https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121687
Bug ID: 121687
Summary: Another early August wrong code bug
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: dcb314 at hotmail dot com
Target Milestone: ---
Created attachment 62211
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=62211&action=edit
C source code
The attached code does this with gcc trunk:
foundBugs $ /home/dcb42/gcc/results.20250804.asan.ubsan/bin/gcc -w -O2
-Werror=return-type -Werror=uninitialized -Werror=overflow
-Werror=sequence-point bug1117.c && valgrind -q ./a.out
checksum = B0C5658A
foundBugs $ /home/dcb42/gcc/results.20250806.asan.ubsan/bin/gcc -w -O2
-Werror=return-type -Werror=uninitialized -Werror=overflow
-Werror=sequence-point bug1117.c && valgrind -q ./a.out
checksum = 693B9C6B
foundBugs $
So something has gone wrong between those two compilers.
foundBugs $ /home/dcb42/gcc/results.20250804.asan.ubsan/bin/gcc -v 2>&1 | grep
exp
gcc version 16.0.0 20250804 (experimental) (b963237a903f73cf)
foundBugs $ /home/dcb42/gcc/results.20250806.asan.ubsan/bin/gcc -v 2>&1 | grep
exp
gcc version 16.0.0 20250806 (experimental) (87262627fd65a1a7)
foundBugs $
There are 259 commits between those two points.
Interestingly:
foundBugs $ /home/dcb42/gcc/results.20250806.asan.ubsan/bin/gcc -w -O1
-Werror=return-type -Werror=uninitialized -Werror=overflow
-Werror=sequence-point bug1117.c && valgrind -q ./a.out
checksum = B0C5658A
foundBugs
I will have a go at a reduction.
