In a recent snapshot of GCC 4.6, writing a member function such as:

struct foo {
 auto f() -> decltype(this) {return this;}
};

produces the error:

test1.cpp:2:24: error: invalid use of 'this' at top level
test1.cpp:2:24: error: invalid use of 'this' at top level

This issue was also mentioned in a Boost list post at <URL:http://
comments.gmane.org/gmane.comp.lib.boost.devel/209601>, but there did
not appear to be a resolution there.  Is this kind of code allowed by
the standard?  Is its failure in GCC a bug there?

-- Jeremiah Willcock


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On 2010-12-16 02:52, Jeremiah Willcock wrote:
>
> In a recent snapshot of GCC 4.6, writing a member function such as:
>
> struct foo {
>   auto f() ->  decltype(this) {return this;}
> };
>
> produces the error:
>
> test1.cpp:2:24: error: invalid use of 'this' at top level
> test1.cpp:2:24: error: invalid use of 'this' at top level
>
> This issue was also mentioned in a Boost list post at<URL:http://
> comments.gmane.org/gmane.comp.lib.boost.devel/209601>, but there did
> not appear to be a resolution there.  Is this kind of code allowed by
> the standard?  Is its failure in GCC a bug there?

This is no GCC error, it is currently not allowed by the upcoming
standard draft. See the open issues

http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#945
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1207

HTH & Greetings from Bremen,

Daniel Kr=FCgler


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