[CMake] Generated files...

[Brad King]

Lars Pechan wrote:
> Hello,
> I'm having some issues with generated files.
> 
> This is the example from the FAQ:
> 
> ADD_CUSTOM_COMMAND(
> OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/foo.c
> COMMAND ${CMAKE_COMMAND}
> ARGS -E copy ${CMAKE_CURRENT_SOURCE_DIR}/bar.c
> ${CMAKE_CURRENT_BINARY_DIR}/foo.c
> DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/bar.c
> )
> ADD_EXECUTABLE(foo foo.c)
> 
> I thought I could do ARGS -E copy_if_different as another means of 
> setting up the dependency. Ie if bar.c has changed a new copy operation 
> will be done. I tested my theory by doing 'touch' on the original file 
> and that didn't have any effect at all. It appears that 
> copy_if_different requires more than just a newer timestamp to trigger?

It acutally compares the file contents and copies only if things have 
changed.  This is not suitable for a custom command because if bar.c 
changes its time but not contents then foo.c will not be updated and the 
rule will run every time the build is performed.

> The FAQ entry as it is written does trigger on a 'touch'ed source file 
> so there is no immediate drama.
> 
> However, I have a cvs:ed source tree where I copy some files from 
> various directories to build in my out-of-source tree. This means the 
> original files are read-only (as they clearly should be). When I do the 
> 'touch' test CMake correctly tries to re-copy the touched file but that 
> fails since the original copy has been copied as a read-only file. Is 
> there any way around this?

This is a known bug in 2.0.3 and will be fixed in 2.0.4.

> Finally, I thought I'd be paranoid and ADDITIONAL_MAKE_CLEAN_FILES to 
> blow the sources away. Regardless of whether I do
> 
> SET(tlSources init.c chomp.c last.c)
> 
> SET_DIRECTORY_PROPERTIES(PROPERTIES ADDITIONAL_MAKE_CLEAN_FILES 
> ${tlSources}) or
> 
> FOREACH(srcFile ${tlSources})
> SET_DIRECTORY_PROPERTIES(PROPERTIES ADDITIONAL_MAKE_CLEAN_FILES ${srcFile})
> ENDFOREACH(srcFile)
> 
> I end up with a ADDITIONAL_MAKE_CLEAN_FILES in the Makefile consisting 
> of the sole entry last.c?

There is only one property and the command "SET"s it.  You need to give 
it one value:

SET_DIRECTORY_PROPERTIES(PROPERTIES ADDITIONAL_MAKE_CLEAN_FILES 
"${tlSources}")

With the double quotes the value becomes one argument and will be set as 
the property.  Without double quotes the value expands into a list of 
arguments to SET_DIRECTORY_PROPERTIES, so only one entry is paired with 
the ADDITIONAL_MAKE_CLEAN_FILES property.

-Brad