[Mesa-dev] [PATCH mesa] build: make passing an incorrect pointer type a hard error

[Eric Engestrom]

On Thursday, 2018-11-22 13:15:05 +0000, Eric Engestrom wrote:
> More or less any of this issue pointed out by the compiler is
> a coding error. Make sure we flag it and bail loudly.
> 
> v2: - apply the change to autotools and scons as well (Emil)
>     - C++ doesn't need this, it's already an error and the flag
>       doesn't exist (Gert)
> 
> Signed-off-by: Eric Engestrom <eric.engestrom at intel.com>
> Reviewed-by: Dylan Baker <dylan at pnwbakers.com> # v1
> Reviewed-by: Emil Velikov <emil.velikov at collabora.com> # v1
> [Emil: apply the same change to autotools and scons]
> Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
> ---
> Emil, I dropped the Android bit as this `-Wno-error` makes it look to me
> like they don't want compiler warnings to stop the build.
> ---
>  configure.ac     | 1 +
>  meson.build      | 1 +
>  scons/gallium.py | 1 +
>  3 files changed, 3 insertions(+)
> 
> diff --git a/configure.ac b/configure.ac
> index 93a52475d50e6ee65432..422c8e3c87c897a88b51 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -307,6 +307,7 @@ dnl
>  AX_CHECK_COMPILE_FLAG([-Wall],                                 [CFLAGS="$CFLAGS -Wall"])
>  AX_CHECK_COMPILE_FLAG([-Werror=implicit-function-declaration], [CFLAGS="$CFLAGS -Werror=implicit-function-declaration"])
>  AX_CHECK_COMPILE_FLAG([-Werror=missing-prototypes],            [CFLAGS="$CFLAGS -Werror=missing-prototypes"])
> +AX_CHECK_COMPILE_FLAG([-Werror=incompatible-pointer-types],    [CFLAGS="$CFLAGS -Werror=incompatible-pointer-types"])
>  AX_CHECK_COMPILE_FLAG([-Wmissing-prototypes],                  [CFLAGS="$CFLAGS -Wmissing-prototypes"])
>  dnl Dylan Baker: gcc and clang always accepr -Wno-*, hence check for the original warning, then set the no-* flag
>  AX_CHECK_COMPILE_FLAG([-Wmissing-field-initializers],          [CFLAGS="$CFLAGS -Wno-missing-field-initializers"])
> diff --git a/meson.build b/meson.build
> index 4ad41fde13a33f546d48..2fde2b23e24fd2e4321e 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -788,6 +788,7 @@ endif
>  c_args = []
>  foreach a : ['-Werror=implicit-function-declaration',
>               '-Werror=missing-prototypes', '-Werror=return-type',
> +             '-Werror=incompatible-pointer-types',
>               '-fno-math-errno',
>               '-fno-trapping-math', '-Qunused-arguments']
>    if cc.has_argument(a)
> diff --git a/scons/gallium.py b/scons/gallium.py
> index 963834a5fbc12a378ad4..04175014925cf088e5ea 100755
> --- a/scons/gallium.py
> +++ b/scons/gallium.py
> @@ -451,6 +451,7 @@ def generate(env):
>          # - http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
>          ccflags += [
>              '-Wall',
> +            '-Werror=incompatible-pointer-types',

Hmm, just got the results from travis, and I hadn't realised that these
flags aren't checked before being given to the compiler, so this just
breaks the scons build. Until someone adds a 'does the compiler
understand this flag' feature to scons, we just can't add this flag.

I'll just revert the scons bit as well, so it's gonna be just meson and
autotools.

>              '-Wno-long-long',
>              '-fmessage-length=0', # be nice to Eclipse
>          ]
> -- 
> Cheers,
>   Eric
> 
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