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* [Bug c/90844] New: Another case of missing use of uninitialized variable warning
@ 2019-06-11 21:03 subscriptions-gnu at vsbe dot com
2021-04-15 22:55 ` [Bug middle-end/90844] missing -Wmaybe-uninitialized with -flto and optimization msebor at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: subscriptions-gnu at vsbe dot com @ 2019-06-11 21:03 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90844
Bug ID: 90844
Summary: Another case of missing use of uninitialized variable
warning
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: subscriptions-gnu at vsbe dot com
Target Milestone: ---
this is somewhat similar to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=18501,
but a bit different. Here is the code to trigger the problem:
vvvvvvvvvvv try.c vvvvvvvvvvvvvvvvvvvvvvvvvvv
static int func1(int x) { return 1; }
static int func2(void)
{
int number;
if (func2() == 0) number += func1(0);
return number;
}
int main(int argc, char **argv)
{
int counter;
counter += func2();
return counter;
}
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Running on 4.19.28-2 x86_64 GNU/Linux, using compiler version
vvvvvvvvvvvvvvvvvvvvvvvvvvvv
arm-eabi-gcc -v
Using built-in specs.
COLLECT_GCC=/usr/local/google/home/vbendeb/new_projects/1grepo/chroot/opt/coreboot-sdk/bin/arm-eabi-gcc
COLLECT_LTO_WRAPPER=/usr/local/google/home/vbendeb/new_projects/1grepo/chroot/opt/coreboot-sdk/bin/../lib/gcc/arm-eabi/8.3.0/lto-wrapper
Target: arm-eabi
Configured with: ../gcc-8.3.0/configure --prefix=/opt/coreboot-sdk
--libexecdir=/opt/coreboot-sdk/lib --target=arm-eabi --disable-werror
--disable-shared --enable-lto --enable-plugins --enable-gold
--enable-ld=default --disable-libssp --disable-bootstrap --disable-nls
--disable-libquadmath --without-headers --disable-threads --enable-interwork
--enable-multilib --enable-targets=all --disable-libatomic --disable-libcc1
--disable-decimal-float --enable-languages=c,ada --with-system-zlib
--with-gmp=/var/tmp/portage/dev-embedded/coreboot-sdk-0.0.1-r74/work/coreboot-sdk-0.0.1/out/opt/coreboot-sdk
--with-mpfr=/var/tmp/portage/dev-embedded/coreboot-sdk-0.0.1-r74/work/coreboot-sdk-0.0.1/out/opt/coreboot-sdk
--with-mpc=/var/tmp/portage/dev-embedded/coreboot-sdk-0.0.1-r74/work/coreboot-sdk-0.0.1/out/opt/coreboot-sdk
--with-gnu-as --with-gnu-ld --with-pkgversion='coreboot toolchain v '
Thread model: single
gcc version 8.3.0 (coreboot toolchain v )
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The below invocation properly highlights two instance of the uninitialized
variable assignment:
$ arm-eabi-gcc -Wall -o try.o -c try.c
try.c: In function 'func2':
try.c:7:34: warning: 'number' may be used uninitialized in this function
[-Wmaybe-uninitialized]
if (func2() == 0) number += func1(0);
^~
try.c: In function 'main':
try.c:14:17: warning: 'counter' is used uninitialized in this function
[-Wuninitialized]
counter += func2();
^~
$
The following invocation triggers only one warning:
$ arm-eabi-gcc -Wall -Os -flto -o try.o -c try.c
try.c: In function 'main':
try.c:14:17: warning: 'counter' is used uninitialized in this function
[-Wuninitialized]
counter += func2();
^~
$
>From gcc-bugs-return-646368-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Jun 11 21:57:06 2019
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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/90397] Incompatibility with clang-tidy on std::variant
Date: Tue, 11 Jun 2019 21:57:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90397
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
G++ allowed it because the mismatch was in a system header. If you use
-Wsystem-headers then GCC 9.1 gives a warning about it:
/xhome/jwakely/gcc/9.1.0/include/c++/9.1.0/variant: In instantiation of 'class
std::variant<A, B>':
var.cc:14:44: required from here
/xhome/jwakely/gcc/9.1.0/include/c++/9.1.0/variant:1559:34: warning:
declaration of 'template<long unsigned int _Np, class _Vp> constexpr
decltype(auto) std::__detail::__variant::__get(_Vp&&)' has a different
exception specifier [-Wsystem-headers]
1559 | friend constexpr decltype(auto) __detail::__variant::__get(_Vp&& __v);
| ^~~~~~~~
/xhome/jwakely/gcc/9.1.0/include/c++/9.1.0/variant:263:5: note: from previous
declaration 'template<long unsigned int _Np, class _Variant> constexpr
decltype(auto) std::__detail::__variant::__get(_Variant&&) noexcept'
263 | __get(_Variant&& __v) noexcept
| ^~~~~
If you use -pedantic-errors then you get an error.
