feat(es/minifier): Implement correct hoist_props (#8593)

**Description:**

 - The option `hoist_props` now does what it's supposed to do.
- Dropping of unused properties now does not drop properties too aggressively.
- The initializer of a dropped variable declaration is now properly visited.
- Indexing with string literals is not marked as a dynamic index anymore. This is required to handle codes like https://github.com/swc-project/swc/blob/c3f67ceb1eb0cab9ef4a47c321acf90684bf216a/crates/swc_ecma_minifier/tests/terser/compress/hoist_props/name_collision_1/input.js#L1-L7.

crates/swc/tests/tsc-references/callSignaturesWithOptionalParameters.2.minified.js

@@ -2,9 +2,5 @@
 import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
 var c, i, a, f = function(x) {}, f2 = function(x, y) {};
 f(1), f(), f2(1), f2(1, 2), c.foo(), c.foo(1), i(), i(1), i.foo(1), i.foo(1, 2), a(), a(1), a.foo(), a.foo(1);
-var b = {
-    foo: function(x) {},
-    a: function(x, y) {},
-    b: function(x) {}
-};
-b.foo(), b.foo(1), b.a(1), b.a(1, 2), b.b(), b.b(1);
+var b_foo = function(x) {}, b_a = function(x, y) {}, b_b = function(x) {};
+b_foo(), b_foo(1), b_a(1), b_a(1, 2), b_b(), b_b(1);

crates/swc/tests/tsc-references/checkJsdocSatisfiesTag10.2.minified.js

@@ -2,6 +2,7 @@
 //// [/a.js]
 var p = {
     a: 0,
-    b: "hello"
+    b: "hello",
+    x: 8
 };
 p.a.toFixed(), p.b.substring(1), p.d;

crates/swc/tests/tsc-references/checkJsdocSatisfiesTag7.2.minified.js

@@ -2,6 +2,7 @@
 //// [/a.js]
 var p = {
     a: 0,
-    b: "hello"
+    b: "hello",
+    x: 8
 };
 p.a.toFixed(), p.b.substring(1), p.d;

crates/swc/tests/tsc-references/checkJsdocTypeTagOnObjectProperty2.2.minified.js

@@ -1,17 +1,2 @@
 //// [checkJsdocTypeTagOnObjectProperty2.ts]
 //// [0.js]
-var lol, obj = {
-    bar: 42,
-    method1: function(n1) {
-        return "42";
-    },
-    method2: function(n1) {
-        return "lol";
-    },
-    arrowFunc: function() {
-        var num = arguments.length > 0 && void 0 !== arguments[0] ? arguments[0] : "0";
-        return num + 42;
-    },
-    lol: lol
-};
-lol = "string", obj.method1(0), obj.method2("0");

crates/swc/tests/tsc-references/destructuringObjectBindingPatternAndAssignment8(target=es2022).2.minified.js

@@ -1,9 +1,6 @@
 //// [destructuringObjectBindingPatternAndAssignment8.ts]
-const K = {
-    a: "a",
-    b: "b"
-}, { [K.a]: aVal, [K.b]: bVal } = {
-    [K.a]: 1,
-    [K.b]: 1
+const { a: aVal, b: bVal } = {
+    a: 1,
+    b: 1
 };
 console.log(aVal, bVal);

crates/swc/tests/tsc-references/destructuringObjectBindingPatternAndAssignment8(target=es5).2.minified.js

@@ -1,7 +1,4 @@
 //// [destructuringObjectBindingPatternAndAssignment8.ts]
 import { _ as _define_property } from "@swc/helpers/_/_define_property";
-var _obj, K = {
-    a: "a",
-    b: "b"
-}, _ref = (_define_property(_obj = {}, K.a, 1), _define_property(_obj, K.b, 1), _obj);
-console.log(_ref[K.a], _ref[K.b]);
+var _obj, _ref = (_define_property(_obj = {}, "a", 1), _define_property(_obj, "b", 1), _obj);
+console.log(_ref.a, _ref.b);

crates/swc/tests/tsc-references/destructuringVariableDeclaration1ES5.2.minified.js

@@ -1,11 +1,6 @@
 //// [destructuringVariableDeclaration1ES5.ts]
 import { _ as _sliced_to_array } from "@swc/helpers/_/_sliced_to_array";
 import { _ as _to_consumable_array } from "@swc/helpers/_/_to_consumable_array";
-var _ref = {
-    a1: 10,
-    a2: "world"
-};
-_ref.a1, _ref.a2;
 var tmp = {
     b11: "world"
 };

crates/swc/tests/tsc-references/destructuringVariableDeclaration1ES5iterable.2.minified.js

