FetchContent: Deprecate FetchContent_Populate(depName)

Projects should use FetchContent_MakeAvailable(depName)
instead. Policy CMP0169 provides backward compatibility.

Help/manual/cmake-policies.7.rst

@@ -57,6 +57,7 @@ Policies Introduced by CMake 3.30
 .. toctree::
    :maxdepth: 1
 
+   CMP0169: FetchContent_Populate(depName) single-argument signature is deprecated. </policy/CMP0169>
    CMP0168: FetchContent implements steps directly instead of through a sub-build. </policy/CMP0168>
    CMP0167: The FindBoost module is removed. </policy/CMP0167>
    CMP0166: TARGET_PROPERTY evaluates link properties transitively over private dependencies of static libraries. </policy/CMP0166>

Help/policy/CMP0169.rst

@@ -0,0 +1,49 @@
+CMP0169
+-------
+
+.. versionadded:: 3.30
+
+Calling :command:`FetchContent_Populate` with a single argument (the name of
+a declared dependency) is deprecated.
+
+Prior to the introduction of :command:`FetchContent_MakeAvailable`, projects
+populated previously declared content (with :command:`FetchContent_Declare`)
+using the following pattern:
+
+.. code-block:: cmake
+
+  FetchContent_GetProperties(depname)
+  if(NOT depname_POPULATED)
+    FetchContent_Populate(depname)
+    add_subdirectory(${depname_SOURCE_DIR} ${depname_BINARY_DIR})
+  endif()
+
+The above pattern does not support a number of features that have been added
+to :module:`FetchContent` over time. It ignores options like ``SYSTEM`` and
+``EXCLUDE_FROM_ALL`` which may be given to :command:`FetchContent_Declare`,
+but can't be made known to the above project code. It also does not support
+:ref:`dependency providers <dependency_providers_overview>`.
+Projects should call :command:`FetchContent_MakeAvailable` instead of using
+the above pattern.
+
+CMake 3.30 and above prefers to reject calls to
+:command:`FetchContent_Populate` with the name of a declared dependency.
+This policy provides compatibility for projects that have not been updated
+to call :command:`FetchContent_MakeAvailable` instead.
+
+The ``OLD`` behavior of this policy allows :command:`FetchContent_Populate`
+to be called with the name of a declared dependency.
+The ``NEW`` behavior halts with a fatal error in such cases.
+
+.. note::
+  Calling :command:`FetchContent_Populate` with the full population details
+  as command arguments rather than just a dependency name remains fully
+  supported. Only the form calling :command:`FetchContent_Populate` with a
+  single argument (the name of a previously declared dependency) is deprecated
+  with this policy.
+
+.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 3.30
+.. |WARNS_OR_DOES_NOT_WARN| replace:: warns
+.. include:: STANDARD_ADVICE.txt
+
+.. include:: DEPRECATED.txt

Help/release/dev/deprecate-fetchcontent_populate.rst

@@ -0,0 +1,8 @@
+deprecate-fetchcontent_populate
+-------------------------------
+
+* Calling :command:`FetchContent_Populate` with just the name of a
+  dependency is now deprecated. Projects should call
+  :command:`FetchContent_MakeAvailable` instead. See policy :policy:`CMP0169`.
+  Calling :command:`FetchContent_Populate` with full population details
+  rather than just a dependency name remains fully supported.

Modules/FetchContent.cmake

@@ -68,33 +68,6 @@ first instead of repeating the population again.
 See the :ref:`Examples <fetch-content-examples>` which demonstrate
 this scenario.
 
