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Re: Cygwin make target is never determined up to date
On 05/05/2010 06:04, Jeremy Bopp wrote:
> MichaelKim wrote:
>> Prerequisite `../bin/build/chrome' is newer than
>> target `../bin/build/chrome/alt.jar'.
>> Must remake target `../bin/build/chrome/alt.jar'.
> So let me get this straight. The JAR file you're trying to build is
> within a directory which is listed as a prerequisite of that JAR file?
> Unless I'm completely off base, it would seem to be that this is
> expected behavior then. If you mess with the contents of a directory,
> such as by adding a file to it, the last modified timestamp of the
> directory is going to be updated. I would expect that to happen after
> the file is added to the directory which could very well be *after* the
> last modified timestamp of the file is set. Thus the directory will
> appear newer than the file.
Yep:
> $(chrome_jar_file): $(jar_sources) $(jar_target_dir)
The idea is supposed to be to make the jar file depend on the output dir, so
that if the output dir doesn't exist, the $(jar_target_dir) rule will get
invoked to mkdir it; but it doesn't anticipate that the timestamp of an
existing dir changes everytime you touch the files within it.
For a discussion of better ways to create an output dir in make, see:
http://www.cmcrossroads.com/cm-articles/columns/ask-mr-make
The particular article you're looking for is #26, "Making directories in GNU
Make":
http://www.cmcrossroads.com/ask-mr-make/6936-making-directories-in-gnu-make
I don't know why this would be working on the old XP machine, unless it's
running an older version of cygwin that had a bug or didn't implement updating
directory timestamps.
cheers,
DaveK
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