FetchContent: Respect the CMP0135 policy setting

Fixes: #23560

5 files changed, 49 insertions, 8 deletions

diff --git a/Tests/RunCMake/CMP0135/CMP0135-Common.cmake b/Tests/RunCMake/CMP0135/CMP0135-Common.cmake
index 4b7cce5..ad60b7c 100644
--- a/Tests/RunCMake/CMP0135/CMP0135-Common.cmake
+++ b/Tests/RunCMake/CMP0135/CMP0135-Common.cmake
@@ -1,7 +1,8 @@
+#==============================================================================
+# ExternalProject
+#==============================================================================
+set(stamp_dir "${CMAKE_CURRENT_BINARY_DIR}/stamps-ep")
 include(ExternalProject)
-
-set(stamp_dir "${CMAKE_CURRENT_BINARY_DIR}/stamps")
-
 ExternalProject_Add(fake_ext_proj
   # We don't actually do a build, so we never try to download from this URL
   URL https://example.com/something.zip
@@ -12,7 +13,33 @@ ExternalProject_Add(fake_ext_proj
 set(extraction_script "${stamp_dir}/extract-fake_ext_proj.cmake")
 file(STRINGS "${extraction_script}" results REGEX "--touch")
 if("${results}" STREQUAL "")
-  message(STATUS "Using timestamps from archive")
+  message(STATUS "ExternalProject: Using timestamps from archive")
+else()
+  message(STATUS "ExternalProject: Using extraction time for the timestamps")
+endif()
+
+#==============================================================================
+# FetchContent
+#==============================================================================
+set(stamp_dir "${CMAKE_CURRENT_BINARY_DIR}/stamps-fc")
+set(archive_file ${CMAKE_CURRENT_BINARY_DIR}/test_archive.7z)
+file(ARCHIVE_CREATE
+  OUTPUT ${archive_file}
+  PATHS ${CMAKE_CURRENT_LIST_DIR}
+  FORMAT 7zip
+)
+include(FetchContent)
+FetchContent_Declare(fake_fc_proj
+  URL file://${archive_file}
+  STAMP_DIR ${stamp_dir}
+)
+FetchContent_MakeAvailable(fake_fc_proj)
+
+# Report whether the --touch option was added to the extraction script
+set(extraction_script "${stamp_dir}/extract-fake_fc_proj-populate.cmake")
+file(STRINGS "${extraction_script}" results REGEX "--touch")
+if("${results}" STREQUAL "")
+  message(STATUS "FetchContent: Using timestamps from archive")
 else()
-  message(STATUS "Using extraction time for the timestamps")
+  message(STATUS "FetchContent: Using extraction time for the timestamps")
 endif()
diff --git a/Tests/RunCMake/CMP0135/CMP0135-NEW-stdout.txt b/Tests/RunCMake/CMP0135/CMP0135-NEW-stdout.txt
index bf53c0b..ceef9b8 100644
--- a/Tests/RunCMake/CMP0135/CMP0135-NEW-stdout.txt
+++ b/Tests/RunCMake/CMP0135/CMP0135-NEW-stdout.txt
@@ -1 +1,2 @@
-Using extraction time for the timestamps
+-- ExternalProject: Using extraction time for the timestamps
+-- FetchContent: Using extraction time for the timestamps
diff --git a/Tests/RunCMake/CMP0135/CMP0135-OLD-stdout.txt b/Tests/RunCMake/CMP0135/CMP0135-OLD-stdout.txt
index ee57beb..1288c20 100644
--- a/Tests/RunCMake/CMP0135/CMP0135-OLD-stdout.txt
+++ b/Tests/RunCMake/CMP0135/CMP0135-OLD-stdout.txt
@@ -1 +1,2 @@
-Using timestamps from archive
+-- ExternalProject: Using timestamps from archive
+-- FetchContent: Using timestamps from archive
diff --git a/Tests/RunCMake/CMP0135/CMP0135-WARN-stderr.txt b/Tests/RunCMake/CMP0135/CMP0135-WARN-stderr.txt
index 8ba0027..6bf944e 100644
--- a/Tests/RunCMake/CMP0135/CMP0135-WARN-stderr.txt
+++ b/Tests/RunCMake/CMP0135/CMP0135-WARN-stderr.txt
@@ -8,3 +8,14 @@ CMake Warning \(dev\) at .*/Modules/ExternalProject.cmake:[0-9]+ \(message\):
   what you want\.  Update your project to the NEW behavior or specify the
   DOWNLOAD_EXTRACT_TIMESTAMP option with a value of true to avoid this
   robustness issue\.
+.*
+CMake Warning \(dev\) at .*/Modules/FetchContent.cmake:[0-9]+ \(message\):
+  The DOWNLOAD_EXTRACT_TIMESTAMP option was not given and policy CMP0135 is
+  not set\.  The policy's OLD behavior will be used\.  When using a URL
+  download, the timestamps of extracted files should preferably be that of
+  the time of extraction, otherwise code that depends on the extracted
+  contents might not be rebuilt if the URL changes\.  The OLD behavior
+  preserves the timestamps from the archive instead, but this is usually not
+  what you want\.  Update your project to the NEW behavior or specify the
+  DOWNLOAD_EXTRACT_TIMESTAMP option with a value of true to avoid this
+  robustness issue\.
diff --git a/Tests/RunCMake/CMP0135/CMP0135-WARN-stdout.txt b/Tests/RunCMake/CMP0135/CMP0135-WARN-stdout.txt
index ee57beb..1288c20 100644
--- a/Tests/RunCMake/CMP0135/CMP0135-WARN-stdout.txt
+++ b/Tests/RunCMake/CMP0135/CMP0135-WARN-stdout.txt
@@ -1 +1,2 @@
-Using timestamps from archive
+-- ExternalProject: Using timestamps from archive
+-- FetchContent: Using timestamps from archive