bogus warning about EXTRA_HEADERS requirement (was: [PATCH 5/7] add _HEADERS primaries to Makefile.am snippets for installable headers)

[Ralf Wildenhues]

Hello, and adding bug-automake,

* Gary V. Vaughan wrote on Wed, Oct 13, 2010 at 12:06:32PM CEST:
> On 13 Oct 2010, at 03:55, Bruno Haible wrote:
> > And what's the role or effect of EXTRA_HEADERS? Automake does not do
> > anything with .h files that it doesn't do with .png files. gnulib-tool
> > already synthesizes EXTRA_DIST augmentations for files that are to be
> > distributed.
> 
> Automake complains if you add a computed (possibly empty) header name
> to xxx_include_HEADERS, without a matching EXTRA_HEADERS containing the
> static name.  I added it purely to silence automake, but would be happy
> to remove it if that can be done without unnecessary automake invocation
> noise.

This looks like an Automake bug.  EXTRA_HEADERS should not be needed,
exactly because automake doesn't do anything special with headers, as
Bruno noted.  Thanks for the report.

Here's a reproducer:

cat >configure.ac <<\EOF
AC_INIT([a], [1])
AM_INIT_AUTOMAKE([foreign])
AC_CONFIG_FILES([Makefile])
AC_SUBST([foo], [bar.h])
AC_OUTPUT
EOF

cat >Makefile.am <<\EOF
nobase_include_HEADERS = $(foo)
EOF

autoreconf -vi

Cheers,
Ralf