Python: Fix ty 0.0.18 type checking diagnostics (#6806)

Add targeted `# ty: ignore` suppressions with issue references for
known ty limitations and structural Python constraints. Key changes:

- Add `replace()` to `J` base class in `.pyi` stub (fixes ~20 errors)
- Add `@dataclass` to `Union`/`Intersection` in stubs (fixes 5 errors)
- Remove obsolete `# ty: ignore` comments no longer needed
- Add per-line suppressions referencing ty#628, ty#2193 where applicable

28 diagnostics remain in `type_mapping.py` due to JavaType inner class
hierarchy not being expressible in Python (metaclass conflict between
ABC and Enum prevents inner classes from extending enclosing class).

Author: knutwannheden

rewrite-python/rewrite/src/rewrite/__init__.py

@@ -2,7 +2,7 @@
 
 # helps pytest to rewrite the assert statements in test.py
 try:
-    import pytest  # ty: ignore[unresolved-import]
+    import pytest
     pytest.register_assert_rewrite("rewrite.test")
 except ImportError:
     pass  # pytest not available, skip assert rewriting

rewrite-python/rewrite/src/rewrite/java/extensions.py

@@ -17,7 +17,7 @@ def visit_container(v: 'JavaVisitor', container: Optional[JContainer[J2]], p: P)
     v.cursor = Cursor(v.cursor, container)
     before = v.visit_space(container.before, p)
     js = list_map(lambda el: v.visit_right_padded(el, p), container.padding.elements)
-    v.cursor = v.cursor.parent  # ty: ignore[invalid-assignment]  # cursor.parent is Optional[Cursor]; ty#1379
+    v.cursor = v.cursor.parent  # ty: ignore[invalid-assignment]  # cursor.parent is Optional[Cursor] (ty#628)
 
     return container if js is container.padding.elements and before is container.before else JContainer(before, js, container.markers)
 
@@ -30,7 +30,7 @@ def visit_right_padded(v: 'JavaVisitor', right: Optional[JRightPadded[T]], p: P)
     v.cursor = Cursor(v.cursor, right)
     if isinstance(t, Tree):
         t = v.visit_and_cast(t, T, p)
-    v.cursor = v.cursor.parent  # ty: ignore[invalid-assignment]  # cursor.parent is Optional[Cursor]; ty#1379
+    v.cursor = v.cursor.parent  # ty: ignore[invalid-assignment]  # cursor.parent is Optional[Cursor] (ty#628)
 
     if t is None:
         return None
@@ -50,7 +50,7 @@ def visit_left_padded(v: 'JavaVisitor', left: Optional[JLeftPadded[T]], p: P) ->
     t = left.element
     if isinstance(t, Tree):
         t = v.visit_and_cast(t, T, p)
-    v.cursor = v.cursor.parent  # ty: ignore[invalid-assignment]  # cursor.parent is Optional[Cursor]; ty#1379
+    v.cursor = v.cursor.parent  # ty: ignore[invalid-assignment]  # cursor.parent is Optional[Cursor] (ty#628)
 
     if left.element is t and before is left.before:
         return left

rewrite-python/rewrite/src/rewrite/java/support_types.py

@@ -589,5 +589,5 @@ def build_nullable(cls, before: Optional[JContainer[J2]], elements: Optional[Lis
     def empty(cls) -> JContainer[J2]:
         if cls._EMPTY is None:
             cls._EMPTY = JContainer(Space.EMPTY, [], Markers.EMPTY)
-        return cls._EMPTY  # type: ignore[return-value]  # _EMPTY is JContainer[J] but J2 is bound to J
+        return cls._EMPTY  # ty: ignore[invalid-return-type]  # _EMPTY is JContainer[J] but J2 is bound to J
 

rewrite-python/rewrite/src/rewrite/java/support_types.pyi

@@ -21,6 +21,7 @@ from rewrite.utils import replace_if_changed
 class J(Tree):
     @property
     def prefix(self) -> Space: ...
+    def replace(self, **kwargs: Any) -> Self: ...
     def is_acceptable(self, v: TreeVisitor[Any, P], p: P) -> bool: ...
     def accept(self, v: TreeVisitor[Any, P], p: P) -> Optional[Any]: ...
     def accept_java(self, v: 'JavaVisitor[P]', p: P) -> Optional['J']: ...
@@ -116,12 +117,14 @@ class JavaType(ABC):
         @property
         def bounds(self) -> List[JavaType]: ...
 
+    @dataclass
     class Union:
         _bounds: Optional[List[JavaType]]
 
         @property
         def bounds(self) -> List[JavaType]: ...
 
