Support several more constructs in stubgen's AliasPrinter (#18888)

Fixes #18886. Added implementations for UnaryExpr, SetExpr and
SliceExpr, and also fallback to _Incomplete for several other constructs
that can sensibly appear in a dataclass field definition.

Author: sterliakov

mypy/stubgen.py

@@ -78,31 +78,38 @@
     Block,
     BytesExpr,
     CallExpr,
+    CastExpr,
     ClassDef,
     ComparisonExpr,
     ComplexExpr,
+    ConditionalExpr,
     Decorator,
     DictExpr,
+    DictionaryComprehension,
     EllipsisExpr,
     Expression,
     ExpressionStmt,
     FloatExpr,
     FuncBase,
     FuncDef,
+    GeneratorExpr,
     IfStmt,
     Import,
     ImportAll,
     ImportFrom,
     IndexExpr,
     IntExpr,
     LambdaExpr,
+    ListComprehension,
     ListExpr,
     MemberExpr,
     MypyFile,
     NameExpr,
     OpExpr,
     OverloadedFuncDef,
+    SetComprehension,
     SetExpr,
+    SliceExpr,
     StarExpr,
     Statement,
     StrExpr,
@@ -355,6 +362,9 @@ def visit_tuple_expr(self, node: TupleExpr) -> str:
     def visit_list_expr(self, node: ListExpr) -> str:
         return f"[{', '.join(n.accept(self) for n in node.items)}]"
 
+    def visit_set_expr(self, node: SetExpr) -> str:
+        return f"{{{', '.join(n.accept(self) for n in node.items)}}}"
+
     def visit_dict_expr(self, o: DictExpr) -> str:
         dict_items = []
         for key, value in o.items:
@@ -369,13 +379,50 @@ def visit_ellipsis(self, node: EllipsisExpr) -> str:
     def visit_op_expr(self, o: OpExpr) -> str:
         return f"{o.left.accept(self)} {o.op} {o.right.accept(self)}"
 
+    def visit_unary_expr(self, o: UnaryExpr, /) -> str:
+        return f"{o.op}{o.expr.accept(self)}"
+
+    def visit_slice_expr(self, o: SliceExpr, /) -> str:
+        blocks = [
+            o.begin_index.accept(self) if o.begin_index is not None else "",
+            o.end_index.accept(self) if o.end_index is not None else "",
+        ]
+        if o.stride is not None:
+            blocks.append(o.stride.accept(self))
+        return ":".join(blocks)
+
     def visit_star_expr(self, o: StarExpr) -> str:
         return f"*{o.expr.accept(self)}"
 
     def visit_lambda_expr(self, o: LambdaExpr) -> str:
         # TODO: Required for among other things dataclass.field default_factory
         return self.stubgen.add_name("_typeshed.Incomplete")
 
+    def _visit_unsupported_expr(self, o: object) -> str:
+        # Something we do not understand.
+        return self.stubgen.add_name("_typeshed.Incomplete")
+
+    def visit_comparison_expr(self, o: ComparisonExpr) -> str:
+        return self._visit_unsupported_expr(o)
+
+    def visit_cast_expr(self, o: CastExpr) -> str:
+        return self._visit_unsupported_expr(o)
+
+    def visit_conditional_expr(self, o: ConditionalExpr) -> str:
+        return self._visit_unsupported_expr(o)
+
+    def visit_list_comprehension(self, o: ListComprehension) -> str:
+        return self._visit_unsupported_expr(o)
+
+    def visit_set_comprehension(self, o: SetComprehension) -> str:
+        return self._visit_unsupported_expr(o)
+
+    def visit_dictionary_comprehension(self, o: DictionaryComprehension) -> str:
+        return self._visit_unsupported_expr(o)
+
+    def visit_generator_expr(self, o: GeneratorExpr) -> str:
+        return self._visit_unsupported_expr(o)
+
 
 def find_defined_names(file: MypyFile) -> set[str]:
     finder = DefinitionFinder()

test-data/unit/stubgen.test

@@ -4277,6 +4277,35 @@ class Y(missing.Base):
     generated_kwargs: float
     generated_kwargs_: float
 
+[case testDataclassAliasPrinterVariations_semanal]
+from dataclasses import dataclass, field
+
+@dataclass
+class X:
+    a: int = field(default=-1)
+    b: set[int] = field(default={0})
+    c: list[int] = field(default=[x for x in range(5)])
+    d: dict[int, int] = field(default={x: x for x in range(5)})
+    e: tuple[int, int] = field(default=(1, 2, 3)[1:])
+    f: tuple[int, int] = field(default=(1, 2, 3)[:2])
+    g: tuple[int, int] = field(default=(1, 2, 3)[::2])
+    h: tuple[int] = field(default=(1, 2, 3)[1::2])
+
+[out]
+from _typeshed import Incomplete
+from dataclasses import dataclass, field
+
+@dataclass
+class X:
+    a: int = field(default=-1)
+    b: set[int] = field(default={0})
+    c: list[int] = field(default=Incomplete)
+    d: dict[int, int] = field(default=Incomplete)
+    e: tuple[int, int] = field(default=(1, 2, 3)[1:])
+    f: tuple[int, int] = field(default=(1, 2, 3)[:2])
+    g: tuple[int, int] = field(default=(1, 2, 3)[::2])
+    h: tuple[int] = field(default=(1, 2, 3)[1::2])
+
 [case testDataclassTransform]
 # dataclass_transform detection only works with semantic analysis.
 # Test stubgen doesn't break too badly without it.