feat(es/modules): Optimize a dynamic import with a literal path (#5049)

crates/swc/tests/fixture/deno/paths/issue-2724/output/src/index.ts

@@ -4,6 +4,6 @@ Object.defineProperty(exports, "__esModule", {
 });
 const _interopRequireWildcard = require("../../../../../../../../../packages/swc-helpers/src/_interop_require_wildcard.mjs").default;
 (async function() {
-    const { displayA  } = await Promise.resolve("../packages/a/src/index").then((p)=>_interopRequireWildcard(require(p)));
+    const { displayA  } = await Promise.resolve().then(()=>_interopRequireWildcard(require("../packages/a/src/index")));
     console.log(displayA());
 })();

crates/swc/tests/fixture/issues-1xxx/1614/case1/output/index.ts

@@ -4,6 +4,6 @@ Object.defineProperty(exports, "__esModule", {
 });
 const _interopRequireWildcard = require("@swc/helpers/lib/_interop_require_wildcard.js").default;
 (async ()=>{
-    const example = await Promise.resolve("./example").then((p)=>_interopRequireWildcard(require(p)));
+    const example = await Promise.resolve().then(()=>_interopRequireWildcard(require("./example")));
     console.log(example.foo);
 })();

crates/swc_ecma_transforms_module/src/common_js.rs

@@ -152,9 +152,13 @@ impl VisitMut for Cjs {
             }) if !self.config.ignore_dynamic => {
                 args.visit_mut_with(self);
 
+                let mut is_lit_path = false;
+
                 args.get_mut(0).into_iter().for_each(|x| {
                     if let ExprOrSpread { spread: None, expr } = x {
                         if let Expr::Lit(Lit::Str(Str { value, raw, .. })) = &mut **expr {
+                            is_lit_path = true;
+
                             *value = self.resolver.resolve(value.clone());
                             *raw = None;
                         }
@@ -168,6 +172,7 @@ impl VisitMut for Cjs {
                     quote_ident!(require_span, "require"),
                     !self.config.no_interop,
                     self.support_arrow,
+                    is_lit_path,
                 );
             }
             Expr::Member(MemberExpr {
@@ -354,23 +359,34 @@ impl Cjs {
     }
 }
 
+/// ```javascript
 /// Promise.resolve(args).then(p => require(p))
+/// // for literial dynamic import:
+/// Promise.resolve().then(() => require(args))
+/// ```
 pub(crate) fn cjs_dynamic_import(
     span: Span,
     args: Vec<ExprOrSpread>,
     require: Ident,
     es_module_interop: bool,
     support_arrow: bool,
+    is_lit_path: bool,
 ) -> Expr {
+    let p = private_ident!("p");
+
+    let (resolve_args, callback_params, require_args) = if is_lit_path {
+        (vec![], vec![], args)
+    } else {
+        (args, vec![p.clone().into()], vec![p.as_arg()])
+    };
+
     let then = member_expr!(DUMMY_SP, Promise.resolve)
         // TODO: handle import assert
-        .as_call(DUMMY_SP, args)
+        .as_call(DUMMY_SP, resolve_args)
         .make_member(quote_ident!("then"));
 
-    let path = private_ident!("p");
-
     let import_expr = {
-        let require = require.as_call(DUMMY_SP, vec![path.clone().as_arg()]);
+        let require = require.as_call(DUMMY_SP, require_args);
 
         if es_module_interop {
             helper_expr!(interop_require_wildcard, "interopRequireWildcard")
@@ -383,7 +399,7 @@ pub(crate) fn cjs_dynamic_import(
     then.as_call(
         span,
         vec![import_expr
-            .into_lazy_auto(vec![path.into()], support_arrow)
+            .into_lazy_auto(callback_params, support_arrow)
             .as_arg()],
     )
 }

crates/swc_ecma_transforms_module/tests/fixture/common/issue-1018/1/output.cjs

@@ -1,4 +1,4 @@
 "use strict";
 async function foo() {
-    await Promise.resolve("foo").then((p)=>_interopRequireWildcard(require(p)));
+    await Promise.resolve().then(()=>_interopRequireWildcard(require("foo")));
 }

crates/swc_ecma_transforms_module/tests/fixture/common/issue-1480/1/output.cjs

@@ -1,2 +1,2 @@
 "use strict";
-const { default: ora  } = await Promise.resolve("ora").then((p)=>_interopRequireWildcard(require(p)));
+const { default: ora  } = await Promise.resolve().then(()=>_interopRequireWildcard(require("ora")));

crates/swc_ecma_transforms_module/tests/fixture/common/issue-1614/1/output.cjs

@@ -1,5 +1,5 @@
 "use strict";
 (async ()=>{
-    const example = await Promise.resolve("./example").then((p)=>_interopRequireWildcard(require(p)));
+    const example = await Promise.resolve().then(()=>_interopRequireWildcard(require("./example")));
     console.log(example.foo);
 })();

node-swc/__tests__/transform/issue_4730_test.mjs

@@ -32,18 +32,18 @@ it("should work", async () => {
         },
     });
     expect(code).toMatchInlineSnapshot(`
-        "\\"use strict\\";
-        Object.defineProperty(exports, \\"__esModule\\", {
-            value: true
-        });
-        const _interopRequireWildcard = require(\\"@swc/helpers/lib/_interop_require_wildcard.js\\").default;
-        const _b = require(\\"../packages/b/src/index\\");
-        async function display() {
-            const displayA = await Promise.resolve(\\"../packages/a/src/index\\").then((p)=>_interopRequireWildcard(require(p))).then((c)=>c.displayA);
-            console.log(displayA());
-            console.log((0, _b.displayB)());
-        }
-        display();
-        "
-    `);
+"\\"use strict\\";
+Object.defineProperty(exports, \\"__esModule\\", {
+    value: true
+});
+const _interopRequireWildcard = require(\\"@swc/helpers/lib/_interop_require_wildcard.js\\").default;
+const _b = require(\\"../packages/b/src/index\\");
+async function display() {
+    const displayA = await Promise.resolve().then(()=>_interopRequireWildcard(require(\\"../packages/a/src/index\\"))).then((c)=>c.displayA);
+    console.log(displayA());
+    console.log((0, _b.displayB)());
+}
+display();
+"
+`);
 });