From f8875c1caa357829b993f3a459db840efbe47540 Mon Sep 17 00:00:00 2001
From: Lucas Duailibe <lucasds@gmail.com>
Date: Mon, 27 May 2019 13:58:26 -0300
Subject: [PATCH] Prevent parens around BindExpressions as properties of
 MemberExpressions (#6159)

---
 CHANGELOG.unreleased.md                           | 15 +++++++++++++++
 src/language-js/needs-parens.js                   |  4 +++-
 .../__snapshots__/jsfmt.spec.js.snap              |  8 ++++++++
 tests/bind_expressions/bind_parens.js             |  2 ++
 4 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.unreleased.md b/CHANGELOG.unreleased.md
index cc6c4bc5e..34391e127 100644
--- a/CHANGELOG.unreleased.md
+++ b/CHANGELOG.unreleased.md
@@ -399,6 +399,20 @@ new a::b();
 new (a::b)();
 ```
 
+### JavaScript: Prevent adding unnecessary parentheses around bind expressions in member expressions' properties ([#6159] by [@duailibe])
+
+<!-- prettier-ignore -->
+```js
+// Input
+f[a::b];
+
+// Output (Prettier stable)
+f[(a::b)];
+
+// Output (Prettier master);
+f[a::b];
+```
+
 [#5979]: https://github.com/prettier/prettier/pull/5979
 [#6086]: https://github.com/prettier/prettier/pull/6086
 [#6088]: https://github.com/prettier/prettier/pull/6088
@@ -418,6 +432,7 @@ new (a::b)();
 [#6148]: https://github.com/prettier/prettier/pull/6148
 [#6146]: https://github.com/prettier/prettier/pull/6146
 [#6152]: https://github.com/prettier/prettier/pull/6152
+[#6159]: https://github.com/prettier/prettier/pull/6159
 [@belochub]: https://github.com/belochub
 [@brainkim]: https://github.com/brainkim
 [@duailibe]: https://github.com/duailibe
diff --git a/src/language-js/needs-parens.js b/src/language-js/needs-parens.js
index f68bcb01d..1d88b910c 100644
--- a/src/language-js/needs-parens.js
+++ b/src/language-js/needs-parens.js
@@ -711,7 +711,9 @@ function needsParens(path, options) {
         (parent.type === "BindExpression" &&
           name === "callee" &&
           parent.callee === node) ||
-        parent.type === "MemberExpression" ||
+        (parent.type === "MemberExpression" &&
+          name === "object" &&
+          parent.object === node) ||
         (parent.type === "NewExpression" &&
           name === "callee" &&
           parent.callee === node)
diff --git a/tests/bind_expressions/__snapshots__/jsfmt.spec.js.snap b/tests/bind_expressions/__snapshots__/jsfmt.spec.js.snap
index 76704e03f..5b0ce3998 100644
--- a/tests/bind_expressions/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/bind_expressions/__snapshots__/jsfmt.spec.js.snap
@@ -79,6 +79,8 @@ b.c::d.e;
 (b::c::d).e;
 new (a::b)();
 new f(a::b);
+f[a::b];
+f[a::b()];
 
 =====================================output=====================================
 (a || b)::c;
@@ -113,6 +115,8 @@ b.c::d.e;
 (b::c::d).e;
 new (a::b)();
 new f(a::b);
+f[a::b];
+f[a::b()];
 
 ================================================================================
 `;
@@ -156,6 +160,8 @@ b.c::d.e;
 (b::c::d).e;
 new (a::b)();
 new f(a::b);
+f[a::b];
+f[a::b()];
 
 =====================================output=====================================
 ;(a || b)::c
@@ -190,6 +196,8 @@ b.c::d.e
 ;(b::c::d).e
 new (a::b)()
 new f(a::b)
+f[a::b]
+f[a::b()]
 
 ================================================================================
 `;
diff --git a/tests/bind_expressions/bind_parens.js b/tests/bind_expressions/bind_parens.js
index 36228ae7e..72f13543e 100644
--- a/tests/bind_expressions/bind_parens.js
+++ b/tests/bind_expressions/bind_parens.js
@@ -30,3 +30,5 @@ b.c::d.e;
 (b::c::d).e;
 new (a::b)();
 new f(a::b);
+f[a::b];
+f[a::b()];