Wrap arithmetic and binary arithmetic expressions in invisible parentheses (#2001)

src/black/__init__.py

@@ -2049,6 +2049,8 @@ def visit_suite(self, node: Node) -> Iterator[Line]:
 
     def visit_simple_stmt(self, node: Node) -> Iterator[Line]:
         """Visit a statement without nested statements."""
+        if first_child_is_arith(node):
+            wrap_in_parentheses(node, node.children[0], visible=False)
         is_suite_like = node.parent and node.parent.type in STATEMENT
         if is_suite_like:
             if self.mode.is_pyi and is_stub_body(node):
@@ -5613,6 +5615,17 @@ def unwrap_singleton_parenthesis(node: LN) -> Optional[LN]:
     return wrapped
 
 
+def first_child_is_arith(node: Node) -> bool:
+    """Whether first child is an arithmetic or a binary arithmetic expression"""
+    expr_types = {
+        syms.arith_expr,
+        syms.shift_expr,
+        syms.xor_expr,
+        syms.and_expr,
+    }
+    return bool(node.children and node.children[0].type in expr_types)
+
+
 def wrap_in_parentheses(parent: Node, child: LN, *, visible: bool = True) -> None:
     """Wrap `child` in parentheses.
 

tests/data/expression.diff

@@ -166,7 +166,7 @@
  slice[0:1:2]
  slice[:]
  slice[:-1]
-@@ -137,113 +173,180 @@
+@@ -137,118 +173,199 @@
  numpy[-(c + 1) :, d]
  numpy[:, l[-2]]
  numpy[:, ::-1]
@@ -346,6 +346,9 @@
 -    return True
 -if (
 -    ~ aaaaaaaaaaaaaaaa.a + aaaaaaaaaaaaaaaa.b - aaaaaaaaaaaaaaaa.c * aaaaaaaaaaaaaaaa.d @ aaaaaaaaaaaaaaaa.e | aaaaaaaaaaaaaaaa.f & aaaaaaaaaaaaaaaa.g % aaaaaaaaaaaaaaaa.h ^ aaaaaaaaaaaaaaaa.i << aaaaaaaaaaaaaaaa.k >> aaaaaaaaaaaaaaaa.l ** aaaaaaaaaaaaaaaa.m // aaaaaaaaaaaaaaaa.n
+-):
+-    return True
+-aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa - aaaaaaaaaaaaaaaa * (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa) / (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
 +a = (
 +    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
 +    in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
@@ -417,7 +420,28 @@
 +    ^ aaaaaaaaaaaaaaaa.i
 +    << aaaaaaaaaaaaaaaa.k
 +    >> aaaaaaaaaaaaaaaa.l ** aaaaaaaaaaaaaaaa.m // aaaaaaaaaaaaaaaa.n
- ):
++):
-     return True
++    return True
++(
++    aaaaaaaaaaaaaaaa
++    + aaaaaaaaaaaaaaaa
++    - aaaaaaaaaaaaaaaa
++    * (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
++    / (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
++)
+ aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa
+-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa >> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++(
++    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++    >> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++    << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++)
+ bbbb >> bbbb * bbbb
+-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ^bbbb.a & aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa^aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++(
++    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++    ^ bbbb.a & aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++    ^ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++)
  last_call()
  # standalone comment at ENDMARKER

tests/data/expression.py

@@ -245,6 +245,11 @@ async def f():
     ~ aaaaaaaaaaaaaaaa.a + aaaaaaaaaaaaaaaa.b - aaaaaaaaaaaaaaaa.c * aaaaaaaaaaaaaaaa.d @ aaaaaaaaaaaaaaaa.e | aaaaaaaaaaaaaaaa.f & aaaaaaaaaaaaaaaa.g % aaaaaaaaaaaaaaaa.h ^ aaaaaaaaaaaaaaaa.i << aaaaaaaaaaaaaaaa.k >> aaaaaaaaaaaaaaaa.l ** aaaaaaaaaaaaaaaa.m // aaaaaaaaaaaaaaaa.n
 ):
     return True
+aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa - aaaaaaaaaaaaaaaa * (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa) / (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
+aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa
+aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa >> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+bbbb >> bbbb * bbbb
+aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ^bbbb.a & aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa^aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 last_call()
 # standalone comment at ENDMARKER
 
@@ -602,5 +607,24 @@ async def f():
     >> aaaaaaaaaaaaaaaa.l ** aaaaaaaaaaaaaaaa.m // aaaaaaaaaaaaaaaa.n
 ):
     return True
+(
+    aaaaaaaaaaaaaaaa
+    + aaaaaaaaaaaaaaaa
+    - aaaaaaaaaaaaaaaa
+    * (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
+    / (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
+)
+aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa
+(
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    >> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+)
+bbbb >> bbbb * bbbb
+(
+    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    ^ bbbb.a & aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+    ^ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+)
 last_call()
 # standalone comment at ENDMARKER

tests/data/expression_skip_magic_trailing_comma.diff

@@ -149,7 +149,7 @@
  slice[0:1:2]
  slice[:]
  slice[:-1]
-@@ -137,113 +156,178 @@
+@@ -137,118 +156,197 @@
  numpy[-(c + 1) :, d]
  numpy[:, l[-2]]
  numpy[:, ::-1]
@@ -327,6 +327,9 @@
 -    return True
 -if (
 -    ~ aaaaaaaaaaaaaaaa.a + aaaaaaaaaaaaaaaa.b - aaaaaaaaaaaaaaaa.c * aaaaaaaaaaaaaaaa.d @ aaaaaaaaaaaaaaaa.e | aaaaaaaaaaaaaaaa.f & aaaaaaaaaaaaaaaa.g % aaaaaaaaaaaaaaaa.h ^ aaaaaaaaaaaaaaaa.i << aaaaaaaaaaaaaaaa.k >> aaaaaaaaaaaaaaaa.l ** aaaaaaaaaaaaaaaa.m // aaaaaaaaaaaaaaaa.n
+-):
+-    return True
+-aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa - aaaaaaaaaaaaaaaa * (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa) / (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
 +a = (
 +    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
 +    in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
@@ -398,7 +401,28 @@
 +    ^ aaaaaaaaaaaaaaaa.i
 +    << aaaaaaaaaaaaaaaa.k
 +    >> aaaaaaaaaaaaaaaa.l ** aaaaaaaaaaaaaaaa.m // aaaaaaaaaaaaaaaa.n
- ):
++):
-     return True
++    return True
++(
++    aaaaaaaaaaaaaaaa
++    + aaaaaaaaaaaaaaaa
++    - aaaaaaaaaaaaaaaa
++    * (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
++    / (aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa)
++)
+ aaaaaaaaaaaaaaaa + aaaaaaaaaaaaaaaa
+-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa >> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++(
++    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++    >> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++    << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++)
+ bbbb >> bbbb * bbbb
+-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ^bbbb.a & aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa^aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++(
++    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++    ^ bbbb.a & aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++    ^ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
++)
  last_call()
  # standalone comment at ENDMARKER