Re: [Buildroot] [RFC v3 1/2] package/pkg-meson.mk: support fortran cross-compilation

["Yann E. MORIN" <yann.morin.1998@free.fr>]

Thomas, All,

On 2022-08-08 21:47 +0200, Yann E. MORIN spake thusly:
> On 2022-08-07 00:13 +0200, Thomas Petazzoni spake thusly:
> [--SNIP--]
> > Now, on to the open issue which explains why I have added Yann in Cc.
> > We are currently setting the C++ compiler and Fortran compiler path in
> > Meson's cross-compilation.conf unconditionally... even when the
> > toolchain has no C++ or Fortran support. So it means we're pointing to
> > compilers that don't exist.
> I think this is fine. They don't exist, so they can't be run, so meson
> will not inadvertently be able to build a C++/Fortran/... program and we
> will notice the issue.
> 
> > Ideally, the cross-compilation.conf should be generated with no
> > reference to a C++ or Fortran compiler, or a /bin/false reference, and
> > ditto for the CXXFLAGS/FCFLAGS when there is no C++ or Fortran support.
> 
> In the past, we used to use false as a C++ compiler (but not for meson
> specifically), and it turned out that that caused quite some
> hard-to-understand issues, see 4cd1ab15886a (core: alternate solution to
> disable C++).
> 
> I'll ask the meson guys in irc://irc.oftc.net/#mesonbuild and se what
> they have to say and suggest.

So, @eliebrokeit there said, quoting:

    If you don't have one defined, cross builds won't try to autodetect
    one, IIRC...
    [...] however setting it to /bin/false will result in it detecting
    that that doesn't work
    I guess the safest bet is to deliberately poison it with /bin/false

So, when we do not have a compiler for a specific language, we should
force it to /bin/false.

Guillaume, would you be willing to tackle that?

Regards,
Yann E. MORIN.

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