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I'm trying to compile a program using cmake and am passing in -DCOMMIT_NUM:STRING="some_number" as a command line argument with the cmake. I see this variable in the CMakeCache.txt file, but I'm not sure of how to access it in my program. I need to print COMMIT_NUM. I try to print this variable. The error I am getting is that COMMIT_NUM is not declared in the scope.

Looked everywhere, so could I please get some help? Thank you

Raiyan Ishmam
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  • [target_compile_options](https://cmake.org/cmake/help/latest/command/target_compile_options.html?highlight=target_com#command:target_compile_options) is your friend. – serkan.tuerker Jul 02 '19 at 20:03
  • Hi, thank you so much. I looked through the documentation for target_compile_options, but am not sure how it is implemented in my case. The following two lines are used to configure and then build my workspace. catkin config --cmake-args -DCISST_cisstStereoVision=ON \ -DEIGEN3_INCLUDE_DIR=/usr/include/eigen3 \ -DCOMMIT_NUM:STRING="some string" catkin build REMS Not sure if it makes a difference, but I'm writing these in a bash script, and am specifically trying to save a bash script variable as a Cmake cached variable so that I can access it in my program. – Raiyan Ishmam Jul 02 '19 at 20:22

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Your COMMIT_NUM is a CMake variable. As such, it is only available in CMake.

If you want your program to have access to this information, you have to make CMake forward it to your program.

I assume that what you call your “program” is a C/C++ program defined in CMake with something like add_executable(targetName). Then to forward the variable, you may use:

target_compile_definitions(targetName PUBLIC COMMIT_NUM=${COMMIT_NUM})

Then, inside any compilation unit of your program, you should have access to a macro COMMIT_NUM whose value is the same you gave CMake.

Shaac
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