fix(es/minifier): Fix bugs of the minifier (#2052)

swc_ecma_minifier:
 - Test mangler using execution test suite.
 - `mangler`: Preserve `arguments`.
 - `mangler`: Handle shorthand. (#2051)
 - `mangler`: Handle object pattern properties.
 - `precompress`: Don't drop function declarations if the variable with same name is in different scope. (#2011)

ecmascript/minifier/Cargo.toml

@@ -7,7 +7,7 @@ include = ["Cargo.toml", "src/**/*.rs", "src/lists/*.json"]
 license = "Apache-2.0/MIT"
 name = "swc_ecma_minifier"
 repository = "https://github.com/swc-project/swc.git"
-version = "0.19.1"
+version = "0.19.2"
 
 [features]
 debug = []

ecmascript/minifier/src/pass/mangle_names/mod.rs

@@ -7,6 +7,7 @@ use crate::option::MangleOptions;
 use crate::util::base54::incr_base54;
 use fxhash::FxHashMap;
 use fxhash::FxHashSet;
+use swc_atoms::js_word;
 use swc_atoms::JsWord;
 use swc_common::SyntaxContext;
 use swc_ecma_ast::*;
@@ -52,21 +53,26 @@ struct Mangler {
 }
 
 impl Mangler {
-    fn rename(&mut self, i: &mut Ident) {
+    fn rename(&mut self, i: &mut Ident) -> bool {
+        match i.sym {
+            js_word!("arguments") => return false,
+            _ => {}
+        }
+
         if self.preserved.contains(&i.to_id()) {
-            return;
+            return false;
         }
 
         if let Some(var) = self.data.as_ref().unwrap().vars.get(&i.to_id()) {
             if !var.declared {
-                return;
+                return false;
             }
         }
 
         if let Some(v) = self.renamed.get(&i.to_id()) {
             i.span.ctxt = SyntaxContext::empty();
             i.sym = v.clone();
-            return;
+            return true;
         }
 
         loop {
@@ -83,6 +89,8 @@ impl Mangler {
             i.span.ctxt = SyntaxContext::empty();
             break;
         }
+
+        true
     }
 
     fn rename_private(&mut self, private_name: &mut PrivateName) {
@@ -121,6 +129,7 @@ impl VisitMut for Mangler {
 
         self.rename(&mut n.orig);
     }
+
     fn visit_mut_expr(&mut self, e: &mut Expr) {
         e.visit_mut_children_with(self);
 
@@ -183,6 +192,52 @@ impl VisitMut for Mangler {
         n.visit_mut_children_with(self)
     }
 
+    fn visit_mut_object_pat_prop(&mut self, n: &mut ObjectPatProp) {
+        match n {
+            ObjectPatProp::Assign(AssignPatProp {
+                value: None, key, ..
+            }) => {
+                let key_span = key.span.with_ctxt(SyntaxContext::empty());
+                let orig = key.sym.clone();
+
+                if self.rename(key) {
+                    *n = ObjectPatProp::KeyValue(KeyValuePatProp {
+                        key: PropName::Ident(Ident::new(orig, key_span)),
+                        value: Box::new(Pat::Ident(key.clone().into())),
+                    });
+                }
+            }
+
+            ObjectPatProp::Assign(p) => {
+                let key_span = p.key.span.with_ctxt(SyntaxContext::empty());
+                let orig = p.key.sym.clone();
+
+                if self.rename(&mut p.key) {
+                    if let Some(right) = p.value.take() {
+                        *n = ObjectPatProp::KeyValue(KeyValuePatProp {
+                            key: PropName::Ident(Ident::new(orig, key_span)),
+                            value: Box::new(Pat::Assign(AssignPat {
+                                span: p.span,
+                                left: Box::new(Pat::Ident(p.key.clone().into())),
+                                right,
+                                type_ann: None,
+                            })),
+                        });
+                    } else {
+                        *n = ObjectPatProp::KeyValue(KeyValuePatProp {
+                            key: PropName::Ident(Ident::new(orig, key_span)),
+                            value: Box::new(Pat::Ident(p.key.clone().into())),
+                        });
+                    }
+                }
+            }
+
+            _ => {
+                n.visit_mut_children_with(self);
+            }
+        }
+    }
+
     fn visit_mut_pat(&mut self, n: &mut Pat) {
         n.visit_mut_children_with(self);
 
@@ -200,6 +255,25 @@ impl VisitMut for Mangler {
         }
     }
 
+    fn visit_mut_prop(&mut self, n: &mut Prop) {
+        match n {
+            Prop::Shorthand(p) => {
+                let span = p.span.with_ctxt(SyntaxContext::empty());
+                let orig = p.sym.clone();
+
+                if self.rename(p) {
+                    *n = Prop::KeyValue(KeyValueProp {
+                        key: PropName::Ident(Ident::new(orig, span)),
+                        value: Box::new(Expr::Ident(p.clone())),
+                    });
+                }
+            }
+            _ => {
+                n.visit_mut_children_with(self);
+            }
+        }
+    }
+
     fn visit_mut_script(&mut self, n: &mut Script) {
         let data = analyze(&*n, None);
         self.data = Some(data);

ecmascript/minifier/src/pass/precompress.rs

@@ -119,7 +119,7 @@ impl VisitMut for PrecompressOptimizer<'_> {
         if self.options.dead_code || self.options.unused {
             if let Some(usage) = self.data.as_ref().unwrap().vars.get(&n.ident.to_id()) {
                 // Remove if variable with same name exists.
-                if usage.var_kind.is_some() && usage.var_initialized {
+                if usage.var_kind.is_some() && usage.var_initialized && usage.is_fn_local {
                     n.ident.take();
                     return;
                 }

