GH-127381: pathlib ABCs: remove PathBase.resolve() and absolute() (…

…#127707)

Remove our implementation of POSIX path resolution in `PathBase.resolve()`.
This functionality is rather fragile and isn't necessary in most cases. It
depends on `PathBase.stat()`, which we're looking to remove.

Also remove `PathBase.absolute()`. Many legitimate virtual filesystems lack
the notion of a 'current directory', so it's wrong to include in the basic
interface.

Lib/pathlib/_abc.py

@@ -13,7 +13,6 @@
 
 import functools
 import operator
-import posixpath
 from errno import EINVAL
 from glob import _GlobberBase, _no_recurse_symlinks
 from stat import S_ISDIR, S_ISLNK, S_ISREG, S_ISSOCK, S_ISBLK, S_ISCHR, S_ISFIFO
@@ -115,11 +114,6 @@ class PurePathBase:
         # The `_raw_paths` slot stores unjoined string paths. This is set in
         # the `__init__()` method.
         '_raw_paths',
-
-        # The '_resolving' slot stores a boolean indicating whether the path
-        # is being processed by `PathBase.resolve()`. This prevents duplicate
-        # work from occurring when `resolve()` calls `stat()` or `readlink()`.
-        '_resolving',
     )
     parser = ParserBase()
     _globber = PathGlobber
@@ -130,7 +124,6 @@ def __init__(self, *args):
                 raise TypeError(
                     f"argument should be a str, not {type(arg).__name__!r}")
         self._raw_paths = list(args)
-        self._resolving = False
 
     def with_segments(self, *pathsegments):
         """Construct a new path object from any number of path-like objects.
@@ -339,9 +332,7 @@ def parent(self):
         path = str(self)
         parent = self.parser.split(path)[0]
         if path != parent:
-            parent = self.with_segments(parent)
-            parent._resolving = self._resolving
-            return parent
+            return self.with_segments(parent)
         return self
 
     @property
@@ -424,9 +415,6 @@ class PathBase(PurePathBase):
     """
     __slots__ = ()
 
-    # Maximum number of symlinks to follow in resolve()
-    _max_symlinks = 40
-
     @classmethod
     def _unsupported_msg(cls, attribute):
         return f"{cls.__name__}.{attribute} is unsupported"
@@ -720,20 +708,6 @@ def walk(self, top_down=True, on_error=None, follow_symlinks=False):
                 yield path, dirnames, filenames
                 paths += [path.joinpath(d) for d in reversed(dirnames)]
 
-    def absolute(self):
-        """Return an absolute version of this path
-        No normalization or symlink resolution is performed.
-
-        Use resolve() to resolve symlinks and remove '..' segments.
-        """
-        if self.is_absolute():
-            return self
-        elif self.parser is not posixpath:
-            raise UnsupportedOperation(self._unsupported_msg('absolute()'))
-        else:
-            # Treat the root directory as the current working directory.
-            return self.with_segments('/', *self._raw_paths)
-
     def expanduser(self):
         """ Return a new path with expanded ~ and ~user constructs
         (as returned by os.path.expanduser)
@@ -745,42 +719,6 @@ def readlink(self):
         Return the path to which the symbolic link points.
         """
         raise UnsupportedOperation(self._unsupported_msg('readlink()'))
-    readlink._supported = False
-
-    def resolve(self, strict=False):
-        """
-        Make the path absolute, resolving all symlinks on the way and also
-        normalizing it.
-        """
-        if self._resolving:
-            return self
-        elif self.parser is not posixpath:
-            raise UnsupportedOperation(self._unsupported_msg('resolve()'))
-
-        def raise_error(*args):
-            raise OSError("Unsupported operation.")
-
-        getcwd = raise_error
-        if strict or getattr(self.readlink, '_supported', True):
-            def lstat(path_str):
-                path = self.with_segments(path_str)
-                path._resolving = True
-                return path.stat(follow_symlinks=False)
-
-            def readlink(path_str):
-                path = self.with_segments(path_str)
-                path._resolving = True
-                return str(path.readlink())
-        else:
-            # If the user has *not* overridden the `readlink()` method, then
-            # symlinks are unsupported and (in non-strict mode) we can improve
-            # performance by not calling `path.lstat()`.
-            lstat = readlink = raise_error
-
-        return self.with_segments(posixpath._realpath(
-            str(self.absolute()), strict, self.parser.sep,
-            getcwd=getcwd, lstat=lstat, readlink=readlink,
-            maxlinks=self._max_symlinks))
 
     def symlink_to(self, target, target_is_directory=False):
         """