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* GCC 12.1, -isystem, -Wsystem-headers, and -Wmaybe-uninitialized
@ 2022-05-18 16:56 Tom Kacvinsky
  2022-05-18 18:32 ` Jonathan Wakely
  0 siblings, 1 reply; 2+ messages in thread
From: Tom Kacvinsky @ 2022-05-18 16:56 UTC (permalink / raw)
  To: gcc-help

We were happily using -Wall -Wextra -Werror with GCC 8.3.0 and -isystem
for Boost header files to squelch any warnings that would come out of
Boost.

I recently switched to GCC 12.1 and now we are getting
-Wmaybe-uninitialized errors out of Boost.  So I am not sure if
-Wsystem-headers was not part of -Wall -Wextra in GCC 8.3.0 but is now
part of GCC 12.1.0.

Optimization level plays a role in this.  With -O0 (GCC 12.1), the
warning does not happen, but with -O3, it does.

So I am not sure of the interaction between optimization, -Wall -Wextra,
-Wsystem-headers, and GCC 8.3.0 and GCC 12.1.0.

Any ideas?

Thanks, Tom

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: GCC 12.1, -isystem, -Wsystem-headers, and -Wmaybe-uninitialized
  2022-05-18 16:56 GCC 12.1, -isystem, -Wsystem-headers, and -Wmaybe-uninitialized Tom Kacvinsky
@ 2022-05-18 18:32 ` Jonathan Wakely
  0 siblings, 0 replies; 2+ messages in thread
From: Jonathan Wakely @ 2022-05-18 18:32 UTC (permalink / raw)
  To: Tom Kacvinsky; +Cc: gcc-help

On Wed, 18 May 2022, 17:57 Tom Kacvinsky via Gcc-help, <gcc-help@gcc.gnu.org>
wrote:

> We were happily using -Wall -Wextra -Werror with GCC 8.3.0 and -isystem
> for Boost header files to squelch any warnings that would come out of
> Boost.
>
> I recently switched to GCC 12.1 and now we are getting
> -Wmaybe-uninitialized errors out of Boost.  So I am not sure if
> -Wsystem-headers was not part of -Wall -Wextra in GCC 8.3.0 but is now
> part of GCC 12.1.0.
>

No it isn't, it's just that some warnings are now given even if they occur
in system headers.



> Optimization level plays a role in this.  With -O0 (GCC 12.1), the
> warning does not happen, but with -O3, it does.
>

The uninitialised warnings depend on data flow analysis, which only happens
with optimization.



> So I am not sure of the interaction between optimization, -Wall -Wextra,
> -Wsystem-headers, and GCC 8.3.0 and GCC 12.1.0.
>
> Any ideas?
>
> Thanks, Tom
>

^ permalink raw reply	[flat|nested] 2+ messages in thread

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