From b4ed564a35054234e9d4393ef538774a4ff10537 Mon Sep 17 00:00:00 2001
From: Dunqing <29533304+Dunqing@users.noreply.github.com>
Date: Fri, 13 Sep 2024 06:00:48 +0000
Subject: [PATCH] fix(linter/no-unused-vars): writes to members triggering
 false positive (#5744)

close: #5246

similar to #5722
---
 .../src/rules/eslint/no_unused_vars/tests/oxc.rs  | 10 ++++++++++
 .../src/rules/eslint/no_unused_vars/usage.rs      | 15 ++++++---------
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs b/crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs
index 2cae8b7bed9e5..332b2edd5718d 100644
--- a/crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs
+++ b/crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs
@@ -41,6 +41,16 @@ fn test_vars_simple() {
             "
                 const a = 0
                 obj[a]++;
+                obj[a] += 1;
+            ",
+            None,
+        ),
+        (
+            "
+                const obj = 0
+                obj.a++;
+                obj.a += 1;
+                obj.b.c++;
             ",
             None,
         ),
diff --git a/crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs b/crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs
index c1f81dadd1bd5..649bbf825c4cd 100644
--- a/crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs
+++ b/crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs
@@ -341,8 +341,12 @@ impl<'s, 'a> Symbol<'s, 'a> {
                 }
                 // When symbol is being assigned a new value, we flag the reference
                 // as only affecting itself until proven otherwise.
-                AstKind::UpdateExpression(_) | AstKind::SimpleAssignmentTarget(_) => {
-                    is_used_by_others = false;
+                AstKind::UpdateExpression(UpdateExpression { argument, .. })
+                | AstKind::SimpleAssignmentTarget(argument) => {
+                    // `a.b++` or `a[b] + 1` are not reassignment of `a`
+                    if !argument.is_member_expression() {
+                        is_used_by_others = false;
+                    }
                 }
                 // RHS usage when LHS != reference's symbol is definitely used by
                 // others
@@ -412,13 +416,6 @@ impl<'s, 'a> Symbol<'s, 'a> {
                 //    a = yield a // <- still considered used b/c it's propagated to the caller
                 // }
                 AstKind::YieldExpression(_) => return false,
-                AstKind::MemberExpression(MemberExpression::ComputedMemberExpression(computed)) => {
-                    // obj[a]++;
-                    //     ^ the reference is used as property
-                    if computed.expression.span().contains_inclusive(ref_span) {
-                        return false;
-                    }
-                }
                 _ => { /* continue up tree */ }
             }
         }