-In some cases, the main project may need to have more precise control over
-the population, or it may be required to explicitly define the population
-steps in a way that cannot be captured by the declared details alone.
-For such situations, the lower level :command:`FetchContent_GetProperties` and
-:command:`FetchContent_Populate` commands can be used.  These lack the richer
-features provided by :command:`FetchContent_MakeAvailable` though, so their
-direct use should be considered a last resort.  The typical pattern of such
-custom steps looks like this:
-
-.. code-block:: cmake
-
-  # NOTE: Where possible, prefer to use FetchContent_MakeAvailable()
-  #       instead of custom logic like this
-
-  # Check if population has already been performed
-  FetchContent_GetProperties(depname)
-  if(NOT depname_POPULATED)
-    # Fetch the content using previously declared details
-    FetchContent_Populate(depname)
-
-    # Set custom variables, policies, etc.
-    # ...
-
-    # Bring the populated content into the build
-    add_subdirectory(${depname_SOURCE_DIR} ${depname_BINARY_DIR})
-  endif()
-
 The ``FetchContent`` module also supports defining and populating
 content in a single call, with no check for whether the content has been
 populated elsewhere already.  This should not be done in projects, but may
@@ -316,8 +289,8 @@ Commands
     :command:`FetchContent_GetProperties`, then skip the remaining steps
     below and move on to the next dependency in the list.
 
-  * Call :command:`FetchContent_Populate` to populate the dependency using
-    the details recorded by an earlier call to :command:`FetchContent_Declare`.
+  * Populate the dependency using the details recorded by an earlier call
+    to :command:`FetchContent_Declare`.
     Halt with a fatal error if no such details have been recorded.
     :variable:`FETCHCONTENT_SOURCE_DIR_<uppercaseName>` can be used to override
     the declared details and use content provided at the specified location
@@ -331,10 +304,10 @@ Commands
       ``<name>Config.cmake`` and ``<name>ConfigVersion.cmake``).
       The directory that the :variable:`CMAKE_FIND_PACKAGE_REDIRECTS_DIR`
       variable points to is cleared at the start of every CMake run.
-      If no config file exists when :command:`FetchContent_Populate` returns,
-      a minimal one will be written which :command:`includes <include>` any
-      ``<lowercaseName>-extra.cmake`` or ``<name>Extra.cmake`` file with the
-      ``OPTIONAL`` flag (so the files can be missing and won't generate a
+      If no config file exists after populating the dependency in the previous
+      step, a minimal one will be written which :command:`includes <include>`
+      any ``<lowercaseName>-extra.cmake`` or ``<name>Extra.cmake`` file with
+      the ``OPTIONAL`` flag (so the files can be missing and won't generate a
       warning).  Similarly, if no config version file exists, a very simple
       one will be written which sets ``PACKAGE_VERSION_COMPATIBLE`` and
       ``PACKAGE_VERSION_EXACT`` to true.  This ensures all future calls to
@@ -428,68 +401,13 @@ Commands
 
 .. command:: FetchContent_Populate
 
-  .. note::
-    Where possible, prefer to use :command:`FetchContent_MakeAvailable`
-    instead of implementing population manually with this command.
-
-  .. code-block:: cmake
-
-    FetchContent_Populate(<name>)
-
-  In most cases, the only argument given to ``FetchContent_Populate()`` is the
-  ``<name>``.  When used this way, the command assumes the content details have
-  been recorded by an earlier call to :command:`FetchContent_Declare`.  The
-  details are stored in a global property, so they are unaffected by things
-  like variable or directory scope.  Therefore, it doesn't matter where in the
-  project the details were previously declared, as long as they have been
-  declared before the call to ``FetchContent_Populate()``.  Those saved details
-  are then used to populate the content using a method based on
-  :command:`ExternalProject_Add` (see policy :policy:`CMP0168` for important
-  behavioral aspects of how that is done).  The implementation ensures that if
-  the content has already been populated in a previous CMake run, that content
-  will be reused rather than repopulating them again.  For the common case
-  where population involves downloading content, the cost of the download is
-  only paid once.
-
-  An internal global property records when a particular content population
-  request has been processed.  If ``FetchContent_Populate()`` is called more
-  than once for the same content name within a configure run, the second call
-  will halt with an error.  Projects can and should check whether content
-  population has already been processed with the
-  :command:`FetchContent_GetProperties` command before calling
-  ``FetchContent_Populate()``.
-
-  ``FetchContent_Populate()`` will set three variables in the scope of the
-  caller:
-
-  ``<lowercaseName>_POPULATED``
-    This will always be set to ``TRUE`` by the call.
-
-  ``<lowercaseName>_SOURCE_DIR``
-    The location where the populated content can be found upon return.
-
-  ``<lowercaseName>_BINARY_DIR``
-    A directory intended for use as a corresponding build directory.
-
-  The main use case for the ``<lowercaseName>_SOURCE_DIR`` and
-  ``<lowercaseName>_BINARY_DIR`` variables is to call
-  :command:`add_subdirectory` immediately after population:
-
-  .. code-block:: cmake
-
-    FetchContent_Populate(FooBar)
-    add_subdirectory(${foobar_SOURCE_DIR} ${foobar_BINARY_DIR})
-
-  The values of the three variables can also be retrieved from anywhere in the
-  project hierarchy using the :command:`FetchContent_GetProperties` command.
-
-  The ``FetchContent_Populate()`` command also supports a syntax allowing the
-  content details to be specified directly rather than using any saved
-  details.  This is more low-level and use of this form is generally to be
-  avoided in favor of using saved content details as outlined above.
-  Nevertheless, in certain situations it can be useful to invoke the content
-  population as an isolated operation (typically as part of implementing some
-  other higher level feature or when using CMake in script mode):
+  The ``FetchContent_Populate()`` command is a self-contained call which can
+  be used to perform content population as an isolated operation.
+  It is rarely the right command to use, projects should almost always use
+  :command:`FetchContent_Declare` and :command:`FetchContent_MakeAvailable`
+  instead. The main use case for ``FetchContent_Populate()`` is in
+  :ref:`CMake script mode <Script Processing Mode>` as part of implementing
+  some other higher level custom feature.
 
