[CMake] avoid rebuilding targets depending on generated source files

[Ajay Panyala]

Please provide a minimal but complete example for this issue.

Please find it in the following link
http://pastie.org/private/pd13u33s9xpfihf2dbzc1q

Thank You
Ajay

On Sat, Mar 3, 2012 at 3:54 PM, Michael Hertling <mhertling at online.de>wrote:

> On 03/04/2012 12:14 AM, Ajay Panyala wrote:
> > No, it wouldn't; check it out:
> >
> > % touch a
> > % rm -f b
> > % ls b
> > ls: cannot access b: No such file or directory
> > % cmake -E copy_if_different a b
> > % ls b
> > b
> > % cksum a b
> > 4294967295 0 a
> > 4294967295 0 b
> >
> > It works with one file, but I have 4 files that are generated.
> > I have 4 cmake -E copy_if_different commands, one for each file.
> > Only the last file is not copied (if similar). The others are copied
> > even if they are the same.
> >
> > I verfied that they are the same with a diff.
> >
> > Any idea what might be happening here ?
>
> Please provide a minimal but complete example for this issue.
>
> Regards,
>
> Michael
>
> > On Sat, Mar 3, 2012 at 2:47 PM, Michael Hertling <mhertling at online.de
> >wrote:
> >
> >> On 03/03/2012 10:36 PM, Ajay Panyala wrote:
> >>> Try "cmake -E copy_if_different ..."
> >>>
> >>> cmake -E copy_if_different build/test1.c build/tests/test1.c
> >>>
> >>> That would work when make is run atleast once.
> >>> When running make for the 1st time test1.c was never
> >>> copied to build/tests before. So I would be comparing a file with
> >>> another non-existant file and that would result in an error halting
> >>> the make process.
> >>
> >> No, it wouldn't; check it out:
> >>
> >> % touch a
> >> % rm -f b
> >> % ls b
> >> ls: cannot access b: No such file or directory
> >> % cmake -E copy_if_different a b
> >> % ls b
> >> b
> >> % cksum a b
> >> 4294967295 0 a
> >> 4294967295 0 b
> >>
> >> Regards,
> >>
> >> Michael
> >>
> >>> On Sat, Mar 3, 2012 at 1:20 PM, Hendrik Sattler <
> post at hendrik-sattler.de
> >>> wrote:
> >>>
> >>>> Am Samstag, 3. März 2012, 21:41:49 schrieb Ajay Panyala:
> >>>>> I have a custom target which runs a command to generate
> >>>>> a C source file say test1.c
> >>>>>
> >>>>> ADD_CUSTOM_TARGET(TestGen ALL
> >>>>> COMMAND genExec ${PROJECT_SOURCE_DIR}/Main.java
> >>>>> DEPENDS ${PROJECT_SOURCE_DIR}/Main.java
> >>>>> )
> >>>>>
> >>>>> And I have a custom command that moves the generated *test1.c *
> >>>>> to a new directory inside the build directory.
> >>>>>
> >>>>> ADD_CUSTOM_COMMAND(
> >>>>> TARGET TestGen
> >>>>> POST_BUILD
> >>>>> COMMAND mv
> >>>>> ARGS ${PROJECT_BINARY_DIR}/test1.c ${PROJECT_BINARY_DIR}/tests/
> >>>>> )
> >>>>>
> >>>>> Each time I run make, the custom target is run (since custom targets
> >> are
> >>>>> always
> >>>>> out-of-date). But I want to avoid moving the new test1.c generated
> each
> >>>>> time if build/test1.c is the same as build/tests/test1.c since there
> >> are
> >>>>> other targets
> >>>>> like add_executable and add_library later in the CMakelists file that
> >> are
> >>>>>  re-built
> >>>>> each time since they depend on test1.c
> >>>>
> >>>> Try "cmake -E copy_if_different ..."
> >>>>
> >>>> HS
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-- 
Ajay Panyala                              | Email: ajay at csc.lsu.edu
Department of Computer Science | Phone: +1 (225) 907 9501
Louisiana State University           |  www.csc.lsu.edu/~ajay
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