CMakeDependentOption: Introduce policy CMP0127 for full Condition Syntax

Fixes: #22303

1 files changed, 32 insertions, 0 deletions

diff --git a/Help/policy/CMP0127.rst b/Help/policy/CMP0127.rst
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+++ b/Help/policy/CMP0127.rst
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+CMP0127
+-------
+
+:command:`cmake_dependent_option` supports full :ref:`Condition Syntax`.
+
+The ``<depends>`` parameter accepts a :ref:`semicolon-separated list <CMake
+Language Lists>` of conditions.  CMake 3.21 and lower evaluates each
+``condition`` as ``if(${condition})``, which does not properly handle
+conditions with nested paren groups.  CMake 3.22 and above instead prefer
+to evaluate each ``condition`` as ``if(<condition>)``, where ``<condition>``
+is re-parsed as if literally written in a call to :command:`if`.  This
+allows expressions like::
+
+  "A AND (B OR C)"
+
+but requires expressions like::
+
+  "FOO MATCHES (UPPER|lower)"
+
+to be re-written as::
+
+  "FOO MATCHES \"(UPPER|lower)\""
+
+Policy ``CMP0127`` provides compatibility for projects that have not
+been updated to expect the new behavior.
+
+This policy was introduced in CMake version 3.22.  CMake version
+|release| warns when the policy is not set and uses ``OLD`` behavior.
+Use the :command:`cmake_policy` command to set it to ``OLD`` or ``NEW``
+explicitly.
+
+.. include:: DEPRECATED.txt