bug#8665: automake should offer APIs to honour silent-rules verbosity from shell code in Makefiles

[Jack Kelly]

Comments inline, after some snipping.

On Fri, May 13, 2011 at 6:27 AM, Stefano Lattarini
<address@hidden> wrote:
> -snip intro-
>
> I thus propose we add an API of this kind.  At first, this might be as
> simple as just defining two proper `AM_V_ECHO' and `AM_Q_ECHO' variables;
> `AM_V_ECHO' should be `echo' when silent rules are in effect, and `:'
> when they are not; viceversa for `AM_Q_ECHO'.
>
> To give a simplified example of what I'm proposing:
>
>  $ cat > Makefile.am <<'END'
>  headers:
>   address@hidden [commands defining a shell variable `$headers']; \
>     $(AM_V_ECHO) "cd somedir && generate-header --flag $$headers"; \
>     $(AM_Q_ECHO) "GEN headers"; \
>     cd somedir && generate-header --flag $$headers

If you're just echoing "GEN headers", is there any reason you can't
use $(AM_V_GEN) here? Maybe we should have a more general method of
declaring silencing variables (like the $(AM_V_GEN), but also the
others that echo 'CC' and friends. Then users who have unconventional
setups can silence things without echoing 'GEN' everywhere.

>  END
>  $ autoreconf ...
>  $ ./configure --disable-silent-rules
>  ...
>  $ make headers
>  cd somedir && generate-header --flag foo.h bar.h baz.h
>  $ make headers V=0
>  GEN headers
>  $ ./configure --enable-silent-rules
>  ...
>  $ make headers
>  GEN headers
>  $ make headers V=1
>  cd somedir && generate-header --flag foo.h bar.h baz.h
>
> Or maybe we could start being more general from the beginning, and define
> a variable `AM_IS_SILENT' (say) that is defined to "yes" when silent rules
> are in effect, and to "no" otherwise.

If you are going to do this, is it sufficient for it to be a variable,
or does it need to be an AM_CONDITIONAL? I'm thinking a variable is
fine.

-- Jack