Build System and portability

Question

I'm wondering how i can make a portable build system (step-by-step), i currently use cmake because it was easy to set up in the first place, with only one arch target, but now that i have to package the library I'm developing I'm wondering how is the best way to make it portable for arch I'm testing.

I know I need a config.h to define things depending on the arch but I don't know how automatic this can be.

Any other way to have a build system are warmly welcome!

Answer 1

You can just use CMake, it's pretty straightforward.

You need these things:

First, means to find out the configuration specifics. For example, if you know that some function is named differently on some platform, you can use TRY_COMPILE to discover that:

TRY_COMPILE(HAVE_ALTERNATIVE_FUNC 
    ${CMAKE_BINARY_DIR}
    ${CMAKE_SOURCE_DIR}/alternative_function_test.cpp
    CMAKE_FLAGS -DINCLUDE_DIRECTORIES=xxx
)

where alternative_function_test.cpp is a file in your source directory that compiles only with the alternative definition.

This will define variable HAVE_ALTERNATIVE_FUNC if the compile succeeds.

Second, you need to make this definition affect your sources. Either you can add it to compile flags

IF(HAVE_TR1_RANDOM)
    ADD_DEFINITIONS(-DHAVE_TR1_RANDOM)
ENDIF(HAVE_TR1_RANDOM)

or you can make a config.h file. Create config.h.in with the following line

#cmakedefine HAVE_ALTERNATIVE_FUNCS

and create a config.h file by this line in CMakeLists.txt (see CONFIGURE_FILE)

CONFIGURE_FILE(config.h.in config.h @ONLY)

the #cmakedefine will be translated to #define or #undef depending on the CMake variable.

BTW, for testing edianness, see this mail