From 82309222300acf68e345b32155df21e1b876144e Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Fri, 20 Sep 2024 17:35:48 +0100 Subject: [PATCH] libstdc++: Document missing features for old std:string ABI [PR116777] There are several features that are not supported when using the old std::string ABI. It's possible that PR 81967 will get fixed, but the missing C++20 features almost certainly won't be. Document this in the manual. libstdc++-v3/ChangeLog: PR libstdc++/116777 * doc/xml/manual/using.xml: Document features that are not supported for the gcc4-compatible ABI. * doc/html/manual/using_dual_abi.html: Regenerate. --- .../doc/html/manual/using_dual_abi.html | 18 ++++++++++++- libstdc++-v3/doc/xml/manual/using.xml | 26 ++++++++++++++++++- 2 files changed, 42 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/doc/html/manual/using_dual_abi.html b/libstdc++-v3/doc/html/manual/using_dual_abi.html index 916ac575f64b..939eedae3629 100644 --- a/libstdc++-v3/doc/html/manual/using_dual_abi.html +++ b/libstdc++-v3/doc/html/manual/using_dual_abi.html @@ -22,7 +22,7 @@ of the macro is 1 which causes the new ABI to be active, so to use the old ABI you must explicitly define the macro to 0 before including any library headers. - (Be aware that some GNU/Linux distributions configure GCC 5 differently so + (Be aware that some GNU/Linux distributions configured GCC 5 differently so that the default value of the macro is 0 and users must define it to 1 to enable the new ABI.)

Although the changes were made for C++11 conformance, the choice of ABI @@ -72,6 +72,22 @@ Handlers for std::exception will always catch iostreams exceptions, because the old and new type both inherit from std::exception. +

+ Some features are not supported when using the old ABI, including: +

Troubleshooting

If you get linker errors about undefined references to symbols that involve types in the std::__cxx11 namespace or the tag [abi:cxx11] then it probably indicates that you are trying to diff --git a/libstdc++-v3/doc/xml/manual/using.xml b/libstdc++-v3/doc/xml/manual/using.xml index 4e1c70040b56..89119f6fb2db 100644 --- a/libstdc++-v3/doc/xml/manual/using.xml +++ b/libstdc++-v3/doc/xml/manual/using.xml @@ -1368,7 +1368,7 @@ g++ -Winvalid-pch -I. -include stdc++.h -H -g -O2 hello.cc -o test.exe of the macro is 1 which causes the new ABI to be active, so to use the old ABI you must explicitly define the macro to 0 before including any library headers. - (Be aware that some GNU/Linux distributions configure GCC 5 differently so + (Be aware that some GNU/Linux distributions configured GCC 5 differently so that the default value of the macro is 0 and users must define it to 1 to enable the new ABI.) @@ -1428,6 +1428,30 @@ g++ -Winvalid-pch -I. -include stdc++.h -H -g -O2 hello.cc -o test.exe std::exception. + + Some features are not supported when using the old ABI, including: + + + Using std::string::const_iterator for + positional arguments to member functions such as + std::string::erase. + + + Allocator propagation in std::string. + + + Using std::string at compile-time in + constexpr functions. + + + Class std::chrono::time_zone and all related APIs. + + + The <syncstream> header. + + + +

Troubleshooting If you get linker errors about undefined references to symbols -- 2.47.2