From 9fdd8bcd69524fa1af3ed4cbff21c2f8240826f4 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard@metafoo.co.uk>
Date: Sun, 21 Jul 2019 15:27:07 +0200
Subject: [PATCH] P1161R3 Deprecate uses of the comma operator in subscripting
 expressions

---
 source/expressions.tex | 16 ++++++++++++++++
 source/future.tex      | 18 ++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/source/expressions.tex b/source/expressions.tex
index a472c33226..b985bbbc77 100644
--- a/source/expressions.tex
+++ b/source/expressions.tex
@@ -2862,6 +2862,14 @@
 if that operand is an lvalue and an xvalue otherwise.
 The expression \tcode{E1} is sequenced before the expression \tcode{E2}.
 
+\pnum
+\begin{note}
+A comma expression\iref{expr.comma}
+appearing as the \grammarterm{expr-or-braced-init-list}
+of a subscripting expression is deprecated;
+see \ref{depr.comma.subscript}.
+\end{note}
+
 \pnum
 \begin{note}
 Despite its asymmetric appearance, subscripting is a commutative
@@ -6793,6 +6801,14 @@
 \tcode{5}.
 \end{example}
 
+\pnum
+\begin{note}
+A comma expression
+appearing as the \grammarterm{expr-or-braced-init-list}
+of a subscripting expression\iref{expr.sub} is deprecated;
+see \ref{depr.comma.subscript}.
+\end{note}
+
 \rSec1[expr.const]{Constant expressions}%
 \indextext{expression!constant}
 
diff --git a/source/future.tex b/source/future.tex
index 5c541d9da3..ba0b570eb3 100644
--- a/source/future.tex
+++ b/source/future.tex
@@ -54,6 +54,24 @@
 \end{codeblock}
 \end{example}
 
+\rSec1[depr.comma.subscript]{Comma operator in subscript expressions}
+
+\pnum
+A comma expression\iref{expr.comma}
+appearing as the \grammarterm{expr-or-braced-init-list}
+of a subscripting expression\iref{expr.sub} is deprecated.
+\begin{note}
+A parenthesized comma expression is not deprecated.
+\end{note}
+\begin{example}
+\begin{codeblock}
+void f(int *a, int b, int c) {
+    a[b,c];                     // deprecated
+    a[(b,c)];                   // OK
+}
+\end{codeblock}
+\end{example}
+
 \rSec1[depr.array.comp]{Array comparisons}
 
 \pnum