From ef04c642ce76e51e4fc09355e0fe4ef549f51ccc Mon Sep 17 00:00:00 2001
From: Marijn Schouten <mhkbst@gmail.com>
Date: Thu, 6 Feb 2025 12:15:06 +0100
Subject: [PATCH] error on empty precision

---
 compiler/rustc_parse_format/src/lib.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_parse_format/src/lib.rs b/compiler/rustc_parse_format/src/lib.rs
index d021ea107ed28..364839f2df8ae 100644
--- a/compiler/rustc_parse_format/src/lib.rs
+++ b/compiler/rustc_parse_format/src/lib.rs
@@ -697,7 +697,12 @@ impl<'a> Parser<'a> {
                 spec.precision = self.count(start + 1);
             }
             let end = self.current_pos();
-            spec.precision_span = Some(self.span(start, end));
+            let span = self.span(start, end);
+            if spec.precision == CountImplied {
+                self.err("expected numerical precision", "missing precision", span);
+            } else {
+                spec.precision_span = Some(span);
+            }
         }
 
         let ty_span_start = self.current_pos();