Swc Plugin Compatibility

SWC Plugin Compatibility

If you see errors like these during your build:

failed to invoke plugin on 'Some("/app/src/file.ts")'
failed to run Wasm plugin transform. Please ensure the version of `swc_core` used by the plugin is compatible with the host runtime.
    swc_plugin_runner: <n>
: Failed to deserialize program received from host
Failed to execute SWC plugin                      (Next.js / Turbopack wording of the same failure)
RuntimeError: out of bounds memory access         (older hosts)
LayoutError called Result::unwrap()               (older hosts)

This is NOT a bug in your code or in Lingui. The installed @lingui/swc-plugin was built against an swc_core version your SWC host cannot run.

Why This Happens

Every @lingui/swc-plugin release is compiled against one pinned swc_core version — the plugin's compatibility table lists them. The host (Next.js's bundled SWC, or the @swc/core that @vitejs/plugin-react-swc / Rspack resolves) accepts plugins from a range of swc_core versions. Outside that range the Wasm plugin cannot deserialize the AST it is handed, and the build fails on every file that uses a macro.

SWC has stabilised the plugin ABI over time, so mismatches are rarer than they were, but hosts still move past plugins and plugins past hosts (see lingui/swc-plugin #250 and #253 for one of each). The pairing is something to check, never assume.

How to Fix

Step 1: Identify the host and its resolved version

Next.js embeds SWC and ignores any @swc/core in package.json; only the Next.js version decides its swc_core. On Vite, two projects with identical package.json can resolve different @swc/core versions — the lockfile is the source of truth.

Step 2: Choose the plugin version

1. Read the host's accepted swc_core range. The error message usually prints a https://plugins.swc.rs/versions/from-plugin-runner/<n> URL — open it in a browser; for Next.js, select runtime next and the resolved version on https://plugins.swc.rs. The site is client-rendered, so a plain fetch returns an empty page; the fallback is the host's own pin: for Next.js, swc_core in the root Cargo.toml of the vercel/next.js tag (v<version>), for @swc/core, its GitHub release notes.
2. In the plugin's compatibility table, take the newest @lingui/swc-plugin whose swc_core falls inside that range.
3. Check its peer: npm view @lingui/swc-plugin@<version> peerDependencies. Each plugin major requires the matching @lingui/core major as a required peer (a newer plugin major may also admit the previous core major). A candidate whose peer excludes the installed @lingui/core is not a candidate — the install fails with ERESOLVE instead of the build failing. Pick the next-newest that passes, or go to "What If No Compatible Version Exists?".

The compatibility site has lagged behind releases before. When the table and the site disagree, or the host is newer than either lists, decide by building: try the newest plugin, then step back one swc_core row at a time until a macro-using file compiles.

Hosts drift independently, so two hosts in one repo (a Next.js app and a Vite app) can legitimately need two different plugin versions.

Step 3: Pin exactly and confirm

{
  "devDependencies": {
    "@lingui/swc-plugin": "<exact version>"
  }
}

Use an exact version (no ^ or ~) so a routine dependency bump cannot move it. Done when the build passes on a file that uses a macro and the rendered output shows translated text rather than raw macro source.

Keeping It Working

1. Pin the plugin exactly and exclude it from Renovate/Dependabot auto-merge; bump it deliberately, after checking the compatibility table.
2. Treat host upgrades as plugin upgrades. Hosts change swc_core in minor and patch releases, so a Next.js or @vitejs/plugin-react-swc bump needs the same check — put both packages in one update group.
3. Build after any upgrade that touches SWC or the plugin. The build, not the changelog, is the confirmation.

@lingui/swc-plugin does not track the other @lingui/* versions; it releases on its own cadence, so its version number carries no information about which @lingui/core it pairs with beyond the peer field.