r265162 - in /branches/gcc-6-branch/libstdc++-v...

[redi@gcc.gnu.org]

Author: redi
Date: Mon Oct 15 11:52:48 2018
New Revision: 265162

URL: https://gcc.gnu.org/viewcvs?rev=265162&root=gcc&view=rev
Log:
PR libstdc++/86751 default assignment operators for std::pair

The solution for PR 77537 causes ambiguities due to the extra copy
assignment operator taking a __nonesuch_no_braces parameter. By making
the base class non-assignable we don't need the extra deleted overload
in std::pair. The copy assignment operator will be implicitly deleted
(and the move assignment operator not declared) as needed. Without the
additional user-provided operator in std::pair the ambiguity is avoided.

Backport from mainline
2018-07-31  Jonathan Wakely  <jwakely@redhat.com>

	PR libstdc++/86751
	* include/bits/stl_pair.h (__pair_base): New class with deleted copy
	assignment operator.
	(pair): Derive from __pair_base.
	(pair::operator=): Remove deleted overload.
	* python/libstdcxx/v6/printers.py (StdPairPrinter): New pretty printer
	so that new base class isn't shown in GDB.
	* testsuite/20_util/pair/86751.cc: New test.
	* testsuite/20_util/pair/ref_assign.cc: New test.

Added:
    branches/gcc-6-branch/libstdc++-v3/testsuite/20_util/pair/86751.cc
    branches/gcc-6-branch/libstdc++-v3/testsuite/20_util/pair/ref_assign.cc
Modified:
    branches/gcc-6-branch/libstdc++-v3/ChangeLog
    branches/gcc-6-branch/libstdc++-v3/include/bits/stl_pair.h
    branches/gcc-6-branch/libstdc++-v3/python/libstdcxx/v6/printers.py