@@ -1,11 +1,6 @@
 //// [destructuringVariableDeclaration1ES5iterable.ts]
 import { _ as _sliced_to_array } from "@swc/helpers/_/_sliced_to_array";
 import { _ as _to_consumable_array } from "@swc/helpers/_/_to_consumable_array";
-var _ref = {
-    a1: 10,
-    a2: "world"
-};
-_ref.a1, _ref.a2;
 var tmp = {
     b11: "world"
 };

crates/swc/tests/tsc-references/destructuringVariableDeclaration2.2.minified.js

@@ -1,9 +1,4 @@
 //// [destructuringVariableDeclaration2.ts]
-var _ref = {
-    a1: !0,
-    a2: 1
-};
-_ref.a1, _ref.a2;
 var _ref1 = [
     1,
     2,

crates/swc/tests/tsc-references/logicalNotOperatorWithAnyOtherType.2.minified.js

@@ -1,14 +1,11 @@
 //// [logicalNotOperatorWithAnyOtherType.ts]
 import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
-var M, obj1 = {
-    x: "",
-    y: function() {}
-}, A = function() {
+var M, A = function() {
     function A() {
         _class_call_check(this, A);
     }
     return A.foo = function() {}, A;
 }();
 M || (M = {});
 var objA = new A();
-obj1.x, obj1.y, objA.a, M.n, A.foo(), objA.a, M.n;
+objA.a, M.n, A.foo(), objA.a, M.n;

crates/swc/tests/tsc-references/objectLiteralNormalization.2.minified.js

@@ -33,14 +33,11 @@ var b2 = _object_spread_props(_object_spread({}, b1), {
     z: 55
 });
 _object_spread({}, b2), opts;
-var d1 = {
-    kind: "a",
-    pos: {
-        x: 0,
-        y: 0
-    }
+var d1_pos = {
+    x: 0,
+    y: 0
 };
-d1.kind, d1.pos, d1.pos.x, d1.pos.y, d1.pos.a, d1.pos.b, f({
+d1_pos.x, d1_pos.y, d1_pos.a, d1_pos.b, f({
     a: 1,
     b: 2
 }, {

crates/swc/tests/tsc-references/parserNotHexLiteral1.2.minified.js

@@ -1,6 +1,2 @@
 //// [parserNotHexLiteral1.ts]
-var x = {
-    e0: "cat",
-    x0: "dog"
-};
-console.info(x.x0), console.info(x.e0);
+console.info("dog"), console.info("cat");

crates/swc/tests/tsc-references/spellingUncheckedJS.2.minified.js

@@ -6,7 +6,9 @@ import { _ as _inherits } from "@swc/helpers/_/_inherits";
 import { _ as _create_super } from "@swc/helpers/_/_create_super";
 export var inModule = 1;
 inmodule.toFixed();
-var object = {};
+var object = {
+    spaaace: 3
+};
 object.spaaaace, object.spaace = 12, object.fresh = 12, other.puuuce, new Date().getGMTDate(), setIntegral(function() {
     return console.log("ok");
 }, 500), AudioBuffin, Jimmy, Jon;

crates/swc/tests/tsc-references/stringLiteralTypesAsTags01.2.minified.js

@@ -1,5 +1 @@
 //// [stringLiteralTypesAsTags01.ts]
-var x = {
-    kind: "A"
-};
-x.kind, x.kind;

crates/swc/tests/tsc-references/stringLiteralTypesAsTags02.2.minified.js

@@ -1,5 +1 @@
 //// [stringLiteralTypesAsTags02.ts]
-var x = {
-    kind: "A"
-};
-x.kind, x.kind;

crates/swc/tests/tsc-references/stringLiteralTypesAsTags03.2.minified.js

@@ -1,5 +1 @@
 //// [stringLiteralTypesAsTags03.ts]
-var x = {
-    kind: "A"
-};
-x.kind, x.kind;

crates/swc/tests/tsc-references/typeGuardFunctionOfFormThis.2.minified.js

@@ -28,11 +28,7 @@ var b, crate, RoyalGuard = function() {
     }
     return FollowerGuard.prototype.follow = function() {}, FollowerGuard;
 }(RoyalGuard), a = new FollowerGuard();
-a.isLeader() ? a.lead() : a.isFollower() && a.follow(), b.isLeader() ? b.lead() : b.isFollower() && b.follow();
-var holder2 = {
-    a: a
-};
-holder2.a.isLeader(), holder2.a;
+a.isLeader() ? a.lead() : a.isFollower() && a.follow(), b.isLeader() ? b.lead() : b.isFollower() && b.follow(), a.isLeader();
 var ArrowGuard = function ArrowGuard() {
     var _this = this;
     _class_call_check(this, ArrowGuard), this.isElite = function() {

