Check*Source{Compiles,Runs}: Rewrite docs for these modules

1 files changed, 58 insertions, 25 deletions

diff --git a/Modules/CheckCSourceRuns.cmake b/Modules/CheckCSourceRuns.cmake
index 70aa9fd2d0..8da9f1ea9b 100644
--- a/Modules/CheckCSourceRuns.cmake
+++ b/Modules/CheckCSourceRuns.cmake
@@ -1,31 +1,64 @@
 # Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
 # file Copyright.txt or https://cmake.org/licensing for details.
 
-#.rst:
-# CheckCSourceRuns
-# ----------------
-#
-# Check if the given C source code compiles and runs.
-#
-# CHECK_C_SOURCE_RUNS(<code> <var>)
-#
-# ::
-#
-#   <code>   - source code to try to compile
-#   <var>    - variable to store the result
-#              (1 for success, empty for failure)
-#              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:
-#
-# ::
-#
-#   CMAKE_REQUIRED_FLAGS = string of compile command line flags
-#   CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar)
-#   CMAKE_REQUIRED_INCLUDES = list of include directories
-#   CMAKE_REQUIRED_LIBRARIES = list of libraries to link
-#   CMAKE_REQUIRED_QUIET = execute quietly without messages
+#[=======================================================================[.rst:
+CheckCSourceRuns
+----------------
+
+Check if given C source compiles and links into an executable and can
+subsequently be run.
+
+.. command:: check_c_source_runs
+
+  ::
+
+    check_c_source_runs(code resultVar)
+
+  Check that the source supplied in ``code`` can be compiled as a C source
+  file, linked as an executable and then run. The ``code`` must contain at
+  least a ``main()`` function. If the code could be built and run successfully,
+  the internal cache variable specified by ``resultVar`` will be set to 1,
+  otherwise it will be set to an value that evaluates to boolean false (e.g.
+  an empty string or an error message).
+
+  The underlying check is performed by the :command:`try_run` command. The
+  compile and link commands can be influenced by setting any of the following
+  variables prior to calling ``check_c_source_runs()``:
+
+  ``CMAKE_REQUIRED_FLAGS``
+    Additional flags to pass to the compiler. Note that the contents of
+    :variable:`CMAKE_C_FLAGS <CMAKE_<LANG>_FLAGS>` and its associated
+    configuration-specific variable are automatically added to the compiler
+    command before the contents of ``CMAKE_REQUIRED_FLAGS``.
+
+  ``CMAKE_REQUIRED_DEFINITIONS``
+    A :ref:`;-list <CMake Language Lists>` of compiler definitions of the form
+    ``-DFOO`` or ``-DFOO=bar``. A definition for the name specified by
+    ``resultVar`` will also be added automatically.
+
+  ``CMAKE_REQUIRED_INCLUDES``
+    A :ref:`;-list <CMake Language Lists>` of header search paths to pass to
+    the compiler. These will be the only header search paths used by
+    ``try_run()``, i.e. the contents of the :prop_dir:`INCLUDE_DIRECTORIES`
+    directory property will be ignored.
+
+  ``CMAKE_REQUIRED_LIBRARIES``
+    A :ref:`;-list <CMake Language Lists>` of libraries to add to the link
+    command. These can be the name of system libraries or they can be
+    :ref:`Imported Targets <Imported Targets>` (see :command:`try_run` for
+    further details).
+
+  ``CMAKE_REQUIRED_QUIET``
+    If this variable evaluates to a boolean true value, all status messages
+    associated with the check will be suppressed.
+
+  The check is only performed once, with the result cached in the variable
+  named by ``resultVar``. Every subsequent CMake run will re-use this cached
+  value rather than performing the check again, even if the ``code`` changes.
+  In order to force the check to be re-evaluated, the variable named by
+  ``resultVar`` must be manually removed from the cache.
+
+#]=======================================================================]
 
 macro(CHECK_C_SOURCE_RUNS SOURCE VAR)
   if(NOT DEFINED "${VAR}")