1 files changed, 69 insertions, 6 deletions

diff --git a/crates/ra_lsp_server/src/world.rs b/crates/ra_lsp_server/src/world.rs
index 927449b45..79431e7e6 100644
--- a/crates/ra_lsp_server/src/world.rs
+++ b/crates/ra_lsp_server/src/world.rs
@@ -1,4 +1,7 @@
-//! FIXME: write short doc here
+//! The context or environment in which the language server functions.
+//! In our server implementation this is know as the `WorldState`.
+//!
+//! Each tick provides an immutable snapshot of the state as `WorldSnapshot`.
 
 use std::{
     path::{Path, PathBuf},
@@ -17,11 +20,13 @@ use ra_project_model::{get_rustc_cfg_options, ProjectWorkspace};
 use ra_vfs::{LineEndings, RootEntry, Vfs, VfsChange, VfsFile, VfsRoot, VfsTask, Watch};
 use ra_vfs_glob::{Glob, RustPackageFilterBuilder};
 use relative_path::RelativePathBuf;
+use std::path::{Component, Prefix};
 
 use crate::{
     main_loop::pending_requests::{CompletedRequest, LatestRequests},
     LspError, Result,
 };
+use std::str::FromStr;
 
 #[derive(Debug, Clone)]
 pub struct Options {
@@ -140,10 +145,10 @@ impl WorldState {
     /// FIXME: better API here
     pub fn process_changes(
         &mut self,
-    ) -> Vec<(SourceRootId, Vec<(FileId, RelativePathBuf, Arc<String>)>)> {
+    ) -> Option<Vec<(SourceRootId, Vec<(FileId, RelativePathBuf, Arc<String>)>)>> {
         let changes = self.vfs.write().commit_changes();
         if changes.is_empty() {
-            return Vec::new();
+            return None;
         }
         let mut libs = Vec::new();
         let mut change = AnalysisChange::new();
@@ -177,7 +182,7 @@ impl WorldState {
             }
         }
         self.analysis_host.apply_change(change);
-        libs
+        Some(libs)
     }
 
     pub fn add_lib(&mut self, data: LibraryData) {
@@ -233,8 +238,8 @@ impl WorldSnapshot {
 
     pub fn file_id_to_uri(&self, id: FileId) -> Result<Url> {
         let path = self.vfs.read().file2path(VfsFile(id.0));
-        let url = Url::from_file_path(&path)
-            .map_err(|_| format!("can't convert path to url: {}", path.display()))?;
+        let url = url_from_path_with_drive_lowercasing(path)?;
+
         Ok(url)
     }
 
@@ -279,3 +284,61 @@ impl WorldSnapshot {
         self.analysis.feature_flags()
     }
 }
+
+/// Returns a `Url` object from a given path, will lowercase drive letters if present.
+/// This will only happen when processing windows paths.
+///
+/// When processing non-windows path, this is essentially the same as `Url::from_file_path`.
+fn url_from_path_with_drive_lowercasing(path: impl AsRef<Path>) -> Result<Url> {
+    let component_has_windows_drive = path.as_ref().components().any(|comp| {
+        if let Component::Prefix(c) = comp {
+            match c.kind() {
+                Prefix::Disk(_) | Prefix::VerbatimDisk(_) => return true,
+                _ => return false,
+            }
+        }
+        false
+    });
+
+    // VSCode expects drive letters to be lowercased, where rust will uppercase the drive letters.
+    if component_has_windows_drive {
+        let url_original = Url::from_file_path(&path)
+            .map_err(|_| format!("can't convert path to url: {}", path.as_ref().display()))?;
+
+        let drive_partition: Vec<&str> = url_original.as_str().rsplitn(2, ':').collect();
+
+        // There is a drive partition, but we never found a colon.
+        // This should not happen, but in this case we just pass it through.
+        if drive_partition.len() == 1 {
+            return Ok(url_original);
+        }
+
+        let joined = drive_partition[1].to_ascii_lowercase() + ":" + drive_partition[0];
+        let url = Url::from_str(&joined).expect("This came from a valid `Url`");
+
+        Ok(url)
+    } else {
+        Ok(Url::from_file_path(&path)
+            .map_err(|_| format!("can't convert path to url: {}", path.as_ref().display()))?)
+    }
+}
+
+// `Url` is not able to parse windows paths on unix machines.
+#[cfg(target_os = "windows")]
+#[cfg(test)]
+mod path_conversion_windows_tests {
+    use super::url_from_path_with_drive_lowercasing;
+    #[test]
+    fn test_lowercase_drive_letter_with_drive() {
+        let url = url_from_path_with_drive_lowercasing("C:\\Test").unwrap();
+
+        assert_eq!(url.to_string(), "file:///c:/Test");
+    }
+
+    #[test]
+    fn test_drive_without_colon_passthrough() {
+        let url = url_from_path_with_drive_lowercasing(r#"\\localhost\C$\my_dir"#).unwrap();
+
+        assert_eq!(url.to_string(), "file://localhost/C$/my_dir");
+    }
+}