while: diagnose errors during condition evaluation

Add a policy to diagnose condition errors in a compatible way.

Fixes: #23296

1 files changed, 32 insertions, 0 deletions

diff --git a/Help/policy/CMP0130.rst b/Help/policy/CMP0130.rst
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+CMP0130
+-------
+
+.. versionadded:: 3.24
+
+:command:`while` diagnoses condition evaluation errors.
+
+CMake 3.23 and below accidentally tolerated errors encountered while
+evaluating the condition passed to the :command:`while` command
+(but not the :command:`if` command).  For example, the code
+
+.. code-block:: cmake
+
+  set(paren "(")
+  while(${paren})
+  endwhile()
+
+creates an unbalanced parenthesis during condition evaluation.
+
+CMake 3.24 and above prefer to diagnose such errors.  This policy
+provides compatibility for projects that have not been updated to
+fix their condition errors.
+
+The ``OLD`` behavior for this policy is to ignore errors in
+:command:`while` conditions.  The ``NEW`` behavior for this
+policy is to diagnose errors in :command:`while` conditions.
+
+This policy was introduced in CMake version 3.24.  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