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Re: [PATCH 04/17] Makefile: a dry-run can error out if no perl. Document the issue

From
Philip Oakley <philipoakley@iee.org>
Date
Jul 14, 2015, 22:42 UTC
Message-ID
<0D1AA32B8D59471B8C528002A460E912@PhilipOakley>
In-Reply-To
<45344004B4CA4B16BD7FB174B4849D77@PhilipOakley>
From: "Philip Oakley" <philipoakley@iee.org>
Sent: Friday, June 26, 2015 12:34 AM
Show 6 quoted lines
> From: "Junio C Hamano" <gitster@pobox.com>
>> "Philip Oakley" <philipoakley@iee.org> writes:
>>
>>> From: "Junio C Hamano" <gitster@pobox.com>
>>>>
>>>> I am not sure what this patch is trying to achieve.
I have been able to repeat the issue, more below.
Show 14 quoted lines
>>>
>>> It was probably a bit of 'don't mess with working code', given that
>>> I'd used the NO_PERL solution, rather 'document the issue'....
>>
>> Then this part applies, I think.
>>
>>>> If you are not touching what this Makefile actually does, then I
>>>> would imagine that you are running the "buildsystems code" that
>>>> actually drives 'make -n' with some "available solution" (perhaps
>>>> you are running 'make -n NO_PERL=NoThanks' or something like that)?
>>>> Then instead of a command like this that nobody would read in this
>>>> file, the same command can instead go there to explain what the
>>>> "workaround" (e.g. unusual-looking 'make -n NO_PERL=NoThanks') is
>>>> doing?
The command sequence:
 $ git clean -dfx
 $ make -n MSVC=1 V=1 2>ErrsFile.txt 1>MakeDry.txt
produces the error
 make[1]: *** No rule to make target 'PM.stamp', needed by 'perl.mak'. 
Stop.
 make: *** [perl/perl.mak] Error 2
the actual MakeDry.txt reaches
 echo "$FLAGS" >GIT-CFLAGS; \
            fi
 make[2]: Leaving directory '/c/msysgit195/git'
 make[1]: Leaving directory '/c/msysgit195/git/perl'
 Makefile:1758: recipe for target 'perl/perl.mak' failed

My understanding of the error is that, first, the PM.stamp is removed by the clean, then the dryrun has by the error time passed the initial PM.stamp update code, but doesn't execute it (being a dry run), thus the file PM.stamp still does not exist.

The makefile then descends into the 'perl/Makefile' pre-requisite to 'perl/perl.mak', and (IIUC) at this point the L25#$(makfile): PM.stamp then barfs because there is no PM.stamp to be a prerequisite for that line.

As noted in the patch, my response at the time (not fully understanding why) was simply to annotate the Makefile's PM.stamp (which is where the error would first leads any future debugging).

Possibly other options would be to add an extra PM.stamp target which, for a dry-run (+recipe), creates any empty PM.stamp file if one does not exist, simply to allow the perl/perl.mak to succeed. Or perhaps simply add the PM.stamp file to the code (or maybe not).

A third option would be to simply convert the PM.stamp recipe to a +recipe so that it's executed during the dry-run, but that may be contrary to the idea of being a dry-run.

Do you have any preference for how I should resolve this? Ideally I like to drop the use of the NO_PERL in the dry run.

-- Philip

Show 32 quoted lines
>>
> I was more of the view that this was about prevention (here), rather
> than retrospective explanation of the code (there).
>
> In my case the errors were showing problems with the PM.stamp in the
> makefile (I didn't have the solution at that point).
>
> So either a short comment "#  consider using 'NO_PERL=YesPlease' for 
> dry
> run invocations" (beware your double negative ;-), or the addition of
> the '+recipe', would still be my preferred change, rather than leaving
> the open manhole for others to fall into.
>
> The thread on my difficulties is at $gmane/263656 (2015-02-10 22:51)
> "
>    At the moment I'm getting (on my old WinXP machine, using Msysgit
>    1.9.5 as a basis)
>
>    $ make -n MSVC=1 V=1 1>makedry.txt
>    make[1]: *** No rule to make target `PM.stamp', needed by 
> `perl.mak'.
>    Stop.
>    make: *** [perl/perl.mak] Error 2
> "
> As you can see, at that time the place to look would be the makefile,
> so I would do think a 'fix' there would still be appropriate.
>
> Do you have a preference among the three options (comment, +recipe, 
> drop)?
> --
> Philip
>
-- 
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Previous: Philip OakleyNext: Philip Oakley
Message 15 of 34 in “Make the msvc-build scripts work again”
  1. 00/17 Make the msvc-build scripts work againPhilip Oakley, Jun 25, 2015
  2. 01/17 .gitignore: improve MSVC ignore patternsPhilip Oakley, Jun 25, 2015
  3. Junio C HamanoJun 25, 2015
  4. Philip OakleyJun 25, 2015
  5. Junio C HamanoJun 25, 2015
  6. 02/17 .gitignore: ignore library directories created by MSVC VS2008 buildsystemPhilip Oakley, Jun 25, 2015
  7. 03/17 (msvc-build) Vcproj.pm: remove duplicate GUIDPhilip Oakley, Jun 25, 2015
  8. Eric SunshineJun 28, 2015
  9. Philip OakleyJun 28, 2015
  10. 04/17 Makefile: a dry-run can error out if no perl. Document the issuePhilip Oakley, Jun 25, 2015
  11. Junio C HamanoJun 25, 2015
  12. Philip OakleyJun 25, 2015
  13. Junio C HamanoJun 25, 2015
  14. Philip OakleyJun 25, 2015
  15. Philip OakleyJul 14, 2015
  16. 05/17 engine.pl: fix error message (lib->link)Philip Oakley, Jun 25, 2015
  17. 06/17 engine.pl: Avoid complications with perl supportPhilip Oakley, Jun 25, 2015
  18. 07/17 engine.pl: Properly accept quoted spaces in filenamesPhilip Oakley, Jun 25, 2015
  19. 08/17 engine.pl: Fix i18n -o option in msvc buildsystem generatorPhilip Oakley, Jun 25, 2015
  20. 09/17 engine.pl: ignore invalidcontinue.obj which is known to MSVCPhilip Oakley, Jun 25, 2015
  21. 10/17 engine.pl: name the msvc buildsystem's makedry error filePhilip Oakley, Jun 25, 2015
  22. 11/17 engine.pl: delete the captured stderr file if emptyPhilip Oakley, Jun 25, 2015
  23. 12/17 engine.pl: add debug line to capture the dry-runPhilip Oakley, Jun 25, 2015
  24. 13/17 engine.pl: provide more debug print statementsPhilip Oakley, Jun 25, 2015
  25. Sebastian SchuberthJun 29, 2015
  26. Philip OakleyJul 7, 2015
  27. Sebastian SchuberthJun 29, 2015
  28. Sebastian SchuberthJun 29, 2015
  29. 14/17 Vcproj.pm: list git.exe first to be startup projectPhilip Oakley, Jun 25, 2015
  30. 15/17 vcbuild/readme: Improve layout and reference msvc-build scriptPhilip Oakley, Jun 25, 2015
  31. 16/17 msvc-build: add complete Microsoft Visual C compilation scriptPhilip Oakley, Jun 25, 2015
  32. 17/17 config.mak.uname: add MSVC No_SafeExeceptionHandler optionPhilip Oakley, Jun 25, 2015
  33. Junio C HamanoJun 25, 2015
  34. Philip OakleyJun 25, 2015

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