From bb5449c8fcf05d917620b64aa6a0e1a36dd4d440 Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Wed, 30 Sep 2026 18:11:01 +0200
Subject: [PATCH] Silence the CMP0169 deprecation in cmake_fetch_content, fix
 stale guards

tests/cmake_fetch_content/project calls the single-argument
FetchContent_Populate(json) after FetchContent_Declare(), which CMake
3.30 deprecated as CMP0169. Since the project declares
cmake_minimum_required(VERSION 3.11...3.14), the policy stays unset,
so every configure with a current CMake prints the deprecation
warning. The test is kept on purpose: it is the only coverage of the
FetchContent_Populate + add_subdirectory pattern for CMake 3.11-3.13
users, which the docs still describe as supported. Explicitly set
CMP0169 to OLD, with a comment explaining why.

Also fix two stale version guards:
- tests/cmake_fetch_content/CMakeLists.txt guarded the test with
  VERSION_GREATER "3.11.0", which is dead now that tests/CMakeLists.txt
  requires CMake 3.13.
- tests/cmake_fetch_content2/CMakeLists.txt guarded with
  VERSION_GREATER "3.14.0", which skips exactly 3.14.0, the first
  version with FetchContent_MakeAvailable. Change it to
  VERSION_GREATER_EQUAL "3.14".

Verified locally: `ctest -R cmake_fetch_content` passes with CMake
4.1, and the CMP0169 deprecation warning that appeared before this
change is gone.

Closes #5714 item 5.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---
 tests/cmake_fetch_content/CMakeLists.txt      | 30 +++++++++----------
 .../project/CMakeLists.txt                    |  8 +++++
 tests/cmake_fetch_content2/CMakeLists.txt     |  2 +-
 3 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/tests/cmake_fetch_content/CMakeLists.txt b/tests/cmake_fetch_content/CMakeLists.txt
index 211a49cee..42fcb5816 100644
--- a/tests/cmake_fetch_content/CMakeLists.txt
+++ b/tests/cmake_fetch_content/CMakeLists.txt
@@ -1,21 +1,19 @@
-if (${CMAKE_VERSION} VERSION_GREATER "3.11.0")
-  add_test(NAME cmake_fetch_content_configure
-    COMMAND ${CMAKE_COMMAND}
+add_test(NAME cmake_fetch_content_configure
+  COMMAND ${CMAKE_COMMAND}
     -G "${CMAKE_GENERATOR}"
     -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
     -DCMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}
     -Dnlohmann_json_source=${PROJECT_SOURCE_DIR}
     ${CMAKE_CURRENT_SOURCE_DIR}/project
-  )
-  add_test(NAME cmake_fetch_content_build
-    COMMAND ${CMAKE_COMMAND} --build .
-  )
-  set_tests_properties(cmake_fetch_content_configure PROPERTIES
-    FIXTURES_SETUP cmake_fetch_content
-    LABELS "git_required;not_reproducible"
-  )
-  set_tests_properties(cmake_fetch_content_build PROPERTIES
-    FIXTURES_REQUIRED cmake_fetch_content
-    LABELS "git_required;not_reproducible"
-  )
-endif()
+)
+add_test(NAME cmake_fetch_content_build
+  COMMAND ${CMAKE_COMMAND} --build .
+)
+set_tests_properties(cmake_fetch_content_configure PROPERTIES
+  FIXTURES_SETUP cmake_fetch_content
+  LABELS "git_required;not_reproducible"
+)
+set_tests_properties(cmake_fetch_content_build PROPERTIES
+  FIXTURES_REQUIRED cmake_fetch_content
+  LABELS "git_required;not_reproducible"
+)
diff --git a/tests/cmake_fetch_content/project/CMakeLists.txt b/tests/cmake_fetch_content/project/CMakeLists.txt
index 9f7488157..ad8a05045 100644
--- a/tests/cmake_fetch_content/project/CMakeLists.txt
+++ b/tests/cmake_fetch_content/project/CMakeLists.txt
@@ -4,6 +4,14 @@ project(DummyImport CXX)
 
 include(FetchContent)
 
+# This test deliberately covers the pre-3.14 FetchContent_Populate pattern
+# (see FetchContent_MakeAvailable in ../../cmake_fetch_content2/project for
+# the 3.14+ alternative), which CMake 3.30 deprecated as CMP0169. Silence the
+# deprecation warning on purpose instead of switching to the new pattern.
+if(POLICY CMP0169)
+  cmake_policy(SET CMP0169 OLD)
+endif()
+
 get_filename_component(GIT_REPOSITORY_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/../../.. ABSOLUTE)
 FetchContent_Declare(json GIT_REPOSITORY ${GIT_REPOSITORY_DIRECTORY} GIT_TAG HEAD)
 
diff --git a/tests/cmake_fetch_content2/CMakeLists.txt b/tests/cmake_fetch_content2/CMakeLists.txt
index b35f93cfd..9b24fee01 100644
--- a/tests/cmake_fetch_content2/CMakeLists.txt
+++ b/tests/cmake_fetch_content2/CMakeLists.txt
@@ -1,4 +1,4 @@
-if (${CMAKE_VERSION} VERSION_GREATER "3.14.0")
+if (${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.14")
   add_test(NAME cmake_fetch_content2_configure
     COMMAND ${CMAKE_COMMAND}
     -G "${CMAKE_GENERATOR}"