // Use a function pointer here so no definition of the function needed.
+ // Just need something that returns a _ValueT (which might be a reference).
+ _ValueT (*__val)();
};
template<typename _Tp>
--
2.34.1
reply other threads:[~2022-02-02 17:38 UTC|newest]
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