cmake - 如何在 CMake Release模式下启用断言？

Question

CMake 用于编译一些 C++ 文件。有assert在代码中调用。这些调用在 CMake 的 Release模式下被禁用。它定义了 NDEBUG在 Release模式下，我猜。

如果我有兴趣在 CMake 的 Release模式下断言，我该如何启用它？

Answer 1

以下是 LLVM 是如何做到的。他们添加了 LLVM_ENABLE_ASSERTIONS项目的选项(将 LLVM 更改为项目的前缀)，然后检查它并过滤编译标志。 MSVC 有一个特殊情况。
总的来说，这对我来说似乎比定义构建配置更明智。启用断言是 IMO 对整体构建配置的正交关注。

# This is commonly needed so define it before we include anything else.
string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)

[...]

if(uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" )
    option(QD_ENABLE_ASSERTIONS "Enable assertions" ON)
else()
    option(QD_ENABLE_ASSERTIONS "Enable assertions" OFF)
endif()

[...]

if(QD_ENABLE_ASSERTIONS)
    if(NOT MSVC)
        add_definitions(-D_DEBUG)
    endif()
    # On non-Debug builds cmake automatically defines NDEBUG, so we explicitly undefine it:
    if(NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG")
        # NOTE: use `add_compile_options` rather than `add_definitions` since
        # `add_definitions` does not support generator expressions.
        add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-UNDEBUG>)

        # Also remove /D NDEBUG to avoid MSVC warnings about conflicting defines.
        foreach (flags_var_to_scrub
                CMAKE_CXX_FLAGS_RELEASE
                CMAKE_CXX_FLAGS_RELWITHDEBINFO
                CMAKE_CXX_FLAGS_MINSIZEREL
                CMAKE_C_FLAGS_RELEASE
                CMAKE_C_FLAGS_RELWITHDEBINFO
                CMAKE_C_FLAGS_MINSIZEREL)
            string (REGEX REPLACE "(^| )[/-]D *NDEBUG($| )" " "
                    "${flags_var_to_scrub}" "${${flags_var_to_scrub}}")
        endforeach()
    endif()
endif()

来源: https://opensource.apple.com/source/llvmCore/llvmCore-2358.3/CMakeLists.txt.auto.html