Sync contrib/tools/python3 layout with upstream

* Move src/ subdir contents to the top of the layout
* Rename self-written lib -> lib2 to avoid CaseFolding warning from the VCS
* Regenerate contrib/libs/python proxy-headers accordingly
4ccc62ac1511abcf0fed14ccade38e984e088f1e

1 files changed, 248 insertions, 0 deletions

diff --git a/contrib/tools/python3/Lib/importlib/util.py b/contrib/tools/python3/Lib/importlib/util.py
new file mode 100644
index 0000000000..f4d6e82331
--- /dev/null
+++ b/contrib/tools/python3/Lib/importlib/util.py
@@ -0,0 +1,248 @@
+"""Utility code for constructing importers, etc."""
+from ._abc import Loader
+from ._bootstrap import module_from_spec
+from ._bootstrap import _resolve_name
+from ._bootstrap import spec_from_loader
+from ._bootstrap import _find_spec
+from ._bootstrap_external import MAGIC_NUMBER
+from ._bootstrap_external import _RAW_MAGIC_NUMBER
+from ._bootstrap_external import cache_from_source
+from ._bootstrap_external import decode_source
+from ._bootstrap_external import source_from_cache
+from ._bootstrap_external import spec_from_file_location
+
+import _imp
+import sys
+import types
+
+
+def source_hash(source_bytes):
+    "Return the hash of *source_bytes* as used in hash-based pyc files."
+    return _imp.source_hash(_RAW_MAGIC_NUMBER, source_bytes)
+
+
+def resolve_name(name, package):
+    """Resolve a relative module name to an absolute one."""
+    if not name.startswith('.'):
+        return name
+    elif not package:
+        raise ImportError(f'no package specified for {repr(name)} '
+                          '(required for relative module names)')
+    level = 0
+    for character in name:
+        if character != '.':
+            break
+        level += 1
+    return _resolve_name(name[level:], package, level)
+
+
+def _find_spec_from_path(name, path=None):
+    """Return the spec for the specified module.
+
+    First, sys.modules is checked to see if the module was already imported. If
+    so, then sys.modules[name].__spec__ is returned. If that happens to be
+    set to None, then ValueError is raised. If the module is not in
+    sys.modules, then sys.meta_path is searched for a suitable spec with the
+    value of 'path' given to the finders. None is returned if no spec could
+    be found.
+
+    Dotted names do not have their parent packages implicitly imported. You will
+    most likely need to explicitly import all parent packages in the proper
+    order for a submodule to get the correct spec.
+
+    """
+    if name not in sys.modules:
+        return _find_spec(name, path)
+    else:
+        module = sys.modules[name]
+        if module is None:
+            return None
+        try:
+            spec = module.__spec__
+        except AttributeError:
+            raise ValueError(f'{name}.__spec__ is not set') from None
+        else:
+            if spec is None:
+                raise ValueError(f'{name}.__spec__ is None')
+            return spec
+
+
+def find_spec(name, package=None):
+    """Return the spec for the specified module.
+
+    First, sys.modules is checked to see if the module was already imported. If
+    so, then sys.modules[name].__spec__ is returned. If that happens to be
+    set to None, then ValueError is raised. If the module is not in
+    sys.modules, then sys.meta_path is searched for a suitable spec with the
+    value of 'path' given to the finders. None is returned if no spec could
+    be found.
+
+    If the name is for submodule (contains a dot), the parent module is
+    automatically imported.
+
+    The name and package arguments work the same as importlib.import_module().
+    In other words, relative module names (with leading dots) work.
+
+    """
+    fullname = resolve_name(name, package) if name.startswith('.') else name
+    if fullname not in sys.modules:
+        parent_name = fullname.rpartition('.')[0]
+        if parent_name:
+            parent = __import__(parent_name, fromlist=['__path__'])
+            try:
+                parent_path = parent.__path__
+            except AttributeError as e:
+                raise ModuleNotFoundError(
+                    f"__path__ attribute not found on {parent_name!r} "
+                    f"while trying to find {fullname!r}", name=fullname) from e
+        else:
+            parent_path = None
+        return _find_spec(fullname, parent_path)
+    else:
+        module = sys.modules[fullname]
+        if module is None:
+            return None
+        try:
+            spec = module.__spec__
+        except AttributeError:
+            raise ValueError(f'{name}.__spec__ is not set') from None
+        else:
+            if spec is None:
+                raise ValueError(f'{name}.__spec__ is None')
+            return spec
+
+
+# Normally we would use contextlib.contextmanager.  However, this module
+# is imported by runpy, which means we want to avoid any unnecessary
+# dependencies.  Thus we use a class.
+
+class _incompatible_extension_module_restrictions:
+    """A context manager that can temporarily skip the compatibility check.
+
+    NOTE: This function is meant to accommodate an unusual case; one
+    which is likely to eventually go away.  There's is a pretty good
