[CMake] Generating include files

[Michael Ellery]

> On May 19, 2017, at 2:00 PM, Urs Thuermann <urs at isnogud.escape.de> wrote:
> 
> Michael Ellery <mellery451 at gmail.com> writes:
> 
>> if your source can be generated by simple substitution of variable
>> values (like a template file), then configure_file() will do the
>> trick. If the process to create the file is more complex, then
>> add_custom_command() with an appropriate OUTPUT specification is
>> probably what you want, something like:
> 
> Yes, the awk example was a simplification.  The table to be generated
> is much larger using a somewhat more complex specification.  I don't
> want to calculate at run-time in foo.c, but at compile-time so that it
> can go into a static const int array.
> 
>> add_custom_command(OUTPUT tab.c  COMMAND "awk -f mktab > tab.c")
> 
> I have tried dozens of combinations with add_custom_command(),
> include_directories(), and ${CMAKE_BINARY_DIR}.  Also the way you
> show.  But the only way I found to have tab.c actually generated was
> to put tab.c into the add_executable() specification, but then it
> generates a tab.o which is linked into the executable.  But I want to
> have the tab[] static, i.e. included into a C file, not linked in.
> 
>> You will need to make sure that some other target explicitly depends
>> on tab.c (or whatever you name the output) to cause this custom rule
>> to be executed.
> 
> Is there a way to specify that foo.o depends on tab.c?  For some
> reason cmake's scan does not seem to find this.
> 

well, if you rename tab.c to tab.h, I’m pretty sure CMAKE will honor it as a dependency but won’t compile it..so that might be the easiest.

Alternatively, use set_source_file_properties to set https://cmake.org/cmake/help/v3.8/prop_sf/OBJECT_DEPENDS.html#prop_sf:OBJECT_DEPENDS

-Mike