8302124: HotSpot Style Guide should permit noreturn attribute

Reviewed-by: dcubed, iveresov, dholmes, tschatzl, jwaters, kvn

doc/hotspot-style.html

@@ -82,6 +82,7 @@ <h1 class="title">HotSpot Coding Style</h1>
 id="toc-local-function-objects">Local Function Objects</a></li>
 <li><a href="#inheriting-constructors"
 id="toc-inheriting-constructors">Inheriting constructors</a></li>
+<li><a href="#attributes" id="toc-attributes">Attributes</a></li>
 <li><a href="#additional-permitted-features"
 id="toc-additional-permitted-features">Additional Permitted
 Features</a></li>
@@ -1057,6 +1058,31 @@ <h3 id="inheriting-constructors">Inheriting constructors</h3>
 C++11/14, as the change is considered a Defect Report that applies to
 those versions. Earlier versions of gcc don't have that option, and
 other supported compilers may not have anything similar.</p>
+<h3 id="attributes">Attributes</h3>
+<p>The use of some attributes (<a
+href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2761.pdf">n2761</a>)
+(listed below) is permitted. (Note that some of the attributes defined
+in that paper didn't make it into the final specification.)</p>
+<p>Attributes are syntactically permitted in a broad set of locations,
+but specific attributes are only permitted in a subset of those
+locations. In some cases an attribute that appertains to a given element
+may be placed in any of several locations with the same meaning. In
+those cases HotSpot has a preferred location.</p>
+<ul>
+<li>An attribute that appertains to a function is placed at the
+beginning of the function's declaration, rather than between the
+function name and the parameter list.</li>
+</ul>
+<p>Only the following attributes are permitted:</p>
+<ul>
+<li><code>[[noreturn]]</code></li>
+</ul>
+<p>The following attributes are expressly forbidden:</p>
+<ul>
+<li><code>[[carries_dependency]]</code> - Related to
+<code>memory_order_consume</code>.</li>
+<li><code>[[deprecated]]</code> - Not relevant in HotSpot code.</li>
+</ul>
 <h3 id="additional-permitted-features">Additional Permitted
 Features</h3>
 <ul>
@@ -1149,9 +1175,6 @@ <h3 id="excluded-features">Excluded Features</h3>
 difficult to deal with and lead to surprises, as can destruction
 ordering. HotSpot doesn't generally try to cleanup on exit, and running
 destructors at exit can also lead to problems.</p></li>
-<li><p><code>[[deprecated]]</code> attribute (<a
-href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3760.html">n3760</a>)
-— Not relevant in HotSpot code.</p></li>
 <li><p>Avoid most operator overloading, preferring named functions. When
 operator overloading is used, ensure the semantics conform to the normal
 expected behavior of the operation.</p></li>
@@ -1171,8 +1194,6 @@ <h3 id="undecided-features">Undecided Features</h3>
 href="https://isocpp.org/files/papers/N3651.pdf">n3651</a>)</p></li>
 <li><p>Member initializers and aggregates (<a
 href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3653.html">n3653</a>)</p></li>
-<li><p><code>[[noreturn]]</code> attribute (<a
-href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2761.pdf">n2761</a>)</p></li>
 <li><p>Rvalue references and move semantics</p></li>
 </ul>
 </body>

doc/hotspot-style.md

@@ -1054,6 +1054,32 @@ and other supported compilers may not have anything similar.
 [p0136r1]: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0136r1.html
   "p0136r1"
 
+### Attributes
+
+The use of some attributes
+([n2761](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2761.pdf))
+(listed below) is permitted.  (Note that some of the attributes defined in
+that paper didn't make it into the final specification.)
+
+Attributes are syntactically permitted in a broad set of locations, but
+specific attributes are only permitted in a subset of those locations.  In
+some cases an attribute that appertains to a given element may be placed in
+any of several locations with the same meaning.  In those cases HotSpot has a
+preferred location.
+
+* An attribute that appertains to a function is placed at the beginning of the
+function's declaration, rather than between the function name and the parameter
+list.
+
+Only the following attributes are permitted:
+
+* `[[noreturn]]`
+
+The following attributes are expressly forbidden:
+
+* `[[carries_dependency]]` - Related to `memory_order_consume`.
+* `[[deprecated]]` - Not relevant in HotSpot code.
+
 ### Additional Permitted Features
 
 * `constexpr`
@@ -1153,10 +1179,6 @@ difficult to deal with and lead to surprises, as can destruction
 ordering.  HotSpot doesn't generally try to cleanup on exit, and
 running destructors at exit can also lead to problems.
 
-* `[[deprecated]]` attribute
-([n3760](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3760.html)) —
-Not relevant in HotSpot code.
-
 * Avoid most operator overloading, preferring named functions.  When
 operator overloading is used, ensure the semantics conform to the
 normal expected behavior of the operation.
@@ -1181,9 +1203,6 @@ features that have not yet been discussed.
 * Member initializers and aggregates
 ([n3653](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3653.html))
 
-* `[[noreturn]]` attribute
-([n2761](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2761.pdf))
-
 * Rvalue references and move semantics
 
 [ADL]: https://en.cppreference.com/w/cpp/language/adl