Add T_STRINGS feature

Author: tusharsadhwani

src/black/__init__.py

@@ -1248,6 +1248,7 @@ def _format_str_once(
         for feature in {
             Feature.PARENTHESIZED_CONTEXT_MANAGERS,
             Feature.UNPARENTHESIZED_EXCEPT_TYPES,
+            Feature.T_STRINGS,
         }
         if supports_feature(versions, feature)
     }
@@ -1364,6 +1365,8 @@ def get_features_used(  # noqa: C901
     for n in node.pre_order():
         if n.type == token.FSTRING_START:
             features.add(Feature.F_STRINGS)
+        elif n.type == token.TSTRING_START:
+            features.add(Feature.T_STRINGS)
         elif (
             n.type == token.RBRACE
             and n.parent is not None

src/black/mode.py

@@ -52,9 +52,10 @@ class Feature(Enum):
     DEBUG_F_STRINGS = 16
     PARENTHESIZED_CONTEXT_MANAGERS = 17
     TYPE_PARAMS = 18
-    FSTRING_PARSING = 19
+    # FSTRING_PARSING = 19  # unused
     TYPE_PARAM_DEFAULTS = 20
     UNPARENTHESIZED_EXCEPT_TYPES = 21
+    T_STRINGS = 22
     FORCE_OPTIONAL_PARENTHESES = 50
 
     # __future__ flags
@@ -165,7 +166,6 @@ class Feature(Enum):
         Feature.EXCEPT_STAR,
         Feature.VARIADIC_GENERICS,
         Feature.TYPE_PARAMS,
-        Feature.FSTRING_PARSING,
     },
     TargetVersion.PY313: {
         Feature.F_STRINGS,
@@ -185,7 +185,6 @@ class Feature(Enum):
         Feature.EXCEPT_STAR,
         Feature.VARIADIC_GENERICS,
         Feature.TYPE_PARAMS,
-        Feature.FSTRING_PARSING,
         Feature.TYPE_PARAM_DEFAULTS,
     },
     TargetVersion.PY314: {
@@ -206,9 +205,9 @@ class Feature(Enum):
         Feature.EXCEPT_STAR,
         Feature.VARIADIC_GENERICS,
         Feature.TYPE_PARAMS,
-        Feature.FSTRING_PARSING,
         Feature.TYPE_PARAM_DEFAULTS,
         Feature.UNPARENTHESIZED_EXCEPT_TYPES,
+        Feature.T_STRINGS,
     },
 }
 

tests/test_black.py

@@ -898,6 +898,9 @@ def test_get_features_used(self) -> None:
         self.check_features_used(
             "with ((a, ((b as c)))): pass", {Feature.PARENTHESIZED_CONTEXT_MANAGERS}
         )
+        self.check_features_used(
+            "x = t'foo {f'bar'}'", {Feature.T_STRINGS, Feature.F_STRINGS}
+        )
 
     def check_features_used(self, source: str, expected: set[Feature]) -> None:
         node = black.lib2to3_parse(source)