On 02/11/2016 09:39 AM, Marek Polacek wrote:
On Thu, Feb 11, 2016 at 03:26:13PM +0000, Jonathan Wakely wrote:
On 11/02/16 15:20 +0100, Marek Polacek wrote:
Does this look ok?
Looks OK, although how about stressing that it was only allowed as an
extension previously, e.g. ...
So like this? I've also added a note about stricter flexarr members rules.
Index: porting_to.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-6/porting_to.html,v
retrieving revision 1.9
diff -u -r1.9 porting_to.html
--- porting_to.html 10 Feb 2016 17:21:54 -0000 1.9
+++ porting_to.html 11 Feb 2016 16:38:38 -0000
@@ -269,6 +269,41 @@
to port the code to use C++11's <code>std::unique_ptr</code> instead.
</p>
+<h3>'constexpr' needed for in-class initialization of static data member</h3>
+
+<p>
+Since C++11, the <code>constexpr</code> keyword is needed when initializing
+a non-integral static data member in a class. Thus the following program is
+accepted in C++03 (albeit with a <tt>-Wpedantic</tt> warning):
+</p>
+
+<pre><code>
+struct X {
+ const static double i = 10;
+};
It''s interesting that when the example is modified to use a double
initializer it is rejected with a hard error even in C++ 03 mode
when -Wpedantic (but not -Werror) is used. That seems like a bug.
If it isn't, it might be worth mentioning the constraint that the
initializer must be a integer in the text above.
struct X {
const static double i = 3.14;
};
error: floating-point literal cannot appear in a constant-expression
const static double i = 3.14;
^~~~
+</pre></code>
+
+<p>
+The C++11 standard supports that in-class initialization using
+<code>constexpr</code> instead, so the GNU extension is no longer supported for
+C++11 or later. Programs relying on the extension will be rejected with an
+error. The fix is to use <code>constexpr</code> instead of <code>const</code>.
+</p>
+
+<h3>Stricter flexible array member rules</h3>
+
+<p>
+As of this release, the C++ compiler is now more strict about flexible array
+member rules. As a consequence, the following code is no longer accepted:
In light of bug 69550 I think it might be useful to also mention
(or show an example) that structs with a flexible array as the
only member are rejected as well.
Martin
+</p>
+
+<pre><code>
+union U {
+ int i;
+ char a[];
+};
+</pre></code>
+
<h2>-Wmisleading-indentation</h2>
<p>
A new warning <code>-Wmisleading-indentation</code> was added
Marek