   .. code-block:: cmake
 
@@ -502,39 +420,29 @@ Commands
       ...
     )
 
-  This form has a number of key differences to that where only ``<name>`` is
-  provided:
-
-  - All required population details are assumed to have been provided directly
-    in the call to ``FetchContent_Populate()``. Any saved details for
-    ``<name>`` are ignored.
-  - No check is made for whether content for ``<name>`` has already been
-    populated.
-  - No global property is set to record that the population has occurred.
-  - No global properties record the source or binary directories used for the
-    populated content.
-  - The ``FETCHCONTENT_FULLY_DISCONNECTED`` and
-    ``FETCHCONTENT_UPDATES_DISCONNECTED`` cache variables are ignored.
-
-  The ``<lowercaseName>_SOURCE_DIR`` and ``<lowercaseName>_BINARY_DIR``
-  variables are still returned to the caller, but since these locations are
-  not stored as global properties when this form is used, they are only
-  available to the calling scope and below rather than the entire project
-  hierarchy.  No ``<lowercaseName>_POPULATED`` variable is set in the caller's
-  scope with this form.
-
+  At least one option must be specified after `<name>`, otherwise the call
+  is interpreted differently (see :ref:`below <FetchContent_Populate-depName>`).
   The supported options for ``FetchContent_Populate()`` are the same as those
-  for :command:`FetchContent_Declare()`.  Those few options shown just
-  above are either specific to ``FetchContent_Populate()`` or their behavior is
-  slightly modified from how :command:`ExternalProject_Add` treats them:
+  for :command:`FetchContent_Declare()`, with a few exceptions. The following
+  do not relate to populating content with ``FetchContent_Populate()`` and
+  therefore are not supported:
+
+  * ``EXCLUDE_FROM_ALL``
+  * ``SYSTEM``
+  * ``OVERRIDE_FIND_PACKAGE``
+  * ``FIND_PACKAGE_ARGS``
+
+  The few options shown in the signature above are either specific to
+  ``FetchContent_Populate()``, or their behavior is slightly modified from how
+  :command:`ExternalProject_Add` treats them:
 
   ``QUIET``
     The ``QUIET`` option can be given to hide the output associated with
     populating the specified content.  If the population fails, the output will
     be shown regardless of whether this option was given or not so that the
     cause of the failure can be diagnosed.  The :variable:`FETCHCONTENT_QUIET`
-    cache variable has no effect on ``FetchContent_Populate()`` calls where the
-    content details are provided directly.
+    variable has no effect on ``FetchContent_Populate()`` calls of this form
+    where the content details are provided directly.
 