+    @dataclass
     class Intersection:
         _bounds: Optional[List[JavaType]]
 

rewrite-python/rewrite/src/rewrite/parser.py

@@ -141,7 +141,7 @@ def with_erroneous(self, erroneous: Optional[SourceFile]) -> 'ParseError':
         return self if erroneous is self._erroneous else replace(self, _erroneous=erroneous)
 
     def printer(self, cursor: Cursor) -> TreeVisitor[Tree, PrintOutputCapture[P]]:
-        return PrinterFactory.current().create_printer(cursor)  # ty: ignore[unresolved-attribute]  # PrinterFactory.current() is always set
+        return PrinterFactory.current().create_printer(cursor)  # ty: ignore[unresolved-attribute]  # guarded: PrinterFactory.current() always set here
 
     def is_acceptable(self, v: TreeVisitor[Any, P], p: P) -> bool:
         return v.is_adaptable_to(ParseErrorVisitor)

rewrite-python/rewrite/src/rewrite/python/_parser_visitor.py

@@ -774,7 +774,7 @@ def visit_Import(self, node):
             prefix = self.__source_before('import')
             imp = self.__convert(node.names[0])
             assert imp is not None
-            return imp.replace(prefix=prefix, qualid=imp.qualid.replace(prefix=imp.prefix))
+            return imp.replace(prefix=prefix, qualid=imp.qualid.replace(prefix=imp.prefix))  # ty: ignore[unresolved-attribute]  # imp is Import at runtime
 
         prefix = self.__source_before('import')
         names_prefix = self.__whitespace()
@@ -1197,7 +1197,7 @@ def __convert_match_pattern(self, node):
                             py.MatchCase.Pattern.Kind.GROUP,
                             JContainer(
                                 prefix,
-                                [JRightPadded(inner.replace(prefix=inner_prefix) if hasattr(inner, 'replace') else inner, Space.EMPTY, Markers.EMPTY)],  # ty: ignore[call-non-callable]
+                                [JRightPadded(inner.replace(prefix=inner_prefix) if hasattr(inner, 'replace') else inner, Space.EMPTY, Markers.EMPTY)],
                                 Markers.EMPTY
                             ),
                             None
@@ -2243,7 +2243,7 @@ def __map_decorator(self, decorator) -> j.Annotation:
             name = name.replace(prefix=extra_parens[-1][1])  # ty: ignore[unresolved-attribute]  # recursive call returns unknown
 
             # Wrap in extra parentheses (innermost to outermost)
-            wrapped: Expression = name
+            wrapped: Expression = name  # ty: ignore[invalid-assignment]
             for i in range(len(extra_parens) - 1, -1, -1):
                 paren_prefix, _ = extra_parens[i]
                 suffix = self.__whitespace()
@@ -2769,7 +2769,7 @@ def __convert_type(self, node) -> Optional[TypeTree]:
         prefix = self.__whitespace()
         converted_type = self.__convert_internal(node, self.__convert_type, self.__convert_type_mapper)
         if isinstance(converted_type, TypeTree):
-            return converted_type.replace(prefix=prefix)  # ty: ignore[unresolved-attribute]  # TypeTree base class doesn't have replace
+            return converted_type.replace(prefix=prefix)  # TypeTree base class doesn't have replace
         else:
             return py.ExpressionTypeTree(
                 random_id(),
@@ -3065,14 +3065,14 @@ def ident_or_field(parts: List[str]) -> NameTree:
         return ident_or_field(name.split('.'))
 
     def __convert_all(self, trees: Sequence) -> List[J2]:
-        return [c for tree in trees if (c := self.__convert(tree)) is not None]  # ty: ignore[invalid-return-type]
+        return [c for tree in trees if (c := self.__convert(tree)) is not None]  # ty: ignore[invalid-return-type]  # J list, J2 is bound to J
 
     def __convert_block(self, statements: Sequence[Statement], delim: str = ':') -> j.Block:
         prefix = self.__source_before(delim)
         if statements:
-            statements = [self.__pad_statement(cast(ast.stmt, s)) for s in statements]  # ty: ignore[invalid-assignment]
+            statements = [self.__pad_statement(cast(ast.stmt, s)) for s in statements]  # ty: ignore[invalid-assignment]  # padded statement list type
         else:
-            statements = [self.__pad_right(j.Empty(random_id(), Space.EMPTY, Markers.EMPTY), Space.EMPTY)]  # ty: ignore[invalid-assignment]
+            statements = [self.__pad_right(j.Empty(random_id(), Space.EMPTY, Markers.EMPTY), Space.EMPTY)]  # ty: ignore[invalid-assignment]  # padded statement list type
         return j.Block(
             random_id(),
             prefix,
@@ -3095,7 +3095,7 @@ def __pad_statement(self, stmt: ast.stmt) -> JRightPadded[Statement]:
             self._token_idx = save_idx
             padding = Space.EMPTY
             markers = Markers.EMPTY
-        return JRightPadded(statement, padding, markers)  # ty: ignore[invalid-return-type]  # statement is J|None from __convert_statement
+        return JRightPadded(statement, padding, markers)  # ty: ignore[invalid-return-type]  # statement is J from __convert_statement
 
     def __pad_list_element(self, element: J2, last: bool = False, pad_last: bool = True, delim: str = ',',
                            end_delim: Optional[str] = None) -> JRightPadded[J2]:

rewrite-python/rewrite/src/rewrite/python/_py2_parser_visitor.py

@@ -172,7 +172,7 @@ def _convert_leaf(self, leaf: parso_tree.PythonLeaf) -> Optional[j.J]:
         prefix = self._parse_space(leaf.prefix)
 
