fix(es/minifier): Handle switch cases (#8854)

**Related issue:**

- Closes #8813

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

@@ -3,9 +3,30 @@ import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
 import { _ as _inherits } from "@swc/helpers/_/_inherits";
 import { _ as _type_of } from "@swc/helpers/_/_type_of";
 import { _ as _create_super } from "@swc/helpers/_/_create_super";
-(M || (M = {})).fn = function(x) {
+switch((M || (M = {})).fn = function(x) {
     return "";
-}, void 0 === x || _type_of(x), void 0 === M || _type_of(M), M.fn(1);
+}, x){
+    case "":
+    case 12:
+    case !0:
+    case null:
+    case void 0:
+    case new Date(12):
+    case {}:
+    case /[a-z]/:
+    case []:
+    case {}:
+    case {
+        id: 12
+    }:
+    case [
+        "a"
+    ]:
+    case void 0 === x ? "undefined" : _type_of(x):
+    case void 0 === M ? "undefined" : _type_of(M):
+    case M.fn(1):
+    default:
+}
 var M, x, C = function C() {
     _class_call_check(this, C);
 }, D = function(C) {

crates/swc_ecma_minifier/tests/fixture/issues/8813/input.js

@@ -0,0 +1,74 @@
+const k1 = (() => {
+    const x = 'asdf';
+    let y = "PASS 1";
+    switch (x) {
+        case x:
+        default:
+        case y = "FAIL":
+    }
+    console.log(y);
+})();
+
+const k2 = (() => {
+    const x = 'asdf';
+    let y = "PASS 2";
+    switch (x) {
+        case x:
+        case y = "FAIL":
+        default:
+    }
+    console.log(y);
+})();
+
+const k3 = (() => {
+    const x = 'asdf';
+    let y = "FAIL";
+    switch (x) {
+        case (y = "PASS 3", x):
+        default:
+    }
+    console.log(y);
+})();
+
+const k4 = (() => {
+    const x = 'asdf';
+    let y = "FAIL";
+    switch (x) {
+        case y = "PASS 4":
+        case x:
+        default:
+    }
+    console.log(y);
+})();
+
+const k5 = (() => {
+    const x = 'asdf';
+    let y = "FAIL";
+    let z = "FAIL";
+    switch (x) {
+        case y = "PASS 5":
+        case z = "PASS 5":
+        case x:
+        default:
+    }
+    console.log(y, z);
+})();
+
+
+var c = "FAIL";
+(function () {
+    function f(a, NaN) {
+        function g() {
+            switch (a) {
+                case a:
+                    break;
+                case ((c = "PASS"), NaN):
+                    c = "FAIL"
+                    break;
+            }
+        }
+        g();
+    }
+    f(0 / 0);
+})();
+console.log(c);

crates/swc_ecma_minifier/tests/fixture/issues/8813/output.js

@@ -0,0 +1,36 @@
+(()=>{
+    const x = 'asdf';
+    let y = "PASS 1";
+    switch(x){
+        case x:
+        default:
+        case y = "FAIL":
+    }
+    console.log(y);
+})(), (()=>{
+    const x = 'asdf';
+    let y = "PASS 2";
+    switch(x){
+        case x:
+        case y = "FAIL":
+        default:
+    }
+    console.log(y);
+})(), console.log("PASS 3"), console.log("PASS 4"), (()=>{
+    let y = "FAIL", z = "FAIL";
+    switch('asdf'){
+        case y = "PASS 5":
+        case z = "PASS 5":
+        default:
+    }
+    console.log(y, z);
+})();
+var a, c = "FAIL";
+a = 0 / 0, function() {
+    switch(a){
+        case a:
+            break;
+        case void (c = "PASS"):
+            c = "FAIL";
+    }
+}(), console.log(c);

crates/swc_ecma_minifier/tests/terser/compress/functions/issue_2620_4/output.js

@@ -1,4 +1,10 @@
 var c = "FAIL";
-var a, NaN;
-a = 0, c = "PASS";
+(function(a, NaN) {
+    (function() {
+        switch(a){
+            case a:
+            case void (c = "PASS"):
+        }
+    })();
+})(0 / 0);
 console.log(c);

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

@@ -729,9 +729,6 @@ impl VisitMut for Remover {
                                         &Expr::Lit(Lit::Bool(Bool { value: d, .. })),
                                     ) => test == d,
                                     (&Expr::Lit(Lit::Null(..)), &Expr::Lit(Lit::Null(..))) => true,
-                                    (Expr::Ident(test), Expr::Ident(d)) => {
-                                        test.sym == d.sym && test.span.ctxt() == d.span.ctxt()
-                                    }
 
                                     _ => {
                                         if !test.is_nan()
@@ -767,16 +764,10 @@ impl VisitMut for Remover {
                                 ignore_result(*s.discriminant, true, &self.expr_ctx).map(Box::new),
                             );
 
-                            let mut stmts = s.cases.remove(i).cons;
-                            let mut cases = s.cases.drain(i..);
+                            let mut stmts = s.cases[i].cons.take();
+                            let mut cases = s.cases.drain((i + 1)..);
 
                             for case in cases.by_ref() {
-                                exprs.extend(
-                                    case.test
-                                        .and_then(|e| ignore_result(*e, true, &self.expr_ctx))
-                                        .map(Box::new),
-                                );
-
                                 let should_stop = has_unconditional_stopper(&case.cons);
                                 stmts.extend(case.cons);
                                 //
@@ -968,8 +959,16 @@ impl VisitMut for Remover {
                             .iter()
                             .all(|case| case.test.is_none() || case.cons.is_empty());
 
+                        let is_all_case_side_effect_free = s.cases.iter().all(|case| {
+                            case.test
+                                .as_ref()
+                                .map(|e| e.is_ident() || !e.may_have_side_effects(&self.expr_ctx))
+                                .unwrap_or(true)
+                        });
+
                         if is_default_last
                             && is_all_case_empty
+                            && is_all_case_side_effect_free
                             && !has_conditional_stopper(&s.cases.last().unwrap().cons)
                         {
                             let mut exprs = vec![];

crates/swc_ecma_transforms_optimization/src/simplify/branch/tests.rs

@@ -867,19 +867,16 @@ fn test_optimize_switch_with_default_case() {
     test_same("switch (x) { default: if (a) break; bar(); }");
 
     // Potentially foldable
-    test(
-        concat!(
-            "switch (x) {",
-            "  case x:",
-            "    foo();",
-            "    break;",
-            "  default:",
-            "    if (a) { break; }",
-            "    bar();",
-            "}",
-        ),
-        "x; foo()",
-    );
+    test_same(concat!(
+        "switch (x) {",
+        "  case x:",
+        "    foo();",
+        "    break;",
+        "  default:",
+        "    if (a) break;",
+        "    bar();",
+        "}",
+    ));
 
     test(
         concat!(