     .. versionchanged:: 3.30
       The ``QUIET`` option and :variable:`FETCHCONTENT_QUIET` variable have no
@@ -575,6 +483,19 @@ Commands
   - ``INSTALL_COMMAND``
   - ``TEST_COMMAND``
 
+  With this form, the :variable:`FETCHCONTENT_FULLY_DISCONNECTED` and
+  :variable:`FETCHCONTENT_UPDATES_DISCONNECTED` variables are ignored.
+
+  When this form of ``FetchContent_Populate()`` returns, the following
+  variables will be set in the scope of the caller:
+
+  ``<lowercaseName>_SOURCE_DIR``
+    The location where the populated content can be found upon return.
+
+  ``<lowercaseName>_BINARY_DIR``
+    A directory originally intended for use as a corresponding build directory,
+    but is unlikely to be relevant when using this form of the command.
+
   If using ``FetchContent_Populate()`` within
   :ref:`CMake script mode <Script Processing Mode>`, be aware that the
   implementation sets up a sub-build which therefore requires a CMake
@@ -592,6 +513,54 @@ Commands
   .. versionadded:: 3.18
     Added support for the ``DOWNLOAD_NO_EXTRACT`` option.
 
+.. _`FetchContent_Populate-depName`:
+
+  The command supports another form, although it should no longer be used:
+
+  .. code-block:: cmake
+
+    FetchContent_Populate(<name>)
+
+  .. versionchanged:: 3.30
+    This form is deprecated. Policy :policy:`CMP0169` provides backward
+    compatibility for projects that still need to use this form, but projects
+    should be updated to use :command:`FetchContent_MakeAvailable` instead.
+
+  In this form, the only argument given to ``FetchContent_Populate()`` is the
+  ``<name>``.  When used this way, the command assumes the content details have
+  been recorded by an earlier call to :command:`FetchContent_Declare`.  The
+  details are stored in a global property, so they are unaffected by things
+  like variable or directory scope.  Therefore, it doesn't matter where in the
+  project the details were previously declared, as long as they have been
+  declared before the call to ``FetchContent_Populate()``.  Those saved details
+  are then used to populate the content using a method based on
+  :command:`ExternalProject_Add` (see policy :policy:`CMP0168` for important
+  behavioral aspects of how that is done).
+
+  When this form of ``FetchContent_Populate()`` returns, the following
+  variables will be set in the scope of the caller:
+
+  ``<lowercaseName>_POPULATED``
+    This will always be set to ``TRUE`` by the call.
+
+  ``<lowercaseName>_SOURCE_DIR``
+    The location where the populated content can be found upon return.
+
+  ``<lowercaseName>_BINARY_DIR``
+    A directory intended for use as a corresponding build directory.
+
+  The values of the three variables can also be retrieved from anywhere in the
+  project hierarchy using the :command:`FetchContent_GetProperties` command.
+
+  The implementation ensures that if the content has already been populated
+  in a previous CMake run, that content will be reused rather than repopulating
+  again.  For the common case where population involves downloading content,
+  the cost of the download is only paid once. But note that it is an error to
+  call ``FetchContent_Populate(<name>)`` with the same ``<name>`` more than
+  once within a single CMake run. See :command:`FetchContent_GetProperties`
+  for how to determine if population of a ``<name>`` has already been
+  performed in the current run.
+
 .. command:: FetchContent_GetProperties
 
   When using saved content details, a call to
@@ -622,13 +591,15 @@ Commands
 
   This command is rarely needed when using
   :command:`FetchContent_MakeAvailable`.  It is more commonly used as part of
-  implementing the following pattern with :command:`FetchContent_Populate`,
+  implementing the deprecated pattern with :command:`FetchContent_Populate`,
   which ensures that the relevant variables will always be defined regardless
   of whether or not the population has been performed elsewhere in the project
   already:
 
   .. code-block:: cmake
 
+    # WARNING: This pattern is deprecated, don't use it!
+    #
     # Check if population has already been performed
     FetchContent_GetProperties(depname)
     if(NOT depname_POPULATED)
@@ -1060,16 +1031,7 @@ that all five projects are available on a company git server.  The
     GIT_TAG        7d9a17ad2c962aa13e2fbb8043fb6b8a
   )
 
