Auto merge of #63544 - Centril:rollup-qhqfcov, r=Centril

Rollup of 17 pull requests

Successful merges:

 - #62760 (Deduplicate error messages in `librsctc_mir`)
 - #62849 (typeck: Prohibit RPIT types that inherit lifetimes)
 - #63383 (`async fn` lifetime elision tests)
 - #63421 (Implement Clone, Display for ascii::EscapeDefault)
 - #63459 (syntax: account for CVarArgs being in the argument list.)
 - #63475 (Bring back suggestion for splitting `<-` into `< -`)
 - #63485 (ci: move mirrors to their standalone bucket)
 - #63486 (Document `From` trait for `BinaryHeap`)
 - #63488 (improve DiagnosticBuilder docs)
 - #63493 (Remove unneeded comment in src/libcore/hash/mod.rs)
 - #63499 (handle elision in async fn correctly)
 - #63501 (use `ParamName` to track in-scope lifetimes instead of Ident)
 - #63508 (Do not ICE when synthesizing spans falling inside unicode chars)
 - #63511 (ci: add a check for clock drift)
 - #63512 (Provide map_ok and map_err method for Poll<Option<Result<T, E>>>)
 - #63529 (RELEASES.md: ? is one of three Kleene operators)
 - #63530 (Fix typo in error message.)

Failed merges:

r? @ghost

1 files changed, 18 insertions, 1 deletions

diff --git a/src/libsyntax/parse/parser/expr.rs b/src/libsyntax/parse/parser/expr.rs
index 4432c1329cb..5376ac2eeee 100644
--- a/src/libsyntax/parse/parser/expr.rs
+++ b/src/libsyntax/parse/parser/expr.rs
@@ -224,6 +224,10 @@ impl<'a> Parser<'a> {
                 self.err_dotdotdot_syntax(self.token.span);
             }
 
+            if self.token == token::LArrow {
+                self.err_larrow_operator(self.token.span);
+            }
+
             self.bump();
             if op.is_comparison() {
                 self.check_no_chained_comparison(&lhs, &op);
@@ -1199,7 +1203,7 @@ impl<'a> Parser<'a> {
         if self.eat_keyword(kw::Else) || !cond.returns() {
             let sp = self.sess.source_map().next_point(lo);
             let mut err = self.diagnostic()
-                .struct_span_err(sp, "missing condition for `if` statemement");
+                .struct_span_err(sp, "missing condition for `if` expression");
             err.span_label(sp, "expected if condition here");
             return Err(err)
         }
@@ -1702,6 +1706,19 @@ impl<'a> Parser<'a> {
             .emit();
     }
 
+    fn err_larrow_operator(&self, span: Span) {
+        self.struct_span_err(
+            span,
+            "unexpected token: `<-`"
+        ).span_suggestion(
+            span,
+            "if you meant to write a comparison against a negative value, add a \
+             space in between `<` and `-`",
+            "< -".to_string(),
+            Applicability::MaybeIncorrect
+        ).emit();
+    }
+
     fn mk_assign_op(&self, binop: BinOp, lhs: P<Expr>, rhs: P<Expr>) -> ExprKind {
         ExprKind::AssignOp(binop, lhs, rhs)
     }