fix(es/minifier): Make name mangler respect toplevel

crates/swc/src/config/mod.rs

@@ -393,7 +393,9 @@ impl Options {
                         _ => None,
                     })
                     .map(|mut c| {
-                        c.top_level = true;
+                        if c.top_level.is_none() {
+                            c.top_level = Some(true);
+                        }
 
                         c
                     })

crates/swc/src/lib.rs

@@ -1009,7 +1009,9 @@ impl Compiler {
                 }
 
                 if let Some(opts) = &mut min_opts.mangle {
-                    opts.top_level = true;
+                    if opts.top_level.is_none() {
+                        opts.top_level = Some(true);
+                    }
                 }
             }
 

crates/swc/tests/fixture/issues-4xxx/4953/output/index.js

@@ -1,5 +1,5 @@
 "use strict";
-function e(e, t) {
+function _default(e, t) {
     "use strict";
     t.vr = function(e, t, r) {
         return function() {
@@ -11,5 +11,5 @@ Object.defineProperty(exports, "__esModule", {
     value: !0
 }), Object.defineProperty(exports, "default", {
     enumerable: !0,
-    get: ()=>e
+    get: ()=>_default
 });

crates/swc/tests/fixture/issues-6xxx/6345/1/output/index.js

@@ -1,17 +1,17 @@
 "use strict";
-function n() {}
-var r = function() {
+function a() {}
+var te = function() {
     var n = function n(n) {};
-    var r = null;
+    var t = null;
     return {
-        init: function t(t) {
-            return r = new n(t);
+        init: function r(r) {
+            return t = new n(r);
         }
     };
 }();
-var t = function() {
-    var r = function r() {
-        n();
+var he = function() {
+    var n = function n() {
+        a();
     };
     ;
     var t = null;

crates/swc/tests/fixture/issues-6xxx/6345/2/output/index.js

@@ -1,17 +1,17 @@
 "use strict";
-function n() {}
-var r = function() {
+function a() {}
+var te = function() {
     var n = function n(n) {};
-    var r = null;
+    var t = null;
     return {
-        init: function t(t) {
-            return r = new n(t);
+        init: function r(r) {
+            return t = new n(r);
         }
     };
 }();
-var t = function() {
-    var r = function r() {
-        n();
+var he = function() {
+    var n = function n() {
+        a();
     };
     ;
     var t = null;

crates/swc/tests/fixture/issues-6xxx/6418/1/input/.swcrc

@@ -0,0 +1,26 @@
+{
+    "jsc": {
+        "parser": {
+            "syntax": "ecmascript",
+            "jsx": false
+        },
+        "target": "es5",
+        "loose": false,
+        "minify": {
+            "compress": false,
+            "mangle": {
+                "toplevel": false,
+                "keep_classnames": false,
+                "keep_fnames": false,
+                "keep_private_props": false,
+                "ie8": false,
+                "safari10": false
+            }
+        }
+    },
+    "module": {
+        "type": "es6"
+    },
+    "minify": false,
+    "isModule": false
+}

crates/swc/tests/fixture/issues-6xxx/6418/1/input/input.js

@@ -0,0 +1,3 @@
+var foo = function () { }
+
+console.log('PASS')

crates/swc/tests/fixture/issues-6xxx/6418/1/output/input.js

@@ -0,0 +1,2 @@
+var foo = function o() {};
+console.log("PASS");

crates/swc_bundler/examples/bundle.rs

@@ -128,7 +128,7 @@ fn do_test(_entry: &Path, entries: HashMap<String, FileName>, inline: bool, mini
                                     ..Default::default()
                                 }),
                                 mangle: Some(MangleOptions {
-                                    top_level: true,
+                                    top_level: Some(true),
                                     ..Default::default()
                                 }),
                                 ..Default::default()

crates/swc_bundler/tests/deno.rs

@@ -1061,7 +1061,7 @@ fn bundle(url: &str, minify: bool) -> String {
                         &swc_ecma_minifier::option::MinifyOptions {
                             compress: Some(Default::default()),
                             mangle: Some(MangleOptions {
-                                top_level: true,
+                                top_level: Some(true),
                                 ..Default::default()
                             }),
                             ..Default::default()

