doc: make gzipped man pages reproducible

gzip includes the name of the uncompressed file and its modification
timestamp into the compressed archive. The latter makes it hard to
reproduce the generated files bit for bit at a later time, so omit this
information from the archive using the "--no-name" option. This is a
reproducibility best practice, see
https://wiki.debian.org/ReproducibleBuilds/TimestampsInGzipHeaders

diff --git a/doc/Makefile.local b/doc/Makefile.local
index 769438ed24756962d34d8b99348df1e0b2d93eac..19b953ed22b8695f982f0e13fff5c344de045735 100644 (file)
--- a/doc/Makefile.local
+++ b/doc/Makefile.local
@@ -40,7 +40,7 @@ INFO_INFO_FILES := $(INFO_TEXI_FILES:.texi=.info)
 .PHONY: install-man build-man apidocs install-apidocs
 
 %.gz: %
-       rm -f $@ && gzip --stdout $^ > $@
+       rm -f $@ && gzip --no-name --stdout $^ > $@
 
 ifeq ($(WITH_EMACS),1)
 $(DOCBUILDDIR)/.roff.stamp sphinx-html sphinx-texinfo: docstring.stamp