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

From: SZEDER Gábor <szeder.dev@gmail.com>
Date: Oct 16, 2018, 22:33 UTC
Message-ID: <20181016223330.GP19800@szeder.dev>
In-Reply-To: <20181016215456.GB96853@aiede.svl.corp.google.com>

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

Show 18 quoted lines

> SZEDER Gábor wrote:
> > Our Makefile has lines like these:
> >
> >   CFLAGS = -g -O2 -Wall
> >   CC = cc
> >   AR = ar
> >   SPATCH = spatch
> >
> > Note the use of '=', not '?='.
> [...]
> > 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').

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.