Merge topic 'CheckIncludeFiles-language-CXX'

b31d5e1d CheckIncludeFiles: improve warning for missing argument
1f1c2a9f CheckIncludeFiles: clean up documentation of new features
c8609992 Help: Add notes for topic 'CheckIncludeFiles-language-CXX'
ea1bb902 CheckIncludeFiles: add unit tests
7669695a CheckIncludeFiles: extend to allow a LANGUAGE argument

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !1464

1 files changed, 35 insertions, 5 deletions

diff --git a/Modules/CheckIncludeFiles.cmake b/Modules/CheckIncludeFiles.cmake
index bef11a5..347231c 100644
--- a/Modules/CheckIncludeFiles.cmake
+++ b/Modules/CheckIncludeFiles.cmake
@@ -6,19 +6,24 @@
 # -----------------
 #
 # Provides a macro to check if a list of one or more header files can
-# be included together in ``C``.
+# be included together.
 #
 # .. command:: CHECK_INCLUDE_FILES
 #
 #   ::
 #
-#     CHECK_INCLUDE_FILES("<includes>" <variable>)
+#     CHECK_INCLUDE_FILES("<includes>" <variable> [LANGUAGE <language>])
 #
 #   Check if the given ``<includes>`` list may be included together
-#   in a ``C`` source file and store the result in an internal cache
+#   in a source file and store the result in an internal cache
 #   entry named ``<variable>``.  Specify the ``<includes>`` argument
 #   as a :ref:`;-list <CMake Language Lists>` of header file names.
 #
+# If LANGUAGE is set, the specified compiler will be used to perform the
+# check. Acceptable values are ``C`` and ``CXX``. If not set, the C compiler
+# will be used if enabled. If the C compiler is not enabled, the C++
+# compiler will be used if enabled.
+#
 # The following variables may be set before calling this macro to modify
 # the way the check is run:
 #
@@ -37,6 +42,31 @@
 macro(CHECK_INCLUDE_FILES INCLUDE VARIABLE)
   if(NOT DEFINED "${VARIABLE}")
     set(CMAKE_CONFIGURABLE_FILE_CONTENT "/* */\n")
+
+    if("x${ARGN}" STREQUAL "x")
+       if(CMAKE_C_COMPILER_LOADED)
+         set(_lang C)
+       elseif(CMAKE_CXX_COMPILER_LOADED)
+         set(_lang CXX)
+       else()
+         message(FATAL_ERROR "CHECK_INCLUDE_FILES needs either C or CXX language enabled.\n")
+       endif()
+    elseif("x${ARGN}" MATCHES "^xLANGUAGE;([a-zA-Z]+)$")
+      set(_lang "${CMAKE_MATCH_1}")
+    elseif("x${ARGN}" MATCHES "^xLANGUAGE$")
+      message(FATAL_ERROR "No languages listed for LANGUAGE option.\nSupported languages: C, CXX.\n")
+    else()
+      message(FATAL_ERROR "Unknown arguments:\n  ${ARGN}\n")
+    endif()
+
+    if(_lang STREQUAL "C")
+      set(src ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CheckIncludeFiles/${var}.c)
+    elseif(_lang STREQUAL "CXX")
+      set(src ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CheckIncludeFiles/${var}.cpp)
+    else()
+      message(FATAL_ERROR "Unknown language:\n  ${_lang}\nSupported languages: C, CXX.\n")
+    endif()
+
     if(CMAKE_REQUIRED_INCLUDES)
       set(CHECK_INCLUDE_FILES_INCLUDE_DIRS "-DINCLUDE_DIRECTORIES=${CMAKE_REQUIRED_INCLUDES}")
     else()
@@ -51,7 +81,7 @@ macro(CHECK_INCLUDE_FILES INCLUDE VARIABLE)
     string(APPEND CMAKE_CONFIGURABLE_FILE_CONTENT
       "\n\nint main(void){return 0;}\n")
     configure_file("${CMAKE_ROOT}/Modules/CMakeConfigurableFile.in"
-      "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckIncludeFiles.c" @ONLY)
+      "${src}" @ONLY)
 
     set(_INCLUDE ${INCLUDE}) # remove empty elements
     if("${_INCLUDE}" MATCHES "^([^;]+);.+;([^;]+)$")
@@ -68,7 +98,7 @@ macro(CHECK_INCLUDE_FILES INCLUDE VARIABLE)
     endif()
     try_compile(${VARIABLE}
       ${CMAKE_BINARY_DIR}
-      ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckIncludeFiles.c
+      ${src}
       COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
       CMAKE_FLAGS
       -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_INCLUDE_FILES_FLAGS}