From a746295cde6bc24f49424f7fc4963e5f36b0458b Mon Sep 17 00:00:00 2001
From: Eisenwave <me@eisenwave.net>
Date: Wed, 30 Sep 2026 07:08:59 +0200
Subject: [PATCH] [diff.expr] Add entry for change in comparison type from int
 to bool

---
 source/compatibility.tex | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/source/compatibility.tex b/source/compatibility.tex
index 5ba3be8773..19e16ac9dc 100644
--- a/source/compatibility.tex
+++ b/source/compatibility.tex
@@ -3222,6 +3222,29 @@
 \howwide
 Rare.
 
+\diffref{expr.rel,expr.eq}
+\change
+Relational and equality comparison expressions are of type \tcode{int} in C,
+but of type \tcode{bool} in \Cpp{}.
+\rationale
+Increased type safety.
+\effect
+Change to semantics of well-defined feature.
+C programs relying on a specific type will yield different results.
+\begin{example}
+\begin{codeblock}
+auto t = (0 == 0);              // of type \tcode{int} in C, of type \tcode{bool} in \Cpp{}
+bool* b = &t;                   // valid \Cpp{}, constraint violation in C
+
+int sum;
+ckd_add(&sum, (0 < 0), 1);      // valid C, ill-formed \Cpp{}\iref{numerics.c.ckdint}
+\end{codeblock}
+\end{example}
+\difficulty
+Programs must add explicit casts to the appropriate type.
+\howwide
+Rare.
+
 \diffref{expr.cond,expr.assign,expr.comma}
 \indextext{conversion!lvalue-to-rvalue}%
 \indextext{rvalue!lvalue conversion to}%