Do not wrap implicitly concatenated strings used as func args in pare…

…ns (#3640)

CHANGES.md

@@ -14,6 +14,9 @@
 
 <!-- Changes that affect Black's preview style -->
 
+- Implicitly concatenated strings used as function args are no longer wrapped inside
+  parentheses (#3640)
+
 ### Configuration
 
 <!-- Changes to how Black can be configured -->

src/black/__init__.py

@@ -503,10 +503,8 @@ def main(  # noqa: C901
             user_level_config = str(find_user_pyproject_toml())
             if config == user_level_config:
                 out(
-                    (
-                        "Using configuration from user-level config at "
-                        f"'{user_level_config}'."
-                    ),
+                    "Using configuration from user-level config at "
+                    f"'{user_level_config}'.",
                     fg="blue",
                 )
             elif config_source in (

src/black/mode.py

@@ -188,10 +188,8 @@ class Mode:
     def __post_init__(self) -> None:
         if self.experimental_string_processing:
             warn(
-                (
-                    "`experimental string processing` has been included in `preview`"
-                    " and deprecated. Use `preview` instead."
-                ),
+                "`experimental string processing` has been included in `preview`"
+                " and deprecated. Use `preview` instead.",
                 Deprecated,
             )
 

src/black/parsing.py

@@ -29,11 +29,9 @@
 except ImportError:
     if sys.version_info < (3, 8) and not _IS_PYPY:
         print(
-            (
-                "The typed_ast package is required but not installed.\n"
-                "You can upgrade to Python 3.8+ or install typed_ast with\n"
-                "`python3 -m pip install typed-ast`."
-            ),
+            "The typed_ast package is required but not installed.\n"
+            "You can upgrade to Python 3.8+ or install typed_ast with\n"
+            "`python3 -m pip install typed-ast`.",
             file=sys.stderr,
         )
         sys.exit(1)

src/black/trans.py

@@ -1186,19 +1186,33 @@ def _prefer_paren_wrap_match(LL: List[Leaf]) -> Optional[int]:
         if LL[0].type != token.STRING:
             return None
 
-        # If the string is surrounded by commas (or is the first/last child)...
-        prev_sibling = LL[0].prev_sibling
-        next_sibling = LL[0].next_sibling
-        if not prev_sibling and not next_sibling and parent_type(LL[0]) == syms.atom:
-            # If it's an atom string, we need to check the parent atom's siblings.
-            parent = LL[0].parent
-            assert parent is not None  # For type checkers.
-            prev_sibling = parent.prev_sibling
-            next_sibling = parent.next_sibling
-        if (not prev_sibling or prev_sibling.type == token.COMMA) and (
-            not next_sibling or next_sibling.type == token.COMMA
+        matching_nodes = [
+            syms.listmaker,
+            syms.dictsetmaker,
+            syms.testlist_gexp,
+        ]
+        # If the string is an immediate child of a list/set/tuple literal...
+        if (
+            parent_type(LL[0]) in matching_nodes
+            or parent_type(LL[0].parent) in matching_nodes
         ):
-            return 0
+            # And the string is surrounded by commas (or is the first/last child)...
+            prev_sibling = LL[0].prev_sibling
+            next_sibling = LL[0].next_sibling
+            if (
+                not prev_sibling
+                and not next_sibling
+                and parent_type(LL[0]) == syms.atom
+            ):
+                # If it's an atom string, we need to check the parent atom's siblings.
+                parent = LL[0].parent
+                assert parent is not None  # For type checkers.
+                prev_sibling = parent.prev_sibling
+                next_sibling = parent.next_sibling
+            if (not prev_sibling or prev_sibling.type == token.COMMA) and (
+                not next_sibling or next_sibling.type == token.COMMA
+            ):
+                return 0
 
         return None
 
@@ -1811,8 +1825,9 @@ class StringParenWrapper(BaseStringSplitter, CustomSplitMapMixin):
         * The line is an lambda expression and the value is a string.
             OR
         * The line starts with an "atom" string that prefers to be wrapped in
-        parens. It's preferred to be wrapped when the string is surrounded by
-        commas (or is the first/last child).
+        parens. It's preferred to be wrapped when it's is an immediate child of
+        a list/set/tuple literal, AND the string is surrounded by commas (or is
+        the first/last child).
 
     Transformations:
         The chosen string is wrapped in parentheses and then split at the LPAR.

tests/data/preview/cantfit.py

@@ -79,14 +79,10 @@
 )
 # long arguments
 normal_name = normal_function_name(
-    (
-        "but with super long string arguments that on their own exceed the line limit"
-        " so there's no way it can ever fit"
-    ),
-    (
-        "eggs with spam and eggs and spam with eggs with spam and eggs and spam with"
-        " eggs with spam and eggs and spam with eggs"
-    ),
+    "but with super long string arguments that on their own exceed the line limit so"
+    " there's no way it can ever fit",
+    "eggs with spam and eggs and spam with eggs with spam and eggs and spam with eggs"
+    " with spam and eggs and spam with eggs",
     this_is_a_ridiculously_long_name_and_nobody_in_their_right_mind_would_use_one_like_it=0,
 )
 string_variable_name = "a string that is waaaaaaaayyyyyyyy too long, even in parens, there's nothing you can do"  # noqa

tests/data/preview/long_strings.py

@@ -323,10 +323,8 @@ def foo():
 y = "Short string"
 
 print(
-    (
-        "This is a really long string inside of a print statement with extra arguments"
-        " attached at the end of it."
-    ),
+    "This is a really long string inside of a print statement with extra arguments"
+    " attached at the end of it.",
     x,
     y,
     z,
@@ -501,15 +499,13 @@ def foo():
 )
 
 bad_split_func1(
-    (
-        "But what should happen when code has already "
-        "been formatted but in the wrong way? Like "
-        "with a space at the end instead of the "
-        "beginning. Or what about when it is split too "
-        "soon? In the case of a split that is too "
-        "short, black will try to honer the custom "
-        "split."
-    ),
+    "But what should happen when code has already "
+    "been formatted but in the wrong way? Like "
+    "with a space at the end instead of the "
+    "beginning. Or what about when it is split too "
+    "soon? In the case of a split that is too "
+    "short, black will try to honer the custom "
+    "split.",
     xxx,
     yyy,
     zzz,
@@ -612,11 +608,9 @@ def foo():
 )
 
 arg_comment_string = print(
-    (  # This comment gets thrown to the top.
-        "Long lines with inline comments which are apart of (and not the only member"
-        " of) an argument list should have their comments appended to the reformatted"
-        " string's enclosing left parentheses."
-    ),
+    "Long lines with inline comments which are apart of (and not the only member of) an"
+    " argument list should have their comments appended to the reformatted string's"
+    " enclosing left parentheses.",  # This comment gets thrown to the top.
     "Arg #2",
     "Arg #3",
     "Arg #4",
@@ -676,31 +670,23 @@ def foo():
 )
 
 func_with_bad_comma(
-    (
-        "This is a really long string argument to a function that has a trailing comma"
-        " which should NOT be there."
-    ),
+    "This is a really long string argument to a function that has a trailing comma"
+    " which should NOT be there.",
 )
 
 func_with_bad_comma(
-    (  # comment after comma
-        "This is a really long string argument to a function that has a trailing comma"
-        " which should NOT be there."
-    ),
+    "This is a really long string argument to a function that has a trailing comma"
+    " which should NOT be there.",  # comment after comma
 )
 
 func_with_bad_comma(
-    (
-        "This is a really long string argument to a function that has a trailing comma"
-        " which should NOT be there."
-    ),
+    "This is a really long string argument to a function that has a trailing comma"
+    " which should NOT be there.",
 )
 
 func_with_bad_comma(
-    (  # comment after comma
-        "This is a really long string argument to a function that has a trailing comma"
-        " which should NOT be there."
-    ),
+    "This is a really long string argument to a function that has a trailing comma"
+    " which should NOT be there.",  # comment after comma
 )
 
 func_with_bad_parens_that_wont_fit_in_one_line(

tests/data/preview/long_strings__regression.py

@@ -715,11 +715,9 @@ class A:
     def foo():
         some_func_call(
             "xxxxxxxxxx",
-            (
-                "xx {xxxxxxxxxxx}/xxxxxxxxxxx.xxx xxxx.xxx && xxxxxx -x "
-                '"xxxx xxxxxxx xxxxxx xxxx; xxxx xxxxxx_xxxxx xxxxxx xxxx; '
-                "xxxx.xxxx_xxxxxx(['xxxx.xxx'], xxxx.xxxxxxx().xxxxxxxxxx)\" "
-            ),
+            "xx {xxxxxxxxxxx}/xxxxxxxxxxx.xxx xxxx.xxx && xxxxxx -x "
+            '"xxxx xxxxxxx xxxxxx xxxx; xxxx xxxxxx_xxxxx xxxxxx xxxx; '
+            "xxxx.xxxx_xxxxxx(['xxxx.xxx'], xxxx.xxxxxxx().xxxxxxxxxx)\" ",
             None,
             ("xxxxxxxxxxx",),
         ),
@@ -728,11 +726,9 @@ def foo():
 class A:
     def foo():
         some_func_call(
-            (
-                "xx {xxxxxxxxxxx}/xxxxxxxxxxx.xxx xxxx.xxx && xxxxxx -x "
-                "xxxx, ('xxxxxxx xxxxxx xxxx, xxxx') xxxxxx_xxxxx xxxxxx xxxx; "
-                "xxxx.xxxx_xxxxxx(['xxxx.xxx'], xxxx.xxxxxxx().xxxxxxxxxx)\" "
-            ),
+            "xx {xxxxxxxxxxx}/xxxxxxxxxxx.xxx xxxx.xxx && xxxxxx -x "
+            "xxxx, ('xxxxxxx xxxxxx xxxx, xxxx') xxxxxx_xxxxx xxxxxx xxxx; "
+            "xxxx.xxxx_xxxxxx(['xxxx.xxx'], xxxx.xxxxxxx().xxxxxxxxxx)\" ",
             None,
             ("xxxxxxxxxxx",),
         ),
@@ -850,10 +846,8 @@ def foo():
 )
 
 lpar_and_rpar_have_comments = func_call(  # LPAR Comment
-    (  # Comma Comment
-        "Long really ridiculous type of string that shouldn't really even exist at all."
-        " I mean commmme onnn!!!"
-    ),
+    "Long really ridiculous type of string that shouldn't really even exist at all. I"
+    " mean commmme onnn!!!",  # Comma Comment
 )  # RPAR Comment
 
 cmd_fstring = (