crates/swc_ecma_minifier/benches/full.rs

@@ -80,7 +80,7 @@ fn run(src: &str) {
                     }),
                     mangle: Some(MangleOptions {
                         props: None,
-                        top_level: true,
+                        top_level: Some(true),
                         keep_class_names: false,
                         keep_fn_names: false,
                         keep_private_props: false,

crates/swc_ecma_minifier/examples/minifier.rs

@@ -47,7 +47,7 @@ fn main() {
                 &MinifyOptions {
                     compress: Some(Default::default()),
                     mangle: Some(MangleOptions {
-                        top_level: true,
+                        top_level: Some(true),
                         ..Default::default()
                     }),
                     ..Default::default()

crates/swc_ecma_minifier/examples/minify-all.rs

@@ -62,7 +62,7 @@ fn main() {
                                 &MinifyOptions {
                                     compress: Some(Default::default()),
                                     mangle: Some(MangleOptions {
-                                        top_level: true,
+                                        top_level: Some(true),
                                         ..Default::default()
                                     }),
                                     ..Default::default()

crates/swc_ecma_minifier/src/option/mod.rs

@@ -59,7 +59,7 @@ pub struct MangleOptions {
     pub props: Option<ManglePropertiesOptions>,
 
     #[serde(default, alias = "toplevel")]
-    pub top_level: bool,
+    pub top_level: Option<bool>,
 
     #[serde(default, alias = "keep_classnames")]
     pub keep_class_names: bool,

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

@@ -37,10 +37,19 @@ impl Preserver {
 impl Visit for Preserver {
     noop_visit_type!();
 
+    fn visit_block_stmt(&mut self, n: &BlockStmt) {
+        let old_top_level = self.in_top_level;
+        for n in n.stmts.iter() {
+            self.in_top_level = false;
+            n.visit_with(self);
+        }
+        self.in_top_level = old_top_level;
+    }
+
     fn visit_catch_clause(&mut self, n: &CatchClause) {
         let old = self.should_preserve;
 
-        if self.options.ie8 && !self.options.top_level {
+        if self.options.ie8 && !self.options.top_level.unwrap_or_default() {
             self.should_preserve = true;
             n.param.visit_with(self);
         }
@@ -52,7 +61,7 @@ impl Visit for Preserver {
     fn visit_class_decl(&mut self, n: &ClassDecl) {
         n.visit_children_with(self);
 
-        if (self.in_top_level && !self.options.top_level)
+        if (self.in_top_level && !self.options.top_level.unwrap_or_default())
             || self.options.keep_class_names
             || self.is_reserved(&n.ident)
         {
@@ -101,7 +110,7 @@ impl Visit for Preserver {
     fn visit_fn_decl(&mut self, n: &FnDecl) {
         n.visit_children_with(self);
 
-        if (self.in_top_level && !self.options.top_level)
+        if (self.in_top_level && !self.options.top_level.unwrap_or_default())
             || self.is_reserved(&n.ident)
             || self.options.keep_fn_names
         {
@@ -121,13 +130,6 @@ impl Visit for Preserver {
 
     fn visit_ident(&mut self, _: &Ident) {}
 
-    fn visit_script(&mut self, n: &Script) {
-        for n in n.body.iter() {
-            self.in_top_level = true;
-            n.visit_with(self);
-        }
-    }
-
     fn visit_module_items(&mut self, n: &[ModuleItem]) {
         for n in n {
             self.in_top_level = true;
@@ -145,19 +147,17 @@ impl Visit for Preserver {
         }
     }
 
-    fn visit_block_stmt(&mut self, n: &BlockStmt) {
-        let old_top_level = self.in_top_level;
-        for n in n.stmts.iter() {
-            self.in_top_level = false;
+    fn visit_script(&mut self, n: &Script) {
+        for n in n.body.iter() {
+            self.in_top_level = true;
             n.visit_with(self);
         }
-        self.in_top_level = old_top_level;
     }
 
     fn visit_var_declarator(&mut self, n: &VarDeclarator) {
         n.visit_children_with(self);
 
