8 files changed, 68 insertions, 30 deletions

diff --git a/crates/assists/src/assist_context.rs b/crates/assists/src/assist_context.rs
index 79574b9ac..11c171fc2 100644
--- a/crates/assists/src/assist_context.rs
+++ b/crates/assists/src/assist_context.rs
@@ -6,6 +6,7 @@ use algo::find_covering_element;
 use base_db::{FileId, FileRange};
 use hir::Semantics;
 use ide_db::{
+    label::Label,
     source_change::{SourceChange, SourceFileEdit},
     RootDatabase,
 };
@@ -157,8 +158,9 @@ impl Assists {
         if !self.is_allowed(&id) {
             return None;
         }
-        let label = Assist::new(id, label.into(), None, target);
-        self.add_impl(label, f)
+        let label = Label::new(label.into());
+        let assist = Assist { id, label, group: None, target };
+        self.add_impl(assist, f)
     }
 
     pub(crate) fn add_group(
@@ -172,12 +174,12 @@ impl Assists {
         if !self.is_allowed(&id) {
             return None;
         }
-
-        let label = Assist::new(id, label.into(), Some(group.clone()), target);
-        self.add_impl(label, f)
+        let label = Label::new(label.into());
+        let assist = Assist { id, label, group: Some(group.clone()), target };
+        self.add_impl(assist, f)
     }
 
-    fn add_impl(&mut self, label: Assist, f: impl FnOnce(&mut AssistBuilder)) -> Option<()> {
+    fn add_impl(&mut self, assist: Assist, f: impl FnOnce(&mut AssistBuilder)) -> Option<()> {
         let source_change = if self.resolve {
             let mut builder = AssistBuilder::new(self.file);
             f(&mut builder);
@@ -186,7 +188,7 @@ impl Assists {
             None
         };
 
-        self.buf.push((label, source_change));
+        self.buf.push((assist, source_change));
         Some(())
     }
 
diff --git a/crates/assists/src/lib.rs b/crates/assists/src/lib.rs
index c589b08dc..14834480a 100644
--- a/crates/assists/src/lib.rs
+++ b/crates/assists/src/lib.rs
@@ -19,7 +19,7 @@ pub mod ast_transform;
 
 use base_db::FileRange;
 use hir::Semantics;
-use ide_db::{source_change::SourceChange, RootDatabase};
+use ide_db::{label::Label, source_change::SourceChange, RootDatabase};
 use syntax::TextRange;
 
 pub(crate) use crate::assist_context::{AssistContext, Assists};
@@ -68,7 +68,7 @@ pub struct GroupLabel(pub String);
 pub struct Assist {
     pub id: AssistId,
     /// Short description of the assist, as shown in the UI.
-    label: String,
+    pub label: Label,
     pub group: Option<GroupLabel>,
     /// Target ranges are used to sort assists: the smaller the target range,
     /// the more specific assist is, and so it should be sorted first.
@@ -82,11 +82,6 @@ pub struct ResolvedAssist {
 }
 
 impl Assist {
-    fn new(id: AssistId, label: String, group: Option<GroupLabel>, target: TextRange) -> Assist {
-        assert!(label.starts_with(char::is_uppercase));
-        Assist { id, label, group, target }
-    }
-
     /// Return all the assists applicable at the given position.
     ///
     /// Assists are returned in the "unresolved" state, that is only labels are
@@ -118,10 +113,6 @@ impl Assist {
         });
         acc.finish_resolved()
     }
-
-    pub fn label(&self) -> &str {
-        self.label.as_str()
-    }
 }
 
 mod handlers {
diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index 1f85805d2..3c36c0e15 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -19,7 +19,7 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use crate::{FileId, SourceChange, SourceFileEdit};
+use crate::{FileId, Label, SourceChange, SourceFileEdit};
 
 use self::fixes::DiagnosticWithFix;
 
