This was extracted from Martin's work on the strlen range fixes.
As the comment indicates, avoid warning for strncpy (a, b, N) where
N == sizeof (a) and N == sizeof (b).
I didn't immediately see a testcase in Martin's changes. I'm pretty
sure I've seen a few Fedora rawhide packages failing builds because of
this issue.
Bootstrapped & regression tested on x86_64. Installing on the trunk.
My Fedora tester will pick it up at the next snapshot. My GCC tester
will pick it up overnight.
Jeff
commit b74ab41ec0b6f590d0c5ff803b42a05b21fb2218
Author: law <law@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri Dec 28 19:26:14 2018 +0000
* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Avoid
undesirable warning.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@267454
138bc75d-0d04-0410-961f-82ee72b054a4
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 741c02d6cda..e79809c50f6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2018-12-28 Martin Sebor <mse...@redhat.com>
+
+ * tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Avoid
+ undesirable warning.
+
2018-12-28 Thomas Schwinge <tho...@codesourcery.com>
* omp-expand.c (expand_omp_target): Restructure OpenACC vs. OpenMP
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index 669c315dce2..c74ce0feac5 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -2114,6 +2114,13 @@ maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree
src, tree cnt)
if (wi::to_wide (dstsize) != cntrange[1])
return false;
+ /* Avoid warning for strncpy(a, b, N) calls where the following
+ equalities hold:
+ N == sizeof a && N == sizeof b */
+ if (tree srcsize = compute_objsize (src, 1))
+ if (wi::to_wide (srcsize) == cntrange[1])
+ return false;
+
if (cntrange[0] == cntrange[1])
return warning_at (callloc, OPT_Wstringop_truncation,
"%G%qD specified bound %E equals destination size",
