Update documentation with regards to template type diffing.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159249 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/www/diagnostics.html b/www/diagnostics.html
index 45f6907..84c6f8b 100644
--- a/www/diagnostics.html
+++ b/www/diagnostics.html
@@ -263,6 +263,39 @@
<span class="snip">template<> </span>
</pre>
+<h2>Template Type Diffing</h2>
+
+<p>Templates types can be long and difficult to read. Moreso when part of an
+error message. Instead of just printing out the type name, Clang has enough
+information to remove the common elements and highlight the differences. To
+show the template structure more clearly, the templated type can also be
+printed as an indented text tree.</p>
+
+Default: template diff with type elision
+<pre>
+t.cc:4:5: <span class="note">note:</span> candidate function not viable: no known conversion from 'vector<map<[...], <span class="template-highlight">float</span>>>' to 'vector<map<[...], <span class="template-highlight">double</span>>>' for 1st argument;
+</pre>
+-fno-elide-type: template diff without elision
+<pre>
+t.cc:4:5: <span class="note">note:</span> candidate function not viable: no known conversion from 'vector<map<int, <span class="template-highlight">float</span>>>' to 'vector<map<int, <span class="template-highlight">double</span>>>' for 1st argument;
+</pre>
+-fdiagnostics-show-template-tree: template tree printing with elision
+<pre>
+t.cc:4:5: <span class="note">note:</span> candidate function not viable: no known conversion for 1st argument;
+ vector<
+ map<
+ [...],
+ [<span class="template-highlight">float</span> != <span class="template-highlight">double</span>]>>
+</pre>
+-fdiagnostics-show-template-tree -fno-elide-type: template tree printing with no elision
+<pre>
+t.cc:4:5: <span class="note">note:M</span> candidate function not viable: no known conversion for 1st argument;
+ vector<
+ map<
+ int,
+ [<span class="template-highlight">float</span> != <span class="template-highlight">double</span>]>>
+</pre>
+
<h2>Automatic Macro Expansion</h2>
<p>Many errors happen in macros that are sometimes deeply nested. With