+    chance this is not what you were looking for.
+
+    WARNING: Using this function to disable the check can lead to
+    unexpected behavior and even crashes.  It should only be used during
+    extension module development.
+
+    If "disable_check" is True then the compatibility check will not
+    happen while the context manager is active.  Otherwise the check
+    *will* happen.
+
+    Normally, extensions that do not support multiple interpreters
+    may not be imported in a subinterpreter.  That implies modules
+    that do not implement multi-phase init or that explicitly of out.
+
+    Likewise for modules import in a subinterpeter with its own GIL
+    when the extension does not support a per-interpreter GIL.  This
+    implies the module does not have a Py_mod_multiple_interpreters slot
+    set to Py_MOD_PER_INTERPRETER_GIL_SUPPORTED.
+
+    In both cases, this context manager may be used to temporarily
+    disable the check for compatible extension modules.
+
+    You can get the same effect as this function by implementing the
+    basic interface of multi-phase init (PEP 489) and lying about
+    support for mulitple interpreters (or per-interpreter GIL).
+    """
+
+    def __init__(self, *, disable_check):
+        self.disable_check = bool(disable_check)
+
+    def __enter__(self):
+        self.old = _imp._override_multi_interp_extensions_check(self.override)
+        return self
+
+    def __exit__(self, *args):
+        old = self.old
+        del self.old
+        _imp._override_multi_interp_extensions_check(old)
+
+    @property
+    def override(self):
+        return -1 if self.disable_check else 1
+
+
+class _LazyModule(types.ModuleType):
+
+    """A subclass of the module type which triggers loading upon attribute access."""
+
+    def __getattribute__(self, attr):
+        """Trigger the load of the module and return the attribute."""
+        # All module metadata must be garnered from __spec__ in order to avoid
+        # using mutated values.
+        # Stop triggering this method.
+        self.__class__ = types.ModuleType
+        # Get the original name to make sure no object substitution occurred
+        # in sys.modules.
+        original_name = self.__spec__.name
+        # Figure out exactly what attributes were mutated between the creation
+        # of the module and now.
+        attrs_then = self.__spec__.loader_state['__dict__']
+        attrs_now = self.__dict__
+        attrs_updated = {}
+        for key, value in attrs_now.items():
+            # Code that set the attribute may have kept a reference to the
+            # assigned object, making identity more important than equality.
+            if key not in attrs_then:
+                attrs_updated[key] = value
+            elif id(attrs_now[key]) != id(attrs_then[key]):
+                attrs_updated[key] = value
+        self.__spec__.loader.exec_module(self)
+        # If exec_module() was used directly there is no guarantee the module
+        # object was put into sys.modules.
+        if original_name in sys.modules:
+            if id(self) != id(sys.modules[original_name]):
+                raise ValueError(f"module object for {original_name!r} "
+                                  "substituted in sys.modules during a lazy "
+                                  "load")
+        # Update after loading since that's what would happen in an eager
+        # loading situation.
+        self.__dict__.update(attrs_updated)
+        return getattr(self, attr)
+
+    def __delattr__(self, attr):
+        """Trigger the load and then perform the deletion."""
+        # To trigger the load and raise an exception if the attribute
+        # doesn't exist.
+        self.__getattribute__(attr)
+        delattr(self, attr)
+
+
+class LazyLoader(Loader):
+
+    """A loader that creates a module which defers loading until attribute access."""
+
+    @staticmethod
+    def __check_eager_loader(loader):
+        if not hasattr(loader, 'exec_module'):
+            raise TypeError('loader must define exec_module()')
+
+    @classmethod
+    def factory(cls, loader):
+        """Construct a callable which returns the eager loader made lazy."""
+        cls.__check_eager_loader(loader)
+        return lambda *args, **kwargs: cls(loader(*args, **kwargs))
+
+    def __init__(self, loader):
+        self.__check_eager_loader(loader)
+        self.loader = loader
+
+    def create_module(self, spec):
+        return self.loader.create_module(spec)
+
+    def exec_module(self, module):
+        """Make the module load lazily."""
+        module.__spec__.loader = self.loader
+        module.__loader__ = self.loader
+        # Don't need to worry about deep-copying as trying to set an attribute
+        # on an object would have triggered the load,
+        # e.g. ``module.__spec__.loader = None`` would trigger a load from
+        # trying to access module.__spec__.
+        loader_state = {}
+        loader_state['__dict__'] = module.__dict__.copy()
+        loader_state['__class__'] = module.__class__
+        module.__spec__.loader_state = loader_state
+        module.__class__ = _LazyModule