vercel · mischnic · Jul 23, 2025 · Jul 17, 2025 · Jul 17, 2025 · Jul 22, 2025
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -299,21 +299,25 @@ turbopack-trace-utils = { path = "turbopack/crates/turbopack-trace-utils" }
 turbopack-wasm = { path = "turbopack/crates/turbopack-wasm" }
 
 # SWC crates
-swc_core = { version = "30.1.1", features = [
+swc_core = { version = "34", features = [
   "ecma_loader_lru",
   "ecma_loader_parking_lot",
   "parallel_rayon",
 ] }
-testing = { version = "14.0.0" }
+testing = "15.0.0"
 
 # Keep consistent with preset_env_base through swc_core
-browserslist-rs = { version = "0.19.0" }
+browserslist-rs = "0.19.0"
 mdxjs = "1.0.3"
-modularize_imports = { version = "0.90.0" }
-styled_components = { version = "0.118.0" }
-styled_jsx = { version = "0.94.0" }
-swc_emotion = { version = "0.94.0" }
-swc_relay = { version = "0.64.0" }
+modularize_imports = "0.93.0"
+styled_components = "0.121.0"
+styled_jsx = "0.97.0"
+swc_emotion = "0.97.0"
+swc_relay = "0.67.0"
+react_remove_properties = "0.47.0"
+remove_console = "0.48.0"
+preset_env_base = "5.0.0"
+
 
 # General Deps
 chromiumoxide = { version = "0.5.4", features = [
@@ -439,6 +443,6 @@ webbrowser = "0.8.7"
 
 [patch.crates-io]
 hyper = { git = "https://github.com/bgw/hyper-rs.git", branch = "v1.6.0-with-macos-intel-miscompilation-workaround" }
+mdxjs = { git = "https://github.com/mischnic/mdxjs-rs.git", branch = "swc-core-32" }
 lightningcss = { git = "https://github.com/parcel-bundler/lightningcss.git", branch = "mischnic/bump-browserslist" }
-mdxjs = { git = "https://github.com/kdy1/mdxjs-rs.git", branch = "swc-core-30" }
 parcel_selectors = { git = "https://github.com/parcel-bundler/lightningcss.git", branch = "mischnic/bump-browserslist" }
diff --git a/crates/napi/Cargo.toml b/crates/napi/Cargo.toml
@@ -82,6 +82,7 @@ swc_core = { workspace = true, features = [
     "ecma_ast",
     "ecma_ast_serde",
     "ecma_codegen",
+    "ecma_helpers_inline",
     "ecma_loader_lru",
     "ecma_loader_node",
     "ecma_minifier",

diff --git a/crates/napi/src/lib.rs b/crates/napi/src/lib.rs
@@ -70,7 +70,15 @@ static ALLOC: dhat::Alloc = dhat::Alloc;
 #[cfg(not(target_arch = "wasm32"))]
 #[napi::module_init]
 fn init() {
-    use std::panic::{set_hook, take_hook};
+    use std::{
+        cell::RefCell,
+        panic::{set_hook, take_hook},
+        time::{Duration, Instant},
+    };
+
+    thread_local! {
+        static LAST_SWC_ATOM_GC_TIME: RefCell<Option<Instant>> = const { RefCell::new(None) };
+    }
 
     use tokio::runtime::Builder;
     use turbo_tasks::panic_hooks::handle_panic;
@@ -87,6 +95,14 @@ fn init() {
         .on_thread_stop(|| {
             TurboMalloc::thread_stop();
         })
+        .on_thread_park(|| {
+            LAST_SWC_ATOM_GC_TIME.with_borrow_mut(|cell| {
+                if cell.is_none_or(|t| t.elapsed() > Duration::from_secs(2)) {
+                    swc_core::ecma::atoms::hstr::global_atom_store_gc();
+                    *cell = Some(Instant::now());
+                }
+            });
+        })
         .disable_lifo_slot()
         .build()
         .unwrap();

