Autogen: Restore target-ordering dependencies in Makefiles with DEPFILE

In commit aebfbcaa46 (AutoGen: Use depfiles for the XXX_autogen ninja
targets, 2020-01-14, v3.17.0-rc1~58^2) the `_autogen_timestamp_deps`
target was given target ordering dependencies through its custom command
rather than direct target dependencies as on the `_autogen` target.
Then commit 895fa3433f (cmQtAutoGenInitializer: support IMPLIB-only
imported targets, 2021-09-23, v3.22.0-rc1~80^2) converted some
target-level dependencies into file-level dependencies on the custom
command.  This only works with a monolithic build graph like Ninja.

Since commit ebc9e448b3 (Autogen: Add depfile support for Makefiles,
2023-09-07, v3.28.0-rc1~101^2~1) we use the `_autogen_timestamp_deps`
target in Makefile generators too.  This exposed the missing target
ordering dependency.

Fixes: #25766

6 files changed, 28 insertions, 1 deletions

diff --git a/Tests/QtAutogen/AutogenTimestampDeps/CMakeLists.txt b/Tests/QtAutogen/AutogenTimestampDeps/CMakeLists.txt
index 3470a02..04cbde6 100644
--- a/Tests/QtAutogen/AutogenTimestampDeps/CMakeLists.txt
+++ b/Tests/QtAutogen/AutogenTimestampDeps/CMakeLists.txt
@@ -8,4 +8,17 @@ add_custom_target(ProjectInfo
   COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/UpdateProjectInfo.cmake
   BYPRODUCTS ${CMAKE_BINARY_DIR}/ProjectInfo.hpp)
 
+set(ext_lib ${CMAKE_CURRENT_BINARY_DIR}/ext-build/${CMAKE_STATIC_LIBRARY_PREFIX}ext${CMAKE_STATIC_LIBRARY_SUFFIX})
+include(ExternalProject)
+ExternalProject_Add(ext_target
+  SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ext"
+  BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/ext-build"
+  DOWNLOAD_COMMAND ""
+  INSTALL_COMMAND ""
+  BUILD_BYPRODUCTS "${ext_lib}"
+  )
+add_library(ext STATIC IMPORTED)
+set_property(TARGET ext PROPERTY IMPORTED_LOCATION "${ext_lib}")
+add_dependencies(ext ext_target)
+
 add_subdirectory(src)
diff --git a/Tests/QtAutogen/AutogenTimestampDeps/ext/CMakeLists.txt b/Tests/QtAutogen/AutogenTimestampDeps/ext/CMakeLists.txt
new file mode 100644
index 0000000..b6f359f
--- /dev/null
+++ b/Tests/QtAutogen/AutogenTimestampDeps/ext/CMakeLists.txt
@@ -0,0 +1,4 @@
+cmake_minimum_required(VERSION 3.28)
+project(Ext C)
+add_library(ext STATIC ext.c)
+set_property(TARGET ext PROPERTY ARCHIVE_OUTPUT_DIRECTORY "$<1:${CMAKE_CURRENT_BINARY_DIR}>")
diff --git a/Tests/QtAutogen/AutogenTimestampDeps/ext/ext.c b/Tests/QtAutogen/AutogenTimestampDeps/ext/ext.c
new file mode 100644
index 0000000..be253f2
--- /dev/null
+++ b/Tests/QtAutogen/AutogenTimestampDeps/ext/ext.c
@@ -0,0 +1,4 @@
+int ext(void)
+{
+  return 0;
+}
diff --git a/Tests/QtAutogen/AutogenTimestampDeps/src/CMakeLists.txt b/Tests/QtAutogen/AutogenTimestampDeps/src/CMakeLists.txt
index e931248..6a0beac 100644
--- a/Tests/QtAutogen/AutogenTimestampDeps/src/CMakeLists.txt
+++ b/Tests/QtAutogen/AutogenTimestampDeps/src/CMakeLists.txt
@@ -2,3 +2,4 @@ add_executable(Exe main.cpp ${CMAKE_BINARY_DIR}/ProjectInfo.hpp)
 add_dependencies(Exe ProjectInfo)
 target_include_directories(Exe PRIVATE ${CMAKE_BINARY_DIR})
 target_link_libraries(Exe PRIVATE ${QT_QTCORE_TARGET})
+target_link_libraries(Exe PRIVATE ext)
diff --git a/Tests/QtAutogen/AutogenTimestampDeps/src/main.cpp b/Tests/QtAutogen/AutogenTimestampDeps/src/main.cpp
index f3c4c4b..d715488 100644
--- a/Tests/QtAutogen/AutogenTimestampDeps/src/main.cpp
+++ b/Tests/QtAutogen/AutogenTimestampDeps/src/main.cpp
@@ -1,5 +1,6 @@
 #include "ProjectInfo.hpp"
+extern "C" int ext();
 int main(int argc, char* argv[])
 {
-  return 0;
+  return ext();
 }
diff --git a/Tests/QtAutogen/Tests.cmake b/Tests/QtAutogen/Tests.cmake
index 80f7329..d37be1c 100644
--- a/Tests/QtAutogen/Tests.cmake
+++ b/Tests/QtAutogen/Tests.cmake
@@ -2,7 +2,11 @@
 ADD_AUTOGEN_TEST(AutogenOriginDependsOff autogenOriginDependsOff)
 ADD_AUTOGEN_TEST(AutogenOriginDependsOn)
 ADD_AUTOGEN_TEST(AutogenTargetDepends)
+
+set(Autogen_CTEST_OPTIONS --build-target Exe)
 ADD_AUTOGEN_TEST(AutogenTimestampDeps)
+unset(Autogen_CTEST_OPTIONS)
+
 ADD_AUTOGEN_TEST(AutoMocGeneratedFile)
 ADD_AUTOGEN_TEST(Complex QtAutogen)
 ADD_AUTOGEN_TEST(GlobalAutogenSystemUseInclude)