automake: bring back the .PHONY git_sha1.h.tmp rule

With earlier commit 3689ef32afd ("automake: rework the git_sha1.h rule,
include in tarball") we/I erroneously removed the PHONY rule and the
temporary file.

The former is used to ensure that the header is regenerated when on each
make invocation, while the latter helps us avoid the unneeded rebuild(s)
when the SHA1 hasn't changed.

Reported-by: Grazvydas Ignotas <notasas@gmail.com>
Tested-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

diff --git a/src/Makefile.am b/src/Makefile.am
index f5c07739deabc97108593bddeda53f1ed5049548..45590c0a07a4ab44c6e539e6aaabac77629b86c5 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -19,13 +19,28 @@
 # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 # IN THE SOFTWARE.
 
-git_sha1.h:
+.PHONY: git_sha1.h.tmp
+git_sha1.h.tmp:
+       @# Don't assume that $(top_srcdir)/.git is a directory. It may be
+       @# a gitlink file if $(top_srcdir) is a submodule checkout or a linked
+       @# worktree.
+       @# If we are building from a release tarball copy the bundled header.
        @if test -e $(top_srcdir)/.git; then \
                if which git > /dev/null; then \
                    git --git-dir=$(top_srcdir)/.git log -n 1 --oneline | \
                        sed 's/^\([^ ]*\) .*/#define MESA_GIT_SHA1 "git-\1"/' \
-                       > git_sha1.h ; \
+                       > git_sha1.h.tmp ; \
                fi \
+       else \
+               cp git_sha1.h git_sha1.h.tmp ;\
+       fi
+
+git_sha1.h: git_sha1.h.tmp
+       @echo "updating git_sha1.h"
+       @if ! cmp -s git_sha1.h.tmp git_sha1.h; then \
+               mv git_sha1.h.tmp git_sha1.h ;\
+       else \
+               rm git_sha1.h.tmp ;\
        fi
 
 BUILT_SOURCES = git_sha1.h