refactor: Create aliases for element attribute mapping and tuple

src/lxml-stubs/_types.pyi

@@ -34,11 +34,34 @@ _AnyStr = str | bytes
 _TagName = str | bytes | bytearray | QName
 _AttrName = str | bytes | bytearray | QName
 _AttrVal = str | bytes | bytearray | QName
+_AttrNameKey = str | bytes | QName
+"""Types supported in attribute name, sans bytearray"""
 
 # On the other hand, Elementpath API doesn't do str/byte canonicalization,
 # only unicode accepted for py3
 _ElemPathArg = str | QName
 
+_AttrMapping = SupportsLaxedItems[_AttrNameKey, _AttrVal]
+"""Attribute dict-like mapping
+
+Used in attrib argument of various factories and methods.
+Bytearray not supported as key (not hashable).
+
+Internal stuff
+--------------
+Anything that delves into `_initNodeAttributes()`
+(in `apihelper.pxi`) should be able to use it.
+Need to make sure `_Attrib` and `dict` are supported in
+places wherever this alias is used.
+"""
+
+_AttrTuples = Iterable[tuple[_AttrNameKey, _AttrVal]]
+"""Tuple form of attribute key/value pairs
+
+Used in attrib argument where tuple form is accepted,
+in place of or in addition to `_AttrMapping`.
+"""
+
 # Due to Mapping having invariant key types, Mapping[A | B, ...]
 # would fail to validate against either Mapping[A, ...] or Mapping[B, ...]
 # Try to settle for simpler solution, assuming python3 users would not
@@ -131,24 +154,24 @@ class _ElementFactory(Protocol, Generic[_ET_co]):
 
     This is callback protocol for `makeelement()` method of
     various element objects, with following signature (which
-    is identical to `etree.Element()` function):
+    is identical to `etree.Element()` factory):
 
     ```python
     (_tag, attrib=..., nsmap=..., **_extra)
     ```
 
     The mapping in `attrib` argument and all `_extra` keyword
-    arguments would be merged together. The result is usually
-    `{**attrib, **_extra}`, but some places may deviate.
+    arguments would be merged together, with `_extra` taking
+    precedence over `attrib`.
     """
 
     def __call__(
         self,
         _tag: _TagName,
         /,
-        attrib: SupportsLaxedItems[str, _AnyStr] | None = None,
+        attrib: _AttrMapping | None = None,
         nsmap: _NSMapArg | None = None,
-        **_extra: _AnyStr,
+        **_extra: _AttrVal,
     ) -> _ET_co: ...
 
 # Note that _TagSelector filters element type not by classes,
@@ -165,9 +188,11 @@ _DefEtreeParsers = XMLParser[_ET_co] | HTMLParser[_ET_co]
 class SupportsLaxedItems(Protocol[_KT_co, _VT_co]):
     """Relaxed form of SupportsItems
 
-    Original SupportsItems from typeshed returns generic set which
-    is compatible with ItemsView. However, _Attrib doesn't conform
-    and returns list instead. Gotta find a common ground here.
+    Original `SupportsItems` from typeshed returns
+    generic set which is compatible with `ItemsView`.
+    However, `_Attrib.items()` returns `list` instead.
+    Here we find a common ground that satisfies both
+    and avoid the mapping invariance culprit.
     """
 
     def items(self) -> Collection[tuple[_KT_co, _VT_co]]: ...

src/lxml-stubs/etree/_classlookup.pyi

@@ -6,9 +6,9 @@ from abc import ABCMeta, abstractmethod
 from typing import Mapping, final
 
 from .._types import (
-    SupportsLaxedItems,
-    _AnyStr,
+    _AttrMapping,
     _AttrName,
+    _AttrVal,
     _ElemClsLookupArg,
     _NSMapArg,
 )
@@ -59,9 +59,9 @@ class ElementBase(_Element):
     def __init__(
         self,
         *children: object,
-        attrib: SupportsLaxedItems[str, _AnyStr] | None = None,
+        attrib: _AttrMapping | None = None,
         nsmap: _NSMapArg | None = None,
-        **_extra: _AnyStr,
+        **_extra: _AttrVal,
     ) -> None: ...
     def _init(self) -> None: ...
 

src/lxml-stubs/etree/_element.pyi

@@ -392,7 +392,8 @@ class _ElementTree(Generic[_t._ET_co]):
 class _Attrib:
     def __setitem__(self, __k: _t._AttrName, __v: _t._AttrVal) -> None: ...
     def __delitem__(self, __k: _t._AttrName) -> None: ...
-    # explicitly checks for dict and _Attrib
+    # _only_ checks for dict and _Attrib to do
+    # .items() conversion, not any Mapping
     def update(
         self,
         sequence_or_dict: (

src/lxml-stubs/etree/_factory_func.pyi

@@ -2,8 +2,8 @@ from typing import overload
 
 from .._types import (
     _ET,
-    SupportsLaxedItems,
-    _AnyStr,
+    _AttrMapping,
+    _AttrVal,
     _DefEtreeParsers,
     _ElementFactory,
     _ET_co,
@@ -45,27 +45,27 @@ def SubElement(
     _parent: ObjectifiedElement,
     _tag: _TagName,
     /,
-    attrib: SupportsLaxedItems[str, _AnyStr] | None = None,
+    attrib: _AttrMapping | None = None,
     nsmap: _NSMapArg | None = None,
-    **_extra: _AnyStr,
+    **_extra: _AttrVal,
 ) -> StringElement: ...
 @overload
 def SubElement(
     _parent: HtmlElement,
     _tag: _TagName,
     /,
-    attrib: SupportsLaxedItems[str, _AnyStr] | None = None,
+    attrib: _AttrMapping | None = None,
     nsmap: _NSMapArg | None = None,
-    **_extra: _AnyStr,
+    **_extra: _AttrVal,
 ) -> HtmlElement: ...
 @overload
 def SubElement(
     _parent: _ET,
     _tag: _TagName,
     /,
-    attrib: SupportsLaxedItems[str, _AnyStr] | None = None,
+    attrib: _AttrMapping | None = None,
     nsmap: _NSMapArg | None = None,
-    **_extra: _AnyStr,
+    **_extra: _AttrVal,
 ) -> _ET: ...
 @overload  # from element, parser ignored
 def ElementTree(element: _ET) -> _ElementTree[_ET]: ...

src/lxml-stubs/etree/_serializer.pyi

@@ -14,6 +14,8 @@ from _typeshed import SupportsWrite
 from .._types import (
     SupportsLaxedItems,
     _AnyStr,
+    _AttrMapping,
+    _AttrVal,
     _ElementOrTree,
     _FileReadSource,
     _FileWriteSource,
@@ -139,10 +141,10 @@ class _IncrementalFileWriter:
     def element(
         self,
         tag: _TagName,
-        attrib: SupportsLaxedItems[str, _AnyStr] | None = None,
+        attrib: _AttrMapping | None = None,
         nsmap: _NSMapArg | None = None,
         method: _OutputMethodArg | None = None,
-        **_extra: _AnyStr,
+        **_extra: _AttrVal,
     ) -> ContextManager[None]: ...
 
 @final
@@ -166,10 +168,10 @@ class _AsyncIncrementalFileWriter:
     def element(
         self,
         tag: _TagName,
-        attrib: SupportsLaxedItems[str, _AnyStr] | None = None,
+        attrib: _AttrMapping | None = None,
         nsmap: _NSMapArg | None = None,
         method: _OutputMethodArg | None = None,
-        **_extra: _AnyStr,
+        **_extra: _AttrVal,
     ) -> AsyncContextManager[None]: ...
 
 class xmlfile(