[Bug libstdc++/79254] [5/6/7 Regression] basic_string::operator= isn't exception safe

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79254

--- Comment #12 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Author: redi
Date: Wed Feb  1 12:12:28 2017
New Revision: 245086

URL: https://gcc.gnu.org/viewcvs?rev=245086&root=gcc&view=rev
Log:
PR libstdc++/79254 fix exception-safety of std::string copy assignment

        PR libstdc++/79254
        * include/bits/basic_string.h [_GLIBCXX_USE_CXX11_ABI]
        (basic_string::operator=(const basic_string&)): If source object is
        small just deallocate, otherwise perform new allocation before
        making any changes.
        * testsuite/21_strings/basic_string/allocator/wchar_t/copy_assign.cc:
        Test exception-safety of copy assignment when allocator propagates.
        * testsuite/21_strings/basic_string/allocator/char/copy_assign.cc:
        Likewise.
        * testsuite/util/testsuite_allocator.h (uneq_allocator::swap): Make
        std::swap visible.

Modified:
    branches/gcc-6-branch/libstdc++-v3/ChangeLog
    branches/gcc-6-branch/libstdc++-v3/include/bits/basic_string.h
   
branches/gcc-6-branch/libstdc++-v3/testsuite/21_strings/basic_string/allocator/char/copy_assign.cc
   
branches/gcc-6-branch/libstdc++-v3/testsuite/21_strings/basic_string/allocator/wchar_t/copy_assign.cc
    branches/gcc-6-branch/libstdc++-v3/testsuite/util/testsuite_allocator.h