Re: AM_SILENT_RULES has no effect

[Bruno Haible]

Ralf Wildenhues wrote:
> Try not setting `silent-rules' in Makefile.am at all.  It is sufficient
> to only use the macro AM_SILENT_RULES in configure.ac.
>
> The setting in Makefile.am has been turned into an error

So there's definitely two things to fix:

1) The error message is misleading. It is even claiming wrong facts. In this
   case, I do have 'silent-rules' as an argument of AM_INIT_AUTOMAKE, and
   automake tells me that I should use 'silent-rules' as an argument of
   AM_INIT_AUTOMAKE:

     $ gnulib-tool --create-testdir --dir=ttt stdint
     $ cd ttt
     # Edit gllib/Makefile.am, setting  AUTOMAKE_OPTIONS = 1.11 gnits 
silent-rules
     # Edit configure.ac, changing the AM_INIT_AUTOMAKE invocation
     # to AM_INIT_AUTOMAKE([silent-rules])
     $ aclocal -I glm4
     $ autoconf
     $ autoheader
     $ automake
     gllib/Makefile.am:13: option `silent-rules' must be an argument of 
AM_INIT_AUTOMAKE
     $ echo $?
     1

   The error message should say to *remove* 'silent-rules' from the Makefile.am
   in the first place.

2) The 'silent-rules' option is described in an 'info' section that starts like
   this:

     Various features of Automake can be controlled by options in the
     `Makefile.am'.  Such options are applied on a per-`Makefile' basis when
     listed in a special `Makefile' variable named `AUTOMAKE_OPTIONS'.  They
     are applied globally to all processed `Makefiles' when listed in the
     first argument of `AM_INIT_AUTOMAKE' in `configure.ac'.  Currently
     understood options are:

   So it is the most natural thing for a user to try to enable it in a
   Makefile.am. 'silent-rules' is probably the only automake option that
   cannot be used in a Makefile.am? The doc should be explicit about this.

> when the developer has to touch
> configure.ac anyway, then there is little reason to build only part of
> the tree with silent rules

The documentation paragraph cited above gave me the impression that
  - The silent-rules feature can be enabled on a per-Makefile basis,
  - An additional modification of configure.ac is needed for it to take effect.

Just like for the 'subdir-objects' option, which
  - can be enabled on a per-Makefile basis,
  - requires the use of AM_PROG_CC_C_O in configure.ac.

So I got the impression that the normal way of using the feature is the one
which you say is impossible. Please fix the documentation! The doc and the
error message completely misled me.

Bruno