-  # This particular version of projD requires workarounds
-  FetchContent_GetProperties(projD)
-  if(NOT projd_POPULATED)
-    FetchContent_Populate(projD)
-
-    # Copy an additional/replacement file into the populated source
-    file(COPY someFile.c DESTINATION ${projd_SOURCE_DIR}/src)
-
-    add_subdirectory(${projd_SOURCE_DIR} ${projd_BINARY_DIR})
-  endif()
+  FetchContent_MakeAvailable(projD)
 
 A few key points should be noted in the above:
 
@@ -1081,15 +1043,20 @@ A few key points should be noted in the above:
   it is up to the higher level project to ensure that the details it does
   define still make sense for the child projects.
 - In the ``projA`` call to :command:`FetchContent_MakeAvailable`, ``projD``
-  is listed ahead of ``projB`` and ``projC`` to ensure that ``projA`` is in
-  control of how ``projD`` is populated.
+  is listed ahead of ``projB`` and ``projC``, so it will be populated before
+  either ``projB`` or ``projC``. It isn't required for ``projA`` to do this,
+  doing so ensures that ``projA`` fully controls the environment in which
+  ``projD`` is brought into the build (directory properties are particularly
+  relevant).
 - While ``projA`` defines content details for ``projE``, it does not need
   to explicitly call ``FetchContent_MakeAvailable(projE)`` or
   ``FetchContent_Populate(projD)`` itself.  Instead, it leaves that to the
   child ``projB``.  For higher level projects, it is often enough to just
   define the override content details and leave the actual population to the
   child projects.  This saves repeating the same thing at each level of the
-  project hierarchy unnecessarily.
+  project hierarchy unnecessarily, but it should only be done if directory
+  properties set by dependencies are not expected to influence the population
+  of the shared dependency (``projE`` in this case).
 
 Populating Content Without Adding It To The Build
 """""""""""""""""""""""""""""""""""""""""""""""""
@@ -1940,6 +1907,24 @@ function(FetchContent_Populate contentName)
   endif()
 
   if(ARGC EQUAL 1)
+    cmake_policy(GET CMP0169 cmp0169
+      PARENT_SCOPE # undocumented, do not use outside of CMake
+    )
+    if(NOT cmp0169 STREQUAL "OLD")
+      string(CONCAT msg
+        "Calling FetchContent_Populate(${contentName}) is deprecated, call "
+        "FetchContent_MakeAvailable(${contentName}) instead. "
+        "Policy CMP0169 can be set to OLD to allow "
+        "FetchContent_Populate(${contentName}) to be called directly for now, "
+        "but the ability to call it with declared details will be removed "
+        "completely in a future version."
+      )
+      if(cmp0169 STREQUAL "NEW")
+        message(FATAL_ERROR "${msg}")
+      else()
+        message(AUTHOR_WARNING "${msg}")
+      endif()
+    endif()
     set(__doDirectArgs)
   else()
     cmake_policy(GET CMP0168 cmp0168
@@ -1952,6 +1937,26 @@ function(FetchContent_Populate contentName)
     endif()
   endif()
 
+  cmake_parse_arguments(PARSE_ARGV 0 __arg "" "" "")
+  set(__argsQuoted)
+  foreach(__item IN LISTS __arg_UNPARSED_ARGUMENTS __doDirectArgs)
+    string(APPEND __argsQuoted " [==[${__item}]==]")
+  endforeach()
+
+  cmake_language(EVAL CODE "__FetchContent_Populate(${__argsQuoted})")
+
+  string(TOLOWER ${contentName} contentNameLower)
+  foreach(var IN ITEMS SOURCE_DIR BINARY_DIR POPULATED)
+    set(var "${contentNameLower}_${var}")
+    if(DEFINED ${var})
+      set(${var} "${${var}}" PARENT_SCOPE)
+    endif()
+  endforeach()
+
+endfunction()
+
+function(__FetchContent_Populate contentName)
+
   string(TOLOWER ${contentName} contentNameLower)
 
   if(ARGN)
@@ -1963,7 +1968,6 @@ function(FetchContent_Populate contentName)
       SOURCE_DIR   "${CMAKE_CURRENT_BINARY_DIR}/${contentNameLower}-src"
       BINARY_DIR   "${CMAKE_CURRENT_BINARY_DIR}/${contentNameLower}-build"
       ${ARGN}  # Could override any of the above ..._DIR variables
-      ${__doDirectArgs}
     )
 
