[Issue 22598] importC: Add support for __extension__ keyword

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22598

dave287091 at gmail.com changed:

           What    |Removed                     |Added
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                 CC|                            |dave287091 at gmail.com

--- Comment #3 from dave287091 at gmail.com ---
(In reply to Walter Bright from comment #2)
> The __extension__ documentation is confusing:
> 
> "You can prevent such warnings within one expression by
> writing `__extension__' before the expression.  `__extension__' has no
> effect aside from this."
> 
> Yet in your example,
> 
>    __extension__({ if (expr); else ...})
> 
> is a statement, not an expression.

It’s a gnu statement expression. See
https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html. It’s also supported by
clang.

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