try_compile: Add SOURCE_FROM_{ARG,VAR}

Add ability to "feed" try_compile (and try_run) sources more directly,
either from literal content, or from a CMake variable which contains
literal content. This saves the user from needing a separate step to
write the content to a file, and allows for the sources to only exist in
the scratch directory.

2 files changed, 38 insertions, 6 deletions

diff --git a/Help/command/try_compile.rst b/Help/command/try_compile.rst
index 97ad481..ed61a2f 100644
--- a/Help/command/try_compile.rst
+++ b/Help/command/try_compile.rst
@@ -55,7 +55,10 @@ Try Compiling Source Files
 
 .. code-block:: cmake
 
-  try_compile(<resultVar> SOURCES <srcfile...>
+  try_compile(<resultVar>
+              <SOURCES <srcfile...>]             |
+               SOURCE_FROM_ARG <name> <content>] |
+               SOURCE_FROM_VAR <name> <var>]     >...
               [CMAKE_FLAGS <flags>...]
               [COMPILE_DEFINITIONS <defs>...]
               [LINK_OPTIONS <options>...]
@@ -74,10 +77,12 @@ Try building an executable or static library from one or more source files
 variable).  The success or failure of the ``try_compile``, i.e. ``TRUE`` or
 ``FALSE`` respectively, is returned in ``<resultVar>``.
 
-In this form, one or more source files must be provided.  If
-:variable:`CMAKE_TRY_COMPILE_TARGET_TYPE` is unset or is set to ``EXECUTABLE``,
-the sources must include a definition for ``main`` and CMake will create a
-``CMakeLists.txt`` file to build the source(s) as an executable.
+In this form, one or more source files must be provided. Additionally, one of
+``SOURCES`` and/or ``SOURCE_FROM_*`` must precede other keywords.
+
+If :variable:`CMAKE_TRY_COMPILE_TARGET_TYPE` is unset or is set to
+``EXECUTABLE``, the sources must include a definition for ``main`` and CMake
+will create a ``CMakeLists.txt`` file to build the source(s) as an executable.
 If :variable:`CMAKE_TRY_COMPILE_TARGET_TYPE` is set to ``STATIC_LIBRARY``,
 a static library will be built instead and no definition for ``main`` is
 required.  For an executable, the generated ``CMakeLists.txt`` file would
@@ -163,6 +168,27 @@ The options are:
 ``OUTPUT_VARIABLE <var>``
   Store the output from the build process in the given variable.
 
+``SOURCE_FROM_ARG <name> <content>``
+  .. versionadded:: 3.25
+
+  Write ``<content>`` to a file named ``<name>`` in the operation directory.
+  This can be used to bypass the need to separately write a source file when
+  the contents of the file are dynamically specified. The specified ``<name>``
+  is not allowed to contain path components.
+
+  ``SOURCE_FROM_ARG`` may be specified multiple times.
+
+``SOURCE_FROM_VAR <name> <content>``
+  .. versionadded:: 3.25
+
+  Write the contents of ``<var>`` to a file named ``<name>`` in the operation
+  directory. This is the same as ``SOURCE_FROM_ARG``, but takes the contents
+  from the specified CMake variable, rather than directly, which may be useful
+  when passing arguments through a function which wraps ``try_compile``. The
+  specified ``<name>`` is not allowed to contain path components.
+
+  ``SOURCE_FROM_VAR`` may be specified multiple times.
+
 ``<LANG>_STANDARD <std>``
   .. versionadded:: 3.8
 
diff --git a/Help/command/try_run.rst b/Help/command/try_run.rst
index 1dc2355..5498344 100644
--- a/Help/command/try_run.rst
+++ b/Help/command/try_run.rst
@@ -12,7 +12,10 @@ Try Compiling and Running Source Files
 
 .. code-block:: cmake
 
-  try_run(<runResultVar> <compileResultVar> SOURCES <srcfile...>
+  try_run(<runResultVar> <compileResultVar>
+          <SOURCES <srcfile...>]             |
+           SOURCE_FROM_ARG <name> <content>] |
+           SOURCE_FROM_VAR <name> <var>]     >...
           [CMAKE_FLAGS <flags>...]
           [COMPILE_DEFINITIONS <defs>...]
           [LINK_OPTIONS <options>...]
@@ -40,6 +43,9 @@ set to ``FAILED_TO_RUN``.  See the :command:`try_compile` command for
 documentation of options common to both commands, and for information on how
 the test project is constructed to build the source file.
 
+One or more source files must be provided. Additionally, one of ``SOURCES``
+and/or ``SOURCE_FROM_*`` must precede other keywords.
+
 This command also supports an alternate signature
 which was present in older versions of CMake: