Add genex support to TEST_LAUNCHER and CROSSCOMPILING_EMULATOR

Evaluate generator expressions in these properties, as they apply to
`add_test`, `add_custom_command`, and `add_custom_target`.

The `CMAKE_CROSSCOMPILING_EMULATOR` variable's `try_run` behavior occurs
at configure time and so cannot support generator expressions.

5 files changed, 20 insertions, 7 deletions

diff --git a/Help/prop_tgt/CROSSCOMPILING_EMULATOR.rst b/Help/prop_tgt/CROSSCOMPILING_EMULATOR.rst
index 8b777e4..d09ff19 100644
--- a/Help/prop_tgt/CROSSCOMPILING_EMULATOR.rst
+++ b/Help/prop_tgt/CROSSCOMPILING_EMULATOR.rst
@@ -13,6 +13,10 @@ for built target system executables.
   Lists>`, then the first value is the command and remaining values are its
   arguments.
 
+.. versionadded:: 3.29
+  Contents of ``CROSSCOMPILING_EMULATOR`` may use
+  :manual:`generator expressions <cmake-generator-expressions(7)>`.
+
 This property is initialized by the value of the
 :variable:`CMAKE_CROSSCOMPILING_EMULATOR` variable if it is set when a target
 is created.
diff --git a/Help/prop_tgt/TEST_LAUNCHER.rst b/Help/prop_tgt/TEST_LAUNCHER.rst
index 2e44492..7eec319 100644
--- a/Help/prop_tgt/TEST_LAUNCHER.rst
+++ b/Help/prop_tgt/TEST_LAUNCHER.rst
@@ -15,6 +15,9 @@ If this property contains a :ref:`semicolon-separated list <CMake Language
 Lists>`, then the first value is the command and remaining values are its
 arguments.
 
+Contents of ``TEST_LAUNCHER`` may use
+:manual:`generator expressions <cmake-generator-expressions(7)>`.
+
 This property is initialized by the value of the
 :variable:`CMAKE_TEST_LAUNCHER` variable if it is set when a target
 is created.
diff --git a/Help/release/dev/cmake-test-launcher.rst b/Help/release/dev/cmake-test-launcher.rst
index a82a8ad..0a5db77 100644
--- a/Help/release/dev/cmake-test-launcher.rst
+++ b/Help/release/dev/cmake-test-launcher.rst
@@ -9,3 +9,6 @@ cmake-test-launcher
 * The :command:`add_test` command now honors
   :variable:`CMAKE_CROSSCOMPILING_EMULATOR` only when cross-compiling.
   See policy :policy:`CMP0158`.
+
+* The :prop_tgt:`CROSSCOMPILING_EMULATOR` target property now
+  supports :manual:`generator expressions <cmake-generator-expressions(7)>`.
diff --git a/Help/variable/CMAKE_CROSSCOMPILING_EMULATOR.rst b/Help/variable/CMAKE_CROSSCOMPILING_EMULATOR.rst
index 1c3a26c..2640389 100644
--- a/Help/variable/CMAKE_CROSSCOMPILING_EMULATOR.rst
+++ b/Help/variable/CMAKE_CROSSCOMPILING_EMULATOR.rst
@@ -19,5 +19,8 @@ for the target system.
 The command will be used to run :command:`try_run` generated executables,
 which avoids manual population of the ``TryRunResults.cmake`` file.
 
-It is also used as the default value for the
-:prop_tgt:`CROSSCOMPILING_EMULATOR` target property of executables.
+This variable is also used as the default value for the
+:prop_tgt:`CROSSCOMPILING_EMULATOR` target property of executables.  However,
+while :manual:`generator expressions <cmake-generator-expressions(7)>` are
+supported by the target property (since CMake 3.29), they are *not* supported
+by this variable's :command:`try_run` functionality.
diff --git a/Help/variable/CMAKE_TEST_LAUNCHER.rst b/Help/variable/CMAKE_TEST_LAUNCHER.rst
index c527188..2a5fe4c 100644
--- a/Help/variable/CMAKE_TEST_LAUNCHER.rst
+++ b/Help/variable/CMAKE_TEST_LAUNCHER.rst
@@ -3,14 +3,14 @@ CMAKE_TEST_LAUNCHER
 
 .. versionadded:: 3.29
 
-This variable is used to specify a launcher for running tests, added
-by the :command:`add_test` command, that run an executable target.
+This variable is used to initialize the :prop_tgt:`TEST_LAUNCHER` target
+property of executable targets as they are created.  It is used to specify
+a launcher for running tests, added by the :command:`add_test` command,
+that run an executable target.
+
 If this variable contains a :ref:`semicolon-separated list <CMake Language
 Lists>`, then the first value is the command and remaining values are its
 arguments.
 
 This variable can be initialized via an
 :envvar:`CMAKE_TEST_LAUNCHER` environment variable.
-
-It is also used as the default value for the
-:prop_tgt:`TEST_LAUNCHER` target property of executables.