Re: [gentoo-dev] [PATCH] meson.eclass: implement basic cross-compiler support

[Mike Gilbert]

On Mon, May 29, 2017 at 5:06 PM, Michał Górny <mgorny@g.o> wrote:
> On pon, 2017-05-29 at 16:58 -0400, Mike Gilbert wrote:
>> +     # system roughly corresponds to uname -s (lowercase)
>> +     local system=unknown
>> +     case ${CHOST} in
>> +             *-aix*)     system=aix ;;
>> +             *-cygwin*)  system=cygwin ;;
>> +             *-darwin*)  system=darwin ;;
>> +             *-freebsd*) system=freebsd ;;
>> +             *-linux*)   system=linux ;;
>> +             *-solaris*) system=sunos ;;
>
> Don't you want to die on unknown system? Or is it likely to work anyway?

Good question.

The 'system' property controls some built-in logic in meson itself
(mainly for MS Windows), and may be referenced by project files as
'host_machine.system()'. Setting it to 'unknown' may cause failures
for projects that actually look at it.

However, I think most projects would work without having this set to a
known value.

>> +     esac
>> +
>> +     local cpu_family=$(tc-arch)
>> +     case ${cpu_family} in
>> +             amd64) cpu_family=x86_64 ;;
>> +             arm64) cpu_family=aarch64 ;;
>
> That's purely mapping from known-wrong values, correct? Maybe it'd be
> reasonable to assert for all correct too, and fail on unknown?

Yes, it corrects two obvious deviations from uname -m on Linux. x86 is
ok since that is what meson expects/generates for i?86.

I'm not sure what you mean by "assert for all correct"; if you mean
check for all valid values for cpu_family, such a list does not exist.

Similar to 'system' this property may or may not be used depending on
the project. Defaulting to "unknown" should be fine in many cases. I
don't think we need to fail.

>> +     # Both meson(1) and _meson_create_cross_file need these
>> +     tc-export AR CC CXX STRIP
>
> Wouldn't it be reasonable to make them local first anyway? I would try
> to avoid polluting the environment.

Makes sense. I'll revise this to "local -x CC=$(tc-getCC)", etc.