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-rw-r--r--Modules/CheckFunctionExists.cmake30
1 files changed, 21 insertions, 9 deletions
diff --git a/Modules/CheckFunctionExists.cmake b/Modules/CheckFunctionExists.cmake
index 5f049e7..ef08062 100644
--- a/Modules/CheckFunctionExists.cmake
+++ b/Modules/CheckFunctionExists.cmake
@@ -5,18 +5,16 @@
# CheckFunctionExists
# -------------------
#
-# Check if a C function can be linked
+# Check if a C function can be linked::
#
-# CHECK_FUNCTION_EXISTS(<function> <variable>)
+# check_function_exists(<function> <variable>)
#
-# Check that the <function> is provided by libraries on the system and
-# store the result in a <variable>. This does not verify that any
-# system header file declares the function, only that it can be found at
-# link time (consider using CheckSymbolExists).
-# <variable> will be created as an internal cache variable.
+# Check that the ``<function>`` is provided by libraries on the system and store
+# the result in a ``<variable>``. ``<variable>`` will be created as an internal
+# cache variable.
#
-# The following variables may be set before calling this macro to modify
-# the way the check is run:
+# The following variables may be set before calling this macro to modify the
+# way the check is run:
#
# ::
#
@@ -25,6 +23,20 @@
# CMAKE_REQUIRED_INCLUDES = list of include directories
# CMAKE_REQUIRED_LIBRARIES = list of libraries to link
# CMAKE_REQUIRED_QUIET = execute quietly without messages
+#
+# .. note::
+#
+# Prefer using :Module:`CheckSymbolExists` instead of this module,
+# for the following reasons:
+#
+# * ``check_function_exists()`` can't detect functions that are inlined
+# in headers or specified as a macro.
+#
+# * ``check_function_exists()`` can't detect anything in the 32-bit
+# versions of the Win32 API, because of a mismatch in calling conventions.
+#
+# * ``check_function_exists()`` only verifies linking, it does not verify
+# that the function is declared in system headers.
macro(CHECK_FUNCTION_EXISTS FUNCTION VARIABLE)
if(NOT DEFINED "${VARIABLE}" OR "x${${VARIABLE}}" STREQUAL "x${VARIABLE}")