Start work on respecting project-specific settings

crates/language/src/buffer.rs

@@ -216,6 +216,11 @@ pub trait File: Send + Sync {
     /// of its worktree, then this method will return the name of the worktree itself.
     fn file_name<'a>(&'a self, cx: &'a AppContext) -> &'a OsStr;
 
+    /// Returns the id of the worktree to which this file belongs.
+    ///
+    /// This is needed for looking up project-specific settings.
+    fn worktree_id(&self) -> usize;
+
     fn is_deleted(&self) -> bool;
 
     fn as_any(&self) -> &dyn Any;
@@ -1803,7 +1808,11 @@ impl BufferSnapshot {
 
     pub fn language_indent_size_at<T: ToOffset>(&self, position: T, cx: &AppContext) -> IndentSize {
         let language_name = self.language_at(position).map(|language| language.name());
-        let settings = language_settings(language_name.as_deref(), cx);
+        let settings = language_settings(
+            language_name.as_deref(),
+            self.file().map(|f| f.as_ref()),
+            cx,
+        );
         if settings.hard_tabs {
             IndentSize::tab()
         } else {
@@ -2128,7 +2137,11 @@ impl BufferSnapshot {
         cx: &'a AppContext,
     ) -> &'a LanguageSettings {
         let language = self.language_at(position);
-        language_settings(language.map(|l| l.name()).as_deref(), cx)
+        language_settings(
+            language.map(|l| l.name()).as_deref(),
+            self.file.as_ref().map(AsRef::as_ref),
+            cx,
+        )
     }
 
     pub fn language_scope_at<D: ToOffset>(&self, position: D) -> Option<LanguageScope> {

crates/language/src/language_settings.rs

@@ -1,3 +1,4 @@
+use crate::File;
 use anyhow::Result;
 use collections::HashMap;
 use globset::GlobMatcher;
@@ -13,8 +14,16 @@ pub fn init(cx: &mut AppContext) {
     settings::register::<AllLanguageSettings>(cx);
 }
 
-pub fn language_settings<'a>(language: Option<&str>, cx: &'a AppContext) -> &'a LanguageSettings {
-    settings::get::<AllLanguageSettings>(cx).language(language)
+pub fn language_settings<'a>(
+    language: Option<&str>,
+    file: Option<&dyn File>,
+    cx: &'a AppContext,
+) -> &'a LanguageSettings {
+    settings::get_local::<AllLanguageSettings>(
+        file.map(|f| (f.worktree_id(), f.path().as_ref())),
+        cx,
+    )
+    .language(language)
 }
 
 pub fn all_language_settings<'a>(cx: &'a AppContext) -> &'a AllLanguageSettings {