cmake官方文档

target_compile_definitions(myapp
  PRIVATE $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CXX_COMPILER_ID:AppleClang,Clang>>:COMPILING_CXX_WITH_CLANG>
          $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CXX_COMPILER_ID:Intel>>:COMPILING_CXX_WITH_INTEL>
          $<$<AND:$<COMPILE_LANGUAGE:C>,$<C_COMPILER_ID:Clang>>:COMPILING_C_WITH_CLANG>
)

Conditional Compilation Options

Libraries may provide entirely different header files depending on requested compiler features.

For example, a header at with_variadics/interface.h may contain:

template<int I, int... Is>
struct Interface;

template<int I>
struct Interface<I>
{
  static int accumulate()
  {
    return I;
  }
};

template<int I, int... Is>
struct Interface
{
  static int accumulate()
  {
    return I + Interface<Is...>::accumulate();
  }
};

while a header at no_variadics/interface.h may contain:

template<int I1, int I2 = 0, int I3 = 0, int I4 = 0>
struct Interface
{
  static int accumulate() { return I1 + I2 + I3 + I4; }
};

It would be possible to write a abstraction interface.h header containing something like:

#include "foo_compiler_detection.h"
#if Foo_COMPILER_CXX_VARIADIC_TEMPLATES
#include "with_variadics/interface.h"
#else
#include "no_variadics/interface.h"
#endif

However this could be unmaintainable if there are many files to abstract. What is needed is to use alternative include directories depending on the compiler capabilities.

CMake provides a COMPILE_FEATURES generator expression to implement such conditions. This may be used with the build-property commands such as target_include_directories() and target_link_libraries() to set the appropriate buildsystem properties:

add_library(foo INTERFACE)
set(with_variadics ${CMAKE_CURRENT_SOURCE_DIR}/with_variadics)
set(no_variadics ${CMAKE_CURRENT_SOURCE_DIR}/no_variadics)
target_include_directories(foo
  INTERFACE
    "$<$<COMPILE_FEATURES:cxx_variadic_templates>:${with_variadics}>"
    "$<$<NOT:$<COMPILE_FEATURES:cxx_variadic_templates>>:${no_variadics}>"
  )

Consuming code then simply links to the foo target as usual and uses the feature-appropriate include directory

add_executable(consumer_with consumer_with.cpp)
target_link_libraries(consumer_with foo)
set_property(TARGET consumer_with CXX_STANDARD 11)

add_executable(consumer_no consumer_no.cpp)
target_link_libraries(consumer_no foo)