>From gcc-bugs-return-646369-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Jun 11 22:04:46 2019
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From: "tkoenig at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/90744] [7/8/9/10 Regression] Bogus length for character temporaries passed to external procedures since r268992
Date: Tue, 11 Jun 2019 22:04:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90744
--- Comment #8 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Author: tkoenig
Date: Tue Jun 11 22:04:10 2019
New Revision: 272173
URL: https://gcc.gnu.org/viewcvs?rev=272173&root=gcc&view=rev
Log:
2019-06-11 Thomas Koenig <tkoenig@gcc.gnu.org>
Tomáš Trnka <trnka@scm.com>
Backport from trunk
PR fortran/90744
* trans-types.c (get_formal_from_actual_arglist): Unset typespec
flags which make no sense for procedures without explicit
interface.
2019-06-11 Thomas Koenig <tkoenig@gcc.gnu.org>
Tomáš Trnka <trnka@scm.com>
Backport from trunk
PR fortran/90744
* gfortran.dg/deferred_character_33.f90: New test.
* gfortran.dg/deferred_character_33a.f90: New test.
Added:
branches/gcc-9-branch/gcc/testsuite/gfortran.dg/deferred_character_33.f90
branches/gcc-9-branch/gcc/testsuite/gfortran.dg/deferred_character_33a.f90
Modified:
branches/gcc-9-branch/gcc/fortran/ChangeLog
branches/gcc-9-branch/gcc/fortran/trans-types.c
branches/gcc-9-branch/gcc/testsuite/ChangeLog
>From gcc-bugs-return-646370-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Jun 11 22:26:51 2019
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From: "segher at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/90513] asm thunks do not work on PowerPC64/VxWorks (kernel mode)
Date: Tue, 11 Jun 2019 22:26:00 -0000
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--- Comment #19 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Also, please post proper patches, to the gcc-patches mailing list, as
detailed in <https://gcc.gnu.org/contribute.html>, if you want those
patches to be approved.
>From gcc-bugs-return-646371-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Jun 11 22:31:48 2019
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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Umesh Kalappa <umesh.kalappa0@gmail.com>
Cc: Alan Modra <amodra@gmail.com>, gcc-bugs@gcc.gnu.org
Subject: Re: [Bug target/90513] asm thunks do not work on PowerPC64/VxWorks (kernel mode)
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On Tue, Jun 11, 2019 at 10:25:58PM +0530, Umesh Kalappa wrote:
> We would like to know comments on the below proposed change ?
As I said in the PR, this is not a proper patch. Also, like Eric says
there, it does not do the right thing for many configurations.
Fix the loader, instead?
Segher
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug middle-end/90844] missing -Wmaybe-uninitialized with -flto and optimization
2019-06-11 21:03 [Bug c/90844] New: Another case of missing use of uninitialized variable warning subscriptions-gnu at vsbe dot com
@ 2021-04-15 22:55 ` msebor at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: msebor at gcc dot gnu.org @ 2021-04-15 22:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90844
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |msebor at gcc dot gnu.org
Summary|Another case of missing use |missing
|of uninitialized variable |-Wmaybe-uninitialized with
|warning (inlining, CCP) |-flto and optimization
Last reconfirmed|2019-06-12 00:00:00 |2021-4-15
Known to fail| |10.2.0, 11.0, 8.3.0, 9.3.0
--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
The late uninit pass doesn't run with -flto; all that runs is the early
uninitialized pass and it disables the "conditional" -Wmaybe-uninitialized when
optimization is enabled:
static unsigned int
execute_early_warn_uninitialized (void)
{
/* Currently, this pass runs always but
execute_late_warn_uninitialized only runs with optimization. With
optimization we want to warn about possible uninitialized as late
as possible, thus don't do it here. However, without
optimization we need to warn here about "may be uninitialized". */
calculate_dominance_info (CDI_POST_DOMINATORS);
warn_uninitialized_vars (/*warn_maybe_uninitialized=*/!optimize);
^^^^^^^^^
Changing that like so lets the warning do its thing even with -flto:
@@ -3086,7 +3079,8 @@ execute_early_warn_uninitialized (void)
optimization we need to warn here about "may be uninitialized". */
calculate_dominance_info (CDI_POST_DOMINATORS);
- warn_uninitialized_vars (/*warn_maybe_uninitialized=*/!optimize);
+ bool wmaybe_uninit = !optimize || flag_lto;
+ warn_uninitialized_vars (wmaybe_uninit);
/* Post-dominator information cannot be reliably updated. Free it
after the use. */
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-04-15 22:55 ` [Bug middle-end/90844] missing -Wmaybe-uninitialized with -flto and optimization msebor at gcc dot gnu.org
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