[Bug c++/11418] implicit typename extension leads to wrong code

[Don at Skyler dot com]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11418



------- Additional Comments From Don at Skyler dot com  2003-07-04 05:40 -------
Subject: Re:  implicit typename extension leads to wrong code

I didn't notice the missing "typename".  I don't think gcc produced
the usual "implicit typenames deprecated" warning.

On 3 Jul 2003 16:45:49 -0000, you wrote:

>PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.
>
>http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11418
>
>
>bangerth at dealii dot org changed:
>
>           What    |Removed                     |Added
>----------------------------------------------------------------------------
>             Status|UNCONFIRMED                 |RESOLVED
>         Resolution|                            |FIXED
>            Summary|Nested template as arg to   |implicit typename extension
>                   |base class template confuses|leads to wrong code
>                   |args                        |
>
>
>------- Additional Comments From bangerth at dealii dot org  2003-07-03 16:45 -------
>Very interesting failure. In fact, I can confirm this with 3.2.x and 3.3,
>but it is fixed in mainline (see below).
>
>In essence: the code is wrong -- but previous versions of gcc accept
>it via the implicit typename extension. Here's the line:
>    struct Derived : public Base<Outer<U>::Inner<T> > { };
>3.2 and 3.3 accept this line, but 3.4 rejects it, as it should
>read correctly as
>    struct Derived : public Base<typename Outer<U>::template Inner<T> > { };
>
>Now, the amazing thing is that 3.2 and 3.3 generate the _wrong_ output for
>the first line, and the correct one for the second. Since 3.4 only accepts
>the last one, it always generates the correct output. Very interesting,
>indeed.
>
>So the proper workaround is to correct your code and don't rely on broken
>gcc extensions :-(
>
>Wolfgang
>
>
>
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