fix(minifier): !!x is not idempotent in RemoveDeadCode

oxc-project · Jan 10, 2025 · 3c0501e · 3c0501e
1 parent 0550e81
commit 3c0501e
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Showing 2 changed files with 11 additions and 8 deletions.
diff --git a/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs b/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs
@@ -1951,6 +1951,7 @@ mod test {
 
     #[test]
     fn minimize_duplicate_nots() {
+        // test("!x", "x"); // TODO: in ExpressionStatement
         test("!!x", "x");
         test("!!!x", "!x");
         test("!!!!x", "x");

diff --git a/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs b/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs
@@ -341,12 +341,12 @@ impl<'a, 'b> PeepholeRemoveDeadCode {
                 {
                     Some(ctx.ast.statement_empty(SPAN))
                 }
-                // `typeof x.y` -> `x`, `!x` -> `x`, `void x` -> `x`...
+                // `typeof x.y` -> `x.y`, `void x` -> `x`
                 // `+0n` -> `Uncaught TypeError: Cannot convert a BigInt value to a number`
                 Expression::UnaryExpression(unary_expr)
-                    if !matches!(
+                    if matches!(
                         unary_expr.operator,
-                        UnaryOperator::Delete | UnaryOperator::UnaryPlus
+                        UnaryOperator::Typeof | UnaryOperator::Void
                     ) =>
                 {
                     Some(ctx.ast.statement_expression(
@@ -700,11 +700,13 @@ mod test {
         fold("void x?.y", "x?.y");
         fold("void x.y", "x.y");
         fold("void x.y.z()", "x.y.z()");
-        fold("!x", "x");
-        fold("!x?.y", "x?.y");
-        fold("!x.y", "x.y");
-        fold("!x.y.z()", "x.y.z()");
-        fold("-x.y.z()", "x.y.z()");
+
+        // Removed in `MinimizeConditions`, to keep this pass idempotent for DCE.
+        fold_same("!x");
+        fold_same("!x?.y");
+        fold_same("!x.y");
+        fold_same("!x.y.z()");
+        fold_same("-x.y.z()");
 
         fold_same("delete x");
         fold_same("delete x.y");