fix(es/transforms/typescript): Allow (foo as any) = bar (#2631)

swc_ecma_transforms_typescript:
 - `strip`: Handle paren in the LHS of assignment expressions properly. (Closes https://github.com/swc-project/swc/issues/2606)

ecmascript/transforms/typescript/src/strip.rs

@@ -2217,6 +2217,34 @@ where
         d.visit_mut_children_with(self);
         d.definite = false;
     }
+
+    fn visit_mut_pat_or_expr(&mut self, node: &mut PatOrExpr) {
+        // Coerce bindingident to assign expr where parenthesis exists due to TsAsExpr
+        // like (warn as any) = v;
+        // We want to do this _before_ visiting children, otherwise handle_expr
+        // wipes out TsAsExpr and there's no way to distinguish between
+        // plain (x) = y vs. (x as any) = y;
+        match node {
+            PatOrExpr::Pat(pat) => match &**pat {
+                Pat::Expr(expr) => match &**expr {
+                    Expr::Paren(ParenExpr { expr, .. }) => match &**expr {
+                        Expr::TsAs(TsAsExpr { expr, .. }) => match &**expr {
+                            Expr::Ident(ident) => {
+                                *node = PatOrExpr::Pat(Box::new(Pat::Ident(ident.clone().into())));
+                            }
+                            _ => (),
+                        },
+                        _ => (),
+                    },
+                    _ => (),
+                },
+                _ => (),
+            },
+            _ => (),
+        }
+
+        node.visit_mut_children_with(self);
+    }
 }
 
 fn module_ref_to_expr(r: TsModuleRef) -> Expr {

tests/fixture/issue-2606/1/input/.swcrc

@@ -0,0 +1,11 @@
+{
+  "jsc": {
+    "parser": {
+      "syntax": "typescript"
+    },
+    "target": "es2015"
+  },
+  "module": {
+    "type": "commonjs"
+  }
+}

tests/fixture/issue-2606/1/input/index.ts

@@ -0,0 +1,17 @@
+export function warn() {
+  throw new Error("this should not be called");
+}
+export const test = {};
+export const test2 = {};
+Object.defineProperty(test, "warn", {
+  get: () => warn,
+  set: (v) => {
+    (warn as any) = v;
+  },
+});
+Object.defineProperty(test2, "work", {
+  get: () => warn,
+  set: (v) => {
+    warn = v;
+  },
+});

tests/fixture/issue-2606/1/output/index.ts

@@ -0,0 +1,29 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.warn = warn;
+exports.test2 = exports.test = void 0;
+function warn() {
+    throw new Error("this should not be called");
+}
+const test = {
+};
+exports.test = test;
+const test2 = {
+};
+exports.test2 = test2;
+Object.defineProperty(test, "warn", {
+    get: ()=>warn
+    ,
+    set: (v)=>{
+        exports.warn = warn = v;
+    }
+});
+Object.defineProperty(test2, "work", {
+    get: ()=>warn
+    ,
+    set: (v)=>{
+        exports.warn = warn = v;
+    }
+});