ecmascript/minifier/tests/compress.rs

@@ -312,7 +312,7 @@ fn projects(input: PathBuf) {
 }
 
 /// Tests used to prevent regressions.
-#[testing::fixture("tests/compress/exec/**/input.js")]
+#[testing::fixture("tests/exec/**/input.js")]
 fn base_exec(input: PathBuf) {
     let dir = input.parent().unwrap();
     let config = dir.join("config.json");

ecmascript/minifier/tests/compress/fixture/issues/2011/actual/input.js

@@ -0,0 +1,55 @@
+function _classCallCheck(instance, Constructor) {
+    if (!(instance instanceof Constructor)) {
+        throw new TypeError("Cannot call a class as a function");
+    }
+}
+function _defineProperties(target, props) {
+    for (var i = 0; i < props.length; i++) {
+        var descriptor = props[i];
+        descriptor.enumerable = descriptor.enumerable || false;
+        descriptor.configurable = true;
+        if ("value" in descriptor) descriptor.writable = true;
+        Object.defineProperty(target, descriptor.key, descriptor);
+    }
+}
+function _createClass(Constructor, protoProps, staticProps) {
+    if (protoProps) _defineProperties(Constructor.prototype, protoProps);
+    if (staticProps) _defineProperties(Constructor, staticProps);
+    return Constructor;
+}
+function _defineProperty(obj, key, value) {
+    if (key in obj) {
+        Object.defineProperty(obj, key, {
+            value: value,
+            enumerable: true,
+            configurable: true,
+            writable: true
+        });
+    } else {
+        obj[key] = value;
+    }
+    return obj;
+}
+var ClassA = function ClassA() {
+    "use strict";
+    _classCallCheck(this, ClassA);
+};
+module.exports = (function () {
+    var ClassB = /*#__PURE__*/ function () {
+        "use strict";
+        function ClassB() {
+            _classCallCheck(this, ClassB);
+        }
+        _createClass(ClassB, [
+            {
+                key: "it",
+                value: function it() {
+                    this.bb = new ClassB.MyA();
+                }
+            }
+        ]);
+        return ClassB;
+    }();
+    _defineProperty(ClassB, "MyA", ClassA);
+    return ClassB;
+})();

ecmascript/minifier/tests/compress/fixture/issues/2011/actual/output.js

@@ -0,0 +1,41 @@
+function _classCallCheck(instance, Constructor) {
+    if (!(instance instanceof Constructor)) throw new TypeError("Cannot call a class as a function");
+}
+function _defineProperties(target, props) {
+    for(var i = 0; i < props.length; i++){
+        var descriptor = props[i];
+        descriptor.enumerable = descriptor.enumerable || !1, descriptor.configurable = !0, "value" in descriptor && (descriptor.writable = !0), Object.defineProperty(target, descriptor.key, descriptor);
+    }
+}
+function _createClass(Constructor, protoProps, staticProps) {
+    return protoProps && _defineProperties(Constructor.prototype, protoProps), staticProps && _defineProperties(Constructor, staticProps), Constructor;
+}
+function _defineProperty(obj, key, value) {
+    return key in obj ? Object.defineProperty(obj, key, {
+        value: value,
+        enumerable: !0,
+        configurable: !0,
+        writable: !0
+    }) : obj[key] = value, obj;
+}
+var ClassA = function ClassA() {
+    "use strict";
+    _classCallCheck(this, ClassA);
+};
+module.exports = (function() {
+    var ClassB = function() {
+        "use strict";
+        function ClassB() {
+            _classCallCheck(this, ClassB);
+        }
+        return _createClass(ClassB, [
+            {
+                key: "it",
+                value: function() {
+                    this.bb = new ClassB.MyA();
+                }
+            }
+        ]), ClassB;
+    }();
+    return _defineProperty(ClassB, "MyA", ClassA), ClassB;
+})();

ecmascript/minifier/tests/compress/fixture/issues/2011/reduced/input.js

@@ -0,0 +1,9 @@
+class ClassA { }
+
+module.exports = class ClassB {
+    static MyA = ClassA;
+
+    it() {
+        this.bb = new ClassB.MyA();
+    }
+}

ecmascript/minifier/tests/compress/fixture/issues/2011/reduced/output.js

@@ -0,0 +1,8 @@
+class ClassA {
+}
+module.exports = class ClassB {
+    static MyA = ClassA;
+    it() {
+        this.bb = new ClassB.MyA();
+    }
+};

ecmascript/minifier/tests/exec/issues/2011/1/config.json

@@ -0,0 +1,3 @@
+{
+    "defaults": true
+}

ecmascript/minifier/tests/exec/issues/2011/1/input.js

@@ -0,0 +1,24 @@
+class ClassA {
+    constructor() {
+        console.log('Class A');
+    }
+}
+
+const cls = class ClassB {
+    static MyA = ClassA;
+
+    constructor() {
+        console.log('Claas B');
+    }
+
+    it() {
+        console.log('method it - start');
+
+        this.bb = new ClassB.MyA();
+
+        console.log('method it - end');
+    }
+}
+
+
+new cls().it();

ecmascript/minifier/tests/exec/issues/2011/2/config.json

@@ -0,0 +1,3 @@
+{
+    "defaults": true
+}