[CMake] VC2005 - ADD_CUSTOM_TARGET problems..

[Brad King]

Shishir Ramam wrote:
> root/
>      PROJECT(MyProject)
>      subdir1/src 
>                      ADD_EXECUTABLE(target1 target1_srcs.c)  
>                      # target1 generates a header file - say gen_header.h
>      subdir2/
>                 ADD_EXECUTABLE(target2 target2_srcs.c)
> 
> target2 includes gen_header.h So my interest is in building and running target1
> before attempting to build target2.

This is a common design and is fully supported by CMake, but not quite 
the way you are doing things.  The custom command for generating the 
header should be added in subdir2/CMakeLists.txt:

ADD_CUSTOM_COMMAND(
   OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/gen_header.h
   COMMAND ${EXE_DIR}/target1 ARGS arg1 arg2
   DEPENDS ${EXE_DIR}/target1
)

Since the header is generated it will not exist when the dependencies of 
the source files are scanned, so you need to add the dependency using a 
source file property:

SET_SOURCE_FILES_PROPERTIES(target2_src.c
   PROPERTIES OBJECT_DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/gen_header.h)

The FOREACH command can help you do this for more than one source in 
target2.

Note that generating source files is much easier than generating header 
files because you do not need the OBJECT_DEPENDS part.  Usually we use 
CONFIGURE_FILE to produce header files at CMake time with build-specific 
information.  Then you don't need the generation step at all.

-Brad