Fix Literal strings containing pipe characters (#17148)

Fixes #16367

During semantic analysis, we try to parse all strings as types,
including those inside Literal[]. Previously, we preserved the original
string in the `UnboundType.original_str_expr` attribute, but if a type
is parsed as a Union, we didn't have a place to put the value.

This PR instead always wraps string types in a RawExpressionType node,
which now optionally includes a `.node` attribute containing the parsed
type. This way, we don't need to worry about preserving the original
string as a custom attribute on different kinds of types that can appear
in this context.

The downside is that more code needs to be aware of RawExpressionType.

mypy/fastparse.py

@@ -319,14 +319,7 @@ def parse_type_string(
     """
     try:
         _, node = parse_type_comment(f"({expr_string})", line=line, column=column, errors=None)
-        if isinstance(node, UnboundType) and node.original_str_expr is None:
-            node.original_str_expr = expr_string
-            node.original_str_fallback = expr_fallback_name
-            return node
-        elif isinstance(node, UnionType):
-            return node
-        else:
-            return RawExpressionType(expr_string, expr_fallback_name, line, column)
+        return RawExpressionType(expr_string, expr_fallback_name, line, column, node=node)
     except (SyntaxError, ValueError):
         # Note: the parser will raise a `ValueError` instead of a SyntaxError if
         # the string happens to contain things like \x00.
@@ -1034,6 +1027,8 @@ def set_type_optional(self, type: Type | None, initializer: Expression | None) -
             return
         # Indicate that type should be wrapped in an Optional if arg is initialized to None.
         optional = isinstance(initializer, NameExpr) and initializer.name == "None"
+        if isinstance(type, RawExpressionType) and type.node is not None:
+            type = type.node
         if isinstance(type, UnboundType):
             type.optional = optional
 

mypy/semanal.py

@@ -3231,10 +3231,10 @@ def analyze_typeddict_assign(self, s: AssignmentStmt) -> bool:
     def analyze_lvalues(self, s: AssignmentStmt) -> None:
         # We cannot use s.type, because analyze_simple_literal_type() will set it.
         explicit = s.unanalyzed_type is not None
-        if self.is_final_type(s.unanalyzed_type):
+        final_type = self.unwrap_final_type(s.unanalyzed_type)
+        if final_type is not None:
             # We need to exclude bare Final.
-            assert isinstance(s.unanalyzed_type, UnboundType)
-            if not s.unanalyzed_type.args:
+            if not final_type.args:
                 explicit = False
 
         if s.rvalue:
@@ -3300,19 +3300,19 @@ def unwrap_final(self, s: AssignmentStmt) -> bool:
 
         Returns True if Final[...] was present.
         """
-        if not s.unanalyzed_type or not self.is_final_type(s.unanalyzed_type):
+        final_type = self.unwrap_final_type(s.unanalyzed_type)
+        if final_type is None:
             return False
-        assert isinstance(s.unanalyzed_type, UnboundType)
-        if len(s.unanalyzed_type.args) > 1:
-            self.fail("Final[...] takes at most one type argument", s.unanalyzed_type)
+        if len(final_type.args) > 1:
+            self.fail("Final[...] takes at most one type argument", final_type)
         invalid_bare_final = False
-        if not s.unanalyzed_type.args:
+        if not final_type.args:
             s.type = None
             if isinstance(s.rvalue, TempNode) and s.rvalue.no_rhs:
                 invalid_bare_final = True
                 self.fail("Type in Final[...] can only be omitted if there is an initializer", s)
         else:
-            s.type = s.unanalyzed_type.args[0]
+            s.type = final_type.args[0]
 
         if s.type is not None and self.is_classvar(s.type):
             self.fail("Variable should not be annotated with both ClassVar and Final", s)
@@ -4713,13 +4713,18 @@ def is_classvar(self, typ: Type) -> bool:
             return False
         return sym.node.fullname == "typing.ClassVar"
 
-    def is_final_type(self, typ: Type | None) -> bool:
+    def unwrap_final_type(self, typ: Type | None) -> UnboundType | None:
+        if typ is None:
+            return None
+        typ = typ.resolve_string_annotation()
         if not isinstance(typ, UnboundType):
-            return False
+            return None
         sym = self.lookup_qualified(typ.name, typ)
         if not sym or not sym.node:
-            return False
-        return sym.node.fullname in FINAL_TYPE_NAMES
+            return None
+        if sym.node.fullname in FINAL_TYPE_NAMES:
+            return typ
+        return None
 
     def fail_invalid_classvar(self, context: Context) -> None:
         self.fail(message_registry.CLASS_VAR_OUTSIDE_OF_CLASS, context)

mypy/server/astmerge.py

@@ -507,7 +507,8 @@ def visit_typeddict_type(self, typ: TypedDictType) -> None:
         typ.fallback.accept(self)
 
     def visit_raw_expression_type(self, t: RawExpressionType) -> None:
-        pass
+        if t.node is not None:
+            t.node.accept(self)
 
     def visit_literal_type(self, typ: LiteralType) -> None:
         typ.fallback.accept(self)

mypy/stubutil.py

@@ -17,7 +17,16 @@
 from mypy.modulefinder import ModuleNotFoundReason
 from mypy.moduleinspect import InspectError, ModuleInspect
 from mypy.stubdoc import ArgSig, FunctionSig
-from mypy.types import AnyType, NoneType, Type, TypeList, TypeStrVisitor, UnboundType, UnionType
+from mypy.types import (
+    AnyType,
+    NoneType,
+    RawExpressionType,
+    Type,
+    TypeList,
+    TypeStrVisitor,
+    UnboundType,
+    UnionType,
+)
 
