add fix for removing unnecessary braces in use statements

3 files changed, 41 insertions, 23 deletions

diff --git a/crates/ra_editor/src/code_actions.rs b/crates/ra_editor/src/code_actions.rs
index 1d78cb7e8..7615f37a6 100644
--- a/crates/ra_editor/src/code_actions.rs
+++ b/crates/ra_editor/src/code_actions.rs
@@ -12,6 +12,7 @@ use crate::{find_node_at_offset, TextEdit, TextEditBuilder};
 
 #[derive(Debug)]
 pub struct LocalEdit {
+    pub label: String,
     pub edit: TextEdit,
     pub cursor_position: Option<TextUnit>,
 }
@@ -30,6 +31,7 @@ pub fn flip_comma<'a>(
         edit.replace(prev.range(), next.text().to_string());
         edit.replace(next.range(), prev.text().to_string());
         LocalEdit {
+            label: "flip comma".to_string(),
             edit: edit.finish(),
             cursor_position: None,
         }
@@ -58,6 +60,7 @@ pub fn add_derive<'a>(
             Some(tt) => tt.syntax().range().end() - TextUnit::of_char(')'),
         };
         LocalEdit {
+            label: "add `#[derive]`".to_string(),
             edit: edit.finish(),
             cursor_position: Some(offset),
         }
@@ -109,6 +112,7 @@ pub fn add_impl<'a>(
         buf.push_str("\n}");
         edit.insert(start_offset, buf);
         LocalEdit {
+            label: "add impl".to_string(),
             edit: edit.finish(),
             cursor_position: Some(offset),
         }
@@ -148,6 +152,7 @@ pub fn introduce_variable<'a>(
         }
         let cursor_position = anchor_stmt.range().start() + TextUnit::of_str("let ");
         LocalEdit {
+            label: "introduce variable".to_string(),
             edit: edit.finish(),
             cursor_position: Some(cursor_position),
         }
@@ -194,6 +199,7 @@ pub fn make_pub_crate<'a>(
             || parent.children().any(|child| child.kind() == VISIBILITY)
         {
             return LocalEdit {
+                label: "make pub crate".to_string(),
                 edit: edit.finish(),
                 cursor_position: Some(offset),
             };
@@ -201,6 +207,7 @@ pub fn make_pub_crate<'a>(
 
         edit.insert(node_start, "pub(crate) ".to_string());
         LocalEdit {
+            label: "make pub crate".to_string(),
             edit: edit.finish(),
             cursor_position: Some(node_start),
         }
diff --git a/crates/ra_editor/src/lib.rs b/crates/ra_editor/src/lib.rs
index 7a689b0f2..898d9b8c7 100644
--- a/crates/ra_editor/src/lib.rs
+++ b/crates/ra_editor/src/lib.rs
@@ -42,6 +42,7 @@ pub struct Diagnostic {
     pub range: TextRange,
     pub msg: String,
     pub severity: Severity,
+    pub fix: Option<LocalEdit>,
 }
 
 #[derive(Debug)]
@@ -111,6 +112,7 @@ pub fn diagnostics(file: &SourceFileNode) -> Vec<Diagnostic> {
             range: location_to_range(err.location()),
             msg: format!("Syntax Error: {}", err),
             severity: Severity::Error,
+            fix: None,
         })
         .collect();
 
