https://gcc.gnu.org/bugzilla/show_bug.cgi?id=29455
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-02-17
CC| |msebor at gcc dot gnu.org
Ever confirmed|0 |1
Known to fail| |4.1.3, 4.2.2, 4.3.2, 4.6.0,
| |5.3.0, 6.3.0, 7.0
--- Comment #10 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed due to the missing warning on a['\300'] with today's top of trunk.
The following test case shows that the C and C++ front ends behave nearly the
same (modulo the -Wmultichar warning), and that with optimization the
out-of-bounds constant character index is diagnosed by -Warray-bounds.
$ (cat t.c && set -x && for lang in c c++; do gcc -O2 -S -Wall -Wextra
-Wpedantic -fsigned-char -x$lang t.c; done)
int a[256];
int A(char c) { return a[c]; } // C and C++ warnings, OK.
int D(void) { return a['%']; } // Spurious C++ warning, no C warning
int B(void) { return a['å']; } // C++ warning, missing C warning
int C(void) { return a['\300']; } // C++ warning, missing C warning
+ for lang in c c++
+ gcc -O2 -S -Wall -Wextra -Wpedantic -fsigned-char -xc t.c
t.c: In function ‘A’:
t.c:2:25: warning: array subscript has type ‘char’ [-Wchar-subscripts]
int A(char c) { return a[c]; } // C and C++ warnings, OK.
^
t.c: In function ‘B’:
t.c:4:26: warning: multi-character character constant [-Wmultichar]
int B(void) { return a['å']; } // C++ warning, missing C warning
^~~~
t.c:4:25: warning: array subscript is above array bounds [-Warray-bounds]
int B(void) { return a['å']; } // C++ warning, missing C warning
~^~~~~~
t.c: In function ‘C’:
t.c:5:25: warning: array subscript is below array bounds [-Warray-bounds]
int C(void) { return a['\300']; } // C++ warning, missing C warning
~^~~~~~~~
+ for lang in c c++
+ gcc -O2 -S -Wall -Wextra -Wpedantic -fsigned-char -xc++ t.c
t.c:4:26: warning: multi-character character constant [-Wmultichar]
int B(void) { return a['å']; } // C++ warning, missing C warning
^~~~
t.c: In function ‘int A(char)’:
t.c:2:27: warning: array subscript has type ‘char’ [-Wchar-subscripts]
int A(char c) { return a[c]; } // C and C++ warnings, OK.
^
t.c: In function ‘int B()’:
t.c:4:30: warning: array subscript is above array bounds [-Warray-bounds]
int B(void) { return a['å']; } // C++ warning, missing C warning
~~~~~~^
t.c: In function ‘int C()’:
t.c:5:32: warning: array subscript is below array bounds [-Warray-bounds]
int C(void) { return a['\300']; } // C++ warning, missing C warning
~~~~~~~~^
