CheckIncludeFiles: Honor CMAKE_REQUIRED_LIBRARIES

Other check modules honor this variable, so include file checks should
too.  Add policy `CMP0075` to enable the behavior in a compatible way.

This change was originally made by commit v3.11.0-rc1~108^2
(CheckIncludeFiles: Honor CMAKE_REQUIRED_LIBRARIES, 2017-12-24) but it
was reverted by commit v3.11.1~9^2 (Revert "CheckIncludeFiles: Honor
CMAKE_REQUIRED_LIBRARIES", 2018-04-04) because the behavior change could
affect checks in existing projects in an incompatible way.

Fixes: #9514

1 files changed, 124 insertions, 0 deletions

diff --git a/Tests/RunCMake/CheckModules/CMP0075.cmake b/Tests/RunCMake/CheckModules/CMP0075.cmake
new file mode 100644
index 0000000..4a3b720
--- /dev/null
+++ b/Tests/RunCMake/CheckModules/CMP0075.cmake
@@ -0,0 +1,124 @@
+enable_language(C)
+enable_language(CXX)
+include(CheckIncludeFile)
+include(CheckIncludeFileCXX)
+include(CheckIncludeFiles)
+
+set(CMAKE_REQUIRED_LIBRARIES does_not_exist)
+
+#============================================================================
+
+check_include_file("stddef.h" HAVE_STDDEF_H_1)
+if(NOT HAVE_STDDEF_H_1)
+  message(SEND_ERROR "HAVE_STDDEF_H_1 failed but should have passed.")
+endif()
+if(NOT _CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDDEF_H_1 did not warn but should have")
+endif()
+check_include_file("stddef.h" HAVE_STDDEF_H_2) # second does not warn
+if(NOT HAVE_STDDEF_H_2)
+  message(SEND_ERROR "HAVE_STDDEF_H_2 failed but should have passed.")
+endif()
+unset(_CIF_CMP0075_WARNED)
+
+#----------------------------------------------------------------------------
+
+check_include_file_cxx("stddef.h" HAVE_STDDEF_H_CXX_1)
+if(NOT HAVE_STDDEF_H_CXX_1)
+  message(SEND_ERROR "HAVE_STDDEF_H_CXX_1 failed but should have passed.")
+endif()
+if(NOT _CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDDEF_H_CXX_1 did not warn but should have")
+endif()
+check_include_file_cxx("stddef.h" HAVE_STDDEF_H_CXX_2) # second does not warn
+if(NOT HAVE_STDDEF_H_CXX_2)
+  message(SEND_ERROR "HAVE_STDDEF_H_CXX_2 failed but should have passed.")
+endif()
+unset(_CIF_CMP0075_WARNED)
+
+#----------------------------------------------------------------------------
+
+check_include_files("stddef.h;stdlib.h" HAVE_STDLIB_H_1)
+if(NOT HAVE_STDLIB_H_1)
+  message(SEND_ERROR "HAVE_STDLIB_H_1 failed but should have passed.")
+endif()
+if(NOT _CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDLIB_H_1 did not warn but should have")
+endif()
+check_include_files("stddef.h;stdlib.h" HAVE_STDLIB_H_2) # second does not warn
+if(NOT HAVE_STDLIB_H_2)
+  message(SEND_ERROR "HAVE_STDLIB_H_2 failed but should have passed.")
+endif()
+unset(_CIF_CMP0075_WARNED)
+
+#============================================================================
+cmake_policy(SET CMP0075 OLD)
+# These should not warn.
+# These should pass the checks due to ignoring 'does_not_exist'.
+
+check_include_file("stddef.h" HAVE_STDDEF_H_3)
+if(NOT HAVE_STDDEF_H_3)
+  message(SEND_ERROR "HAVE_STDDEF_H_3 failed but should have passed.")
+endif()
+if(_CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDDEF_H_3 warned but should not have")
+endif()
+unset(_CIF_CMP0075_WARNED)
+
+#----------------------------------------------------------------------------
+
+check_include_file_cxx("stddef.h" HAVE_STDDEF_H_CXX_3)
+if(NOT HAVE_STDDEF_H_CXX_3)
+  message(SEND_ERROR "HAVE_STDDEF_H_CXX_3 failed but should have passed.")
+endif()
+if(_CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDDEF_H_CXX_3 warned but should not have")
+endif()
+unset(_CIF_CMP0075_WARNED)
+
+#----------------------------------------------------------------------------
+
+check_include_files("stddef.h;stdlib.h" HAVE_STDLIB_H_3)
+if(NOT HAVE_STDLIB_H_3)
+  message(SEND_ERROR "HAVE_STDLIB_H_3 failed but should have passed.")
+endif()
+if(_CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDLIB_H_3 warned but should not have")
+endif()
+unset(_CIF_CMP0075_WARNED)
+
+#============================================================================
+cmake_policy(SET CMP0075 NEW)
+# These should not warn.
+# These should fail the checks due to requiring 'does_not_exist'.
+
+check_include_file("stddef.h" HAVE_STDDEF_H_4)
+if(HAVE_STDDEF_H_4)
+  message(SEND_ERROR "HAVE_STDDEF_H_4 passed but should have failed.")
+endif()
+if(_CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDDEF_H_4 warned but should not have")
+endif()
+unset(_CIF_CMP0075_WARNED)
+
+#----------------------------------------------------------------------------
+
+check_include_file_cxx("stddef.h" HAVE_STDDEF_H_CXX_4)
+if(HAVE_STDDEF_H_CXX_4)
+  message(SEND_ERROR "HAVE_STDDEF_H_CXX_4 passed but should have failed.")
+endif()
+if(_CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDDEF_H_CXX_4 warned but should not have")
+endif()
+unset(_CIF_CMP0075_WARNED)
+
+#----------------------------------------------------------------------------
+
+check_include_files("stddef.h;stdlib.h" HAVE_STDLIB_H_4)
+if(HAVE_STDLIB_H_4)
+  message(SEND_ERROR "HAVE_STDLIB_H_4 passed but should have failed.")
+endif()
+if(_CIF_CMP0075_WARNED)
+  message(SEND_ERROR "HAVE_STDLIB_H_4 warned but should not have")
+endif()
+unset(_CIF_CMP0075_WARNED)