r259854 - in /trunk/libstdc++-v3: ChangeLog inc...

[redi@gcc.gnu.org]

Author: redi
Date: Wed May  2 19:04:55 2018
New Revision: 259854

URL: https://gcc.gnu.org/viewcvs?rev=259854&root=gcc&view=rev
Log:
PR libstdc++/68197 fail on negative iword/pword indices

The suggested resolution of LWG 3083 is to make invalid indices
undefined, but we can fairly easily check for them and treat them as
errors in the same way as allocation failure. This avoids a segfault or
worse, setting an error flag on the stream instead.

	PR libstdc++/68197
	* include/bits/ios_base.h (ios_base::iword, ios_base::pword): Cast
	indices to unsigned.
	* src/c++11/ios.cc (ios_base::_M_grow_words): Treat negative indices
	as failure. Refactor error handling.
	* testsuite/27_io/ios_base/storage/68197.cc: New.

Added:
    trunk/libstdc++-v3/testsuite/27_io/ios_base/storage/68197.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/ios_base.h
    trunk/libstdc++-v3/src/c++11/ios.cc