     # Pass source and binary dir variables back to the caller
@@ -2301,7 +2305,7 @@ macro(FetchContent_MakeAvailable)
 
     FetchContent_GetProperties(${__cmake_contentName})
     if(NOT ${__cmake_contentNameLower}_POPULATED)
-      FetchContent_Populate(${__cmake_contentName})
+      __FetchContent_Populate(${__cmake_contentName})
       __FetchContent_setupFindPackageRedirection(${__cmake_contentName})
 
       # Only try to call add_subdirectory() if the populated content

Source/cmPolicies.h

@@ -518,6 +518,10 @@ class cmMakefile;
   SELECT(POLICY, CMP0168,                                                     \
          "FetchContent implements steps directly instead of through a "       \
          "sub-build.",                                                        \
+         3, 30, 0, cmPolicies::WARN)                                          \
+  SELECT(POLICY, CMP0169,                                                     \
+         "FetchContent_Populate(depName) single-argument signature is "       \
+         "deprecated.",                                                       \
          3, 30, 0, cmPolicies::WARN)
 
 #define CM_SELECT_ID(F, A1, A2, A3, A4, A5, A6) F(A1)

Tests/RunCMake/CMP0169/CMP0169-NEW-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/CMP0169/CMP0169-NEW-stderr.txt

@@ -0,0 +1,10 @@
+CMake Error at .*/Modules/FetchContent\.cmake:[0-9]+ \(message\):
+  Calling FetchContent_Populate\(t2\) is deprecated, call
+  FetchContent_MakeAvailable\(t2\) instead\.  Policy CMP0169 can be set to OLD
+  to allow FetchContent_Populate\(t2\) to be called directly for now, but the
+  ability to call it with declared details will be removed completely in a
+  future version\.
+Call Stack \(most recent call first\):
+  CMP0169\.cmake:[0-9]+ \(FetchContent_Populate\)
+  CMP0169-NEW\.cmake:[0-9]+ \(include\)
+  CMakeLists\.txt:[0-9]+ \(include\)

Tests/RunCMake/CMP0169/CMP0169-NEW-stdout.txt

@@ -0,0 +1,2 @@
+Direct download
+-- Configuring incomplete, errors occurred!

Tests/RunCMake/CMP0169/CMP0169-NEW.cmake

@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0169 NEW)
+include(CMP0169.cmake)

Tests/RunCMake/CMP0169/CMP0169-OLD-stdout.txt

@@ -0,0 +1,4 @@
+Direct download
+Declared download
+-- Configuring done \([0-9]+\.[0-9]s\)
+-- Generating done \([0-9]+\.[0-9]s\)

Tests/RunCMake/CMP0169/CMP0169-OLD.cmake

@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0169 OLD)
+include(CMP0169.cmake)

Tests/RunCMake/CMP0169/CMP0169-WARN-stderr.txt

@@ -0,0 +1,11 @@
+CMake Warning \(dev\) at .*/Modules/FetchContent\.cmake:[0-9]+ \(message\):
+  Calling FetchContent_Populate\(t2\) is deprecated, call
+  FetchContent_MakeAvailable\(t2\) instead\.  Policy CMP0169 can be set to OLD
+  to allow FetchContent_Populate\(t2\) to be called directly for now, but the
+  ability to call it with declared details will be removed completely in a
+  future version\.
+Call Stack \(most recent call first\):
+  CMP0169\.cmake:[0-9]+ \(FetchContent_Populate\)
+  CMP0169-WARN\.cmake:[0-9]+ \(include\)
+  CMakeLists\.txt:[0-9]+ \(include\)
+This warning is for project developers\.  Use -Wno-dev to suppress it\.

