From 16d85c762d884edd7c2781c58ffa290d41d5a486 Mon Sep 17 00:00:00 2001
From: Tymi <tymi@tymi.org>
Date: Mon, 29 Jun 2026 20:08:23 +0200
Subject: [PATCH] Allow rejection of programs when they add declarations to the
 namespace std

undefined => ill-formed (no diagnostics required) in [namespace.std]
---
 source/lib-intro.tex | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/source/lib-intro.tex b/source/lib-intro.tex
index 99420d7c6d..3bacbb2bb5 100644
--- a/source/lib-intro.tex
+++ b/source/lib-intro.tex
@@ -3009,10 +3009,10 @@
 
 \pnum
 Unless otherwise specified,
-the behavior of a \Cpp{} program is undefined if it adds declarations or definitions to namespace
+a \Cpp{} program shall not add declarations or definitions to namespace
 \tcode{std}
 or to a namespace within namespace
-\tcode{std}.
+\tcode{std}; no diagnostic is required.
 
 \pnum
 Unless explicitly prohibited,