Auto merge of #68377 - estebank:fn-obligations-spans, r=oli-obk

Tweak obligation error output

- Point at arguments or output when fn obligations come from them, or ident when they don't
- Point at `Sized` bound (fix #47990)
- When object unsafe trait uses itself in associated item suggest using `Self` (fix #66424, fix #33375, partially address #38376, cc #61525)
-  Point at reason in object unsafe trait with `Self` in supertraits or `where`-clause (cc #40533, cc #68377)
- On implicit type parameter `Sized` obligations, suggest `?Sized` (fix #57744, fix #46683)

1 files changed, 1 insertions, 1 deletions

diff --git a/src/librustc_parse/parser/generics.rs b/src/librustc_parse/parser/generics.rs
index 075583711f5..0984263bb28 100644
--- a/src/librustc_parse/parser/generics.rs
+++ b/src/librustc_parse/parser/generics.rs
@@ -172,7 +172,7 @@ impl<'a> Parser<'a> {
     /// ```
     pub(super) fn parse_where_clause(&mut self) -> PResult<'a, WhereClause> {
         let mut where_clause =
-            WhereClause { predicates: Vec::new(), span: self.prev_span.to(self.prev_span) };
+            WhereClause { predicates: Vec::new(), span: self.prev_span.shrink_to_hi() };
 
         if !self.eat_keyword(kw::Where) {
             return Ok(where_clause);