diff --git a/crates/next-api/benches/hmr.rs b/crates/next-api/benches/hmr.rs
@@ -1,4 +1,5 @@
 use std::{
+    cell::RefCell,
     fs::{create_dir_all, write},
     mem::forget,
     path::{Path, PathBuf},
@@ -154,11 +155,23 @@ fn load_next_config() -> RcStr {
 }
 
 fn runtime() -> Runtime {
+    thread_local! {
+        static LAST_SWC_ATOM_GC_TIME: RefCell<Option<Instant>> = const { RefCell::new(None) };
+    }
+
     tokio::runtime::Builder::new_multi_thread()
         .enable_all()
         .on_thread_stop(|| {
             turbo_tasks_malloc::TurboMalloc::thread_stop();
         })
+        .on_thread_park(|| {
+            LAST_SWC_ATOM_GC_TIME.with_borrow_mut(|cell| {
+                if cell.is_none_or(|t| t.elapsed() > Duration::from_secs(2)) {
+                    swc_core::ecma::atoms::hstr::global_atom_store_gc();
+                    *cell = Some(Instant::now());
+                }
+            });
+        })
         .build()
         .context("Failed to build tokio runtime")
         .unwrap()

diff --git a/crates/next-build-test/Cargo.toml b/crates/next-build-test/Cargo.toml
@@ -16,6 +16,7 @@ next-api = { workspace = true }
 next-core = { workspace = true }
 num_cpus = "1.16.0"
 rand = { workspace = true, features = ["small_rng"] }
+swc_core = { workspace = true }
 serde_json = { workspace = true }
 tokio = { workspace = true, features = ["full"] }
 tokio-stream = "0.1.15"

diff --git a/crates/next-build-test/src/main.rs b/crates/next-build-test/src/main.rs
@@ -1,4 +1,9 @@
-use std::{convert::Infallible, str::FromStr, time::Instant};
+use std::{
+    cell::RefCell,
+    convert::Infallible,
+    str::FromStr,
+    time::{Duration, Instant},
+};
 
 use next_api::project::{DefineEnv, ProjectOptions};
 use next_build_test::{Strategy, main_inner};
@@ -70,12 +75,23 @@ fn main() {
                 factor = 1;
             }
 
+            thread_local! {
+                static LAST_SWC_ATOM_GC_TIME: RefCell<Option<Instant>> = const { RefCell::new(None) };
+            }
             tokio::runtime::Builder::new_multi_thread()
                 .enable_all()
                 .on_thread_stop(|| {
                     TurboMalloc::thread_stop();
                     tracing::debug!("threads stopped");
                 })
+                .on_thread_park(|| {
+                    LAST_SWC_ATOM_GC_TIME.with_borrow_mut(|cell| {
+                        if cell.is_none_or(|t| t.elapsed() > Duration::from_secs(2)) {
+                            swc_core::ecma::atoms::hstr::global_atom_store_gc();
+                            *cell = Some(Instant::now());
+                        }
+                    });
+                })
                 .build()
                 .unwrap()
                 .block_on(async {

diff --git a/crates/next-core/Cargo.toml b/crates/next-core/Cargo.toml
@@ -31,8 +31,8 @@ futures = { workspace = true }
 thiserror = { workspace = true }
 tracing = { workspace = true }
 rustc-hash = { workspace = true }
-react_remove_properties = "0.44.0"
-remove_console = "0.45.0"
+react_remove_properties = { workspace = true }
+remove_console = { workspace = true }
 itertools = { workspace = true }
 percent-encoding = "2.3.1"
 serde_path_to_error = { workspace = true }

diff --git a/crates/next-custom-transforms/Cargo.toml b/crates/next-custom-transforms/Cargo.toml
@@ -67,9 +67,9 @@ turbopack-ecmascript-plugins = { workspace = true, optional = true }
 turbo-rcstr = { workspace = true }
 urlencoding = { workspace = true }
 
-react_remove_properties = "0.44.0"
-remove_console = "0.45.0"
-preset_env_base = "4.0.0"
+react_remove_properties = { workspace = true }
+remove_console = { workspace = true }
+preset_env_base = { workspace = true }
 
