What causes "Minify command is not yet implemented" in swc-project/swc?

Minify via the supported surface: `swc compile` with a .swcrc containing `"minify": true` (jsc.minifier options), or the JS API `@swc/core`'s minify().

swc-project/swc · error

Minify command is not yet implemented

Error message

Minify command is not yet implemented

What it means

The `swc` CLI's `minify` subcommand is registered in clap but MinifyOptions::execute is a stub that calls unimplemented!() at minify.rs:8, so `swc minify ...` panics immediately (exit 101). The minifier itself exists in swc_core::ecma_minifier — only the CLI wiring is missing.

Source

Thrown at crates/swc_cli_impl/src/commands/minify.rs:8

use clap::Parser;

#[derive(Parser)]
pub struct MinifyOptions {}

impl super::CommandRunner for MinifyOptions {
    fn execute(&self) -> anyhow::Result<()> {
        unimplemented!("Minify command is not yet implemented")
    }
}

View on GitHub (pinned to d7d7434666)

Solutions

Minify via the supported surface: `swc compile` with a .swcrc containing `"minify": true` (jsc.minifier options), or the JS API `@swc/core`'s minify().
From Rust, call swc_core::ecma_minifier directly (optimize() with MinifyOptions).
Alternatively use esbuild/terser for the minify step.
If you own the binary, implement CommandRunner for MinifyOptions or make the stub return a clean anyhow error.

Example fix

# before
swc minify ./src/app.js

# after (via compile + .swcrc with jsc.minifier, or JS API)
# .swcrc: { "jsc": { "minify": { "compress": true, "mangle": true } } }
swc compile ./src/app.js

Defensive patterns

Strategy: try-catch

Validate before calling

# Verify minify support before adding it to a pipeline
printf 'const x=1;' > /tmp/probe.js
swc minify /tmp/probe.js >/dev/null 2>/tmp/swc_min.err
if grep -q 'Minify command is not yet implemented' /tmp/swc_min.err; then
  echo 'swc minify is a stub — use swc compile with jsc.minify, or @swc/core minify()'
fi

Try / catch

set +e
swc minify app.js 2>/tmp/min.err
status=$?
set -e
if [ "$status" -eq 101 ] && grep -q 'Minify command is not yet implemented' /tmp/min.err; then
  echo 'falling back to @swc/core minify' >&2
  exec node -e 'const swc=require("@swc/core");const fs=require("fs");swc.minify(fs.readFileSync("app.js","utf8")).then(r=>fs.writeFileSync("app.min.js",r.code));'
fi
exit "$status"

Prevention

Reach for `swc compile` + `.swcrc` jsc.minify settings, or the JS/Rust minifier API — not the CLI subcommand.
Probe third-party CLIs in a subprocess before relying on them in build scripts.
Keep terser/esbuild as a fallback minifier in the pipeline.
Pin tool versions and smoke-test after upgrades.

When it happens

Trigger: Executing `swc minify file.js` with the swc_cli_impl binary; clap parses successfully, lib.rs dispatches Command::Minify(options) => options.execute(), and the process panics.

Common situations: Teams switching from terser/esbuild assuming the native CLI exposes minification; npm scripts calling `swc minify`; users surprised the subcommand shows in help yet aborts.

Related errors

AI-assisted analysis of swc-project/swc@d7d7434666 (2026-08-16). Data as JSON: /api/errors/917b8146758bc474. Report an issue: GitHub.