From 2e2fae32dff6cab508768953bbd34b88b5bea166 Mon Sep 17 00:00:00 2001
From: Omer Ben-Amram <omerbenamram@gmail.com>
Date: Sun, 15 Dec 2019 17:46:00 +0200
Subject: improved path checking to consider only paths that may contain a
 windows drive.

---
 crates/ra_lsp_server/src/world.rs | 64 +++++++++++++++++++++++++++------------
 1 file changed, 44 insertions(+), 20 deletions(-)

diff --git a/crates/ra_lsp_server/src/world.rs b/crates/ra_lsp_server/src/world.rs
index f139a5728..63a820012 100644
--- a/crates/ra_lsp_server/src/world.rs
+++ b/crates/ra_lsp_server/src/world.rs
@@ -17,11 +17,13 @@ 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 {
@@ -233,11 +235,8 @@ 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)?;
 
-        #[cfg(target_os = "windows")]
-        let url = lowercase_drive_letter(&url);
         Ok(url)
     }
 
@@ -283,34 +282,59 @@ impl WorldSnapshot {
     }
 }
 
-#[cfg(target_os = "windows")]
-fn lowercase_drive_letter(url: &Url) -> Url {
-    use std::str::FromStr;
+/// 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()
+        .find(|comp| {
+            if let Component::Prefix(c) = comp {
+                match c.kind() {
+                    Prefix::Disk(_) | Prefix::VerbatimDisk(_) => return true,
+                    _ => return false,
+                }
+            }
+            false
+        })
+        .is_some();
+
+    // 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::<Vec<&str>>();
+
+        // 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 s = url.to_string();
-    let drive_partition: Vec<&str> = s.rsplitn(2, ':').collect::<Vec<&str>>();
+        let joined = drive_partition[1].to_ascii_lowercase() + ":" + drive_partition[0];
+        let url = Url::from_str(&joined).expect("This came from a valid `Url`");
 
-    if drive_partition.len() == 1 {
-        return url.clone();
+        Ok(url)
+    } else {
+        Ok(Url::from_file_path(&path)
+            .map_err(|_| format!("can't convert path to url: {}", path.as_ref().display()))?)
     }
-
-    let joined = drive_partition[1].to_ascii_lowercase() + ":" + drive_partition[0];
-    let url = Url::from_str(&joined).expect("This came from a valid `Url`");
-    url
 }
 
 #[test]
 fn test_lowercase_drive_letter_with_drive() {
-    let url = Url::from_file_path("C:\\Test").unwrap();
-    let url = lowercase_drive_letter(&url);
+    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_file_path(r#"\\localhost\C$\my_dir"#).expect("Should work");
-    let url = lowercase_drive_letter(&url);
+    let url = url_from_path_with_drive_lowercasing(r#"\\localhost\C$\my_dir"#).unwrap();
 
-    assert_eq!(url.to_string(), "file:///C$/my_dir");
+    assert_eq!(url.to_string(), "file://localhost/C$/my_dir");
 }
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