 [dev-dependencies]
 swc_core = { workspace = true, features = ["testing_transform"] }

diff --git a/packages/next/src/build/swc/generated-native.d.ts b/packages/next/src/build/swc/generated-native.d.ts
@@ -100,19 +100,19 @@ export interface NapiWatchOptions {
 }
 export interface NapiProjectOptions {
   /**
-   * An absolute root path from which all files must be nested under. Trying to access
-   * a file outside this root will fail, so think of this as a chroot.
+   * An absolute root path (Unix or Windows path) from which all files must be nested under.
+   * Trying to access a file outside this root will fail, so think of this as a chroot.
    * E.g. `/home/user/projects/my-repo`.
    */
   rootPath: RcStr
   /**
-   * A path which contains the app/pages directories, relative to [`Project::root_path`].
-   * E.g. `apps/my-app`
+   * A path which contains the app/pages directories, relative to [`Project::root_path`], always
+   * Unix path. E.g. `apps/my-app`
    */
   projectPath: RcStr
   /**
-   * A path where to emit the build outputs, relative to [`Project::project_path`].
-   * Corresponds to next.config.js's `distDir`.
+   * A path where to emit the build outputs, relative to [`Project::project_path`], always Unix
+   * path. Corresponds to next.config.js's `distDir`.
    * E.g. `.next`
    */
   distDir: RcStr
@@ -151,19 +151,20 @@ export interface NapiProjectOptions {
 /** [NapiProjectOptions] with all fields optional. */
 export interface NapiPartialProjectOptions {
   /**
-   * An absolute root path from which all files must be nested under. Trying to access
-   * a file outside this root will fail, so think of this as a chroot.
+   * An absolute root path  (Unix or Windows path) from which all files must be nested under.
+   * Trying to access a file outside this root will fail, so think of this as a chroot.
    * E.g. `/home/user/projects/my-repo`.
    */
   rootPath?: RcStr
   /**
-   * A path which contains the app/pages directories, relative to [`Project::root_path`].
+   * A path which contains the app/pages directories, relative to [`Project::root_path`], always
+   * a Unix path.
    * E.g. `apps/my-app`
    */
   projectPath?: RcStr
   /**
-   * A path where to emit the build outputs, relative to [`Project::project_path`].
-   * Corresponds to next.config.js's `distDir`.
+   * A path where to emit the build outputs, relative to [`Project::project_path`], always a
+   * Unix path. Corresponds to next.config.js's `distDir`.
    * E.g. `.next`
    */
   distDir?: RcStr | undefined | null

diff --git a/test/development/acceptance-app/error-recovery.test.ts b/test/development/acceptance-app/error-recovery.test.ts
@@ -142,10 +142,10 @@ describe('Error recovery app', () => {
          "description": "Parsing ecmascript source code failed",
          "environmentLabel": null,
          "label": "Build Error",
-         "source": "./app/server/page.js (2:27)
+         "source": "./app/server/page.js (2:26)
        Parsing ecmascript source code failed
        > 2 |   return <p>Hello world</p>
-           |                           ^",
+           |                          ^",
          "stack": [],
        }
       `)
@@ -160,7 +160,7 @@ describe('Error recovery app', () => {
           ,-[2:1]
         1 | export default function Page() {
         2 |   return <p>Hello world</p>
-          :                           ^
+          :                          ^
           \`----
        Caused by:
            Syntax Error
@@ -206,10 +206,10 @@ describe('Error recovery app', () => {
          "description": "Parsing ecmascript source code failed",
          "environmentLabel": null,
          "label": "Build Error",
-         "source": "./app/client/page.js (2:27)
+         "source": "./app/client/page.js (2:26)
        Parsing ecmascript source code failed
        > 2 |   return <p>Hello world</p>
-           |                           ^",
+           |                          ^",
          "stack": [],
        }
       `)
@@ -224,7 +224,7 @@ describe('Error recovery app', () => {
           ,-[2:1]
         1 | export default function Page() {
         2 |   return <p>Hello world</p>
-          :                           ^
+          :                          ^
           \`----
        Caused by:
            Syntax Error
@@ -619,10 +619,10 @@ describe('Error recovery app', () => {
          "description": "Parsing ecmascript source code failed",
          "environmentLabel": null,
          "label": "Build Error",
-         "source": "./index.js (10:41)
+         "source": "./index.js (10:39)
        Parsing ecmascript source code failed
        > 10 | export default function FunctionNamed() {
-            |                                         ^",
+            |                                       ^",
          "stack": [],
        }
       `)
@@ -636,7 +636,7 @@ describe('Error recovery app', () => {
        Error:   x Expected '}', got '<eof>'
            ,-[10:1]
         10 | export default function FunctionNamed() {
-           :                                         ^
+           :                                       ^
            \`----
        Caused by:
            Syntax Error
@@ -656,10 +656,10 @@ describe('Error recovery app', () => {
          "description": "Parsing ecmascript source code failed",
          "environmentLabel": null,
          "label": "Build Error",
-         "source": "./index.js (10:41)
+         "source": "./index.js (10:39)
        Parsing ecmascript source code failed
        > 10 | export default function FunctionNamed() {
-            |                                         ^",
+            |                                       ^",
          "stack": [],
        }
       `)
@@ -673,7 +673,7 @@ describe('Error recovery app', () => {
        Error:   x Expected '}', got '<eof>'
            ,-[10:1]
         10 | export default function FunctionNamed() {
-           :                                         ^
+           :                                       ^
            \`----
        Caused by:
            Syntax Error
@@ -1012,10 +1012,10 @@ describe('Error recovery app', () => {
          "description": "Parsing ecmascript source code failed",
          "environmentLabel": null,
          "label": "Build Error",
-         "source": "./app/page.js (1:3)
+         "source": "./app/page.js (1:2)
        Parsing ecmascript source code failed
        > 1 | {{{
-           |   ^",
+           |  ^",
          "stack": [],
        }
       `)
@@ -1029,7 +1029,7 @@ describe('Error recovery app', () => {
        Error:   x Expected '}', got '<eof>'
           ,----
         1 | {{{
-          :   ^
+          :  ^
           \`----
        Caused by:
            Syntax Error",

diff --git a/test/development/acceptance/error-recovery.test.ts b/test/development/acceptance/error-recovery.test.ts
@@ -840,10 +840,10 @@ describe('pages/ error recovery', () => {
          "description": "Parsing ecmascript source code failed",
          "environmentLabel": null,
          "label": "Build Error",
-         "source": "./index.js (7:41)
+         "source": "./index.js (7:39)
        Parsing ecmascript source code failed
        > 7 | export default function FunctionNamed() {
-           |                                         ^",
+           |                                       ^",
          "stack": [],
        }
       `)
@@ -886,7 +886,7 @@ describe('pages/ error recovery', () => {
         5 |   throw Error('no ' + i)
         6 | }, 1000)
         7 | export default function FunctionNamed() {
-          :                                         ^
+          :                                       ^
           \`----
        Caused by:
            Syntax Error
@@ -908,10 +908,10 @@ describe('pages/ error recovery', () => {
          "description": "Parsing ecmascript source code failed",
          "environmentLabel": null,
          "label": "Build Error",
-         "source": "./index.js (7:41)
+         "source": "./index.js (7:39)
        Parsing ecmascript source code failed
        > 7 | export default function FunctionNamed() {
-           |                                         ^",
+           |                                       ^",
          "stack": [],
        }
       `)
@@ -954,7 +954,7 @@ describe('pages/ error recovery', () => {
         5 |   throw Error('no ' + i)
         6 | }, 1000)
         7 | export default function FunctionNamed() {
-          :                                         ^
+          :                                       ^
           \`----
        Caused by:
            Syntax Error

diff --git a/test/integration/custom-error/test/index.test.js b/test/integration/custom-error/test/index.test.js
@@ -41,7 +41,7 @@ describe('Custom _error', () => {
         await retry(async () => {
           // retry because the page might not be built yet
           const html = await renderViaHTTP(appPort, '/404')
-          expect(html).toContain('Unexpected token')
+          expect(html).toContain('Unexpected eof')
           expect(stderr).not.toMatch(customErrNo404Match)
         })
       } finally {