fix(es/minifier): Avoid generating reserved mangling names (#9710)

**Description:**

Copy user defined `reserved` to `preserved_symbols`, so the generated name will be skipped by
https://github.com/swc-project/swc/blob/56e83e2392c8ae89ce3854b36c64fed5e90f14c4/crates/swc_ecma_transforms_base/src/rename/analyzer/scope.rs#L296


**Related issue:**

 - Closes #9650

Author: CPunisher

.changeset/spicy-otters-rule.md

@@ -0,0 +1,5 @@
+---
+swc_ecma_transforms_base: major
+---
+
+fix(es/minifier): Avoid generating reserved mangling names

crates/swc_ecma_minifier/src/lib.rs

@@ -230,7 +230,7 @@ pub fn optimize(
         let _timer = timer!("mangle names");
         // TODO: base54.reset();
 
-        let preserved = idents_to_preserve(mangle.clone(), marks, &n);
+        let preserved = idents_to_preserve(mangle, marks, &n);
 
         let chars = CharFreq::compute(
             &n,
@@ -241,7 +241,7 @@ pub fn optimize(
 
         mangle_names(
             &mut n,
-            mangle.clone(),
+            mangle,
             preserved,
             chars,
             extra.top_level_mark,

crates/swc_ecma_minifier/src/pass/mangle_names/mod.rs

@@ -18,7 +18,7 @@ mod private_name;
 
 pub(crate) fn mangle_names(
     program: &mut Program,
-    options: MangleOptions,
+    options: &MangleOptions,
     preserved: FxHashSet<Id>,
     chars: Base54Chars,
     top_level_mark: Mark,
@@ -48,6 +48,7 @@ pub(crate) fn mangle_names(
             keep_class_names: options.keep_class_names,
             top_level_mark,
             ignore_eval: options.eval,
+            preserved_symbols: options.reserved.iter().cloned().collect(),
             ..Default::default()
         },
         ManglingRenamer {

crates/swc_ecma_minifier/src/pass/mangle_names/preserver.rs

@@ -7,12 +7,12 @@ use swc_ecma_visit::{noop_visit_type, Visit, VisitWith};
 use crate::option::MangleOptions;
 
 /// Returns `(preserved, unresolved)`
-pub(crate) fn idents_to_preserve<N>(options: MangleOptions, marks: Marks, n: &N) -> FxHashSet<Id>
+pub(crate) fn idents_to_preserve<N>(options: &MangleOptions, marks: Marks, n: &N) -> FxHashSet<Id>
 where
     N: for<'a> VisitWith<Preserver<'a>>,
 {
     let mut v = Preserver {
-        options: &options,
+        options,
         preserved: Default::default(),
         should_preserve: false,
         in_top_level: false,

crates/swc_ecma_minifier/tests/fixture/issues/9650/input.js

@@ -0,0 +1,95 @@
+export function logVariables(
+    var1,
+    var2,
+    var3,
+    var4,
+    var5,
+    var6,
+    var7,
+    var8,
+    var9,
+    var10,
+    var11,
+    var12,
+    var13,
+    var14,
+    var15,
+    var16,
+    var17,
+    var18,
+    var19,
+    var20,
+    var21,
+    var22,
+    var23,
+    var24,
+    var25,
+    var26,
+    var27,
+    var28,
+    var29,
+    var30,
+    var101,
+    var201,
+    var301,
+    var401,
+    var501,
+    var601,
+    var701,
+    var801,
+    var901,
+    var1001,
+    var1101,
+    var1201,
+    var1301,
+    var1401,
+    var1501,
+    var1601,
+    var1701,
+    var1801,
+    var1901,
+    var2001,
+    var2101,
+    var2201,
+    var2301,
+    var2401,
+    var2501,
+    var2601,
+    var2701,
+    var2801,
+    var2901,
+    var3001
+) {
+    console.log(
+        var1,
+        var2,
+        var3,
+        var4,
+        var5,
+        var6,
+        var7,
+        var8,
+        var9,
+        var10,
+        var11,
+        var12,
+        var13,
+        var14,
+        var15,
+        var16,
+        var17,
+        var18,
+        var19,
+        var20,
+        var21,
+        var22,
+        var23,
+        var24,
+        var25,
+        var26,
+        var27,
+        var28,
+        var29,
+        var30
+    );
+}

crates/swc_ecma_minifier/tests/fixture/issues/9650/mangle.json

@@ -0,0 +1,3 @@
+{
+    "reserved": ["$"]
+}

crates/swc_ecma_minifier/tests/fixture/issues/9650/output.js

@@ -0,0 +1,3 @@
+export function logVariables(o, l, e, n, a, c, g, i, r, s, t, b, f, p, u, x, V, d, h, j, k, m, q, v, w, y, z, A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, W, X, Y, Z, _, oo, ol, oe, on, oa, oc, og) {
+    console.log(o, l, e, n, a, c, g, i, r, s, t, b, f, p, u, x, V, d, h, j, k, m, q, v, w, y, z, A, B, C);
+}

crates/swc_ecma_transforms_base/src/hygiene/mod.rs

@@ -1,3 +1,5 @@
+use rustc_hash::FxHashSet;
+use swc_atoms::Atom;
 use swc_common::Mark;
 use swc_ecma_ast::*;
 use swc_ecma_utils::stack_size::maybe_grow_default;
@@ -24,6 +26,9 @@ pub struct Config {
 
     /// Mangle even if vars are visible to `eval` or `with`.
     pub ignore_eval: bool,
+
+    /// Used for preventing mangler from renaming variables to reserved names.
+    pub preserved_symbols: FxHashSet<Atom>,
 }
 
 /// See [hygiene_with_config] for doc. Creates a `hygiene` pass with default

crates/swc_ecma_transforms_base/src/rename/mod.rs

@@ -176,6 +176,12 @@ where
                 .extend(self.preserved.iter().map(|v| v.0.clone()));
         }
 
+        if !self.config.preserved_symbols.is_empty() {
+            unresolved
+                .to_mut()
+                .extend(self.config.preserved_symbols.iter().cloned());
+        }
+
         if R::MANGLE {
             let cost = scope.rename_cost();
             scope.rename_in_mangle_mode(