Fix drive-letter case-sensitivity on Windows

Author: thecrypticace

packages/tailwindcss-language-server/src/resolver/index.ts

@@ -8,6 +8,7 @@ import {
 } from 'enhanced-resolve'
 import { loadPnPApi, type PnpApi } from './pnp'
 import { loadTsConfig, type TSConfigApi } from './tsconfig'
+import { normalizeYarnPnPDriveLetter } from '../utils'
 
 export interface ResolverOptions {
   /**
@@ -183,6 +184,10 @@ export async function createResolver(opts: ResolverOptions): Promise<Resolver> {
       if (match) id = match
     }
 
+    // 2. Normalize the drive letters to the case that the PnP API expects
+    id = normalizeYarnPnPDriveLetter(id)
+    base = normalizeYarnPnPDriveLetter(base)
+
     return new Promise((resolve, reject) => {
       resolver.resolve({}, base, id, {}, (err, res) => {
         if (err) {

packages/tailwindcss-language-server/src/utils.ts

@@ -74,14 +74,42 @@ export function dirContains(dir: string, file: string): boolean {
 }
 
 const WIN_DRIVE_LETTER = /^([a-zA-Z]):/
+const POSIX_DRIVE_LETTER = /^\/([a-zA-Z]):/
 
 /**
  * Windows drive letters are case-insensitive and we may get them as either
  * lower or upper case. This function normalizes the drive letter to uppercase
  * to be consistent with the rest of the codebase.
  */
 export function normalizeDriveLetter(filepath: string) {
-  return filepath.replace(WIN_DRIVE_LETTER, (_, letter) => letter.toUpperCase() + ':')
+  return filepath
+    .replace(WIN_DRIVE_LETTER, (_, letter) => `${letter.toUpperCase()}:`)
+    .replace(POSIX_DRIVE_LETTER, (_, letter) => `/${letter.toUpperCase()}:`)
+}
+
+/**
+ * Windows drive letters are case-insensitive and we may get them as either
+ * lower or upper case.
+ *
+ * Yarn PnP only works when requests have the correct case for the drive letter
+ * that matches the drive letter of the current working directory.
+ *
+ * Even using makeApi with a custom base path doesn't work around this.
+ */
+export function normalizeYarnPnPDriveLetter(filepath: string) {
+  let cwdDriveLetter = process.cwd().match(WIN_DRIVE_LETTER)?.[1]
+
+  return filepath
+    .replace(WIN_DRIVE_LETTER, (_, letter) => {
+      return letter.toUpperCase() === cwdDriveLetter.toUpperCase()
+        ? `${cwdDriveLetter}:`
+        : `${letter.toUpperCase()}:`
+    })
+    .replace(POSIX_DRIVE_LETTER, (_, letter) => {
+      return letter.toUpperCase() === cwdDriveLetter.toUpperCase()
+        ? `/${cwdDriveLetter}:`
+        : `/${letter.toUpperCase()}:`
+    })
 }
 
 export function changeAffectsFile(change: string, files: Iterable<string>): boolean {