[Bug c/85623] strncmp() warns about attribute 'nonstring' incorrectly in -Wstringop-overflow

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85623

--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
Author: msebor
Date: Tue May 22 17:45:35 2018
New Revision: 260541

URL: https://gcc.gnu.org/viewcvs?rev=260541&root=gcc&view=rev
Log:
PR c/85623 - strncmp() warns about attribute 'nonstring' incorrectly in
-Wstringop-overflow

gcc/ChangeLog:

        PR c/85623
        * calls.c (maybe_warn_nonstring_arg): Use string length to set
        or ajust the presumed bound on an operation to avoid unnecessary
        warnings.

gcc/testsuite/ChangeLog:

        PR c/85623
        * c-c++-common/attr-nonstring-3.c: Adjust.
        * c-c++-common/attr-nonstring-4.c: Adjust.
        * c-c++-common/attr-nonstring-6.c: New test.


Added:
    trunk/gcc/testsuite/c-c++-common/attr-nonstring-6.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/calls.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/c-c++-common/attr-nonstring-3.c
    trunk/gcc/testsuite/c-c++-common/attr-nonstring-4.c