From bb61f10399e5243f57da0eeab2e18aac8ef6e361 Mon Sep 17 00:00:00 2001
From: Boshen <boshenc@gmail.com>
Date: Fri, 1 Dec 2023 21:29:56 +0800
Subject: [PATCH] feat(prettier): handle parens for `(x % y) % z` (#1603)

---
 crates/oxc_prettier/src/binaryish.rs        | 30 ++++++++++++++-------
 crates/oxc_prettier/src/needs_parens.rs     |  6 +++++
 tasks/prettier_conformance/prettier.snap.md |  3 +--
 3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/crates/oxc_prettier/src/binaryish.rs b/crates/oxc_prettier/src/binaryish.rs
index 3b56a778e..260a50715 100644
--- a/crates/oxc_prettier/src/binaryish.rs
+++ b/crates/oxc_prettier/src/binaryish.rs
@@ -84,26 +84,36 @@ impl BinaryishOperator {
             return false;
         }
 
-        if matches!(parent_op, Self::BinaryOperator(op) if op == BinaryOperator::Exponential) {
+        let Self::BinaryOperator(op) = self else { return true };
+
+        let Self::BinaryOperator(parent_op) = parent_op else { return true };
+
+        // ** is right-associative
+        // x ** y ** z --> x ** (y ** z)
+        if parent_op == BinaryOperator::Exponential {
             return false;
         }
 
-        if matches!(parent_op, Self::BinaryOperator(op) if op.is_equality())
-            && matches!(self, Self::BinaryOperator(op) if op.is_equality())
+        // x == y == z --> (x == y) == z
+        if parent_op.is_equality() && op.is_equality() {
+            return false;
+        }
+
+        // x * y % z --> (x * y) % z
+        if (op == BinaryOperator::Remainder && parent_op.is_multiplicative())
+            || (parent_op == BinaryOperator::Remainder && op.is_multiplicative())
         {
             return false;
         }
 
-        if self != parent_op
-            && matches!(parent_op, Self::BinaryOperator(op) if op.is_multiplicative())
-            && matches!(self, Self::BinaryOperator(op) if op.is_multiplicative())
-        {
+        // x * y / z --> (x * y) / z
+        // x / y * z --> (x / y) * z
+        if op != parent_op && parent_op.is_multiplicative() && op.is_multiplicative() {
             return false;
         }
 
-        if matches!(parent_op, Self::BinaryOperator(op) if op.is_bitshift())
-            && matches!(self, Self::BinaryOperator(op) if op.is_bitshift())
-        {
+        // x << y << z --> (x << y) << z
+        if parent_op.is_bitshift() && op.is_bitshift() {
             return false;
         }
 
diff --git a/crates/oxc_prettier/src/needs_parens.rs b/crates/oxc_prettier/src/needs_parens.rs
index 88adf7e52..6aaf80fb6 100644
--- a/crates/oxc_prettier/src/needs_parens.rs
+++ b/crates/oxc_prettier/src/needs_parens.rs
@@ -452,6 +452,12 @@ impl<'a> Prettier<'a> {
             return true;
         }
 
+        if parent_precedence < precedence
+            && matches!(operator, BinaryishOperator::BinaryOperator(op) if op == BinaryOperator::Remainder)
+        {
+            return matches!(parent_operator, BinaryishOperator::BinaryOperator(op) if matches!(op, BinaryOperator::Addition | BinaryOperator::Subtraction));
+        }
+
         // Add parenthesis when working with bitwise operators
         // It's not strictly needed but helps with code understanding
         if matches!(parent_kind, AstKind::BinaryExpression(binary_expr) if binary_expr.operator.is_bitwise())
diff --git a/tasks/prettier_conformance/prettier.snap.md b/tasks/prettier_conformance/prettier.snap.md
index 9c8b800f2..f4add2de7 100644
--- a/tasks/prettier_conformance/prettier.snap.md
+++ b/tasks/prettier_conformance/prettier.snap.md
@@ -1,4 +1,4 @@
-Compatibility: 212/561 (37.79%)
+Compatibility: 215/561 (38.32%)
 
 # Failed
 
@@ -75,7 +75,6 @@ Compatibility: 212/561 (37.79%)
 * binary-expressions/inline-jsx.js
 * binary-expressions/inline-object-array.js
 * binary-expressions/jsx_parent.js
-* binary-expressions/math.js
 * binary-expressions/return.js
 * binary-expressions/short-right.js
 * binary-expressions/test.js