Re: On overriding make variables from the environment...

[Jonathan Nieder <jrnieder@gmail.com>]

SZEDER Gábor wrote:
> On Tue, Oct 16, 2018 at 02:54:56PM -0700, Jonathan Nieder wrote:
>> SZEDER Gábor wrote:

>>> Our Makefile has lines like these:
>>>
>>>   CFLAGS = -g -O2 -Wall
>>>   CC = cc
>>>   AR = ar
>>>   SPATCH = spatch
[...]
>>> I'm not sure what to do.  I'm fine with updating our 'ci/' scripts to
>>> explicitly respect CC in the environment (either by running 'make
>>> CC=$CC' or by writing $CC into 'config.mak').  Or I could update our
>>> Makefile to use '?=' for specific variables, but:
>>
>> That's a good question.  I don't have a strong opinion myself, so I
>> tend to trust larger projects like Linux to have thought this through
>> more, and they use 'CC = cc' as well.
>
> I don't think Linux is a good example to follow in this case, see e.g.
> 6d62c983f7 (Makefile: Change the default compiler from "gcc" to "cc",
> 2011-12-20) (in short: Git is supposed to be buildable with compilers
> other than GCC as well, while Linux not really, so they can hardcode
> 'CC = gcc').

Nowadays Linux builds with clang as well.  People also have other
reasons to override the CC setting (cross-compiling, etc) and to
override other settings like CFLAGS.

> Also, the projects I have on hand usually have 'CC = gcc' hardcoded in
> their Makefiles, too, but those Makefiles were generated by their
> ./configure script (which in turn by ./autogen.sh...), and those tend
> to write CC from the environment into the generated Makefiles.

Yes, I think that's what makes travis's setup normally work.  It makes
sense to me since ./configure is expected to have more implicit or
automatic behavior.  For "make", I kind of like that it doesn't depend
on environment variables that I am not thinking about when debugging a
reported build problem.

When building Git without autoconf, the corresponding place for
settings is config.mak.  Would it make sense for the ci scripts to
write a config.mak file?

Thanks,
Jonathan