On 03/05/2018 01:54 PM, Martin Sebor wrote:
Attribute nonstring is currently only allowed on arrays and
pointers to plain char, but -Wstringop-truncation triggers
even for strncpy calls whose arguments are arrays of signed
or unsigned char (with or without a cast to char*).
To help deal with -Wstringop-truncation in the Linux kernel
it was suggested to me that it would be useful to be able
to make use of the attribute on all three narrow char types.
Apparently, there are enough calls to strncpy in the Linux
kernel with arguments of the other char types that trigger
the new warning, and the warning is considered sufficiently
useful that making use of the attribute to suppress
the warning rather than changing it ignore the other
two char types is preferable.
The attached patch relaxes the restriction and lets GCC
accept attribute nonstring on all three narrow character
types as well as their qualified forms.
Tested on x86_64-linux.
Martin
gcc-84725.diff
PR tree-optimization/84725 - enable attribute nonstring for all narrow character types
gcc/c-family/ChangeLog:
PR tree-optimization/84725
* c-attribs.c (handle_nonstring_attribute): Allow attribute nonstring
with all three narrow character types, including their qualified forms.
gcc/testsuite/ChangeLog:
PR tree-optimization/84725
* c-c++-common/Wstringop-truncation-4.c: New test.
* c-c++-common/attr-nonstring-5.c: New test.
While it's not a regression, I think getting this warning to a point
where it's usable by the linux kernel is a notable win. So I'm going to
ACK it as an exception to the regression bugfixes only policy.