From bff9884df185fb0e3c03a981d37efad177dab5f3 Mon Sep 17 00:00:00 2001
From: Dimitris Fasarakis Hilliard <d.f.hilliard@gmail.com>
Date: Wed, 1 Feb 2023 12:17:33 +0200
Subject: [PATCH] Hint that the unwrap should always succeed.

---
 parser/src/lexer.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/parser/src/lexer.rs b/parser/src/lexer.rs
index 61bff37..5eeaf88 100644
--- a/parser/src/lexer.rs
+++ b/parser/src/lexer.rs
@@ -1125,7 +1125,11 @@ where
 
     fn eat_single_char(&mut self, ty: Tok) {
         let tok_start = self.get_pos();
-        self.next_char();
+        self.next_char().unwrap_or_else(|| unsafe {
+            // SAFETY: eat_single_char has been called only after a character has been read
+            // from the window, so the window is guaranteed to be non-empty.
+            std::hint::unreachable_unchecked()
+        });
         let tok_end = self.get_pos();
         self.emit((tok_start, ty, tok_end));
     }