git/list[1] front-page[2] threads[3] people[4] search[5] about
 

[PATCH 2/3] Makefile: avoid timestamp updates to GIT-BUILD-OPTIONS

From
Jeff King <peff@peff.net>
Date
May 29, 2015, 07:26 UTC
Message-ID
<20150529072630.GB9670@peff.net>
In-Reply-To
<20150529072119.GA5415@peff.net>

We force the GIT-BUILD-OPTIONS recipe to run every time "make" is invoked. We must do this to catch new options which may have come from the command-line or environment.

However, we actually update the file's timestamp each time the recipe is run, whether anything changed or not. As a result, any files which depend on it (for example, all of the perl scripts, which need to know whether NO_PERL was set) will be re-built every time.

Let's do our usual trick of writing to a tempfile, then doing a "cmp || mv" to update the file only when something changed.

Signed-off-by: Jeff King <peff@peff.net>
---
 Makefile | 45 +++++++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 22 deletions(-)
diff --git a/Makefile b/Makefile
index 6283353..6b4fbeb 100644
--- a/Makefile
+++ b/Makefile
@@ -2103,46 +2103,47 @@ GIT-LDFLAGS: FORCE
 # that runs GIT-BUILD-OPTIONS, and then again to protect it
 # and the first level quoting from the shell that runs "echo".
 GIT-BUILD-OPTIONS: FORCE
-	@echo SHELL_PATH=\''$(subst ','\'',$(SHELL_PATH_SQ))'\' >$@
-	@echo PERL_PATH=\''$(subst ','\'',$(PERL_PATH_SQ))'\' >>$@
-	@echo DIFF=\''$(subst ','\'',$(subst ','\'',$(DIFF)))'\' >>$@
-	@echo PYTHON_PATH=\''$(subst ','\'',$(PYTHON_PATH_SQ))'\' >>$@
-	@echo TAR=\''$(subst ','\'',$(subst ','\'',$(TAR)))'\' >>$@
-	@echo NO_CURL=\''$(subst ','\'',$(subst ','\'',$(NO_CURL)))'\' >>$@
-	@echo NO_EXPAT=\''$(subst ','\'',$(subst ','\'',$(NO_EXPAT)))'\' >>$@
-	@echo USE_LIBPCRE=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@
-	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@
-	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@
-	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@
+	@echo SHELL_PATH=\''$(subst ','\'',$(SHELL_PATH_SQ))'\' >$@+
+	@echo PERL_PATH=\''$(subst ','\'',$(PERL_PATH_SQ))'\' >>$@+
+	@echo DIFF=\''$(subst ','\'',$(subst ','\'',$(DIFF)))'\' >>$@+
+	@echo PYTHON_PATH=\''$(subst ','\'',$(PYTHON_PATH_SQ))'\' >>$@+
+	@echo TAR=\''$(subst ','\'',$(subst ','\'',$(TAR)))'\' >>$@+
+	@echo NO_CURL=\''$(subst ','\'',$(subst ','\'',$(NO_CURL)))'\' >>$@+
+	@echo NO_EXPAT=\''$(subst ','\'',$(subst ','\'',$(NO_EXPAT)))'\' >>$@+
+	@echo USE_LIBPCRE=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
+	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
+	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+
+	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+
 ifdef TEST_OUTPUT_DIRECTORY
-	@echo TEST_OUTPUT_DIRECTORY=\''$(subst ','\'',$(subst ','\'',$(TEST_OUTPUT_DIRECTORY)))'\' >>$@
+	@echo TEST_OUTPUT_DIRECTORY=\''$(subst ','\'',$(subst ','\'',$(TEST_OUTPUT_DIRECTORY)))'\' >>$@+
 endif
 ifdef GIT_TEST_OPTS
-	@echo GIT_TEST_OPTS=\''$(subst ','\'',$(subst ','\'',$(GIT_TEST_OPTS)))'\' >>$@
+	@echo GIT_TEST_OPTS=\''$(subst ','\'',$(subst ','\'',$(GIT_TEST_OPTS)))'\' >>$@+
 endif
 ifdef GIT_TEST_CMP
-	@echo GIT_TEST_CMP=\''$(subst ','\'',$(subst ','\'',$(GIT_TEST_CMP)))'\' >>$@
+	@echo GIT_TEST_CMP=\''$(subst ','\'',$(subst ','\'',$(GIT_TEST_CMP)))'\' >>$@+
 endif
 ifdef GIT_TEST_CMP_USE_COPIED_CONTEXT
-	@echo GIT_TEST_CMP_USE_COPIED_CONTEXT=YesPlease >>$@
+	@echo GIT_TEST_CMP_USE_COPIED_CONTEXT=YesPlease >>$@+
 endif
-	@echo NO_GETTEXT=\''$(subst ','\'',$(subst ','\'',$(NO_GETTEXT)))'\' >>$@
-	@echo GETTEXT_POISON=\''$(subst ','\'',$(subst ','\'',$(GETTEXT_POISON)))'\' >>$@
+	@echo NO_GETTEXT=\''$(subst ','\'',$(subst ','\'',$(NO_GETTEXT)))'\' >>$@+
+	@echo GETTEXT_POISON=\''$(subst ','\'',$(subst ','\'',$(GETTEXT_POISON)))'\' >>$@+
 ifdef GIT_PERF_REPEAT_COUNT
-	@echo GIT_PERF_REPEAT_COUNT=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_REPEAT_COUNT)))'\' >>$@
+	@echo GIT_PERF_REPEAT_COUNT=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_REPEAT_COUNT)))'\' >>$@+
 endif
 ifdef GIT_PERF_REPO
-	@echo GIT_PERF_REPO=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_REPO)))'\' >>$@
+	@echo GIT_PERF_REPO=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_REPO)))'\' >>$@+
 endif
 ifdef GIT_PERF_LARGE_REPO
-	@echo GIT_PERF_LARGE_REPO=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_LARGE_REPO)))'\' >>$@
+	@echo GIT_PERF_LARGE_REPO=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_LARGE_REPO)))'\' >>$@+
 endif
 ifdef GIT_PERF_MAKE_OPTS
-	@echo GIT_PERF_MAKE_OPTS=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_MAKE_OPTS)))'\' >>$@
+	@echo GIT_PERF_MAKE_OPTS=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_MAKE_OPTS)))'\' >>$@+
 endif
 ifdef TEST_GIT_INDEX_VERSION
-	@echo TEST_GIT_INDEX_VERSION=\''$(subst ','\'',$(subst ','\'',$(TEST_GIT_INDEX_VERSION)))'\' >>$@
+	@echo TEST_GIT_INDEX_VERSION=\''$(subst ','\'',$(subst ','\'',$(TEST_GIT_INDEX_VERSION)))'\' >>$@+
 endif
+	@if cmp $@+ $@ >/dev/null 2>&1; then $(RM) $@+; else mv $@+ $@; fi
 
 ### Detect Python interpreter path changes
 ifndef NO_PYTHON
-- 
2.4.2.668.gc3b1ade.dirty
Previous: Jeff KingNext: Jeff King
Message 3 of 4 in “fix minor Makefile annoyances”
  1. 0/3 fix minor Makefile annoyancesJeff King, May 29, 2015
  2. 1/3 Makefile: drop dependency between git-instaweb and gitwebJeff King, May 29, 2015
  3. 2/3 Makefile: avoid timestamp updates to GIT-BUILD-OPTIONSJeff King, May 29, 2015
  4. 3/3 Makefile: silence perl/PM.stamp recipeJeff King, May 29, 2015

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.