 # Modules that may fail when imported, or that may have side effects (fully qualified).
 NOT_IMPORTABLE_MODULES = ()
@@ -291,12 +300,11 @@ def args_str(self, args: Iterable[Type]) -> str:
         The main difference from list_str is the preservation of quotes for string
         arguments
         """
-        types = ["builtins.bytes", "builtins.str"]
         res = []
         for arg in args:
             arg_str = arg.accept(self)
-            if isinstance(arg, UnboundType) and arg.original_str_fallback in types:
-                res.append(f"'{arg_str}'")
+            if isinstance(arg, RawExpressionType):
+                res.append(repr(arg.literal_value))
             else:
                 res.append(arg_str)
         return ", ".join(res)

mypy/type_visitor.py

@@ -376,6 +376,8 @@ def visit_typeddict_type(self, t: TypedDictType) -> T:
         return self.query_types(t.items.values())
 
     def visit_raw_expression_type(self, t: RawExpressionType) -> T:
+        if t.node is not None:
+            return t.node.accept(self)
         return self.strategy([])
 
     def visit_literal_type(self, t: LiteralType) -> T:
@@ -516,6 +518,8 @@ def visit_typeddict_type(self, t: TypedDictType) -> bool:
         return self.query_types(list(t.items.values()))
 
     def visit_raw_expression_type(self, t: RawExpressionType) -> bool:
+        if t.node is not None:
+            return t.node.accept(self)
         return self.default
 
     def visit_literal_type(self, t: LiteralType) -> bool:

mypy/typeanal.py

@@ -1070,6 +1070,7 @@ def visit_callable_type(self, t: CallableType, nested: bool = True) -> Type:
         return ret
 
     def anal_type_guard(self, t: Type) -> Type | None:
+        t = t.resolve_string_annotation()
         if isinstance(t, UnboundType):
             sym = self.lookup_qualified(t.name, t)
             if sym is not None and sym.node is not None:
@@ -1088,6 +1089,7 @@ def anal_type_guard_arg(self, t: UnboundType, fullname: str) -> Type | None:
         return None
 
     def anal_type_is(self, t: Type) -> Type | None:
+        t = t.resolve_string_annotation()
         if isinstance(t, UnboundType):
             sym = self.lookup_qualified(t.name, t)
             if sym is not None and sym.node is not None:
@@ -1105,6 +1107,7 @@ def anal_type_is_arg(self, t: UnboundType, fullname: str) -> Type | None:
 
     def anal_star_arg_type(self, t: Type, kind: ArgKind, nested: bool) -> Type:
         """Analyze signature argument type for *args and **kwargs argument."""
+        t = t.resolve_string_annotation()
         if isinstance(t, UnboundType) and t.name and "." in t.name and not t.args:
             components = t.name.split(".")
             tvar_name = ".".join(components[:-1])
@@ -1195,6 +1198,8 @@ def visit_raw_expression_type(self, t: RawExpressionType) -> Type:
         # make signatures like "foo(x: 20) -> None" legal, we can change
         # this method so it generates and returns an actual LiteralType
         # instead.
+        if t.node is not None:
+            return t.node.accept(self)
 
         if self.report_invalid_types:
             if t.base_type_name in ("builtins.int", "builtins.bool"):
@@ -1455,6 +1460,7 @@ def analyze_callable_args(
         invalid_unpacks: list[Type] = []
         second_unpack_last = False
         for i, arg in enumerate(arglist.items):
+            arg = arg.resolve_string_annotation()
             if isinstance(arg, CallableArgument):
                 args.append(arg.typ)
                 names.append(arg.name)
@@ -1535,18 +1541,6 @@ def analyze_literal_type(self, t: UnboundType) -> Type:
         return UnionType.make_union(output, line=t.line)
 
     def analyze_literal_param(self, idx: int, arg: Type, ctx: Context) -> list[Type] | None:
-        # This UnboundType was originally defined as a string.
-        if isinstance(arg, UnboundType) and arg.original_str_expr is not None:
-            assert arg.original_str_fallback is not None
-            return [
-                LiteralType(
-                    value=arg.original_str_expr,
-                    fallback=self.named_type(arg.original_str_fallback),
-                    line=arg.line,
-                    column=arg.column,
-                )
-            ]
-
         # If arg is an UnboundType that was *not* originally defined as
         # a string, try expanding it in case it's a type alias or something.
         if isinstance(arg, UnboundType):
@@ -2528,7 +2522,8 @@ def visit_typeddict_type(self, t: TypedDictType) -> None:
         self.process_types(list(t.items.values()))
 
     def visit_raw_expression_type(self, t: RawExpressionType) -> None:
-        pass
+        if t.node is not None:
+            t.node.accept(self)
 
     def visit_literal_type(self, t: LiteralType) -> None:
         pass