GCC Wiki Warning History

[Jonathan Wakely]

On Wed, 29 Oct 2025 at 21:53, Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
>
> On Wed, 29 Oct 2025 at 21:47, Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
> >
> > On Wed, 29 Oct 2025 at 21:31, Joel Sherrill <joel.sherrill@gmail.com> wrote:
> > >
> > > Hi
> > >
> > > I am starting a new thread on https://gcc.gnu.org/wiki/WarningHistory. It looks useful but in need of an update. Before I spend more itme on it, I wanted to make sure I am doing the archeology correctly.
> > >
> > > Use git diff with pairs of "adjacent" release tags. I did this for 8.2.0->8.3.0->8.4.0->8.5.0 but didn't see any. This is the command for what's new in 9.1.0.
> > >
> > > $ git diff releases/gcc-8.1.0 releases/gcc-9.1.0 -- common.opt
> > >
> > > And after wading through the output, I think this is the new set of warnings in gcc 9.1.0.
> > >
> > > New in 9.1.0
> > > ============
> > > -Wattribute-alias
> > > -Wattribute-warning
> > > -Wcannot-profile
> > > -Wdeprecated
> > > -Wmissing-profile
> > >
> > > Does this process look correct to everyone? If so, I will update the wiki page.
> >
> > -Wdeprecated is much older than GCC 9. You can check the manual for
> > GCC 8.5.0 to see if the new warnings really are new, or were already
> > documented for 8.5.0, and that shows -Wno-deprecated was present
> > already.
> >
> > https://gcc.gnu.org/gcc-9/changes.html#c-family suggests that
> > -Wattribute-alias already existed and was "enhanced" in gcc-9.
> >
> > That page also lists -Waddress-of-packed-member and -Wabsolute-value
> > as new warnings, and five new C++ warnings, which weren't found by
> > your method. Maybe there are other .opt files to consider, for
> > C-specific and C++-specific warnings?
>
> Ah, I think I remembered the method I used for creating the content of
> that page:
> diff <( ~/gcc/8.5.0/bin/gcc --help=warnings -Q | sort) <(
> ~/gcc/9.1.0/bin/gcc --help=warnings -Q | sort)
>
> Of course, this means you need to have every version of GCC installed!
>
> For the command above I get this output:
>
> 7a8
> >   -Wabsolute-value                            [disabled]
> 8a10
> >   -Waddress-of-packed-member                  [enabled]
> 15c17
> <   -Walloc-size-larger-than=
> ---
> >   -Walloc-size-larger-than=                   -1
> 18c20
> <   -Walloca-larger-than=<number>       0
> ---
> >   -Walloca-larger-than=<number>       -1
> 25c27,29
> <   -Wattribute-alias                           [enabled]
> ---
> >   -Wattribute-alias
> >   -Wattribute-alias=<0,2>                     1
> >   -Wattribute-warning                         [enabled]
> 38a43
> >   -Wc11-c2x-compat                            [enabled]
> 40a46
> >   -Wcannot-profile                            [enabled]
> 44a51
> >   -Wcast-result                               [disabled]
> 49c56,57
> <   -Wchkp                                      [disabled]
> ---
> >   -Wchkp
> >   -Wclass-conversion                          [enabled]
> 67a76,77
> >   -Wdeprecated-copy                           [disabled]
> >   -Wdeprecated-copy-dtor                      [disabled]
> 103c113
> <   -Wframe-larger-than=<number>
> ---
> >   -Wframe-larger-than=<byte-size>     -1
> 118a129
> >   -Winit-list-lifetime                        [enabled]
> 132c143
> <   -Wlarger-than=<number>
> ---
> >   -Wlarger-than=<byte-size>                   -1
> 151a163
> >   -Wmissing-profile                           [enabled]
> 158a171,173
> >   -Wno-alloc-size-larger-than
> >   -Wno-alloca-larger-than
> >   -Wno-vla-larger-than
> 183a199
> >   -Wpessimizing-move                          [disabled]
> 191a208
> >   -Wprio-ctor-dtor                            [enabled]
> 198a216
> >   -Wredundant-move                            [disabled]
> 227c245
> <   -Wstack-usage=<number>                      0
> ---
> >   -Wstack-usage=<byte-size>                   -1
> 298c316
> <   -Wvla-larger-than=<number>                  0
> ---
> >   -Wvla-larger-than=<number>                  -1
>
> Some of these are changes to the default values, so not new warnings,
> but it tells me these are new:
>
> -Wabsolute-value
>  -Waddress-of-packed-member
>  -Wattribute-warning
> -Wc11-c2x-compat
> -Wcannot-profile
> -Wcast-result
>  -Wclass-conversion
> -Wdeprecated-copy
>  -Wdeprecated-copy-dtor
>  -Winit-list-lifetime
> -Wmissing-profile
> -Wno-alloc-size-larger-than
> -Wno-alloca-larger-than
> -Wno-vla-larger-than
> -Wpessimizing-move
> -Wprio-ctor-dtor
> -Wredundant-move

I've added everything up to 13.1