maint: Cater for running `make dist' from a tarball.

* Makefile.am: Use in_git_p conditional to disable Autotools' cache
consistency assert and removal when bulding from tarball.
(dist): Depend on doc-pot-update again when building from tarball.
(dist-hook): Remove dependencies on gen-ChangeLog and gen-AUTHORS when
building from tarball.
(gen-ChangeLog, gen-AUTHORS): Remove guarding for building from tarball.
Use set -e to avoid silently failing.
(gen-tarball-version): Use $(SOURCE_DATE_EPOCH) instead of re-generating it
using git; this also works running from a tarball.

Change-Id: I9ebdd28a70837f6a4db610c4816bb283d176e2d9

1 files changed, 36 insertions, 24 deletions

diff --git a/Makefile.am b/Makefile.am
index ca3fa0a6930..af08bc546f5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -955,6 +955,20 @@ guix-binary.%.tar.xz:
           guix` ;                                       \
         cp "$$tarball" "$@.tmp" ; mv "$@.tmp" "$@"
 
+# The `dist' target has other dependencies when building from Git
+# to assert and achieve reproducibility.
+if in_git_p
+
+# The dependency on dist-doc-pot-update is to clean possibly stale doc and po
+# files and only then generate the .pot files, which are not checked in.
+dist: dist-doc-pot-update
+dist-doc-pot-update: auto-clean
+        $(MAKE) guile$(EXEEXT)
+        $(MAKE) -C po/guix all
+        $(MAKE) -C po/packages all
+        $(MAKE) doc-pot-update
+
+dist-hook: gen-ChangeLog gen-AUTHORS
 
 # Assert that Autotools cache is up to date with Git, by checking
 # PACKAGE_VERSION against HEAD.  Indented to get past Automake.
@@ -969,20 +983,20 @@ guix-binary.%.tar.xz:
  $(error Cannot create reproducible tarball)
  else
  $(warning Tarball will be irreproducible; distdir will not get removed!)
- endif
- endif
- endif
+ endif # !GUIX_ALLOW_IRREPRODUCIBLE_TARBALL
+ endif # PACKAGE_VERSION != git_version
+ endif # MAKECMDGOALS dist
 
-# The dependency on dist-doc-pot-update is to clean possibly stale doc and po
-# files and only then generate the .pot files, which are not checked in.
-dist: dist-doc-pot-update
-dist-doc-pot-update: auto-clean
-        $(MAKE) guile$(EXEEXT)
-        $(MAKE) -C po/guix all
-        $(MAKE) -C po/packages all
-        $(MAKE) doc-pot-update
+else # !in_git_p
+
+dist: doc-pot-update
 
-dist-hook: gen-ChangeLog gen-AUTHORS gen-tarball-version
+ ifeq ($(MAKECMDGOALS),dist)
+$(warning Not using Git, tarball will likely be irreproducible!)
+ endif # MAKECMDGOALS dist
+endif # !in_git_p
+
+dist-hook: gen-tarball-version
 dist-hook: assert-no-store-file-names
 
 distcheck-hook: assert-binaries-available assert-final-inputs-self-contained
@@ -994,27 +1008,25 @@ $(top_srcdir)/.version: config.status
 
 gen-tarball-version:
         echo $(VERSION) > "$(distdir)/.tarball-version"
-        git show HEAD --format=%ct --no-patch > $(distdir)/.tarball-timestamp
+        echo $(SOURCE_DATE_EPOCH) > $(distdir)/.tarball-timestamp
 
 gen-ChangeLog:
-        $(AM_V_GEN)if test -e .git; then                \
-          export LC_ALL=en_US.UTF-8;                    \
-          export TZ=UTC0;                               \
-          $(top_srcdir)/build-aux/gitlog-to-changelog   \
-            > $(distdir)/ChangeLog.tmp;                 \
-          rm -f $(distdir)/ChangeLog;                   \
-          mv $(distdir)/ChangeLog.tmp $(distdir)/ChangeLog;     \
-        fi
+        $(AM_V_GEN)set -e;                                      \
+          export LC_ALL=en_US.UTF-8;                            \
+          export TZ=UTC0;                                       \
+          $(top_srcdir)/build-aux/gitlog-to-changelog           \
+            > $(distdir)/ChangeLog.tmp;                         \
+          rm -f $(distdir)/ChangeLog;                           \
+          mv $(distdir)/ChangeLog.tmp $(distdir)/ChangeLog;
 
 gen-AUTHORS:
-        $(AM_V_GEN)if test -e .git; then                        \
+        $(AM_V_GEN)set -e;                                      \
           rm -f "$(distdir)/AUTHORS";                           \
           export LC_ALL=en_US.UTF-8;                            \
           export TZ=UTC0;                                       \
           $(top_builddir)/pre-inst-env "$(GUILE)"               \
             "$(top_srcdir)/build-aux/generate-authors.scm"      \
-            "$(top_srcdir)" "$(distdir)/AUTHORS";               \
-        fi
+            "$(top_srcdir)" "$(distdir)/AUTHORS";
 
 # Like 'dist', but regenerate 'configure' so we get an up-to-date
 # 'PACKAGE_VERSION' string.  (In Gnulib, 'GNUmakefile' has a special trick to