The powerpc64 ICE is fixed, so I'm committing the std::string ABI transition patch.
This replaces our venerable Copy-on-Write std::string with a C++11-conforming* Small-String Optimized std::__cxx11::string. (* It's not quite 100% conforming, as it's missing some allocator features. Of course. Always with the allocators. But that's only a small fix to make next week.) Since the last version of this patch Jason has added support for attribute((abi_tag)) on namespaces, so the new types can be defined in an inline namespace that has the tag, rather than co-existing in namespace std with the un-tagged types. This makes overloading and exporting symbols a bit more straightforward as the different linkage names can be expressed with a fully-qualified name without needing the attribute. I've also added regex templates to the new __cxx11 namespace, as they depend on std::string. There are now two new configure options, --disable-libstdcxx-dual-abi and --with-default-libstdcxx-abi. The former disables all support for the new __cxx11 ABI pieces. The latter is only relevant when the dual ABI is enabled and can be used to make the old definitions the default ones you get without defining the _GLIBCXX_USE_CXX11_ABI macro. As described previously, the locale facets that depend on the std::string ABI exist twice as "twinned facets" and if users replace a twinned facet the library generates a shim to replace its twin. Also as described previously, the types in <stdexcept> continue to use the COW string, to ensure nothrow copying and ABI stability. The Python pretty printer problems I was seeing with the new string turned out to be a GDB bug (17728). Target maintainers will see a *lot* of new exports at the latest symbol version if they generate a new baseline-symbols.txt file. I suggest waiting and doing that nearer the end of stage 3 in case there are any fixes needed after this change. Bootstrapped and tested in various configurations on x86_64-linux and powerpc64-linux. Committed to trunk! Phew.
patch.txt.bz2
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