spec: adjust conversion rules for type parameters

Change-Id: I7bfddf4be0d1d95419f312bb349ae2e16b74b795
Reviewed-on: https://go-review.googlesource.com/c/go/+/365915
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/doc/go_spec.html b/doc/go_spec.html
index 904132adf05c271a4c885a3d7e7f80b1c824598e..d8e6bb7b8eb3d0cf77d87b30092586311a5dcfc0 100644 (file)
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -4633,7 +4633,9 @@ as for non-constant <code>x</code>.
 </p>
 
 <p>
-Converting a constant yields a typed constant as result.
+Converting a constant to a type that is not a <a href="#Type_parameters">type parameter</a>
+yields a typed constant.
+Converting a constant to a type parameter yields a non-constant value of that type.    
 </p>
 
 <pre>
@@ -4669,7 +4671,7 @@ in any of these cases:
        <li>
        ignoring struct tags (see below),
        <code>x</code>'s type and <code>T</code> are pointer types
-       that are not <a href="#Type_definitions">defined types</a>,
+       that are not <a href="#Types">named types</a>,
        and their pointer base types have identical underlying types.
        </li>
        <li>
@@ -4692,6 +4694,28 @@ in any of these cases:
        </li>
 </ul>
 
+<p>
+Additionally, if <code>T</code> or </code><code>x's</code> type <code>V</code> are type
+parameters with <a href="#Structure_of_interfaces">specific types</a>, <code>x</code>
+can also be converted to type <code>T</code> if one of the following conditions applies:
+</p>
+
+<ul>
+<li>
+Both <code>V</code> and <code>T</code> are type parameters and a value of each
+specific type of <code>V</code> can be converted to each specific type
+of <code>T</code>.
+</li>
+<li>
+Only <code>V</code> is a type parameter and a value of each
+specific type of <code>V</code> can be converted to <code>T</code>.
+</li>
+<li>
+Only <code>T</code> is a type parameter and <code>x</code> can can be converted to each
+specific type of <code>T</code>.
+</li>
+</ul>
+
 <p>
 <a href="#Struct_types">Struct tags</a> are ignored when comparing struct types
 for identity for the purpose of conversion: