Binops with parentheses keep their parentheses

compiler/fmt/src/expr.rs

@@ -133,7 +133,7 @@ impl<'a> Formattable<'a> for Expr<'a> {
                 }
             }
             ParensAround(sub_expr) => {
-                if parens == Parens::NotNeeded {
+                if parens == Parens::NotNeeded && !sub_expr_requests_parens(&sub_expr) {
                     sub_expr.format_with_options(buf, Parens::NotNeeded, Newlines::Yes, indent);
                 } else {
                     buf.push('(');
@@ -319,7 +319,7 @@ impl<'a> Formattable<'a> for Expr<'a> {
                 buf.push_str(key);
             }
             Access(expr, key) => {
-                expr.format_with_options(buf, parens, Newlines::Yes, indent);
+                expr.format_with_options(buf, Parens::InApply, Newlines::Yes, indent);
                 buf.push('.');
                 buf.push_str(key);
             }
@@ -398,6 +398,8 @@ fn fmt_bin_ops<'a>(
         || lefts.iter().any(|(expr, _)| expr.value.is_multiline());
 
     for (loc_left_side, loc_bin_op) in lefts {
+        let bin_op = loc_bin_op.value;
+
         loc_left_side.format_with_options(buf, apply_needs_parens, Newlines::No, indent);
 
         if is_multiline {
@@ -406,7 +408,7 @@ fn fmt_bin_ops<'a>(
             buf.push(' ');
         }
 
-        push_op(buf, loc_bin_op.value);
+        push_op(buf, bin_op);
 
         buf.push(' ');
     }
@@ -1050,3 +1052,32 @@ fn format_field_multiline<'a, T>(
         }
     }
 }
+
+fn sub_expr_requests_parens(expr: &Expr<'_>) -> bool {
+    match expr {
+        Expr::BinOps(left_side, _) => {
+            left_side
+                .iter()
+                .any(|(_, loc_bin_op)| match loc_bin_op.value {
+                    BinOp::Caret
+                    | BinOp::Star
+                    | BinOp::Slash
+                    | BinOp::DoubleSlash
+                    | BinOp::Percent
+                    | BinOp::DoublePercent
+                    | BinOp::Plus
+                    | BinOp::Minus
+                    | BinOp::Equals
+                    | BinOp::NotEquals
+                    | BinOp::LessThan
+                    | BinOp::GreaterThan
+                    | BinOp::LessThanOrEq
+                    | BinOp::GreaterThanOrEq
+                    | BinOp::And
+                    | BinOp::Or => true,
+                    BinOp::Pizza | BinOp::Assignment | BinOp::HasType | BinOp::Backpassing => false,
+                })
+        }
+        _ => false,
+    }
+}

compiler/fmt/tests/test_fmt.rs

@@ -2249,7 +2249,7 @@ mod test_fmt {
     }
 
     #[test]
-    fn precedence_conflict_exponents() {
+    fn binop_parens() {
         expr_formats_same(indoc!(
             r#"
             if 4 == (6 ^ 6 ^ 7 ^ 8) then
@@ -2258,6 +2258,39 @@ mod test_fmt {
                 "Naturally"
             "#
         ));
+
+        expr_formats_same(indoc!(
+            r#"
+            if 5 == 1 ^ 1 ^ 1 ^ 1 then
+                "Not buying it"
+            else
+                "True"
+            "#
+        ));
+
+        expr_formats_to(
+            indoc!(
+                r#"
+            if (1 == 1)
+                && (2 == 1) && (3 == 2) then
+                "true"
+            else
+                "false"
+            "#
+            ),
+            indoc!(
+                r#"
+            if
+                (1 == 1)
+                    && (2 == 1)
+                    && (3 == 2)
+            then
+                "true"
+            else
+                "false"
+            "#
+            ),
+        );
     }
 
     #[test]