Fix Trac #3012: allow more free-wheeling in standalone deriving

[ghc-hetmet.git] / Makefile

diff --git a/Makefile b/Makefile
index 69c419c..94d6df8 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -51,10 +51,19 @@ include mk/custom-settings.mk
 # No need to update makefiles for these targets:
 REALGOALS=$(filter-out bootstrapping-files framework-pkg clean clean_% distclean maintainer-clean show help,$(MAKECMDGOALS))
 
+# configure touches certain files even if they haven't changed.  This
+# can mean a lot of unnecessary recompilation after a re-configure, so
+# here we cache the old versions of these files so we can restore the
+# timestamps.
+%.old:  %
+       @set -x && test -f $@ && cmp -s $< $@ || cp -p $< $@
+       touch -r $@ $<
+
+
 # NB. not the same as saying '%: ...', which doesn't do the right thing:
 # it does nothing if we specify a target that already exists.
 .PHONY: $(REALGOALS)
-$(REALGOALS) all:
+$(REALGOALS) all: mk/config.mk.old mk/project.mk.old compiler/ghc.cabal.old
        @echo "===--- updating makefiles phase 0"
        $(MAKE) -r --no-print-directory -f ghc.mk phase=0 just-makefiles
 ifneq "$(OMIT_PHASE_1)" "YES"