gh-132322: Ensure shutil functions return str when using pathlib

Fixes issue #132322 by normalizing return types in shutil.copy, copy2, copyfile, copytree, and move using os.fspath(), so that they consistently return str even when pathlib.Path is passed.

All relevant tests pass locally

Author: rpxchoudhury

Lib/shutil.py

@@ -310,7 +310,7 @@ def copyfile(src, dst, *, follow_symlinks=True):
                     if _HAS_FCOPYFILE:
                         try:
                             _fastcopy_fcopyfile(fsrc, fdst, posix._COPYFILE_DATA)
-                            return dst
+                            return os.fspath(dst)
                         except _GiveupOnFastCopy:
                             pass
                     # Linux / Android / Solaris
@@ -319,20 +319,20 @@ def copyfile(src, dst, *, follow_symlinks=True):
                         if _USE_CP_COPY_FILE_RANGE:
                             try:
                                 _fastcopy_copy_file_range(fsrc, fdst)
-                                return dst
+                                return os.fspath(dst)
                             except _GiveupOnFastCopy:
                                 pass
                         if _USE_CP_SENDFILE:
                             try:
                                 _fastcopy_sendfile(fsrc, fdst)
-                                return dst
+                                return os.fspath(dst)
                             except _GiveupOnFastCopy:
                                 pass
                     # Windows, see:
                     # https://github.com/python/cpython/pull/7160#discussion_r195405230
                     elif _WINDOWS and file_size > 0:
                         _copyfileobj_readinto(fsrc, fdst, min(file_size, COPY_BUFSIZE))
-                        return dst
+                        return os.fspath(dst)
 
                     copyfileobj(fsrc, fdst)
 
@@ -343,7 +343,7 @@ def copyfile(src, dst, *, follow_symlinks=True):
                 else:
                     raise
 
-    return dst
+    return os.fspath(dst)
 
 def copymode(src, dst, *, follow_symlinks=True):
     """Copy mode bits from src to dst.
@@ -481,7 +481,7 @@ def copy(src, dst, *, follow_symlinks=True):
         dst = os.path.join(dst, os.path.basename(src))
     copyfile(src, dst, follow_symlinks=follow_symlinks)
     copymode(src, dst, follow_symlinks=follow_symlinks)
-    return dst
+    return os.fspath(dst)
 
 def copy2(src, dst, *, follow_symlinks=True):
     """Copy data and metadata. Return the file's destination.
@@ -505,7 +505,7 @@ def copy2(src, dst, *, follow_symlinks=True):
             flags |= _winapi.COPY_FILE_COPY_SYMLINK
         try:
             _winapi.CopyFile2(src_, dst_, flags)
-            return dst
+            return os.fspath(dst)
         except OSError as exc:
             if (exc.winerror == _winapi.ERROR_PRIVILEGE_NOT_HELD
                 and not follow_symlinks):
@@ -521,7 +521,7 @@ def copy2(src, dst, *, follow_symlinks=True):
 
     copyfile(src, dst, follow_symlinks=follow_symlinks)
     copystat(src, dst, follow_symlinks=follow_symlinks)
-    return dst
+    return os.fspath(dst)
 
 def ignore_patterns(*patterns):
     """Function that can be used as copytree() ignore parameter.
@@ -599,7 +599,7 @@ def _copytree(entries, src, dst, symlinks, ignore, copy_function,
             errors.append((src, dst, str(why)))
     if errors:
         raise Error(errors)
-    return dst
+    return os.fspath(dst)
 
 def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,
              ignore_dangling_symlinks=False, dirs_exist_ok=False):
@@ -930,7 +930,7 @@ def move(src, dst, copy_function=copy2):
         else:
             copy_function(src, real_dst)
             os.unlink(src)
-    return real_dst
+    return os.fspath(real_dst)
 
 def _destinsrc(src, dst):
     src = os.path.abspath(src)