Remove from_python_3 field from StrExpr

mypy/exprtotype.py

@@ -169,11 +169,7 @@ def expr_to_unanalyzed_type(
         )
     elif isinstance(expr, StrExpr):
         return parse_type_string(
-            expr.value,
-            "builtins.str",
-            expr.line,
-            expr.column,
-            assume_str_is_unicode=expr.from_python_3,
+            expr.value, "builtins.str", expr.line, expr.column, assume_str_is_unicode=True
         )
     elif isinstance(expr, BytesExpr):
         return parse_type_string(

mypy/literals.py

@@ -140,7 +140,7 @@ def visit_int_expr(self, e: IntExpr) -> Key:
         return ("Literal", e.value)
 
     def visit_str_expr(self, e: StrExpr) -> Key:
-        return ("Literal", e.value, e.from_python_3)
+        return ("Literal", e.value)
 
     def visit_bytes_expr(self, e: BytesExpr) -> Key:
         return ("Literal", e.value)

mypy/nodes.py

@@ -1568,28 +1568,13 @@ def accept(self, visitor: ExpressionVisitor[T]) -> T:
 class StrExpr(Expression):
     """String literal"""
 
-    __slots__ = ("value", "from_python_3")
+    __slots__ = ("value",)
 
     value: str  # '' by default
 
-    # Keeps track of whether this string originated from Python 2 source code vs
-    # Python 3 source code. We need to keep track of this information so we can
-    # correctly handle types that have "nested strings". For example, consider this
-    # type alias, where we have a forward reference to a literal type:
-    #
-    #     Alias = List["Literal['foo']"]
-    #
-    # When parsing this, we need to know whether the outer string and alias came from
-    # Python 2 code vs Python 3 code so we can determine whether the inner `Literal['foo']`
-    # is meant to be `Literal[u'foo']` or `Literal[b'foo']`.
-    #
-    # This field keeps track of that information.
-    from_python_3: bool
-
-    def __init__(self, value: str, from_python_3: bool = False) -> None:
+    def __init__(self, value: str) -> None:
         super().__init__()
         self.value = value
-        self.from_python_3 = from_python_3
 
     def accept(self, visitor: ExpressionVisitor[T]) -> T:
         return visitor.visit_str_expr(self)

mypy/treetransform.py

@@ -386,7 +386,7 @@ def visit_int_expr(self, node: IntExpr) -> IntExpr:
         return IntExpr(node.value)
 
     def visit_str_expr(self, node: StrExpr) -> StrExpr:
-        return StrExpr(node.value, node.from_python_3)
+        return StrExpr(node.value)
 
     def visit_bytes_expr(self, node: BytesExpr) -> BytesExpr:
         return BytesExpr(node.value)