Re: [PATCH] gnulib-tool: new option --gnu-make

[Paul Eggert]

Bruno Haible wrote:
> > Anything that uses an Automake-specific feature other than "if FOO /
> > else / endif" would be suspect, yes. For example, I suppose there would
> > be trouble if a module uses the Automake syntax "if FOO / else !FOO /
> > endif !FOO".
> Hmm. We use this pattern a lot. In particular, in every module that overrides
> an system include file:
>
> $ grep -r '^if[^;]*$' modules | grep -v ' test ' | LC_ALL=C sort
> modules/alloca-opt:if GL_GENERATE_ALLOCA_H
> ...

These should all be OK. I should have been clearer: those 'if FOO' lines should 
be fine, as 'gnulib-tool --gnu-make' should transform them into 'ifneq 
(,$(FOO))' lines and should define FOO properly. The problem is merely a 
syntactic one, in that gnulib-tool doesn't handle 'else !FOO' or 'endif !FOO' 
lines, and insists on plain 'else' and 'endif' lines. Luckly, Gnulib uses only 
plain 'else' and 'endif' lines so this is not a problem in practice.

I ran into another glitch when testing --gnu-make. When building GNU Emacs on 
Solaris 10 (which bundles GNU Make 3.82), an out-of-source build (which uses 
VPATH) fails to use the build-aux/snippets/*.h files correctly. For example, 
'make V=1 getopt.h' executes this:

  rm -f getopt.h-t getopt.h && \
  { echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
    sed -e 's|@''GUARD_PREFIX''@|GL|g' \
        -e 's|@''HAVE_GETOPT_H''@|1|g' \
        -e 's|@''INCLUDE_NEXT''@|include_next|g' \
        -e 's|@''PRAGMA_SYSTEM_HEADER''@||g' \
        -e 's|@''PRAGMA_COLUMNS''@||g' \
        -e 's|@''NEXT_GETOPT_H''@|<getopt.h>|g' \
        -e '/definition of _GL_ARG_NONNULL/r arg-nonnull.h' \
        < ../../emacs-26.0.50/lib/getopt.in.h; \
  } > getopt.h-t && \
  mv -f getopt.h-t getopt.h

without first building arg-nonnull.h, even though the makefile line says 
'getopt.h: getopt.in.h $(top_builddir)/config.status $(ARG_NONNULL_H)' so that 
arg-nonnull.h is a dependency. Unfortunately POSIX requires 'sed' to ignore the 
fact that arg-nonnull.h is missing, so the rule succeeds and creates a getopt.h 
file that does not work. I don't know whether this is a bug in this old version 
of GNU Make, but regardless of whether it is a bug it's probably better to work 
around the problem, which I did by applying the attached patch to Gnulib. This 
patch simply omits the copyright-notice-stripping nicety for all the affected 
modules other than link-warning. I'm not sure how to work around the problem in 
the link-warning module (which also does a substitution), so I merely added a 
FIXME for it (Emacs does not use this module).

I still don't have a GNU Make-based Gnulib working quite right on Solaris; I 
have another problem with the faccessat module on Solaris 10 and plan to look 
into that next.

0001-snippets-work-around-GNU-Make-3.82-VPATH.txt
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