[BUG] Setuptools copies source files to build lib even if the targets are up to date with sources #5079
Description
setuptools version
80.9.0
Python version
Python 3.11.8
OS
RHEL 8
Additional environment information
No response
Description
Setuptools copies the source files to build_lib even if the target files already exist and are up-to-date with the sources and force was not set to 1.
This is happening because the _newer function uses os.path.getmtime which returns a float but the copy_file function uses st[ST_MTIME] which is an int, while copying the mod time. Due to this the target file is always older than source when preserve_timestamps is true.
This should be easily fixed by using st.st_mtime in the copy function as well.
Expected behavior
Setuptools should not copy the files if targets are up to date.
How to Reproduce
Build any simple project using setuptools consecutively. The target files will be overwritten the second time even if no changes are done to source.
Output
(test) rajputa@rajputa-rh8.hdc1(hyd):/codemill/rajputa/test-project$ python setup.py build
running build
running build_py
creating build/lib
copying foo.py -> build/lib
running egg_info
writing test_project.egg-info/PKG-INFO
writing dependency_links to test_project.egg-info/dependency_links.txt
writing top-level names to test_project.egg-info/top_level.txt
reading manifest file 'test_project.egg-info/SOURCES.txt'
writing manifest file 'test_project.egg-info/SOURCES.txt'
(test) rajputa@rajputa-rh8.hdc1(hyd):/codemill/rajputa/test-project$ ll foo.py
-rw-rw-r-- 1 rajputa rajputa 0 Sep 5 18:39 foo.py
(test) rajputa@rajputa-rh8.hdc1(hyd):/codemill/rajputa/test-project$ ll build/lib/foo.py
-rw-rw-r-- 1 rajputa rajputa 0 Sep 5 18:39 build/lib/foo.py
(test) rajputa@rajputa-rh8.hdc1(hyd):/codemill/rajputa/test-project$ python setup.py build
running build
running build_py
copying foo.py -> build/lib
running egg_info
writing test_project.egg-info/PKG-INFO
writing dependency_links to test_project.egg-info/dependency_links.txt
writing top-level names to test_project.egg-info/top_level.txt
reading manifest file 'test_project.egg-info/SOURCES.txt'
writing manifest file 'test_project.egg-info/SOURCES.txt'
(test) rajputa@rajputa-rh8.hdc1(hyd):/codemill/rajputa/test-project$