LWG2582 §[res.on.functions]/2's prohibition against incomplete types shouldn't apply to type traits

Author: Dawn Perchik

source/utilities.tex

@@ -9504,6 +9504,10 @@
 The behavior of a program that adds specializations for any of
 the templates defined in this subclause is undefined unless otherwise specified.
 
+\pnum
+Unless otherwise specified, an incomplete type may be used
+to instantiate a template in this subclause.
+
 \rSec2[meta.help]{Helper classes}
 
 \begin{codeblock}