fix(es/minifier): Don't drop an inlined parameter as a duplicate (#6293)

crates/swc_ecma_minifier/src/compress/optimize/mod.rs

@@ -1,4 +1,4 @@
-use std::{iter::once, mem::take};
+use std::iter::once;
 
 use rustc_hash::{FxHashMap, FxHashSet};
 use swc_atoms::{js_word, JsWord};
@@ -19,7 +19,7 @@ use Value::Known;
 
 use self::{
     unused::PropertyAccessOpts,
-    util::{extract_class_side_effect, Finalizer, NormalMultiReplacer},
+    util::{extract_class_side_effect, Finalizer, NormalMultiReplacer, SynthesizedStmts},
 };
 use super::util::{drop_invalid_stmts, is_fine_for_if_cons};
 #[cfg(feature = "debug")]
@@ -1383,8 +1383,8 @@ where
         let mut old_prepend_stmts = self.prepend_stmts.take();
         let old_append_stmts = self.append_stmts.take();
         n.visit_mut_with(self);
-        old_prepend_stmts.append(&mut *self.prepend_stmts);
-        old_prepend_stmts.append(&mut *self.append_stmts);
+        old_prepend_stmts.append(&mut self.prepend_stmts);
+        old_prepend_stmts.append(&mut self.append_stmts);
 
         self.prepend_stmts = old_prepend_stmts;
         self.append_stmts = old_append_stmts;
@@ -2423,11 +2423,15 @@ where
                 // We use var decl with no declarator to indicate we dropped an decl.
                 Stmt::Decl(Decl::Var(v)) if v.decls.is_empty() => {
                     *s = Stmt::Empty(EmptyStmt { span: DUMMY_SP });
+                    self.prepend_stmts = old_prepend;
+                    self.append_stmts = old_append;
                     return;
                 }
                 Stmt::Expr(es) => {
                     if es.expr.is_invalid() {
                         *s = Stmt::Empty(EmptyStmt { span: DUMMY_SP });
+                        self.prepend_stmts = old_prepend;
+                        self.append_stmts = old_append;
                         return;
                     }
                 }
@@ -2459,6 +2463,8 @@ where
             Stmt::Decl(Decl::Var(v)) if v.decls.is_empty() => {
                 s.take();
                 if self.prepend_stmts.is_empty() && self.append_stmts.is_empty() {
+                    self.prepend_stmts = old_prepend;
+                    self.append_stmts = old_append;
                     return;
                 }
             }
@@ -3062,42 +3068,3 @@ fn is_left_access_to_arguments(l: &PatOrExpr) -> bool {
         },
     }
 }
-
-#[derive(Debug, Default, PartialEq, Eq)]
-struct SynthesizedStmts(Vec<Stmt>);
-
-impl SynthesizedStmts {
-    fn take_stmts(&mut self) -> Vec<Stmt> {
-        take(&mut self.0)
-    }
-}
-
-impl std::ops::Deref for SynthesizedStmts {
-    type Target = Vec<Stmt>;
-
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl std::ops::DerefMut for SynthesizedStmts {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.0
-    }
-}
-
-impl Take for SynthesizedStmts {
-    fn dummy() -> Self {
-        Self(Take::dummy())
-    }
-}
-
-impl Drop for SynthesizedStmts {
-    fn drop(&mut self) {
-        if !self.0.is_empty() {
-            if !std::thread::panicking() {
-                panic!("We should not drop synthesized stmts");
-            }
-        }
-    }
-}

crates/swc_ecma_minifier/src/compress/optimize/sequences.rs

@@ -492,7 +492,7 @@ where
             prepend_stmts(stmts, self.prepend_stmts.drain(..).map(T::from_stmt));
         }
 
-        if self.append_stmts.is_empty() {
+        if !self.append_stmts.is_empty() {
             stmts.extend(self.append_stmts.drain(..).map(T::from_stmt));
         }
 

crates/swc_ecma_minifier/src/compress/optimize/unused.rs

@@ -759,9 +759,14 @@ where
         for d in var.decls.iter_mut() {
             if d.init.is_none() {
                 if let Pat::Ident(name) = &d.name {
-                    if let Some(usage) = self.data.vars.get(&name.to_id()) {
-                        if usage.is_fn_local && usage.declared_as_fn_param {
+                    if let Some(usage) = self.data.vars.get_mut(&name.to_id()) {
+                        if usage.is_fn_local
+                            && usage.declared_as_fn_param
+                            && usage.declared_count >= 2
+                        {
                             d.name.take();
+                            usage.declared_count -= 1;
+
                             report_change!(
                                 "Removing a variable statement because it's a function parameter"
                             );

crates/swc_ecma_minifier/src/compress/optimize/util.rs

@@ -1,4 +1,7 @@
-use std::ops::{Deref, DerefMut};
+use std::{
+    mem::take,
+    ops::{Deref, DerefMut},
+};
 
 use rustc_hash::{FxHashMap, FxHashSet};
 use swc_atoms::js_word;
@@ -532,3 +535,56 @@ impl VisitMut for ExprReplacer {
         }
     }
 }
+
+#[derive(Debug, Default, PartialEq, Eq)]
+pub(super) struct SynthesizedStmts(Vec<Stmt>);
+
+impl SynthesizedStmts {
+    pub fn take_stmts(&mut self) -> Vec<Stmt> {
+        take(&mut self.0)
+    }
+}
+
+impl std::ops::Deref for SynthesizedStmts {
+    type Target = Vec<Stmt>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl SynthesizedStmts {
+    pub fn push(&mut self, stmt: Stmt) {
+        self.0.push(stmt);
+    }
+
+    pub fn extend(&mut self, stmts: impl IntoIterator<Item = Stmt>) {
+        self.0.extend(stmts);
+    }
+
+    pub fn append(&mut self, other: &mut SynthesizedStmts) {
+        self.0.append(&mut other.0);
+    }
+}
+
+impl std::ops::DerefMut for SynthesizedStmts {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+impl Take for SynthesizedStmts {
+    fn dummy() -> Self {
+        Self(Take::dummy())
+    }
+}
+
+impl Drop for SynthesizedStmts {
+    fn drop(&mut self) {
+        if !self.0.is_empty() {
+            if !std::thread::panicking() {
+                panic!("We should not drop synthesized stmts");
+            }
+        }
+    }
+}

crates/swc_ecma_minifier/tests/fixture/next/tinymce/1/input.js

@@ -0,0 +1,14 @@
+Yp.revoke, (a => Yp.config((b => ({
+    aria: {
+        mode: "checked"
+    },
+    ...ge(b, ((e, t) => "exclusive" !== t)),
+    onToggled: (c, d) => {
+        p(b.onToggled) && b.onToggled(c, d), ((e, f) => {
+            Or(e, th, {
+                item: e,
+                state: f
+            })
+        })(c, d)
+    }
+}))(a)))

crates/swc_ecma_minifier/tests/fixture/next/tinymce/1/output.js

@@ -0,0 +1,12 @@
+Yp.revoke, (a)=>Yp.config({
+        aria: {
+            mode: "checked"
+        },
+        ...ge(a, (e, t)=>"exclusive" !== t),
+        onToggled (c, d) {
+            p(a.onToggled) && a.onToggled(c, d), Or(c, th, {
+                item: c,
+                state: d
+            });
+        }
+    });