From 3f0e69591934bdc90577f2af41c0981ea2d1651b Mon Sep 17 00:00:00 2001
From: Fabian Wolff <fabian.wolff@alumni.ethz.ch>
Date: Sun, 12 Sep 2021 22:05:52 +0200
Subject: Improve error message for missing trait in trait impl

---
 compiler/rustc_parse/src/parser/item.rs | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

(limited to 'compiler/rustc_parse/src')

diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index 10c73fd64bc..04a7948e8c9 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -493,7 +493,20 @@ impl<'a> Parser<'a> {
         let ty_first = if self.token.is_keyword(kw::For) && self.look_ahead(1, |t| t != &token::Lt)
         {
             let span = self.prev_token.span.between(self.token.span);
-            self.struct_span_err(span, "missing trait in a trait impl").emit();
+            self.struct_span_err(span, "missing trait in a trait impl")
+                .span_suggestion(
+                    span,
+                    "add a trait here",
+                    " Trait ".into(),
+                    Applicability::HasPlaceholders,
+                )
+                .span_suggestion(
+                    span.to(self.token.span),
+                    "for an inherent impl, drop this `for`",
+                    "".into(),
+                    Applicability::MaybeIncorrect,
+                )
+                .emit();
             P(Ty {
                 kind: TyKind::Path(None, err_path(span)),
                 span,
-- 
cgit 1.4.1-3-g733a5