threads / discuss / 32507

Makefile dependency from 'configure' to 'GIT-VERSION-FILE'

Subject: Makefile dependency from 'configure' to 'GIT-VERSION-FILE'

## tl;dr

13 messages between Jan 2, 2013 and Jan 2, 2013.

replies: 12people: 5as markdown or json

Martin von Zweigbergk· Jan 2, 2013, 01:11 UTC · lore
Hi,

I use autoconf with git.git. I have noticed lately, especially when doing things like "git rebase -i --exec make", that ./configure is run every time. If I understand correctly, this is because of 8242ff4 (build: reconfigure automatically if configure.ac changes, 2012-07-19). Just a few days before that commit, on 2012-07-15, the branch jn/makefile-cleanup including 520a6cd (Makefile: move GIT-VERSION-FILE dependencies closer to use, 2012-06-20) was merged (to next?). I wonder if these two subjects were aware of each other.

The reason 'configure' depends on GIT-VERSION-FILE is because it inserts the version into the call to AC_INIT. I have close to no experience with autoconf or even make and it's not at all clear to me why we need to pass the verison to AC_INIT. It seems like it's just for messages printed by ./configure. If that's the case, we shouldn't need to generate a new 'configure' file ever time. At the very least, we shouldn't need to run it.

Do you think we should simply remove the dependency from 'configure' to 'GIT-VERSION-FILE' and leave a comment there instead? Or should we instead somehow make 'reconfigure' depend only on 'configure.ac'? Both of these feel a little wrong to me, because they would remove real dependencies. Maybe the (probably mangled) patch at the end of this message is better?

Martin
diff --git a/Makefile b/Makefile
index 736ecd4..ec5d7ca 100644
--- a/Makefile
+++ b/Makefile
@@ -2267,12 +2267,9 @@ $(patsubst %.py,%,$(SCRIPT_PYTHON)): % : unimplemented.sh
        mv $@+ $@
 endif # NO_PYTHON

-configure: configure.ac GIT-VERSION-FILE
-       $(QUIET_GEN)$(RM) $@ $<+ && \
-       sed -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' \
-           $< > $<+ && \
-       autoconf -o $@ $<+ && \
-       $(RM) $<+
+configure: configure.ac
+       $(QUIET_GEN)$(RM) $@ && \
+       autoconf -o $@ $<

 ifdef AUTOCONFIGURED
 config.status: configure
diff --git a/configure.ac b/configure.ac
index ad215cc..00c3e38 100644
--- a/configure.ac
+++ b/configure.ac
@@ -142,7 +142,10 @@ fi
 ## Configure body starts here.

 AC_PREREQ(2.59)
-AC_INIT([git], [@@GIT_VERSION@@], [git@vger.kernel.org])
+AC_INIT([git],
+       m4_esyscmd([ ./GIT-VERSION-GEN &&
+                    { sed -ne 's/GIT_VERSION = //p' GIT-VERSION-FILE
| xargs echo -n; } ]),
+       [git@vger.kernel.org])

 AC_CONFIG_SRCDIR([git.c])
Jonathan Nieder· Jan 2, 2013, 07:21 UTC · re: Martin von Zweigbergk · lore

Re: Makefile dependency from 'configure' to 'GIT-VERSION-FILE'

Hi Martin,
Martin von Zweigbergk wrote:
Show 5 quoted lines
> I use autoconf with git.git. I have noticed lately, especially when
> doing things like "git rebase -i --exec make", that ./configure is run
> every time. If I understand correctly, this is because of 8242ff4
> (build: reconfigure automatically if configure.ac changes,
> 2012-07-19).
How about this patch (untested)?
-- >8 --
Subject: build: do not automatically reconfigure unless configure.ac changed

Starting with v1.7.12-rc0~4^2 (build: reconfigure automatically if configure.ac changes, 2012-07-19), "config.status --recheck" is automatically run every time the "configure" script changes. In particular, that means the configuration procedure repeats whenever the version number changes (since the configure script changes to support "./configure --version" and "./configure --help"), making bisecting painfully slow.

The intent was to make the reconfiguration process only trigger for changes to configure.ac's logic. Tweak the Makefile rule to match that intent by depending on configure.ac instead of configure.