-        if self.in_top_level && !self.options.top_level {
+        if self.in_top_level && !self.options.top_level.unwrap_or_default() {
             let old = self.should_preserve;
             self.should_preserve = true;
             n.name.visit_with(self);

crates/swc_ecma_minifier/tests/compress.rs

@@ -105,7 +105,7 @@ impl TestMangleOptions {
         let mut data = serde_json::from_str::<Self>(s).expect("failed to deserialize mangle.json");
 
         if let TestMangleOptions::Normal(v) = &mut data {
-            v.top_level = top_level.top_level;
+            v.top_level = Some(top_level.top_level);
         }
 
         data
@@ -216,7 +216,7 @@ fn run(
                     TestMangleOptions::Bool(v) => {
                         if v {
                             Some(MangleOptions {
-                                top_level: false,
+                                top_level: Some(false),
                                 ..Default::default()
                             })
                         } else {
@@ -359,7 +359,7 @@ fn projects(input: PathBuf) {
                 &input,
                 r#"{ "defaults": true, "toplevel": true, "passes": 3 }"#,
                 Some(TestMangleOptions::Normal(MangleOptions {
-                    top_level: true,
+                    top_level: Some(true),
                     ..Default::default()
                 })),
                 false,
@@ -1690,7 +1690,7 @@ fn full(input: PathBuf) {
             &input,
             &config,
             Some(TestMangleOptions::Normal(MangleOptions {
-                top_level: true,
+                top_level: Some(true),
                 ..Default::default()
             })),
             false,

crates/swc_ecma_minifier/tests/exec.rs

@@ -215,7 +215,7 @@ fn run_exec_test(input_src: &str, config: &str, skip_mangle: bool) {
                 None,
                 Some(MangleOptions {
                     keep_fn_names: true,
-                    top_level: true,
+                    top_level: Some(true),
                     ..Default::default()
                 }),
             );

crates/swc_ecma_minifier/tests/mangle.rs

@@ -98,7 +98,7 @@ fn snapshot_compress_fixture(input: PathBuf) {
             None,
             &MinifyOptions {
                 mangle: Some(MangleOptions {
-                    top_level: true,
+                    top_level: Some(true),
                     ..Default::default()
                 }),
                 compress: None,
@@ -161,7 +161,7 @@ fn fixture(input: PathBuf) {
             None,
             &MinifyOptions {
                 mangle: Some(MangleOptions {
-                    top_level: true,
+                    top_level: Some(true),
                     ..Default::default()
                 }),
                 compress: None,
@@ -243,7 +243,7 @@ function n() {
         src,
         expected,
         MangleOptions {
-            top_level: true,
+            top_level: Some(true),
             reserved: vec!["func1".into()],
             ..Default::default()
         },
@@ -270,7 +270,7 @@ class l {
         src,
         expected,
         MangleOptions {
-            top_level: true,
+            top_level: Some(true),
             reserved: vec!["Class1".into()],
             ..Default::default()
         },
@@ -297,7 +297,7 @@ class s {
         src,
         expected,
         MangleOptions {
-            top_level: true,
+            top_level: Some(true),
             reserved: vec!["hello1".into()],
             props: Some(ManglePropertiesOptions {
                 reserved: vec!["hello2".into()],
@@ -328,7 +328,7 @@ class a {
         src,
         expected,
         MangleOptions {
-            top_level: true,
+            top_level: Some(true),
             reserved: vec!["hello1".into()],
             ..Default::default()
         },
@@ -355,7 +355,7 @@ class a {
         src,
         expected,
         MangleOptions {
-            top_level: true,
+            top_level: Some(true),
             keep_private_props: true,
             ..Default::default()
         },

crates/swc_ecma_transforms_optimization/src/simplify/dce/mod.rs

@@ -633,6 +633,14 @@ impl TreeShaker {
             } else if !self.in_block_stmt {
                 return false;
             }
+
+            // Abort if the variable is declared on top level scope.
+            let ix = self.data.graph_ix.get_index_of(&name);
+            if let Some(ix) = ix {
+                if self.data.entries.contains(&(ix as u32)) {
+                    return false;
+                }
+            }
         }
 
         if self.config.top_retain.contains(&name.0) {