Rollup merge of #107493 - clubby789:range-fat-arrow-followup, r=estebank

Improve diagnostic for missing space in range pattern

Improves the diagnostic in #107425 by turning it into a note explaining the parsing issue.

r? `@compiler-errors`

compiler/rustc_parse/src/parser/pat.rs

@@ -743,7 +743,7 @@ impl<'a> Parser<'a> {
             }
             token::Gt if no_space => {
                 let after_pat = span.with_hi(span.hi() - rustc_span::BytePos(1)).shrink_to_hi();
-                self.sess.emit_err(InclusiveRangeMatchArrow { span, after_pat });
+                self.sess.emit_err(InclusiveRangeMatchArrow { span, arrow: tok.span, after_pat });
             }
             _ => {
                 self.sess.emit_err(InclusiveRangeNoEnd { span });