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Re: [PATCH] build: do not require help2man at build-from-tarball time
From: |
Jim Meyering |
Subject: |
Re: [PATCH] build: do not require help2man at build-from-tarball time |
Date: |
Mon, 10 Sep 2012 16:15:17 +0200 |
Stefano Lattarini wrote:
...
> Just out of curiosity: is [test FILE -nt OTHER_FILE] a feature in POSIX?
Not in any current standard.
> Anyway, maybe it could be emulated with "find -newer" or something
> similar...
Sure, but not worth it, because some find programs probably lack support
for the -newer predicate. Besides, I abandoned that approach because
it seemed like it would not be worthwhile, and because it would impose
overhead all of the time.
>> or when things are out of date, the regular commands
>> would run. Otherwise, it would simply touch the .1 file and exit
>> successfully.
>>
>> AFAIK, there is no way in GNU make to specify dependencies that vary
>> depending on the existence of a target. Does anyone know otherwise?
>> I.e., a rule that would apply when foo.1 does not exist, vs. another
>> one (with different dependents) that would apply when it does exist.
>>
> What about this (untested)?
>
> ifeq ($(wildcard target)$(wildcard $(srcdir)/target),)
> target: prereq1
> @echo target existed already
> else
> target: prereq2
> @echo target did not exist
> endif
>
> That would only work assuming 'target' is relative to be builddir
> (i.e., 'dir/file', not $(srcdir)/dir/file'), but might be enough.
Nice. That looks like it would work.
If only we could depend on GNU make...