Re: [PATCH 04/13] Kbuild: Rust support

[Masahiro Yamada]

On Thu, Apr 15, 2021 at 9:43 AM Miguel Ojeda
<miguel.ojeda.sandonis@xxxxxxxxx> wrote:
>
> On Thu, Apr 15, 2021 at 1:19 AM Nick Desaulniers
> <ndesaulniers@xxxxxxxxxx> wrote:
> >
> > Rather than check the origin (yikes, are we intentionally avoiding env
> > vars?), can this simply be
> > ifneq ($(CLIPPY),)
> >   KBUILD_CLIPPY := $(CLIPPY)
> > endif
> >
> > Then you can specify whatever value you want, support command line or
> > env vars, etc.?
>
> I was following the other existing cases like `V`. Masahiro can
> probably answer why they are done like this.

You are asking about this code:

ifeq ("$(origin V)", "command line")
  KBUILD_VERBOSE = $(V)
endif


You can pass V=1 from the Make command line,
but not from the environment.


KBUILD_VERBOSE is intended as an environment variable,
but you can use it from the Make command line.


Work:
 - make V=1
 - make KBUILD_VERBOSE=1
 - KBUILD_VERBOSE=1 make

Not work:
 - V=1 make



The behavior is like that before I became the maintainer.
In my best guess, the reason is,
V=1 is a useful shorthand of KBUILD_VERBOSE=1,
but it is too short. It should not accidentally
pick up an unintended environment variable.










-- 
Best Regards
Masahiro Yamada