@@ -124,11 +126,27 @@ fn check_unnecessary_braces_in_use_statement(file: &SourceFileNode) -> Vec<Diagn
     let mut diagnostics = Vec::new();
     for node in file.syntax().descendants() {
         if let Some(use_tree_list) = ast::UseTreeList::cast(node) {
-            if use_tree_list.use_trees().count() <= 1 {
+            if use_tree_list.use_trees().count() == 1 {
+                let range = use_tree_list.syntax().range();
+                // use_tree_list always has one child, so we use unwrap directly here.
+                let to_replace = typing::single_use_tree(use_tree_list)
+                    .unwrap()
+                    .syntax()
+                    .text()
+                    .to_string();
+                let mut edit_builder = TextEditBuilder::new();
+                edit_builder.delete(range);
+                edit_builder.insert(range.start(), to_replace);
+
                 diagnostics.push(Diagnostic {
-                    range: use_tree_list.syntax().range(),
+                    range: range,
                     msg: format!("Unnecessary braces in use statement"),
                     severity: Severity::WeakWarning,
+                    fix: Some(LocalEdit {
+                        label: "Remove unnecessary braces".to_string(),
+                        edit: edit_builder.finish(),
+                        cursor_position: None,
+                    }),
                 })
             }
         }
@@ -250,9 +268,7 @@ fn main() {}
         );
         let diagnostics = check_unnecessary_braces_in_use_statement(&file);
         assert_eq_dbg(
-            r#"[Diagnostic { range: [12; 15), msg: "Unnecessary braces in use statement", severity: WeakWarning },
-                Diagnostic { range: [24; 27), msg: "Unnecessary braces in use statement", severity: WeakWarning },
-                Diagnostic { range: [61; 64), msg: "Unnecessary braces in use statement", severity: WeakWarning }]"#,
+            "[Diagnostic { range: [12; 15), msg: \"Unnecessary braces in use statement\", severity: WeakWarning, fix: Some(LocalEdit { label: \"Remove unnecessary braces\", edit: TextEdit { atoms: [AtomTextEdit { delete: [12; 12), insert: \"b\" }, AtomTextEdit { delete: [12; 15), insert: \"\" }] }, cursor_position: Some(12) }) }, Diagnostic { range: [24; 27), msg: \"Unnecessary braces in use statement\", severity: WeakWarning, fix: Some(LocalEdit { label: \"Remove unnecessary braces\", edit: TextEdit { atoms: [AtomTextEdit { delete: [24; 24), insert: \"c\" }, AtomTextEdit { delete: [24; 27), insert: \"\" }] }, cursor_position: Some(24) }) }, Diagnostic { range: [61; 64), msg: \"Unnecessary braces in use statement\", severity: WeakWarning, fix: Some(LocalEdit { label: \"Remove unnecessary braces\", edit: TextEdit { atoms: [AtomTextEdit { delete: [61; 61), insert: \"e\" }, AtomTextEdit { delete: [61; 64), insert: \"\" }] }, cursor_position: Some(61) }) }]",
             &diagnostics,
         )
     }
diff --git a/crates/ra_editor/src/typing.rs b/crates/ra_editor/src/typing.rs
index 5e412bcfa..dcc8793af 100644
--- a/crates/ra_editor/src/typing.rs
+++ b/crates/ra_editor/src/typing.rs
@@ -8,7 +8,9 @@ use ra_syntax::{
     SyntaxKind::*,
     SyntaxNodeRef, TextRange, TextUnit,
 };
-use ra_text_edit::text_utils::contains_offset_nonstrict;
+use ra_text_edit::text_utils::{
+    contains_offset_nonstrict
+};
 
 use crate::{find_node_at_offset, TextEditBuilder, LocalEdit};
 
@@ -19,6 +21,7 @@ pub fn join_lines(file: &SourceFileNode, range: TextRange) -> LocalEdit {
         let pos = match text.find('\n') {
             None => {
                 return LocalEdit {
+                    label: "join lines".to_string(),
                     edit: TextEditBuilder::new().finish(),
                     cursor_position: None,
                 };
@@ -51,6 +54,7 @@ pub fn join_lines(file: &SourceFileNode, range: TextRange) -> LocalEdit {
     }
 
     LocalEdit {
+        label: "join lines".to_string(),
         edit: edit.finish(),
         cursor_position: None,
     }
@@ -76,6 +80,7 @@ pub fn on_enter(file: &SourceFileNode, offset: TextUnit) -> Option<LocalEdit> {
     let mut edit = TextEditBuilder::new();
     edit.insert(offset, inserted);
     Some(LocalEdit {
+        label: "on enter".to_string(),
         edit: edit.finish(),
         cursor_position: Some(cursor_position),
     })
@@ -126,6 +131,7 @@ pub fn on_eq_typed(file: &SourceFileNode, offset: TextUnit) -> Option<LocalEdit>
     let mut edit = TextEditBuilder::new();
     edit.insert(offset, ";".to_string());
     Some(LocalEdit {
+        label: "add semicolon".to_string(),
         edit: edit.finish(),
         cursor_position: None,
     })
@@ -248,24 +254,13 @@ fn join_single_use_tree(edit: &mut TextEditBuilder, node: SyntaxNodeRef) -> Opti
     Some(())
 }
 
-fn single_use_tree(tree_list: ast::UseTreeList) -> Option<ast::UseTree> {
-    let mut res = None;
-    for child in tree_list.syntax().children() {
-        if let Some(tree) = ast::UseTree::cast(child) {
-            if tree.syntax().text().contains('\n') {
-                return None;
-            }
-            if mem::replace(&mut res, Some(tree)).is_some() {
-                return None;
-            }
-        } else {
-            match child.kind() {
-                WHITESPACE | L_CURLY | R_CURLY | COMMA => (),
-                _ => return None,
-            }
-        }
+pub(crate) fn single_use_tree(tree_list: ast::UseTreeList) -> Option<ast::UseTree> {
+    let sub_use_trees = tree_list.use_trees().count();
+    if sub_use_trees != 1 {
+        return None;
     }
-    res
+
+    tree_list.use_trees().next()
 }
 
 fn compute_ws(left: SyntaxNodeRef, right: SyntaxNodeRef) -> &'static str {