Dedup suggestions

src/librustc_mir/borrow_check/move_errors.rs

@@ -380,11 +380,14 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
         }
     }
 
+    // FIXME: Move the loop outside this method and add_move_error_labels()
+    // so they can share it.
     fn add_move_error_suggestions(
         &self,
         err: &mut DiagnosticBuilder<'a>,
         binds_to: &[Local],
     ) {
+        let mut suggestions: Vec<(Span, String, String)> = Vec::new();
         for local in binds_to {
             let bind_to = &self.mir.local_decls[*local];
             if let Some(
@@ -410,14 +413,19 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
                         suggestion = pat_snippet;
                         to_remove = "&";
                     }
-                    err.span_suggestion(
+                    suggestions.push((
                         pat_span,
-                        &format!("consider removing the `{}`", to_remove),
+                        format!("consider removing the `{}`", to_remove),
                         suggestion.to_owned(),
-                    );
+                    ));
                 }
             }
         }
+        suggestions.sort_unstable_by_key(|&(span, _, _)| span);
+        suggestions.dedup_by_key(|&mut (span, _, _)| span);
+        for (span, msg, suggestion) in suggestions {
+            err.span_suggestion(span, &msg, suggestion);
+        }
     }
 
     fn add_move_error_labels(

src/test/ui/suggestions/dont-suggest-ref.rs

@@ -10,13 +10,16 @@
 
 #![feature(nll)]
 
+#[derive(Clone)]
 enum Either {
     One(X),
     Two(X),
 }
 
+#[derive(Clone)]
 struct X(Y);
 
+#[derive(Clone)]
 struct Y;
 
 pub fn main() {
@@ -338,4 +341,118 @@ pub fn main() {
         //~| SUGGESTION Either::One(_t)
         Either::Two(_t) => (),
     }
+
+    // --------
+
+    let &(X(_t), X(_u)) = &(x.clone(), x.clone());
+    //~^ ERROR cannot move
+    //~| HELP consider removing the `&`
+    //~| SUGGESTION (X(_t), X(_u))
+    if let &(Either::One(_t), Either::Two(_u)) = &(e.clone(), e.clone()) { }
+    //~^ ERROR cannot move
+    //~| HELP consider removing the `&`
+    //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+    while let &(Either::One(_t), Either::Two(_u)) = &(e.clone(), e.clone()) { }
+    //~^ ERROR cannot move
+    //~| HELP consider removing the `&`
+    //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+    match &(e.clone(), e.clone()) {
+        //~^ ERROR cannot move
+        &(Either::One(_t), Either::Two(_u)) => (),
+        //~^ HELP consider removing the `&`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        &(Either::Two(_t), Either::One(_u)) => (),
+        //~^ HELP consider removing the `&`
+        //~| SUGGESTION (Either::Two(_t), Either::One(_u))
+        _ => (),
+    }
+    match &(e.clone(), e.clone()) {
+        //~^ ERROR cannot move
+        &(Either::One(_t), Either::Two(_u))
+        //~^ HELP consider removing the `&`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        | &(Either::Two(_t), Either::One(_u)) => (),
+        // FIXME: would really like a suggestion here too
+        _ => (),
+    }
+    match &(e.clone(), e.clone()) {
+        //~^ ERROR cannot move
+        &(Either::One(_t), Either::Two(_u)) => (),
+        //~^ HELP consider removing the `&`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        &(Either::Two(ref _t), Either::One(ref _u)) => (),
+        _ => (),
+    }
+    match &(e.clone(), e.clone()) {
+        //~^ ERROR cannot move
+        &(Either::One(_t), Either::Two(_u)) => (),
+        //~^ HELP consider removing the `&`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        (Either::Two(_t), Either::One(_u)) => (),
+        _ => (),
+    }
+    fn f3(&(X(_t), X(_u)): &(X, X)) { }
+    //~^ ERROR cannot move
+    //~| HELP consider removing the `&`
+    //~| SUGGESTION (X(_t), X(_u))
+
+    let &mut (X(_t), X(_u)) = &mut (xm.clone(), xm.clone());
+    //~^ ERROR cannot move
+    //~| HELP consider removing the `&mut`
+    //~| SUGGESTION (X(_t), X(_u))
+    if let &mut (Either::One(_t), Either::Two(_u)) = &mut (em.clone(), em.clone()) { }
+    //~^ ERROR cannot move
+    //~| HELP consider removing the `&mut`
+    //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+    while let &mut (Either::One(_t), Either::Two(_u)) = &mut (em.clone(), em.clone()) { }
+    //~^ ERROR cannot move
+    //~| HELP consider removing the `&mut`
+    //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+    match &mut (em.clone(), em.clone()) {
+        //~^ ERROR cannot move
+        &mut (Either::One(_t), Either::Two(_u)) => (),
+        //~^ HELP consider removing the `&mut`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        &mut (Either::Two(_t), Either::One(_u)) => (),
+        //~^ HELP consider removing the `&mut`
+        //~| SUGGESTION (Either::Two(_t), Either::One(_u))
+        _ => (),
+    }
+    match &mut (em.clone(), em.clone()) {
+        //~^ ERROR cannot move
+        &mut (Either::One(_t), Either::Two(_u))
+        //~^ HELP consider removing the `&mut`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        | &mut (Either::Two(_t), Either::One(_u)) => (),
+        // FIXME: would really like a suggestion here too
+        _ => (),
+    }
+    match &mut (em.clone(), em.clone()) {
+        //~^ ERROR cannot move
+        &mut (Either::One(_t), Either::Two(_u)) => (),
+        //~^ HELP consider removing the `&mut`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        &mut (Either::Two(ref _t), Either::One(ref _u)) => (),
+        _ => (),
+    }
+    match &mut (em.clone(), em.clone()) {
+        //~^ ERROR cannot move
+        &mut (Either::One(_t), Either::Two(_u)) => (),
+        //~^ HELP consider removing the `&mut`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        &mut (Either::Two(ref mut _t), Either::One(ref mut _u)) => (),
+        _ => (),
+    }
+    match &mut (em.clone(), em.clone()) {
+        //~^ ERROR cannot move
+        &mut (Either::One(_t), Either::Two(_u)) => (),
+        //~^ HELP consider removing the `&mut`
+        //~| SUGGESTION (Either::One(_t), Either::Two(_u))
+        (Either::Two(_t), Either::One(_u)) => (),
+        _ => (),
+    }
+    fn f4(&mut (X(_t), X(_u)): &mut (X, X)) { }
+    //~^ ERROR cannot move
+    //~| HELP consider removing the `&mut`
+    //~| SUGGESTION (X(_t), X(_u))
 }