nodes: micro-optimize _imply_path

src/_pytest/nodes.py

@@ -93,26 +93,40 @@ def iterparentnodeids(nodeid: str) -> Iterator[str]:
         yield nodeid
 
 
+def _check_path(path: Path, fspath: LEGACY_PATH) -> None:
+    if Path(fspath) != path:
+        raise ValueError(
+            f"Path({fspath!r}) != {path!r}\n"
+            "if both path and fspath are given they need to be equal"
+        )
+
+
 def _imply_path(
     path: Optional[Path], fspath: Optional[LEGACY_PATH]
 ) -> Tuple[Path, LEGACY_PATH]:
     if path is not None:
         if fspath is not None:
-            if Path(fspath) != path:
-                raise ValueError(
-                    f"Path({fspath!r}) != {path!r}\n"
-                    "if both path and fspath are given they need to be equal"
-                )
-            assert Path(fspath) == path, f"{fspath} != {path}"
+            _check_path(path, fspath)
         else:
             fspath = legacy_path(path)
         return path, fspath
-
     else:
         assert fspath is not None
         return Path(fspath), fspath
 
 
+# Optimization: use _imply_path_only over _imply_path when only need Path.
+# This is to avoid `legacy_path(path)` which is surprisingly heavy.
+def _imply_path_only(path: Optional[Path], fspath: Optional[LEGACY_PATH]) -> Path:
+    if path is not None:
+        if fspath is not None:
+            _check_path(path, fspath)
+        return path
+    else:
+        assert fspath is not None
+        return Path(fspath)
+
+
 _NodeType = TypeVar("_NodeType", bound="Node")
 
 
@@ -196,7 +210,9 @@ class Node(metaclass=NodeMeta):
             self.session = parent.session
 
         #: Filesystem path where this node was collected from (can be None).
-        self.path = _imply_path(path or getattr(parent, "path", None), fspath=fspath)[0]
+        self.path = _imply_path_only(
+            path or getattr(parent, "path", None), fspath=fspath
+        )
 
         # The explicit annotation is to avoid publicly exposing NodeKeywords.
         #: Keywords/markers collected from all scopes.
@@ -573,7 +589,7 @@ class FSCollector(Collector):
                 assert path is None
                 path = path_or_parent
 
-        path, fspath = _imply_path(path, fspath=fspath)
+        path = _imply_path_only(path, fspath=fspath)
         if name is None:
             name = path.name
             if parent is not None and parent.path != path:

src/_pytest/python.py

@@ -639,7 +639,6 @@ class Package(Module):
     ) -> None:
         # NOTE: Could be just the following, but kept as-is for compat.
         # nodes.FSCollector.__init__(self, fspath, parent=parent)
-        path, fspath = nodes._imply_path(path, fspath=fspath)
         session = parent.session
         nodes.FSCollector.__init__(
             self,
@@ -650,7 +649,7 @@ class Package(Module):
             session=session,
             nodeid=nodeid,
         )
-        self.name = path.parent.name
+        self.name = self.path.parent.name
 
     def setup(self) -> None:
         # Not using fixtures to call setup_module here because autouse fixtures

testing/deprecated_test.py

@@ -1,6 +1,7 @@
 import re
 import sys
 import warnings
+from pathlib import Path
 from unittest import mock
 
 import pytest
@@ -179,6 +180,13 @@ def test_hookproxy_warnings_for_fspath(tmp_path, hooktype, request):
 
     hooks.pytest_ignore_collect(config=request.config, fspath=tmp_path)
 
+    # Passing entirely *different* paths is an outright error.
+    with pytest.raises(ValueError, match=r"path.*fspath.*need to be equal"):
+        with pytest.warns(PytestDeprecationWarning, match=PATH_WARN_MATCH) as r:
+            hooks.pytest_ignore_collect(
+                config=request.config, path=path, fspath=Path("/bla/bla")
+            )
+
 
 def test_warns_none_is_deprecated():
     with pytest.warns(