crates/swc/tests/tsc-references/typeTagOnPropertyAssignment.2.minified.js

@@ -1,8 +1 @@
 //// [typeTagOnPropertyAssignment.js]
-var o = {
-    a: "a",
-    n: function() {
-        return "b";
-    }
-};
-o.a, o.n;

crates/swc/tests/tsc-references/typedefTagExtraneousProperty.2.minified.js

@@ -1,3 +1,5 @@
 //// [typedefTagExtraneousProperty.js]
-var y = {};
+var y = {
+    bye: "no"
+};
 y.ignoreMe = "ok but just because of the index signature", y.hi = "yes";

crates/swc/tests/tsc-references/typedefTagNested.2.minified.js

@@ -1,7 +1 @@
 //// [a.js]
-var sala = {
-    name: "uppsala",
-    not: 0,
-    nested: "ok"
-};
-sala.name, sala.not, sala.nested;

crates/swc/tests/tsc-references/unannotatedParametersAreOptional.2.minified.js

@@ -7,8 +7,3 @@ var C = function() {
     return C.prototype.m = function(x) {}, C.m = function(x) {}, C;
 }();
 C.m(), new C().m(), new C().p();
-var obj = {
-    m: function(x) {},
-    p: function(x) {}
-};
-obj.m(), obj.p();

crates/swc/tests/tsc-references/voidOperatorWithAnyOtherType.2.minified.js

@@ -1,14 +1,11 @@
 //// [voidOperatorWithAnyOtherType.ts]
 import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
-var M, obj1 = {
-    x: "",
-    y: 1
-}, A = function() {
+var M, A = function() {
     function A() {
         _class_call_check(this, A);
     }
     return A.foo = function() {}, A;
 }();
 M || (M = {});
 var objA = new A();
-obj1.x, obj1.y, objA.a, M.n, A.foo(), objA.a, M.n;
+objA.a, M.n, A.foo(), objA.a, M.n;

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

@@ -75,6 +75,8 @@ impl Optimizer<'_> {
 
             // No use => dropped
             if ref_count == 0 {
+                self.mode.store(ident.to_id(), &*init);
+
                 if init.may_have_side_effects(&self.expr_ctx) {
                     // TODO: Inline partially
                     return;

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

@@ -89,8 +89,6 @@ pub(super) fn optimizer<'a>(
         prepend_stmts: Default::default(),
         append_stmts: Default::default(),
         vars: Default::default(),
-        vars_for_prop_hoisting: Default::default(),
-        simple_props: Default::default(),
         typeofs: Default::default(),
         data,
         ctx,
@@ -209,10 +207,6 @@ struct Optimizer<'a> {
 
     vars: Vars,
 
-    /// Used for `hoist_props`.
-    vars_for_prop_hoisting: Box<FxHashMap<Id, Box<Expr>>>,
-    /// Used for `hoist_props`.
-    simple_props: Box<FxHashMap<(Id, JsWord), Box<Expr>>>,
     typeofs: Box<AHashMap<Id, JsWord>>,
     /// This information is created by analyzing identifier usages.
     ///
@@ -236,6 +230,9 @@ struct Vars {
     /// Used for inlining.
     lits: FxHashMap<Id, Box<Expr>>,
 
+    /// Used for `hoist_props`.
+    hoisted_props: Box<FxHashMap<(Id, JsWord), Ident>>,
+
     /// Literals which are cheap to clone, but not sure if we can inline without
     /// making output bigger.
     ///
@@ -279,6 +276,7 @@ impl Vars {
                 lits_for_cmp: &self.lits_for_cmp,
                 lits_for_array_access: &self.lits_for_array_access,
                 lits: &self.lits,
+                hoisted_props: &self.hoisted_props,
                 vars_to_remove: &self.removed,
                 changed: false,
             };
@@ -2920,8 +2918,6 @@ impl VisitMut for Optimizer<'_> {
             }
         };
 
-        self.store_var_for_prop_hoisting(var);
-
         self.drop_unused_properties(var);
 
         debug_assert_valid(&var.init);
@@ -2948,6 +2944,8 @@ impl VisitMut for Optimizer<'_> {
             true
         });
 
+        self.hoist_props_of_vars(vars);
+
         let uses_eval = self.data.scopes.get(&self.ctx.scope).unwrap().has_eval_call;
 
         if !uses_eval && !self.ctx.dont_use_prepend_nor_append {
@@ -2967,6 +2965,9 @@ impl VisitMut for Optimizer<'_> {
             for v in vars.iter_mut() {
                 let mut storage = None;
                 self.drop_unused_var_declarator(v, &mut storage);
+                if let Some(expr) = &mut storage {
+                    expr.visit_mut_with(self);
+                }
                 side_effects.extend(storage);
 
                 // Dropped. Side effects of the initializer is stored in `side_effects`.