Reported-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
[...]
Show 8 quoted lines
> --- a/Makefile
> +++ b/Makefile
> @@ -2267,12 +2267,9 @@ $(patsubst %.py,%,$(SCRIPT_PYTHON)): % : unimplemented.sh
>         mv $@+ $@
>  endif # NO_PYTHON
> 
> -configure: configure.ac GIT-VERSION-FILE
> +configure: configure.ac
[...]
Show 11 quoted lines
> --- a/configure.ac
> +++ b/configure.ac
> @@ -142,7 +142,10 @@ fi
>  ## Configure body starts here.
> 
>  AC_PREREQ(2.59)
> -AC_INIT([git], [@@GIT_VERSION@@], [git@vger.kernel.org])
> +AC_INIT([git],
> +       m4_esyscmd([ ./GIT-VERSION-GEN &&
> +                    { sed -ne 's/GIT_VERSION = //p' GIT-VERSION-FILE | xargs echo -n; } ]),
> +       [git@vger.kernel.org])

I don't think that would warrant dropping the GIT-VERSION-FILE dependency, since the resulting configure script still hard-codes the version number.

Sane?
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
index 736ecd45..2a22041f 100644
--- a/Makefile
+++ b/Makefile
@@ -2275,7 +2275,7 @@ configure: configure.ac GIT-VERSION-FILE
 	$(RM) $<+
 
 ifdef AUTOCONFIGURED
-config.status: configure
+config.status: configure.ac
 	$(QUIET_GEN)if test -f config.status; then \
 	  ./config.status --recheck; \
 	else \

-- 
1.8.1
Martin von Zweigbergk· Jan 2, 2013, 07:47 UTC · re: Jonathan Nieder · lore

Re: Makefile dependency from 'configure' to 'GIT-VERSION-FILE'

On Tue, Jan 1, 2013 at 11:21 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:
>
> How about this patch (untested)?
Looks good. Thanks!
Show 24 quoted lines
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -2267,12 +2267,9 @@ $(patsubst %.py,%,$(SCRIPT_PYTHON)): % : unimplemented.sh
>>         mv $@+ $@
>>  endif # NO_PYTHON
>>
>> -configure: configure.ac GIT-VERSION-FILE
>> +configure: configure.ac
> [...]
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -142,7 +142,10 @@ fi
>>  ## Configure body starts here.
>>
>>  AC_PREREQ(2.59)
>> -AC_INIT([git], [@@GIT_VERSION@@], [git@vger.kernel.org])
>> +AC_INIT([git],
>> +       m4_esyscmd([ ./GIT-VERSION-GEN &&
>> +                    { sed -ne 's/GIT_VERSION = //p' GIT-VERSION-FILE | xargs echo -n; } ]),
>> +       [git@vger.kernel.org])
>
> I don't think that would warrant dropping the GIT-VERSION-FILE
> dependency, since the resulting configure script still hard-codes the
> version number.
Yeah, you're right. I was merely sweeping the dependency under the rug :-(
Show 14 quoted lines
>
> diff --git a/Makefile b/Makefile
> index 736ecd45..2a22041f 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2275,7 +2275,7 @@ configure: configure.ac GIT-VERSION-FILE
>         $(RM) $<+
>
>  ifdef AUTOCONFIGURED
> -config.status: configure
> +config.status: configure.ac
>         $(QUIET_GEN)if test -f config.status; then \
>           ./config.status --recheck; \
>         else \

The next line just outside the context here does depend on 'configure', which is why I thought this would not be right. But it seems impossible to get away from that, and AUTOCONFIGURED should only be set when ./configure has been run (IIUC), so it's not even realistic to have "git reconfigure" fail to find "./configure". So, again, looks good.

Jonathan Nieder· Jan 2, 2013, 08:25 UTC · re: Martin von Zweigbergk · lore

[PATCH v2] build: do not automatically reconfigure unless configure.ac changed

Starting with v1.7.12-rc0~4^2 (build: reconfigure automatically if configure.ac changes, 2012-07-19), configure is automatically run every time the "configure" script changes. In particular, that means configure is automatically rerun whenever the version number changes (which changes the configure script to support "./configure --helpe"), which makes bisecting painfully slow.

The intent was to make the reconfiguration process only trigger for changes to configure.ac's logic. Tweak the Makefile rule to match that intent by depending on configure.ac instead of configure.

Reported-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
Martin von Zweigbergk wrote:
> The next line just outside the context here does depend on
> 'configure', which is why I thought this would not be right.

Yes, the 'configure' script that is run needs to reflect the changes to configure.ac. Hopefully this version will work better.

 Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
index 736ecd45..be3bbcd4 100644
--- a/Makefile
+++ b/Makefile
@@ -2275,10 +2275,11 @@ configure: configure.ac GIT-VERSION-FILE
 	$(RM) $<+
 
 ifdef AUTOCONFIGURED
-config.status: configure
+config.status: configure.ac
 	$(QUIET_GEN)if test -f config.status; then \
 	  ./config.status --recheck; \
 	else \
+	  $(MAKE) configure && \
 	  ./configure; \
 	fi
 reconfigure config.mak.autogen: config.status

-- 
1.8.1
Jeff King· Jan 2, 2013, 08:38 UTC · re: Jonathan Nieder · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

On Wed, Jan 02, 2013 at 12:25:44AM -0800, Jonathan Nieder wrote:
Show 10 quoted lines
> Starting with v1.7.12-rc0~4^2 (build: reconfigure automatically if
> configure.ac changes, 2012-07-19), configure is automatically run
> every time the "configure" script changes.  In particular, that
> means configure is automatically rerun whenever the version number
> changes (which changes the configure script to support "./configure
> --helpe"), which makes bisecting painfully slow.
> 
> The intent was to make the reconfiguration process only trigger for
> changes to configure.ac's logic.  Tweak the Makefile rule to match
> that intent by depending on configure.ac instead of configure.

It seems I am late to the party. But FWIW, this looks the most sane to me of the patches posted in this thread.

-Peff
Jonathan Nieder· Jan 2, 2013, 08:48 UTC · re: Jeff King · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

Jeff King wrote:
> It seems I am late to the party. But FWIW, this looks the most sane to
> me of the patches posted in this thread.

Thanks. config.status runs ./configure itself, though, so the rule should actually be

	config.status: configure.ac
		$(QUIET_GEN)$(MAKE) configure && \
		if test -f config.status; then \
		  ./config.status --recheck; \
		else \
		  ./configure;
		fi

Rather than screw it up yet again, I'm going to sleep. :) If someone else corrects the patch before tomorrow, I won't mind.

Stefano Lattarini· Jan 2, 2013, 14:13 UTC · re: Jonathan Nieder · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

On 01/02/2013 09:48 AM, Jonathan Nieder wrote:
Show 19 quoted lines
> Jeff King wrote:
> 
>> It seems I am late to the party. But FWIW, this looks the most sane to
>> me of the patches posted in this thread.
> 
> Thanks.  config.status runs ./configure itself, though, so the rule
> should actually be
> 
> 	config.status: configure.ac
> 		$(QUIET_GEN)$(MAKE) configure && \
> 		if test -f config.status; then \
> 		  ./config.status --recheck; \
> 		else \
> 		  ./configure;
> 		fi
> 
> Rather than screw it up yet again, I'm going to sleep. :)  If someone
> else corrects the patch before tomorrow, I won't mind.
>

FYI, this seems a sane approach to me. At least until Autoconf is improved to offer better (read: some :-) support to "dynamic" package version numbers specified at configure runtime. I hope that day isn't too far, since the current Autoconf limitation has been causing its share of annoyances small woes in Automake and Gnulib as well.

The only nit I have to offer is that I'd like to see more comments in the git Makefile about why this "semi-hack" is needed.

Thanks,
  Stefano
Junio C Hamano· Jan 2, 2013, 16:50 UTC · re: Stefano Lattarini · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

Stefano Lattarini <stefano.lattarini@gmail.com> writes:
Show 9 quoted lines
> On 01/02/2013 09:48 AM, Jonathan Nieder wrote:
>> Jeff King wrote:
>> 
>>> It seems I am late to the party. But FWIW, this looks the most sane to
>>> me of the patches posted in this thread.
>> ...
> FYI, this seems a sane approach to me....
> The only nit I have to offer is that I'd like to see more comments in
> the git Makefile about why this "semi-hack" is needed.
Thanks, everybody.

Please eyeball the below for (hopefully) the last time, to be eventually merged to maint-1.7.12, maint-1.8.0 and maint (aka maint-1.8.1) branches.

-- >8 --
From: Jonathan Nieder <jrnieder@gmail.com>
Date: Wed, 2 Jan 2013 00:25:44 -0800
Subject: [PATCH] build: do not automatically reconfigure unless configure.ac changed

Starting with v1.7.12-rc0~4^2 (build: reconfigure automatically if configure.ac changes, 2012-07-19), "config.status --recheck" is automatically run every time the "configure" script changes. In particular, that means the configuration procedure repeats whenever the version number changes (since the configure script changes to support "./configure --version" and "./configure --help"), making bisecting painfully slow.

The intent was to make the reconfiguration process only trigger for changes to configure.ac's logic. Tweak the Makefile rule to match that intent by depending on configure.ac instead of configure.

