[mm-common] Check libstdc++.tag for updates on every build

[Daniel Elstner <daniel src gnome org>]

commit 189a457ebc0a817743885aaaa817d4d37c59bf27
Author: Daniel Elstner <danielk openismus com>
Date:   Wed Aug 5 19:41:37 2009 +0200

    Check libstdc++.tag for updates on every build
    
    * Makefile.am (tags/libstdc++.tag): Make the tag file a phony target
    if maintainer mode is enabled, so that its commands will always run.
    Use the time-stamping features of curl and wget to avoid downloading
    the tag file again if it has not changed.

 Makefile.am |   21 ++++++++++++++++-----
 1 files changed, 16 insertions(+), 5 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index ecd0727..052677d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -50,15 +50,26 @@ dist_noinst_SCRIPTS = autogen.sh
 
 MAINTAINERCLEANFILES = $(dist_doxygen_tags_DATA)
 
-curl_flags = --compressed --connect-timeout 300 -g -L -m 3600 --retry 5
-wget_flags = -T 300 -t 5
 libstdcxx_tag_url = http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/libstdc++.tag
 
+download_curl = $(CURL) --compressed --connect-timeout 300 -g -L -m 3600 -R --retry 5 \
+		$(if $(wildcard $@),-z '$@') -o '$@'
+download_wget = $(WGET) -N -T 300 -t 5 -P tags
+
+# In maintainer mode, always check the tag file for updates.
+if MAINTAINER_MODE
+tagfile_phony = $(dist_doxygen_tags_DATA)
+else
+tagfile_phony =
+endif
+
+.PHONY: $(tagfile_phony)
+
 .DELETE_ON_ERROR:
 
-# Download the GNU libstdc++ Doxygen tag file from the GCC site
+# Download the GNU libstdc++ Doxygen tag file from the GCC site.
 tags/libstdc++.tag:
-	$(if $(CURL),$(CURL) $(curl_flags) -o '$@' '$(libstdcxx_tag_url)',$(if\
-	     $(WGET),$(WGET) $(wget_flags) -O '$@' '$(libstdcxx_tag_url)',exit 1))
+	$(if $(CURL),$(download_curl) '$(libstdcxx_tag_url)',$(if\
+	     $(WGET),$(download_wget) '$(libstdcxx_tag_url)',exit 1))
 
 include $(top_srcdir)/build/dist-changelog.am