dlib C++ Library - test_for_odr_violations.h

    // Copyright (C) 2014  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_TEST_FOR_ODR_VIOLATIONS_H_
    #define DLIB_TEST_FOR_ODR_VIOLATIONS_H_

    #include "assert.h"
    #include "config.h"

    extern "C"
    {
    // =========================>>> WHY YOU ARE GETTING AN ERROR HERE <<<=========================
    // The point of this block of code is to cause a link time error that will prevent a user
    // from compiling part of their application with DLIB_ASSERT enabled and part with it
    // disabled since doing that would be a violation of C++'s one definition rule.  So if you
    // are getting an error here then you are either not enabling DLIB_ASSERT consistently
    // (e.g. by compiling part of your program in a debug mode and part in a release mode) or
    // you have simply forgotten to compile dlib/all/source.cpp into your application.
    // =========================>>> WHY YOU ARE GETTING AN ERROR HERE <<<=========================
    #ifdef ENABLE_ASSERTS
        const extern int USER_ERROR__inconsistent_build_configuration__see_dlib_faq_1;
        const int DLIB_NO_WARN_UNUSED dlib_check_assert_helper_variable = USER_ERROR__inconsistent_build_configuration__see_dlib_faq_1;
    #else
        const extern int USER_ERROR__inconsistent_build_configuration__see_dlib_faq_1_;
        const int DLIB_NO_WARN_UNUSED dlib_check_assert_helper_variable = USER_ERROR__inconsistent_build_configuration__see_dlib_faq_1_;
    #endif

    // The point of this block of code is to cause a link time error if someone builds dlib via
    // cmake as a separately installable library, and therefore generates a dlib/config.h from
    // cmake, but then proceeds to use the default unconfigured dlib/config.h from version
    // control.  It should be obvious why this is bad, if it isn't you need to read a book
    // about C++.  Moreover, it can only happen if someone manually copies files around and
    // messes things up.  If instead they run `make install` or `cmake --build .  --target
    // install` things will be setup correctly, which is what they should do.  To summarize: DO
    // NOT BUILD A STANDALONE DLIB AND THEN GO CHERRY PICKING FILES FROM THE BUILD FOLDER AND
    // MIXING THEM WITH THE SOURCE FROM GITHUB.  USE CMAKE'S INSTALL SCRIPTS TO INSTALL DLIB.
    // Or even better, don't install dlib at all and instead build your program as shown in
    // examples/CMakeLists.txt
    #if defined(DLIB_NOT_CONFIGURED) && !defined(DLIB__CMAKE_GENERATED_A_CONFIG_H_FILE)
        const extern int USER_ERROR__inconsistent_build_configuration__see_dlib_faq_2;
        const int DLIB_NO_WARN_UNUSED dlib_check_not_configured_helper_variable = USER_ERROR__inconsistent_build_configuration__see_dlib_faq_2;
    #endif

    // Cause the user to get a linker error if they try to use header files from one version of
    // dlib with the compiled binary from a different version of dlib.
    #ifdef DLIB_CHECK_FOR_VERSION_MISMATCH
        const extern int DLIB_CHECK_FOR_VERSION_MISMATCH;
        const int DLIB_NO_WARN_UNUSED dlib_check_for_version_mismatch = DLIB_CHECK_FOR_VERSION_MISMATCH;
    #endif

    }

    #endif // DLIB_TEST_FOR_ODR_VIOLATIONS_H_