Reported-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Reviewed-by: Stefano Lattarini <stefano.lattarini@gmail.com>
---
 Makefile | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/Makefile b/Makefile
index 26b697d..2f5e2ab 100644
--- a/Makefile
+++ b/Makefile
@@ -2167,8 +2167,14 @@ configure: configure.ac GIT-VERSION-FILE
 	$(RM) $<+
 
 ifdef AUTOCONFIGURED
-config.status: configure
-	$(QUIET_GEN)if test -f config.status; then \
+# We avoid depending on 'configure' here, because it gets rebuilt
+# every time GIT-VERSION-FILE is modified, only to update the embedded
+# version number string, which config.status does not care about.  We
+# do want to recheck when the platform/environment detection logic
+# changes, hence this depends on configure.ac.
+config.status: configure.ac
+	$(QUIET_GEN)$(MAKE) configure && \
+	if test -f config.status; then \
 	  ./config.status --recheck; \
 	else \
 	  ./configure; \

-- 
1.8.1.200.gd2acdf2
Martin von Zweigbergk· Jan 2, 2013, 17:07 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

Show 21 quoted lines
> diff --git a/Makefile b/Makefile
> index 26b697d..2f5e2ab 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2167,8 +2167,14 @@ configure: configure.ac GIT-VERSION-FILE
>         $(RM) $<+
>
>  ifdef AUTOCONFIGURED
> -config.status: configure
> -       $(QUIET_GEN)if test -f config.status; then \
> +# We avoid depending on 'configure' here, because it gets rebuilt
> +# every time GIT-VERSION-FILE is modified, only to update the embedded
> +# version number string, which config.status does not care about.  We
> +# do want to recheck when the platform/environment detection logic
> +# changes, hence this depends on configure.ac.
> +config.status: configure.ac
> +       $(QUIET_GEN)$(MAKE) configure && \
> +       if test -f config.status; then \
>           ./config.status --recheck; \
>         else \
>           ./configure; \

Looks great (at least from my 'make'-incompetent point of view :-)). I do appreciate the comment. Thanks, everyone.

Stefano Lattarini· Jan 2, 2013, 19:35 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

On 01/02/2013 05:50 PM, Junio C Hamano wrote:
Show 57 quoted lines
> Stefano Lattarini <stefano.lattarini@gmail.com> writes:
> 
>> On 01/02/2013 09:48 AM, Jonathan Nieder wrote:
>>> Jeff King wrote:
>>>
>>>> It seems I am late to the party. But FWIW, this looks the most sane to
>>>> me of the patches posted in this thread.
>>> ...
>> FYI, this seems a sane approach to me....
>> The only nit I have to offer is that I'd like to see more comments in
>> the git Makefile about why this "semi-hack" is needed.
> 
> Thanks, everybody.
> 
> Please eyeball the below for (hopefully) the last time, to be
> eventually merged to maint-1.7.12, maint-1.8.0 and maint (aka
> maint-1.8.1) branches.
> 
> -- >8 --
> From: Jonathan Nieder <jrnieder@gmail.com>
> Date: Wed, 2 Jan 2013 00:25:44 -0800
> Subject: [PATCH] build: do not automatically reconfigure unless configure.ac changed
> 
> Starting with v1.7.12-rc0~4^2 (build: reconfigure automatically if
> configure.ac changes, 2012-07-19), "config.status --recheck" is
> automatically run every time the "configure" script changes.  In
> particular, that means the configuration procedure repeats whenever
> the version number changes (since the configure script changes to
> support "./configure --version" and "./configure --help"), making
> bisecting painfully slow.
> 
> The intent was to make the reconfiguration process only trigger for
> changes to configure.ac's logic.  Tweak the Makefile rule to match
> that intent by depending on configure.ac instead of configure.
> 
> Reported-by: Martin von Zweigbergk <martinvonz@gmail.com>
> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
> Reviewed-by: Jeff King <peff@peff.net>
> Reviewed-by: Stefano Lattarini <stefano.lattarini@gmail.com>
> ---
>  Makefile | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 26b697d..2f5e2ab 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -2167,8 +2167,14 @@ configure: configure.ac GIT-VERSION-FILE
>  	$(RM) $<+
>  
>  ifdef AUTOCONFIGURED
> -config.status: configure
> -	$(QUIET_GEN)if test -f config.status; then \
> +# We avoid depending on 'configure' here, because it gets rebuilt
> +# every time GIT-VERSION-FILE is modified, only to update the embedded
> +# version number string, which config.status does not care about.
>

Alas, config.status *do* care about it, in that the '@PACKAGE_VERSION@', '@PACKAGE_STRING@' and '@DEFS@' substitutions are affected by what is hard-coded in configure as the version number [1]. But if we do not use those substitutions in any of our files (and I believe we don't), then *we* can happily not care about the configure embedded version number string, and thus avoid the extra configure runs. Phew.

