add_test: Honor CROSSCOMPILING_EMULATOR only when cross-compiling

Add policy CMP0158 to provide compatibility for existing projects.

Fixes: #23672

1 files changed, 27 insertions, 0 deletions

diff --git a/Help/policy/CMP0158.rst b/Help/policy/CMP0158.rst
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+++ b/Help/policy/CMP0158.rst
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+CMP0158
+-------
+
+.. versionadded:: 3.29
+
+:command:`add_test` honors :variable:`CMAKE_CROSSCOMPILING_EMULATOR` only
+when :variable:`cross-compiling <CMAKE_CROSSCOMPILING>`.
+
+In CMake 3.28 and below, :command:`add_test` unconditionally used the
+:prop_tgt:`CROSSCOMPILING_EMULATOR` target property (initialized by the
+:variable:`CMAKE_CROSSCOMPILING_EMULATOR` variable) to run test commands
+naming executable targets.  CMake 3.29 and above prefer to use the emulator
+only when the :variable:`CMAKE_CROSSCOMPILING` variable is enabled.  The
+:variable:`CMAKE_TEST_LAUNCHER` variable may be used instead when not
+cross-compiling.  This policy provides compatibility for projects that
+have not been updated.
+
+The ``OLD`` behavior for this policy is for :command:`add_test` to use
+the :prop_tgt:`CROSSCOMPILING_EMULATOR` target property unconditionally.
+The ``NEW`` behavior for this policy is for :command:`add_test` to use
+the :prop_tgt:`CROSSCOMPILING_EMULATOR` target property only when
+:variable:`cross-compiling <CMAKE_CROSSCOMPILING>`.
+
+This policy was introduced in CMake version 3.29. Use the
+:command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly.
+Unlike many policies, CMake version |release| does *not* warn
+when this policy is not set and simply uses ``OLD`` behavior.