Resolve PathLike via os.fspath in io.open (#7743)

CPython splits PathLike resolution across two layers: _io.FileIO
preserves the raw argument on .name (low-level contract), while
the high-level open() wrapper resolves it via os.fspath before
delegating. RustPython's io_open skipped that step, so
builtins.open(PathLike).name returned the PathLike object instead
of the resolved str/bytes.

Match Lib/_pyio.py:193-194 by resolving non-int inputs at the
io_open boundary, leaving _io.FileIO unchanged.

Lib/test/test_bz2.py

@@ -740,7 +740,6 @@ class BZ2FileTest(BaseTest):
             self.assertEqual(f.read(), self.DATA)
             self.assertEqual(f.name, str_filename)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: <FakePath 'Z:\\TEMP\\tmphoipjcen'> != 'Z:\\TEMP\\tmphoipjcen'
     def testOpenPathLikeFilename(self):
         filename = FakePath(self.filename)
         with BZ2File(filename, "wb") as f:

Lib/test/test_lzma.py

@@ -555,7 +555,6 @@ class FileTestCase(unittest.TestCase):
             self.assertIsInstance(f, LZMAFile)
             self.assertEqual(f.mode, "wb")
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: <FakePath '@test_23396_tmp챈'> != '@test_23396_tmp챈'
     def test_init_with_PathLike_filename(self):
         filename = FakePath(TESTFN)
         with TempFile(filename, COMPRESSED_XZ):
@@ -1438,7 +1437,6 @@ class OpenTestCase(unittest.TestCase):
             with lzma.open(TESTFN, "rb") as f:
                 self.assertEqual(f.read(), INPUT * 2)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: <FakePath '@test_23396_tmp챈'> != '@test_23396_tmp챈'
     def test_with_pathlike_filename(self):
         filename = FakePath(TESTFN)
         with TempFile(filename):

crates/vm/src/stdlib/_io.rs

@@ -121,8 +121,8 @@ mod _io {
         convert::ToPyObject,
         exceptions::cstring_error,
         function::{
-            ArgBytesLike, ArgIterable, ArgMemoryBuffer, ArgSize, Either, FuncArgs, IntoFuncArgs,
-            OptionalArg, OptionalOption, PySetterValue,
+            ArgBytesLike, ArgIterable, ArgMemoryBuffer, ArgSize, Either, FsPath, FuncArgs,
+            IntoFuncArgs, OptionalArg, OptionalOption, PySetterValue,
         },
         protocol::{
             BufferDescriptor, BufferMethods, BufferResizeGuard, PyBuffer, PyIterReturn, VecBuffer,
@@ -5069,6 +5069,15 @@ mod _io {
             }
         }
 
+        // Match CPython's _pyio.open (Lib/_pyio.py): resolve PathLike here so
+        // _io.FileIO still receives (and preserves on .name) the raw argument
+        // when called directly.
+        let file = if file.fast_isinstance(vm.ctx.types.int_type) {
+            file
+        } else {
+            FsPath::try_from_path_like(file, true, vm)?.to_pyobject(vm)
+        };
+
         // check file descriptor validity
         #[cfg(all(unix, feature = "host_env"))]
         if let Ok(crate::ospath::OsPathOrFd::Fd(fd)) = file.clone().try_into_value(vm) {