Improve logic operations on path handling

Author: abravalheri

setuptools/command/build_ext.py

@@ -271,10 +271,11 @@ def _get_internal_depends(self) -> Iterator[str]:
  depends = (dep for ext in self.extensions for dep in ext.depends)
  for dep in depends:
  try:
- path = os.path.abspath(dep)
- rel_path = str(Path(path).relative_to(project_root))
- assert ".." not in rel_path # abspath should have taken care of that
- yield rel_path.replace(os.sep, "/") # POSIX-style relative paths
+ path = os.path.abspath(os.path.join(project_root, dep))
+ # if dep is absolute, os.path.join will ignore project_root
+ rel_path = Path(path).relative_to(project_root)
+ assert ".." not in rel_path.parts # abspath should take care of that
+ yield rel_path.as_posix() # POSIX-style relative paths
  except ValueError:
  log.warn(f"ignoring {dep} for distribution: outside of project dir")