doc: comment Vala -newer test.

This change updates https://bugs.gnu.org/44772.

* bin/automake.in (lang_vala_finish_target): comment that
we're checking "C file not older than Vala file", and the
log message misleadingly says "reversed".

diff --git a/bin/automake.in b/bin/automake.in
index 96e8c634cdb4713febd2ef98e4dae4c8daf5ba6c..8edd0c7a385a29db8180f51b6d42a9a7e1a392aa 100644 (file)
--- a/bin/automake.in
+++ b/bin/automake.in
@@ -5738,6 +5738,12 @@ sub lang_vala_finish_target
           my $built_c_file = "\$(builddir)/$c_file";
           my $built_dir = dirname $built_c_file;
           my $base_c_file = basename $c_file;
+          #
+          # The -newer test here is checking "C file not older than Vala
+          # file" (not "C file newer than Vala file"; see
+          # https://bugs.gnu.org/44772. The log message on the commit
+          # misleadingly says "reversed".
+          #
           $output_rules .= "$built_c_file: \$(builddir)/${derived}_vala.stamp\n"
             . "\t\@if test ! -f \$@ && test \$(srcdir) != \$(builddir) && test -n \"\$\$(find -L \$(srcdir)/$vala_file -prune \! -newer \$(srcdir)/$c_file)\"; then cp -p \$(srcdir)/$c_file $built_c_file; fi\n"
             . "\t\@if test -f \$@; then :; else rm -f \$(builddir)/${derived}_vala.stamp; fi\n"