fix(semantic): implicit return UpdateExpression in `ArrowFunctionEx…

…pression` does not as read reference (#5161) close: #5158 close: #5156
oxc-project · Aug 26, 2024 · 293413f · 293413f
1 parent 04c5ca2
commit 293413f
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diff --git a/crates/oxc_semantic/src/builder.rs b/crates/oxc_semantic/src/builder.rs
@@ -2013,7 +2013,19 @@ impl<'a> SemanticBuilder<'a> {
         for node in self.nodes.iter_parents(self.current_node_id).skip(1) {
             return match node.kind() {
                 AstKind::ParenthesizedExpression(_) => continue,
-                AstKind::ExpressionStatement(_) => false,
+                AstKind::ExpressionStatement(_) => {
+                    if self.current_scope_flags().is_arrow() {
+                        if let Some(node) = self.nodes.iter_parents(node.id()).nth(2) {
+                            // (x) => x++
+                            //        ^^^ implicit return, we need to treat `x` as a read reference
+                            if matches!(node.kind(), AstKind::ArrowFunctionExpression(arrow) if arrow.expression)
+                            {
+                                return true;
+                            }
+                        }
+                    }
+                    false
+                }
                 _ => true,
             };
         }

diff --git a/crates/oxc_semantic/tests/integration/symbols.rs b/crates/oxc_semantic/tests/integration/symbols.rs
@@ -372,3 +372,57 @@ fn test_ts_interface_heritage() {
     .has_number_of_references(1)
     .test();
 }
+
+#[test]
+fn test_arrow_implicit_return() {
+    SemanticTester::js("let i = 0; const x = () => i")
+        .has_root_symbol("i")
+        .has_number_of_reads(1)
+        .has_number_of_writes(0)
+        .test();
+
+    SemanticTester::js("let i = 0; const x = () => ++i")
+        .has_root_symbol("i")
+        .has_number_of_reads(1)
+        .has_number_of_writes(1)
+        .test();
+
+    SemanticTester::js("let i = 0; const x = () => { ++i }")
+        .has_root_symbol("i")
+        .has_number_of_reads(0)
+        .has_number_of_writes(1)
+        .test();
+
+    SemanticTester::js("let i = 0; const x = () => (0, ++i)")
+        .has_root_symbol("i")
+        .has_number_of_reads(1)
+        .has_number_of_writes(1)
+        .test();
+
+    SemanticTester::js("let i = 0; const x = () => (++i, 0)")
+        .has_root_symbol("i")
+        .has_number_of_reads(1)
+        .has_number_of_writes(1)
+        .test();
+
+    SemanticTester::js("let i = 1; const foo = () => () => { i++ }")
+        .has_root_symbol("i")
+        .has_number_of_reads(0)
+        .has_number_of_writes(1)
+        .test();
+}
+
+#[test]
+fn test_arrow_explicit_return() {
+    SemanticTester::js("let i = 0; const x = () => { return i }")
+        .has_root_symbol("i")
+        .has_number_of_reads(1)
+        .has_number_of_writes(0)
+        .test();
+
+    SemanticTester::js("let i = 0; const x = () => { return ++i }")
+        .has_root_symbol("i")
+        .has_number_of_reads(1)
+        .has_number_of_writes(1)
+        .test();
+}