From 49474954cb440175fea291c528c22a4ed3687f6f Mon Sep 17 00:00:00 2001
From: Lucas Mirelmann <lgalfaso@gmail.com>
Date: Thu, 20 Nov 2025 19:46:34 +0100
Subject: [PATCH] Fix grammar for slices

Fix the grammar for slices to allow expressions of the form `a[0::2]`.

The refactor of the grammar done in ea603026297111a1c8c1ce0c95eb92443d03950d made the unexpected change to disallow this expression.
---
 spec.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/spec.md b/spec.md
index 7707b3e..7d16b6b 100644
--- a/spec.md
+++ b/spec.md
@@ -2642,7 +2642,7 @@ that can be indexed with an integer as above, such as `Sequence`s, `string`,
 and `bytes`.
 
 ```text
-SubscriptSuffix = '[' [Expressions] [':' Expression [':' Expression]] ']' .
+SubscriptSuffix = '[' [Expressions] ':' [Expression] [':' [Expression]] ']' .
 ```
 
 A slice expression `a[start:stop:stride]` yields a copy of `a` containing
@@ -4781,7 +4781,7 @@ Operand = identifier
         .
 
 DotSuffix   = '.' identifier .
-SubscriptSuffix = '[' [Expressions] [':' Expression [':' Expression]] ']'
+SubscriptSuffix = '[' [Expressions] ':' [Expression] [':' [Expression]] ']'
                 | '[' Expressions ']'
                 .
 CallSuffix  = '(' [Arguments [',']] ')' .