Turbopack: resolve sourceMap.file (#80625)

This information is needed in #79459 to match up the right input source maps.

Author: mischnic

turbopack/crates/turbopack-core/src/source_map/utils.rs

@@ -69,15 +69,15 @@ struct SourceMapJson {
     sections: Option<Vec<SourceMapSectionItemJson>>,
 }
 
-/// Replace the origin prefix in the `sources` with `turbopack:///` and read the the
+/// Replace the origin prefix in the `file` and `sources` with `turbopack:///` and read the the
 /// `sourceContent`s from disk.
 pub async fn resolve_source_map_sources(
     map: Option<&Rope>,
     origin: Vc<FileSystemPath>,
 ) -> Result<Option<Rope>> {
     async fn resolve_source(
         original_source: &mut String,
-        original_content: &mut Option<String>,
+        original_content: Option<&mut Option<String>>,
         origin: Vc<FileSystemPath>,
     ) -> Result<()> {
         if let Some(path) = *origin
@@ -89,7 +89,9 @@ pub async fn resolve_source_map_sources(
             let source = format!("{SOURCE_URL_PROTOCOL}///{path_str}");
             *original_source = source;
 
-            if original_content.is_none() {
+            if let Some(original_content) = original_content
+                && original_content.is_none()
+            {
                 if let FileContent::Content(file) = &*path.read().await? {
                     let text = file.content().to_str()?;
                     *original_content = Some(text.to_string())
@@ -105,7 +107,9 @@ pub async fn resolve_source_map_sources(
                 s[0].replace('.', "_")
             });
             *original_source = format!("{SOURCE_URL_PROTOCOL}///{origin_str}/{source}");
-            if original_content.is_none() {
+            if let Some(original_content) = original_content
+                && original_content.is_none()
+            {
                 *original_content = Some(format!(
                     "unable to access {original_source} in {origin_str} (it's leaving the \
                      filesystem root)"
@@ -126,7 +130,7 @@ pub async fn resolve_source_map_sources(
 
             for (source, content) in sources.iter_mut().zip(contents.iter_mut()) {
                 if let Some(source) = source {
-                    resolve_source(source, content, origin).await?;
+                    resolve_source(source, Some(content), origin).await?;
                 }
             }
 
@@ -144,6 +148,10 @@ pub async fn resolve_source_map_sources(
         return Ok(None);
     };
 
+    if let Some(file) = &mut map.file {
+        resolve_source(file, None, origin).await?;
+    }
+
     resolve_map(&mut map, origin).await?;
     for section in map.sections.iter_mut().flatten() {
         resolve_map(&mut section.map, origin).await?;