Tests/RunCMake/CMP0169/CMP0169-WARN-stdout.txt

@@ -0,0 +1,4 @@
+Direct download
+Declared download
+-- Configuring done \([0-9]+\.[0-9]s\)
+-- Generating done \([0-9]+\.[0-9]s\)

Tests/RunCMake/CMP0169/CMP0169-WARN.cmake

@@ -0,0 +1 @@
+include(CMP0169.cmake)

Tests/RunCMake/CMP0169/CMP0169.cmake

@@ -0,0 +1,14 @@
+cmake_policy(SET CMP0168 NEW)  # Faster, don't need to test with sub-build
+
+include(FetchContent)
+
+FetchContent_Populate(t1
+  DOWNLOAD_COMMAND ${CMAKE_COMMAND} -E echo "Direct download"
+  UPDATE_COMMAND ""
+)
+
+FetchContent_Declare(t2
+  DOWNLOAD_COMMAND ${CMAKE_COMMAND} -E echo "Declared download"
+  UPDATE_COMMAND ""
+)
+FetchContent_Populate(t2)

Tests/RunCMake/CMP0169/CMakeLists.txt

@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.29)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)

Tests/RunCMake/CMP0169/RunCMakeTest.cmake

@@ -0,0 +1,5 @@
+include(RunCMake)
+
+run_cmake(CMP0169-WARN)
+run_cmake(CMP0169-OLD)
+run_cmake(CMP0169-NEW)

Tests/RunCMake/CMakeLists.txt

@@ -175,6 +175,7 @@ add_RunCMake_test(CMP0156 -DCMAKE_C_COMPILER_ID=${CMAKE_C_COMPILER_ID}
 add_RunCMake_test(CMP0160)
 add_RunCMake_test(CMP0163)
 add_RunCMake_test(CMP0165)
+add_RunCMake_test(CMP0169)
 
 # The test for Policy 65 requires the use of the
 # CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS variable, which both the VS and Xcode

Tests/RunCMake/FetchContent/DirOverrides.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 # Test using saved details

Tests/RunCMake/FetchContent/DirOverridesDisconnected.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 # Test using saved details. We are re-using a SOURCE_DIR from a previous test

Tests/RunCMake/FetchContent/DirectIgnoresDetails.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 FetchContent_Declare(

Tests/RunCMake/FetchContent/DownloadFile.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 # The file hash depends on the line endings used by git

Tests/RunCMake/FetchContent/DownloadTwice.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 FetchContent_Declare(

Tests/RunCMake/FetchContent/FirstDetailsWin.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 # Need to see the download command output

Tests/RunCMake/FetchContent/GetProperties.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 # First confirm properties are empty even before declare

Tests/RunCMake/FetchContent/MissingDetails.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 FetchContent_Populate(t1)

Tests/RunCMake/FetchContent/PreserveEmptyArgs.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 # Need to see the download command output

Tests/RunCMake/FetchContent/SameGenerator.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 FetchContent_Declare(

Tests/RunCMake/FetchContent/UsesTerminalOverride.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 set(FETCHCONTENT_QUIET NO)

Tests/RunCMake/FetchContent/VarDefinitions.cmake

@@ -3,6 +3,8 @@ unset(FETCHCONTENT_UPDATES_DISCONNECTED CACHE)
 unset(FETCHCONTENT_QUIET CACHE)
 unset(FETCHCONTENT_BASE_DIR CACHE)
 
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 # Each of the cache entries should be defined and have the

Tests/RunCMake/FetchContent/VarPassthroughs.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 set(CMAKE_EP_GIT_REMOTE_UPDATE_STRATEGY AAAA)

Tests/RunCMake/FetchContent_find_package/MissingDetails.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 FetchContent_Populate(t1)

Tests/RunCMake/FetchContent_find_package/PreserveEmptyArgs.cmake

@@ -1,3 +1,5 @@
+cmake_policy(SET CMP0169 OLD)
+
 include(FetchContent)
 
 # Need to see the download command output