Autoconf 2.71 tries to call gtkdocize

[sethrj]

A change to version 2.71 of autoconf means that calling autoreconf will try to call gtkdocize when a project's autom4te macros contain GTK_DOC_CHECK, even when docs aren't being built at configure time. This currently causes cairo to fail to build:

==> cairo: Executing phase: 'autoreconf'
==> [2021-05-27-13:14:41.253237] '/bin/sh' './autogen.sh'
*** No GTK-Doc found, documentation won't be generated ***
autoreconf: export WARNINGS=
autoreconf: Entering directory '.'
autoreconf: configure.ac: not using Gettext
autoreconf: running: aclocal -I build ${ACLOCAL_FLAGS}
autoreconf: configure.ac: tracing
autoreconf: running: glibtoolize --copy
autoreconf: configure.ac: not using Intltool
autoreconf: running: gtkdocize --copy
Can't exec "gtkdocize": No such file or directory at /usr/local/Cellar/autoconf/2.71/share/autoconf/Autom4te/FileUtils.pm line 293.
autoreconf: error: gtkdocize failed with exit status: 2

Possible solutions:

• adding gtk-doc dependency on packages that require autoreconfiguring (bad; it's a heavy dependency if it's not used)
• preferring autotools 2.70 and hope this "feature" gets reverted upstream? because other people are complaining about it too
• trying to hack around the problem by exporting GTKDOCIZE=echo if the package doesn't explicitly depend on gtk-doc

The solution I have set up for the last case is:

    def setup_dependent_build_environment(self, env, dependent_spec):
        if (self.spec.satisfies('@2.71:')
            and not dependent_spec.satisfies('^gtk-doc')):
            # If an autoconf script calls GTK_DOC_CHECK, newer
            # versions of autoreconf try to call `gtkdocize --copy`, which
            # would require an extra dependency on `gtk-doc`, even if
            # documentation is disabled at configure time.
            env.set('GTKDOCIZE', 'echo')

but unfortunately it doesn't work in the particular case of cairo because its autogen.sh script clears GTKDOCIZE if there's no gtkdocize in the path. ☹️

[KangmingYang2008]

If gtkdocize isn't installed, it will fail. And it can be ignored by exporting GTKDOCIZE=echo.