Improve E0178 suggestion placement

src/librustc_errors/emitter.rs

@@ -37,9 +37,12 @@ impl Emitter for EmitterWriter {
 
         if let Some(sugg) = db.suggestion.clone() {
             assert_eq!(sugg.msp.primary_spans().len(), sugg.substitutes.len());
-            if sugg.substitutes.len() == 1 && // don't display multispans as labels
-               sugg.msg.split_whitespace().count() < 10 && // don't display long messages as labels
-               sugg.substitutes[0].find('\n').is_none() { // don't display multiline suggestions as labels
+            // don't display multispans as labels
+            if sugg.substitutes.len() == 1 &&
+               // don't display long messages as labels
+               sugg.msg.split_whitespace().count() < 10 &&
+               // don't display multiline suggestions as labels
+               sugg.substitutes[0].find('\n').is_none() {
                 let msg = format!("{} `{}`", sugg.msg, sugg.substitutes[0]);
                 primary_span.push_span_label(sugg.msp.primary_spans()[0], msg);
             } else {

src/libsyntax/parse/parser.rs

@@ -1490,9 +1490,8 @@ impl<'a> Parser<'a> {
         let bounds = self.parse_ty_param_bounds()?;
         let sum_span = ty.span.to(self.prev_span);
 
-        let mut err = struct_span_err!(self.sess.span_diagnostic, ty.span, E0178,
+        let mut err = struct_span_err!(self.sess.span_diagnostic, sum_span, E0178,
             "expected a path on the left-hand side of `+`, not `{}`", pprust::ty_to_string(&ty));
-        err.span_label(ty.span, &format!("expected a path"));
 
         match ty.node {
             TyKind::Rptr(ref lifetime, ref mut_ty) => {
@@ -1511,9 +1510,11 @@ impl<'a> Parser<'a> {
                 err.span_suggestion(sum_span, "try adding parentheses:", sum_with_parens);
             }
             TyKind::Ptr(..) | TyKind::BareFn(..) => {
-                help!(&mut err, "perhaps you forgot parentheses?");
+                err.span_label(sum_span, &"perhaps you forgot parentheses?");
             }
-            _ => {}
+            _ => {
+                err.span_label(sum_span, &"expected a path");
+            },
         }
         err.emit();
         Ok(())

src/test/ui/did_you_mean/E0178.rs

@@ -12,17 +12,9 @@ trait Foo {}
 
 struct Bar<'a> {
     w: &'a Foo + Copy,
-    //~^ ERROR E0178
-    //~| NOTE expected a path
     x: &'a Foo + 'a,
-    //~^ ERROR E0178
-    //~| NOTE expected a path
     y: &'a mut Foo + 'a,
-    //~^ ERROR E0178
-    //~| NOTE expected a path
     z: fn() -> Foo + 'a,
-    //~^ ERROR E0178
-    //~| NOTE expected a path
 }
 
 fn main() {

src/test/ui/did_you_mean/E0178.stderr

@@ -0,0 +1,26 @@
+error[E0178]: expected a path on the left-hand side of `+`, not `&'a Foo`
+  --> $DIR/E0178.rs:14:8
+   |
+14 |     w: &'a Foo + Copy,
+   |        ^^^^^^^^^^^^^^ try adding parentheses: `&'a (Foo + Copy)`
+
+error[E0178]: expected a path on the left-hand side of `+`, not `&'a Foo`
+  --> $DIR/E0178.rs:15:8
+   |
+15 |     x: &'a Foo + 'a,
+   |        ^^^^^^^^^^^^ try adding parentheses: `&'a (Foo + 'a)`
+
+error[E0178]: expected a path on the left-hand side of `+`, not `&'a mut Foo`
+  --> $DIR/E0178.rs:16:8
+   |
+16 |     y: &'a mut Foo + 'a,
+   |        ^^^^^^^^^^^^^^^^ try adding parentheses: `&'a mut (Foo + 'a)`
+
+error[E0178]: expected a path on the left-hand side of `+`, not `fn() -> Foo`
+  --> $DIR/E0178.rs:17:8
+   |
+17 |     z: fn() -> Foo + 'a,
+   |        ^^^^^^^^^^^^^^^^ perhaps you forgot parentheses?
+
+error: aborting due to 4 previous errors
+

src/test/ui/did_you_mean/trait-object-reference-without-parens-suggestion.rs

@@ -10,12 +10,5 @@
 
 fn main() {
     let _: &Copy + 'static;
-    //~^ ERROR expected a path
-    //~| HELP try adding parentheses
-    //~| SUGGESTION let _: &(Copy + 'static);
-    //~| ERROR the trait `std::marker::Copy` cannot be made into an object
     let _: &'static Copy + 'static;
-    //~^ ERROR expected a path
-    //~| HELP try adding parentheses
-    //~| SUGGESTION let _: &'static (Copy + 'static);
 }

src/test/ui/did_you_mean/trait-object-reference-without-parens-suggestion.stderr

@@ -0,0 +1,22 @@
+error[E0178]: expected a path on the left-hand side of `+`, not `&Copy`
+  --> $DIR/trait-object-reference-without-parens-suggestion.rs:12:12
+   |
+12 |     let _: &Copy + 'static;
+   |            ^^^^^^^^^^^^^^^ try adding parentheses: `&(Copy + 'static)`
+
+error[E0178]: expected a path on the left-hand side of `+`, not `&'static Copy`
+  --> $DIR/trait-object-reference-without-parens-suggestion.rs:13:12
+   |
+13 |     let _: &'static Copy + 'static;
+   |            ^^^^^^^^^^^^^^^^^^^^^^^ try adding parentheses: `&'static (Copy + 'static)`
+
+error[E0038]: the trait `std::marker::Copy` cannot be made into an object
+  --> $DIR/trait-object-reference-without-parens-suggestion.rs:12:12
+   |
+12 |     let _: &Copy + 'static;
+   |            ^^^^^ the trait `std::marker::Copy` cannot be made into an object
+   |
+   = note: the trait cannot require that `Self : Sized`
+
+error: aborting due to previous error
+