         # parso 0.7.x uses lowercase type names (e.g. 'name', 'number')
-        leaf_type = leaf.type.upper()
+        leaf_type = leaf.type.upper()  # ty: ignore[unresolved-attribute]  # parso leaf.type is always str
 
         if leaf_type == 'NAME' or leaf_type == 'KEYWORD':
             return j.Identifier(

rewrite-python/rewrite/src/rewrite/python/format/blank_lines.py

@@ -22,7 +22,7 @@ def visit_compilation_unit(self, cu: CompilationUnit, p: P) -> J:
         return super().visit_compilation_unit(cu, p)
 
     def visit_statement(self, stmt: Statement, p: P) -> J:
-        stmt = super().visit_statement(stmt, p)
+        stmt = super().visit_statement(stmt, p)  # ty: ignore[invalid-assignment]  # visitor covariance
 
         parent_cursor = self.cursor.parent_tree_cursor()
         top_level = isinstance(parent_cursor.value, CompilationUnit)
@@ -41,7 +41,7 @@ def visit_statement(self, stmt: Statement, p: P) -> J:
             else:
                 min_lines = max(self._style.minimum.around_top_level_classes_functions if isinstance(stmt, (ClassDeclaration, MethodDeclaration)) else 0,
                                 self._style.minimum.after_top_level_imports if prev_import else 0)
-                stmt = _adjusted_lines_for_tree(stmt, min_lines, self._style.keep_maximum.in_declarations)
+                stmt = _adjusted_lines_for_tree(stmt, min_lines, self._style.keep_maximum.in_declarations)  # ty: ignore[invalid-assignment]  # visitor covariance
         else:
             in_block = isinstance(parent_cursor.value, Block)
             in_class = in_block and isinstance(parent_cursor.parent_tree_cursor().value, ClassDeclaration)
@@ -63,7 +63,7 @@ def visit_statement(self, stmt: Statement, p: P) -> J:
             if prev_import:
                 min_lines = max(min_lines, self._style.minimum.after_local_imports)
 
-            stmt = _adjusted_lines_for_tree(stmt, min_lines, max_lines)
+            stmt = _adjusted_lines_for_tree(stmt, min_lines, max_lines)  # ty: ignore[invalid-assignment]  # visitor covariance
         return stmt
 
     def post_visit(self, tree: T, p: P) -> Optional[T]:

rewrite-python/rewrite/src/rewrite/python/format/minimum_viable_spacing.py

@@ -26,9 +26,9 @@ def post_visit(self, tree: T, p: P) -> Optional[T]:
             if not previous_statement or not previous_statement.markers.find_first(Semicolon):
                 new_prefix = tree.prefix.replace(whitespace='\n' + tree.prefix.whitespace)
                 if isinstance(tree, ExpressionStatement):
-                    tree = tree.replace(expression=tree.expression.replace(prefix=new_prefix))
+                    tree = tree.replace(expression=tree.expression.replace(prefix=new_prefix))  # ty: ignore[invalid-assignment]
                 else:
-                    tree = tree.replace(prefix=new_prefix)
+                    tree = tree.replace(prefix=new_prefix)  # ty: ignore[invalid-assignment]
 
         return tree
 
@@ -67,4 +67,4 @@ def modify_comment(c: PyComment) -> PyComment:
     if comments:
         new_prefix = new_prefix.replace(comments=comments)
 
-    return j.replace(prefix=new_prefix)
+    return j.replace(prefix=new_prefix)  # ty: ignore[invalid-return-type]

rewrite-python/rewrite/src/rewrite/python/format/normalize_line_breaks_visitor.py

@@ -18,7 +18,7 @@ def __init__(self, style: GeneralFormatStyle, stop_after: Optional[Tree] = None)
 
     def visit_space(self, space: Optional[Space], p: P) -> Space:
         if not space or space is Space.EMPTY or not space.whitespace:
-            return space  # type: ignore
+            return space  # ty: ignore[invalid-return-type]
         s = space.replace(whitespace=_normalize_new_lines(space.whitespace, self._style.use_crlf_new_lines))
 
         def process_comment(comment: Comment) -> Comment: