Cursed (but functional!) Rspack compatibility layer for `vite-plugin-magical-svg`

magical-svg-loader.mjs

/*!
 * SPDX-FileCopyrightText: 2026 Cynthia Rey
 * SPDX-License-Identifier: 0BSD
 */

async function process() {
	const plugin = this._compilation.options.plugins.find((p) => p.__is_magical_svg__)
	const ctx = {
		error: (msg) => this.emitError(new Error(msg)),
		warn: (msg) => this.emitWarning(new Error(msg)),
	}

	const { code } = await plugin.instance.load.handler.call(ctx, this.resource)
	const { code: res } = await plugin.instance.transform.handler.call(ctx, code, this.resource)
	return res
}

export default function () {
	const cb = this.async()
	process.call(this)
		.then(
			(r) => cb(null, r),
			(e) => cb(e),
		)
}

magical-svg-plugin.mjs

/*!
 * SPDX-FileCopyrightText: 2026 Cynthia Rey
 * SPDX-License-Identifier: 0BSD
 */

import { sources } from '@rspack/core'
import magicalSvgPlugin from 'vite-plugin-magical-svg'

export default class MagicalSvg {
	__is_magical_svg__ = true

	constructor(opts) {
		this.instance = magicalSvgPlugin(opts)
	}

	apply(compiler) {
		compiler.hooks.compilation.tap('MagicalSvg', (compilation) => {
			compilation.hooks.processAssets.tapPromise(
				{ name: 'MagicalSvg', stage: compiler.rspack.PROCESS_ASSETS_STAGE_PRE_PROCESS },
				(assets) => {
					let current
					const ctx = {
						getModuleInfo: () => ({}),
						emitFile: ({ fileName, source }) =>
							compilation.emitAsset(
								fileName,
								new sources.RawSource(source),
								{ immutable: true, minimized: true },
							),
						error: ({ message, cause, loc: { line, column } }) => {
							const err = new Error(`${message} (at ${line}:${column})`)
							err.cause = cause
							err.file = current
							throw err
						},
					}

					for (const assetName in assets) {
						const asset = assets[current = assetName]
						try {
							const { code: transformed } = this.instance.renderChunk.call(ctx, asset.source().toString())
							if (transformed) compilation.updateAsset(assetName, new sources.RawSource(transformed.toString()))
						} catch (e) {
							compilation.errors.push(e)
						}
					}

					return this.instance.generateBundle.call(ctx)
				}
			)
		})
	}
}

rspack.config.mjs

/*!
 * SPDX-FileCopyrightText: 2026 Cynthia Rey
 * SPDX-License-Identifier: 0BSD
 */

import MagicalSvg from './magical-svg-plugin.mjs'

export default {
	entry: {
		main: '...'
	},
	module: {
		rules: [
			{
				test: /\.svg$/,
				loader: './magical-svg-loader.mjs',
				type: 'javascript/esm',
			},
		],
	},
	plugins: [
		new MagicalSvg(/* magical-svg options... */),
	],
}