From 2eb4ccd3199f085b5863f85be11e552058ddaa24 Mon Sep 17 00:00:00 2001
From: Frank Steffahn <frank.steffahn@stu.uni-kiel.de>
Date: Fri, 1 Jan 2021 22:53:34 +0100
Subject: [PATCH] Improve grammar in documentation of format strings

---
 library/alloc/src/fmt.rs | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/library/alloc/src/fmt.rs b/library/alloc/src/fmt.rs
index 5ebc4d6c4c1..f9424b1d747 100644
--- a/library/alloc/src/fmt.rs
+++ b/library/alloc/src/fmt.rs
@@ -282,21 +282,22 @@
 //! `%`. The actual grammar for the formatting syntax is:
 //!
 //! ```text
-//! format_string := <text> [ maybe-format <text> ] *
-//! maybe-format := '{' '{' | '}' '}' | <format>
+//! format_string := text [ maybe_format text ] *
+//! maybe_format := '{' '{' | '}' '}' | format
 //! format := '{' [ argument ] [ ':' format_spec ] '}'
 //! argument := integer | identifier
 //!
-//! format_spec := [[fill]align][sign]['#']['0'][width]['.' precision][type]
+//! format_spec := [[fill]align][sign]['#']['0'][width]['.' precision]type
 //! fill := character
 //! align := '<' | '^' | '>'
 //! sign := '+' | '-'
 //! width := count
 //! precision := count | '*'
-//! type := identifier | '?' | ''
+//! type := '' | '?' | 'x?' | 'X?' | identifier
 //! count := parameter | integer
 //! parameter := argument '$'
 //! ```
+//! In the above grammar, `text` may not contain any `'{'` or `'}'` characters.
 //!
 //! # Formatting traits
 //!