New issue from Jiang An: "Ill-formed, no diagnostic required on runtime behavior"

Author: Dani-Hub

xml/issue4185.xml

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+<?xml version='1.0' encoding='utf-8' standalone='no'?>
+<!DOCTYPE issue SYSTEM "lwg-issue.dtd">
+
+<issue num="4185" status="New">
+<title>Ill-formed, no diagnostic required on runtime behavior</title>
+<section><sref ref="[linalg.helpers]"/><sref ref="[concept.swappable]"/><sref ref="[iterator.cust.swap]"/></section>
+<submitter>Jiang An</submitter>
+<date>18 Dec 2024</date>
+<priority>99</priority>
+
+<discussion>
+<p>
+Several exposition-only function objects in <sref ref="[linalg.helpers]"/> are specified with strange 
+wording &mdash; "If the function selected by overload resolution does not return [&hellip;], the program 
+is ill-formed, no diagnostic required;". These conditions don't seem to be static properties because what 
+the selected function returns can be completely dependent on the runtime environment and input.
+<p/>
+Likewise, <sref ref="[concept.swappable]"/> and <sref ref="[iterator.cust.swap]"/> also contain such weird 
+usage. Presumably we should say the behavior is undefined in these cases.
+</p>
+</discussion>
+
+<resolution>
+</resolution>
+
+</issue>