Merge 2025-11 CWG Motion 2b

P3921R0 Core Language Working Group "ready" Issues for the November, 2025 meeting; issue 1670.

Author: tkoeppe

source/classes.tex

@@ -2712,7 +2712,6 @@
 \begin{example}
 \begin{codeblock}
 struct S {
-  operator auto() const { return 10; }      // OK
   template<class T>
   operator auto() const { return 1.2; }     // error: conversion function template
 };

source/declarations.tex

@@ -1859,7 +1859,8 @@
 \pnum
 A placeholder type can appear in
 the \grammarterm{decl-specifier-seq} or \grammarterm{type-specifier-seq}
-in the declared return type of a function declarator that declares a function;
+in the declared return type of a function declarator
+that declares a function other than a conversion function\iref{class.conv.fct};
 the return type of the function is
 deduced from non-discarded \tcode{return} statements, if any, in the body
 of the function\iref{stmt.if}.