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alliedmodders / ambuild

AlliedModders C++ Build System
BSD 3-Clause "New" or "Revised" License
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Add support for cross-compilation. #112

Closed dvander closed 4 years ago

dvander commented 4 years ago

This introduces a new "target" option to DetectCxx, which can be a full platform triple (or partial identifier). Currently, this only supports systems which are trivially configured, eg, do not have extra include or ldflag requirements. However, support for more advanced systems could be easily added.

AMBuild achieves this on Linux by looking for a compiler in the following form:

    <arch>-<platform>-<abi>-[gcc|g++]

The "platform" is currently always Linux. The abi defaults to "gnu" if no disambiguation is needed.

On Mac and Windows, both native compilers have first-class support for cross-compilation. The only effective change here is how AMBuild tests the compiler.

For cross-compilation targets, we still emit test C and C++ source files. However, the linked executable is never ran - we only verify that compilation succeeded. We also do an extra preprocess step to grab critical information about the compiler.

Example of this working for SourcePawn:

    python3 configure.py --targets=arm-gnueabihf,x86_64,x86

    Warning: build is being configured in the source tree.
    Re-using build folder: objdir
    Checking CC compiler (vendor test gcc)... ['arm-linux-gnueabihf-gcc', '-E', 'test.c']
    found gcc version 9.3, arm
    Checking CXX compiler (vendor test gcc)... ['arm-linux-gnueabihf-g++', '-E', 'test.cpp']
    found gcc version 9.3, arm
    Checking CC compiler (vendor test gcc)... ['clang', '-m64', 'test.c', '-o', 'test-c']
    found clang version 10.0, x86_64
    Checking CXX compiler (vendor test gcc)... ['clang++', '-m64', 'test.cpp', '-o', 'test-cxx']
    found clang version 10.0, x86_64
    Checking CC compiler (vendor test gcc)... ['clang', '-m32', 'test.c', '-o', 'test-c']
    found clang version 10.0, x86
    Checking CXX compiler (vendor test gcc)... ['clang++', '-m32', 'test.cpp', '-o', 'test-cxx']
    found clang version 10.0, x86

And on Windows:

    Warning: build is being configured in the source tree.
    Re-using build folder: objdir
    Checking CC compiler (vendor test msvc)... ['C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.27.29110\\bin\\HostX64\\ARM\\cl.exe', '-E', 'test.c', '-nologo']
    found msvc version 1927, arm
    Checking CXX compiler (vendor test msvc)... ['C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.27.29110\\bin\\HostX64\\ARM\\cl.exe', '-E', 'test.cpp', '-nologo']
    found msvc version 1927, arm