From 1315e91f1161399cafe4bfd1a9622b8056a45dd3 Mon Sep 17 00:00:00 2001 From: Nick Bowler Date: Sun, 18 Sep 2011 23:01:18 -0400 Subject: [PATCH] Eliminate use of BUILT_SOURCES from Gnulib. As with recursive make, BUILT_SOURCES is harmful because of inadequate dependency information. We can achieve a similar effect with by using order-only dependencies: These force the headers to be up-to-date before anything that might require them is built: but rebuilds are only triggered based on the accurate dependency information generated by the normal mechanisms. Unfortunately, order-only dependencies are a GNU make feature, so we use a hack which should fall back to ordinary dependencies on other make implementations. The worst effect of using ordinary dependencies will be that files might be needlessly rebuilt when a header changes. --- scripts/fix-gnulib.pl | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/scripts/fix-gnulib.pl b/scripts/fix-gnulib.pl index 6663e6e..b93cf22 100755 --- a/scripts/fix-gnulib.pl +++ b/scripts/fix-gnulib.pl @@ -87,7 +87,14 @@ while () { next if (/^#/); if (!$printed_header) { - print "# Postprocessed by ", basename($0), "\n"; + print "# Postprocessed by ", basename($0), "\n\n"; + print <<'EOF'; +# This trick should define gnulib_orderonly to | iff we're using GNU make. +gnulib_have_orderonly = $(findstring order-only,$(.FEATURES)) +gnulib_orderonly = $(gnulib_have_orderonly:order-only=|) +gnulib_headers = $(gnulib_orderonly) +EOF + $printed_header = 1; drop; } @@ -122,6 +129,11 @@ while () { } } + # BUILT_SOURCES has similar problems to recursive make: inadequate + # dependencies lead to incorrect builds. Collect them into an + # ordinary variable so we can deal with them later. + s/BUILT_SOURCES/gnulib_headers/; + # Targets are similar to variables: the target and its dependencies # need to be mangled. if (/:/) { @@ -133,6 +145,8 @@ while () { s:\$\(builddir\):\$\(top_builddir\)/lib:g; } continue { print }; +print "\$(libgnu_la_OBJECTS): \$(gnulib_headers)\n"; + # Some filenames are AC_SUBSTed by the Gnulib macros, and thus we need to # prepend lib/ if and only if they're not empty. Unfortunately, make is not # powerful to do this, so we need to put this transformation into configure -- 2.43.0