fix(turbopack): Backport sourcemap bugfix (#78881)

#78453 is a bugfix for sourcemap on windows

Author: kdy1

turbopack/crates/turbo-tasks-fs/src/lib.rs

@@ -1278,6 +1278,10 @@ impl FileSystemPath {
     /// None when the joined path would leave the filesystem root.
     #[turbo_tasks::function]
     pub async fn try_join(&self, path: RcStr) -> Result<Vc<FileSystemPathOption>> {
+        // TODO(PACK-3279): Remove this once we do not produce invalid paths at the first place.
+        #[cfg(target_os = "windows")]
+        let path = path.replace('\\', "/");
+
         if let Some(path) = join_path(&self.path, &path) {
             Ok(Vc::cell(Some(
                 Self::new_normalized(*self.fs, path.into())

turbopack/crates/turbo-tasks-fs/src/util.rs

@@ -138,6 +138,7 @@ pub fn extract_disk_access<T>(value: io::Result<T>, path: &Path) -> Result<Optio
     }
 }
 
+#[cfg(not(target_os = "windows"))]
 pub async fn uri_from_file(root: Vc<FileSystemPath>, path: Option<&str>) -> Result<String> {
     let root_fs = root.fs();
     let root_fs = &*Vc::try_resolve_downcast_type::<DiskFileSystem>(root_fs)
@@ -162,3 +163,34 @@ pub async fn uri_from_file(root: Vc<FileSystemPath>, path: Option<&str>) -> Resu
         .join("/")
     ))
 }
+
+#[cfg(target_os = "windows")]
+pub async fn uri_from_file(root: Vc<FileSystemPath>, path: Option<&str>) -> Result<String> {
+    let root_fs = root.fs();
+    let root_fs = &*Vc::try_resolve_downcast_type::<DiskFileSystem>(root_fs)
+        .await?
+        .context("Expected root to have a DiskFileSystem")?
+        .await?;
+
+    let sys_path = root_fs
+        .to_sys_path(match path {
+            Some(path) => root.join(path.into()),
+            None => root,
+        })
+        .await?;
+
+    let raw_path = sys_path.to_string_lossy().to_string();
+    let normalized_path = raw_path.replace('\\', "/");
+
+    let mut segments = normalized_path.split('/');
+
+    let first = segments.next().unwrap_or_default(); // e.g., "C:"
+    let encoded_path = std::iter::once(first.to_string()) // keep "C:" intact
+        .chain(segments.map(|s| urlencoding::encode(s).into_owned()))
+        .collect::<Vec<_>>()
+        .join("/");
+
+    let uri = format!("file:///{}", encoded_path);
+
+    Ok(uri)
+}