[temp.res] Fix self-contradiction in paragraph describing when a template

with valid specializations can be diagnosed.

Also convert to bulleted form for clarity.

Author: zygoloid

source/templates.tex

@@ -3100,25 +3100,25 @@
 \indextext{checking!point~of error}%
 Knowing which names are type names allows the syntax of every template
 to be checked.
-No diagnostic shall be issued for a template
-for which a valid specialization can be generated.
-If no valid specialization can be generated
-for a template,
-and that template is not instantiated, the template is ill-formed,
-no diagnostic required.
-If every valid specialization of a variadic template requires an empty template
-parameter pack, the template is ill-formed, no diagnostic required.
-If a hypothetical instantiation of a template
+The program is ill-formed, no diagnostic required, if:
+\begin{itemize}
+\item
+no valid specialization can be generated for a template
+and that template is not instantiated, or
+\item
+every valid specialization of a variadic template requires an empty template
+parameter pack, or
+\item
+a hypothetical instantiation of a template
 immediately following its definition
 would be ill-formed
-due to a construct that does not depend on a template parameter,
-the program is ill-formed; no diagnostic is required.
-If the interpretation of such a construct
+due to a construct that does not depend on a template parameter, or
+\item
+the interpretation of such a construct
 in the hypothetical instantiation
 is different from
 the interpretation of the corresponding construct
-in any actual instantiation of the template,
-the program is ill-formed; no diagnostic is required.
+in any actual instantiation of the template.
 \enternote
 This can happen in situations including the following:
 \begin{itemize}
@@ -3146,6 +3146,9 @@
 specialization that was not declared when the template was defined.
 \end{itemize}
 \exitnote
+\end{itemize}
+Otherwise, no diagnostic shall be issued for a template
+for which a valid specialization can be generated.
 \enternote
 If a template is instantiated, errors will be diagnosed according
 to the other rules in this Standard.