From 8281e3b8ea4fe692c92c8781636a36e81f4e038f Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Fri, 26 Apr 2019 15:04:45 +0100 Subject: [PATCH] Reduce code instantiated by filesystem::path::_S_convert_loc Jakub noted in https://gcc.gnu.org/ml/libstdc++/2019-04/msg00140.html that an unwanted std::wstring::_M_replace_dispatch symbol has started to be exported from the Fedora shared library. This symbol is triggered by the instantiation of std::wstring::assign(const char*, const char*) from std::__str_codecvt_in which is called from path::_S_convert_loc. The branch that triggers that instantiation can't actually happen in that case, because codecvt facets will only return noconv when the input and output types are the same. Guarding the assign call with an if-constexpr check that the types are the same avoids instantiating template specializations that will never actually be needed. * config/abi/pre/gnu.ver (GLIBCXX_3.4): Replace wildcard that matches wstring::_M_replace_dispatch with more specific patterns. * include/bits/fs_path.h (path::_S_convert_loc<_InputIterator>): Create const std::string to avoid redundant call to _S_convert_loc with non-const pointers. * include/bits/locale_conv.h (__do_str_codecvt): Use if-constexpr to avoid unnecessary basic_string::assign instantiations. From-SVN: r270602 --- libstdc++-v3/ChangeLog | 8 ++++++++ libstdc++-v3/config/abi/pre/gnu.ver | 3 ++- libstdc++-v3/include/bits/fs_path.h | 2 +- libstdc++-v3/include/bits/locale_conv.h | 10 ++++++++-- 4 files changed, 19 insertions(+), 4 deletions(-) diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index d2f8ed4f1aa..61841e87ce8 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,13 @@ 2019-04-26 Jonathan Wakely + * config/abi/pre/gnu.ver (GLIBCXX_3.4): Replace wildcard that matches + wstring::_M_replace_dispatch with more specific patterns. + * include/bits/fs_path.h (path::_S_convert_loc<_InputIterator>): + Create const std::string to avoid redundant call to _S_convert_loc + with non-const pointers. + * include/bits/locale_conv.h (__do_str_codecvt): Use if-constexpr to + avoid unnecessary basic_string::assign instantiations. + * include/std/memory (__uses_alloc_args): Add string-literal to static_assert, to match the one in __uses_alloc. [__cpp_concepts] (_Std_pair): Use C++2a syntax for concept. diff --git a/libstdc++-v3/config/abi/pre/gnu.ver b/libstdc++-v3/config/abi/pre/gnu.ver index e8cf6f0a4a9..7eff4e983f3 100644 --- a/libstdc++-v3/config/abi/pre/gnu.ver +++ b/libstdc++-v3/config/abi/pre/gnu.ver @@ -299,7 +299,8 @@ GLIBCXX_3.4 { _ZNSbIwSt11char_traitsIwESaIwEE12_S_constructE[jmy]wRKS1_; _ZNSbIwSt11char_traitsIwESaIwEE12_S_empty_repEv; _ZNSbIwSt11char_traitsIwESaIwEE13_S_copy_chars*; - _ZNSbIwSt11char_traitsIwESaIwEE[0-9][0-9]_M_replace*; + _ZNSbIwSt11char_traitsIwESaIwEE14_M_replace_aux*; + _ZNSbIwSt11char_traitsIwESaIwEE15_M_replace_safe*; _ZNSbIwSt11char_traitsIwESaIwEE4_Rep10_M_destroy*; _ZNSbIwSt11char_traitsIwESaIwEE4_Rep10_M_dispose*; _ZNSbIwSt11char_traitsIwESaIwEE4_Rep10_M_refcopyEv; diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h index 3674b4391f8..28878c627a7 100644 --- a/libstdc++-v3/include/bits/fs_path.h +++ b/libstdc++-v3/include/bits/fs_path.h @@ -539,7 +539,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 _S_convert_loc(_InputIterator __src, __null_terminated, const std::locale& __loc) { - std::string __s = _S_string_from_iter(__src); + const std::string __s = _S_string_from_iter(__src); return _S_convert_loc(__s.data(), __s.data() + __s.size(), __loc); } diff --git a/libstdc++-v3/include/bits/locale_conv.h b/libstdc++-v3/include/bits/locale_conv.h index d7510dff80e..4cb9c39ebb4 100644 --- a/libstdc++-v3/include/bits/locale_conv.h +++ b/libstdc++-v3/include/bits/locale_conv.h @@ -88,8 +88,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION if (__result == codecvt_base::noconv) { - __outstr.assign(__first, __last); - __count = __last - __first; + // The codecvt facet will only return noconv when the types are + // the same, so avoid instantiating basic_string::assign otherwise + if _GLIBCXX17_CONSTEXPR (is_same()) + { + __outstr.assign(__first, __last); + __count = __last - __first; + } } else { -- 2.30.2