Re: [PATCH] Makefile: make COMPUTE_HEADER_DEPENDENCIES=auto work with DEVOPTS=pedantic

From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date: Sep 22, 2021, 11:04 UTC
Message-ID: <87o88k7tr6.fsf@evledraar.gmail.com>
In-Reply-To: <CAPUEsph8TYokqLmiZjvu3VgmzLh4AFhp+0vh0nv+2+m351=n_A@mail.gmail.com>

On Wed, Sep 22 2021, Carlo Arenas wrote:

Show 12 quoted lines

> On Wed, Sep 22, 2021 at 3:38 AM Ævar Arnfjörð Bjarmason
> <avarab@gmail.com> wrote:
>>
>> The "COMPUTE_HEADER_DEPENDENCIES" feature added in [1] was extended to
>> use auto-detection in [2]. Then when -Wpedantic support was added to
>> DEVOPTS in [3] we started passing -Wpedantic in combination with
>> -Werror to the compiler here.
>
> It is my impression though that header dependencies computation is
> something that might only work in gcc and clang (because of its gcc
> compatibility), so shouldn't this be restricted to those compilers
> instead of forcing all others to error?

I think it's better to just have those not supporting COMPUTE_HEADER_DEPENDENCIES define that, wanting to auto-detect things is what led to the current breakage.

I.e. our whitelisting of GCC and Clang will be out of date if some other compiler grows support for this, and even if we whitelist gcc and clang we'll need some script like detect-compiler etc.

> Also, why is this process run with DEVELOPER=1 to begin with, if we
> obviously don't need/want any compilations warnings?

Hrm? We run the COMPUTE_HEADER_DEPENDENCIES=yes process with and without DEVELOPER=1, it's just that DEVELOPER=1 breaks it since it turns on pedantic compilation flags now.

We want -Werror for the actual compilation under DEVELOPER=1, but a one-off command to see if a compiler has support for something is entirely different.