CMake Run Built Executable Before Building Another?

Question

How would i tell CMake to build and run an executable before building another? So i have 2 executable files "a" and "b", where "a" is required to run in order to generate header files for "b". So "a" takes 2 folders as a parameter, in which it generates header files from xml files from an input directory to an output directory.

Is there a way to tell CMake to do this as well as to know when the xml files are modified or when project "a" is modified to regenerate the files?

Answer 1

If test1 being built from test1.c needs prior execution of test2 being built from test2.c, then the solution should look like this:

-- test1.c --

#include <stdio.h>
int main(void) {
    printf("Hello world from test1\n");
    return 0;
}

-- test2.c --

#include <stdio.h>

int main(void) {
    printf("Hello world from test2\n");
    return 0;
}

-- CMakeLists.txt --

cmake_minimum_required(VERSION 2.8.11)

project(Test)

set(test1_SOURCES test1.c)
set(test2_SOURCES test2.c)

add_executable(test1 ${test1_SOURCES})

add_executable(test2 ${test2_SOURCES})
add_custom_target(test2_run
  COMMAND test2
  WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
  COMMENT "run generated test2 in ${CMAKE_CURRENT_SOURCE_DIR}"
  SOURCES ${test2_SOURCES}
)

add_dependencies(test1 test2_run)

It generates the following output:

alex@rhyme cmake/TestDep/build $ cmake ..             
-- The C compiler identification is GNU 4.8.2
-- The CXX compiler identification is GNU 4.8.2
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/alex/tmp/cmake/TestDep/build
alex@rhyme cmake/TestDep/build $ make test1
Scanning dependencies of target test2
[ 25%] Building C object CMakeFiles/test2.dir/test2.c.o
Linking C executable test2
[ 25%] Built target test2
Scanning dependencies of target test2_run
[ 50%] run generated test2 in /home/alex/tmp/cmake/TestDep
Hello world from test2
[ 75%] Built target test2_run
Scanning dependencies of target test1
[100%] Building C object CMakeFiles/test1.dir/test1.c.o
Linking C executable test1
[100%] Built target test1

You may also need to use add_custom_command and other related CMake directives if your task demands it.