 [1] Yes, this is a mess.  We know.  Sorry!
Show 9 quoted lines
> +# We
> +# do want to recheck when the platform/environment detection logic
> +# changes, hence this depends on configure.ac.
> +config.status: configure.ac
> +	$(QUIET_GEN)$(MAKE) configure && \
> +	if test -f config.status; then \
>  	  ./config.status --recheck; \
>  	else \
>  	  ./configure; \
HTH,
  Stefano
Junio C Hamano· Jan 2, 2013, 20:25 UTC · re: Stefano Lattarini · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

Stefano Lattarini <stefano.lattarini@gmail.com> writes:
Show 15 quoted lines
>>  ifdef AUTOCONFIGURED
>> -config.status: configure
>> -	$(QUIET_GEN)if test -f config.status; then \
>> +# We avoid depending on 'configure' here, because it gets rebuilt
>> +# every time GIT-VERSION-FILE is modified, only to update the embedded
>> +# version number string, which config.status does not care about.
>>
> Alas, config.status *do* care about it, in that the '@PACKAGE_VERSION@',
> '@PACKAGE_STRING@' and '@DEFS@' substitutions are affected by what is
> hard-coded in configure as the version number [1].  But if we do not
> use those substitutions in any of our files (and I believe we don't),
> then *we* can happily not care about the configure embedded version
> number string, and thus avoid the extra configure runs.  Phew.
>
>  [1] Yes, this is a mess.  We know.  Sorry!

Heh. Should we warn against the use of these symbols somewhere in configure.ac, perhaps, then?

Stefano Lattarini· Jan 2, 2013, 20:53 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

On 01/02/2013 09:25 PM, Junio C Hamano wrote:
Show 21 quoted lines
> Stefano Lattarini <stefano.lattarini@gmail.com> writes:
> 
>>>  ifdef AUTOCONFIGURED
>>> -config.status: configure
>>> -	$(QUIET_GEN)if test -f config.status; then \
>>> +# We avoid depending on 'configure' here, because it gets rebuilt
>>> +# every time GIT-VERSION-FILE is modified, only to update the embedded
>>> +# version number string, which config.status does not care about.
>>>
>> Alas, config.status *do* care about it, in that the '@PACKAGE_VERSION@',
>> '@PACKAGE_STRING@' and '@DEFS@' substitutions are affected by what is
>> hard-coded in configure as the version number [1].  But if we do not
>> use those substitutions in any of our files (and I believe we don't),
>> then *we* can happily not care about the configure embedded version
>> number string, and thus avoid the extra configure runs.  Phew.
>>
>>  [1] Yes, this is a mess.  We know.  Sorry!
> 
> Heh.  Should we warn against the use of these symbols somewhere in
> configure.ac, perhaps, then?
>

Actually, they should be checked against in files processed by 'config.status', i.e., files listed in AC_CONFIG_FILES calls in 'configure.ac'. But I honestly believe that would be overkill; I say we simply adjust your comment to read something like:

  # We avoid depending on 'configure' here, because it gets rebuilt
  # every time GIT-VERSION-FILE is modified, only to update the
  # embedded version number string, which we however do not
  # substitute in any file processed by config.status.
Thanks,
  Stefano
Jonathan Nieder· Jan 2, 2013, 08:42 UTC · re: Jonathan Nieder · lore

Re: [PATCH v2] build: do not automatically reconfigure unless configure.ac changed

Jonathan Nieder wrote:
Show 6 quoted lines
> Starting with v1.7.12-rc0~4^2 (build: reconfigure automatically if
> configure.ac changes, 2012-07-19), configure is automatically run
> every time the "configure" script changes.  In particular, that
> means configure is automatically rerun whenever the version number
> changes (which changes the configure script to support "./configure
> --helpe")

Gah, I sent the log commit message --- the patch description from v1 is the right one. Sorry for the trouble. Here is the fixed description again.

Subject: build: do not automatically reconfigure unless configure.ac changed

Starting with v1.7.12-rc0~4^2 (build: reconfigure automatically if configure.ac changes, 2012-07-19), "config.status --recheck" is automatically run every time the "configure" script changes. In particular, that means the configuration procedure repeats whenever the version number changes (since the configure script changes to support "./configure --version" and "./configure --help"), making bisecting painfully slow.

The intent was to make the reconfiguration process only trigger for changes to configure.ac's logic. Tweak the Makefile rule to match that intent by depending on configure.ac instead of configure.

Reported-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

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