[CMake] Restrictions on where a binary can be put?

[Michael Hertling]

On 01/09/2011 12:58 PM, Andreas Pakulat wrote:
> Hi,
> 
> I'm having a bit of a problem here changing the runtime output directory
> for a binary. Its an executable target named 'setup' and I'd like to put it
> into the top-level directory. Unfortunately it always ends up in the bin/
> directory, which is what CMAKE_RUNTIME_OUTPUT_DIRECTORY is being set to.
> 
> I'm using
>     set_target_properties( setup PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR} )
> after creating the target currently, which should work as far as I can see
> from the documentation. Are there maybe any restrictions on what the
> directory may be or what targets can be put there?
> 
> If not, any suggestions how to debug this? I can see that the build.make
> does already have the rule setup for putting the binary into bin/, so it
> must be going wrong somewhere in the generation stage, but a simple cmake
> --trace doesn't show up anything suspicious. Is there a switch to follow
> the steps that cmake does during makefile-generation?

Could you provide a minimal but complete example? Currently, I can't
confirm this issue, i.e. the RUNTIME_OUTPUT_DIRECTORY property seems
to take precedence over the CMAKE_RUNTIME_OUTPUT_DIRECTORY variable.
Nevertheless, if RUNTIME_OUTPUT_DIRECTORY is set to CMAKE_BINARY_DIR
from within a subdirectory, i.e. CMAKE_CURRENT_BINARY_DIR isn't equal
to CMAKE_BINARY_DIR, I can see quite strange things happening:

# CMakeLists.txt:
CMAKE_MINIMUM_REQUIRED(VERSION 2.8 FATAL_ERROR)
PROJECT(ROD C)
ADD_SUBDIRECTORY(main)

# main/CMakeLists.txt:
FILE(WRITE ${CMAKE_CURRENT_BINARY_DIR}/main.c
    "int main(void){return 0;}\n"
)
ADD_EXECUTABLE(main ${CMAKE_CURRENT_BINARY_DIR}/main.c)
SET_TARGET_PROPERTIES(main PROPERTIES
    RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}
)

After CMaking from within an empty directory, building fails with:

.../gcc CMakeFiles/main.dir/main.c.o -o . -rdynamic
.../ld: cannot open output file .: Is a directory

If the RUNTIME_OUTPUT_DIRECTORY property is set to CMAKE_BINARY_DIR/bin,
e.g., everything works as expected, i.e. the executable gets written to
CMAKE_BINARY_DIR/bin. Also, no such problem occurs from within the top-
level directory, i.e. CMAKE_CURRENT_BINARY_DIR == CMAKE_BINARY_DIR.
Perhaps, these two phenomena are related?

Regards,

Michael