@@ -34,20 +34,15 @@ pub struct Diagnostic {
 
 #[derive(Debug)]
 pub struct Fix {
-    pub label: String,
+    pub label: Label,
     pub source_change: SourceChange,
     /// Allows to trigger the fix only when the caret is in the range given
     pub fix_trigger_range: TextRange,
 }
 
 impl Fix {
-    fn new(
-        label: impl Into<String>,
-        source_change: SourceChange,
-        fix_trigger_range: TextRange,
-    ) -> Self {
-        let label = label.into();
-        assert!(label.starts_with(char::is_uppercase) && !label.ends_with('.'));
+    fn new(label: &str, source_change: SourceChange, fix_trigger_range: TextRange) -> Self {
+        let label = Label::new(label);
         Self { label, source_change, fix_trigger_range }
     }
 }
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index f37119e28..e3af6d5bc 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -88,6 +88,7 @@ pub use base_db::{
 pub use hir::{Documentation, Semantics};
 pub use ide_db::{
     change::AnalysisChange,
+    label::Label,
     line_index::{LineCol, LineIndex},
     search::SearchScope,
     source_change::{FileSystemEdit, SourceChange, SourceFileEdit},
diff --git a/crates/ide_db/src/label.rs b/crates/ide_db/src/label.rs
new file mode 100644
index 000000000..c0e89e72f
--- /dev/null
+++ b/crates/ide_db/src/label.rs
@@ -0,0 +1,49 @@
+//! See `Label`
+use std::fmt;
+
+/// A type to specify UI label, like an entry in the list of assists. Enforces
+/// proper casing:
+///
+///    Frobnicate bar
+///
+/// Note the upper-case first letter and the absence of `.` at the end.
+#[derive(Clone)]
+pub struct Label(String);
+
+impl PartialEq<str> for Label {
+    fn eq(&self, other: &str) -> bool {
+        self.0 == other
+    }
+}
+
+impl PartialEq<&'_ str> for Label {
+    fn eq(&self, other: &&str) -> bool {
+        self == *other
+    }
+}
+
+impl From<Label> for String {
+    fn from(label: Label) -> String {
+        label.0
+    }
+}
+
+impl Label {
+    pub fn new(label: impl Into<String>) -> Label {
+        let label = label.into();
+        assert!(label.starts_with(char::is_uppercase) && !label.ends_with('.'));
+        Label(label)
+    }
+}
+
+impl fmt::Display for Label {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.0, f)
+    }
+}
+
+impl fmt::Debug for Label {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.0, f)
+    }
+}
diff --git a/crates/ide_db/src/lib.rs b/crates/ide_db/src/lib.rs
index fd474cd0f..70ada02f3 100644
--- a/crates/ide_db/src/lib.rs
+++ b/crates/ide_db/src/lib.rs
@@ -2,6 +2,7 @@
 //!
 //! It is mainly a `HirDatabase` for semantic analysis, plus a `SymbolsDatabase`, for fuzzy search.
 
+pub mod label;
 pub mod line_index;
 pub mod symbol_index;
 pub mod change;
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index 67ca9f055..33e60b500 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -782,10 +782,9 @@ fn handle_fixes(
         .filter_map(|d| d.fix)
         .filter(|fix| fix.fix_trigger_range.intersect(range).is_some())
     {
-        let title = fix.label;
         let edit = to_proto::snippet_workspace_edit(&snap, fix.source_change)?;
         let action = lsp_ext::CodeAction {
-            title,
+            title: fix.label.to_string(),
             id: None,
             group: None,
             kind: Some(CodeActionKind::QUICKFIX),
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 535de2f71..643dcb4fc 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -704,7 +704,7 @@ pub(crate) fn unresolved_code_action(
     index: usize,
 ) -> Result<lsp_ext::CodeAction> {
     let res = lsp_ext::CodeAction {
-        title: assist.label().to_string(),
+        title: assist.label.to_string(),
         id: Some(format!("{}:{}", assist.id.0, index.to_string())),
         group: assist.group.filter(|_| snap.config.client_caps.code_action_group).map(|gr| gr.0),
         kind: Some(code_action_kind(assist.id.1)),