make migrations async

packages/@tailwindcss-upgrade/src/codemods/migrate-at-apply.ts

@@ -34,17 +34,26 @@ export function migrateAtApply({
       return [...variants, utility].join(':')
     })
 
-    // If we have a valid designSystem and config setup, we can run all
-    // candidate migrations on each utility
-    params = params.map((param) => migrateCandidate(designSystem, userConfig, param))
-
-    atRule.params = params.join('').trim()
+    return async () => {
+      // If we have a valid designSystem and config setup, we can run all
+      // candidate migrations on each utility
+      params = await Promise.all(
+        params.map(async (param) => await migrateCandidate(designSystem, userConfig, param)),
+      )
+
+      atRule.params = params.join('').trim()
+    }
   }
 
   return {
     postcssPlugin: '@tailwindcss/upgrade/migrate-at-apply',
-    OnceExit(root) {
-      root.walkAtRules('apply', migrate)
+    async OnceExit(root) {
+      let migrations: (() => void)[] = []
+      root.walkAtRules('apply', (atRule) => {
+        migrations.push(migrate(atRule))
+      })
+
+      await Promise.allSettled(migrations.map((m) => m()))
     },
   }
 }

packages/@tailwindcss-upgrade/src/template/codemods/simple-legacy-classes.test.ts

@@ -39,5 +39,5 @@ test.each([
     base: __dirname,
   })
 
-  expect(simpleLegacyClasses(designSystem, {}, candidate)).toEqual(result)
+  expect(await simpleLegacyClasses(designSystem, {}, candidate)).toEqual(result)
 })

packages/@tailwindcss-upgrade/src/template/migrate.ts

@@ -25,7 +25,7 @@ export type Migration = (
     start: number
     end: number
   },
-) => string
+) => string | Promise<string>
 
 export const DEFAULT_MIGRATIONS: Migration[] = [
   prefix,
@@ -41,7 +41,7 @@ export const DEFAULT_MIGRATIONS: Migration[] = [
   modernizeArbitraryValues,
 ]
 
-export function migrateCandidate(
+export async function migrateCandidate(
   designSystem: DesignSystem,
   userConfig: Config,
   rawCandidate: string,
@@ -51,9 +51,9 @@ export function migrateCandidate(
     start: number
     end: number
   },
-): string {
+): Promise<string> {
   for (let migration of DEFAULT_MIGRATIONS) {
-    rawCandidate = migration(designSystem, userConfig, rawCandidate, location)
+    rawCandidate = await migration(designSystem, userConfig, rawCandidate, location)
   }
   return rawCandidate
 }
@@ -69,7 +69,7 @@ export default async function migrateContents(
   let changes: StringChange[] = []
 
   for (let { rawCandidate, start, end } of candidates) {
-    let migratedCandidate = migrateCandidate(designSystem, userConfig, rawCandidate, {
+    let migratedCandidate = await migrateCandidate(designSystem, userConfig, rawCandidate, {
       contents,
       start,
       end,