Merge topic 'ExternalProject-no-extract-timestamp'

a283e58b51 ExternalProject: Add DOWNLOAD_EXTRACT_TIMESTAMP option and policy

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !7137

3 files changed, 38 insertions, 0 deletions

diff --git a/Help/manual/cmake-policies.7.rst b/Help/manual/cmake-policies.7.rst
index d1fafb5..b3091fa 100644
--- a/Help/manual/cmake-policies.7.rst
+++ b/Help/manual/cmake-policies.7.rst
@@ -58,6 +58,7 @@ Policies Introduced by CMake 3.24
 .. toctree::
    :maxdepth: 1
 
+   CMP0135: ExternalProject ignores timestamps in archives by default for the URL download method. </policy/CMP0135>
    CMP0134: Fallback to \"HOST\" Windows registry view when \"TARGET\" view is not usable. </policy/CMP0134>
    CMP0133: The CPack module disables SLA by default in the CPack DragNDrop Generator. </policy/CMP0133>
    CMP0132: Do not set compiler environment variables on first run. </policy/CMP0132>
diff --git a/Help/policy/CMP0135.rst b/Help/policy/CMP0135.rst
new file mode 100644
index 0000000..1c0c134
--- /dev/null
+++ b/Help/policy/CMP0135.rst
@@ -0,0 +1,29 @@
+CMP0135
+-------
+
+.. versionadded:: 3.24
+
+When using the ``URL`` download method with the :command:`ExternalProject_Add`
+command, CMake 3.23 and below sets the timestamps of the extracted contents
+to the same as the timestamps in the archive. When the ``URL`` changes, the
+new archive is downloaded and extracted, but the timestamps of the extracted
+contents might not be newer than the previous contents. Anything that depends
+on the extracted contents might not be rebuilt, even though the contents may
+change.
+
+CMake 3.24 and above prefers to set the timestamps of all extracted contents
+to the time of the extraction. This ensures that anything that depends on the
+extracted contents will be rebuilt whenever the ``URL`` changes.
+
+The ``DOWNLOAD_EXTRACT_TIMESTAMP`` option to the
+:command:`ExternalProject_Add` command can be used to explicitly specify how
+timestamps should be handled. When ``DOWNLOAD_EXTRACT_TIMESTAMP`` is not
+given, this policy controls the default behavior. The ``OLD`` behavior for
+this policy is to restore the timestamps from the archive. The ``NEW``
+behavior sets the timestamps of extracted contents to the time of extraction.
+
+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
diff --git a/Help/release/dev/ExternalProject-no-extract-timestamp.rst b/Help/release/dev/ExternalProject-no-extract-timestamp.rst
new file mode 100644
index 0000000..0e8c01e
--- /dev/null
+++ b/Help/release/dev/ExternalProject-no-extract-timestamp.rst
@@ -0,0 +1,8 @@
+ExternalProject-no-extract-timestamp
+------------------------------------
+
+* The :command:`ExternalProject_Add` command gained a new
+  ``DOWNLOAD_EXTRACT_TIMESTAMP`` option for controlling whether the timestamps
+  of extracted contents are set to match those in the archive when the ``URL``
+  download method is used. A new policy :policy:`CMP0135` was added to control
+  the default behavior when the new option is not used.