r210925 - Adds a Pragma spelling for attributes to tablegen and makes use of it for loop

[Aaron Ballman]

On Thu, Nov 20, 2014 at 3:59 PM, Douglas Gregor <dgregor at apple.com> wrote:
>
> On Jun 13, 2014, at 10:57 AM, Tyler Nowicki <tnowicki at apple.com> wrote:
> Modified: cfe/trunk/include/clang/Sema/AttributeList.h
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/AttributeList.h?rev=210925&r1=210924&r2=210925&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Sema/AttributeList.h (original)
> +++ cfe/trunk/include/clang/Sema/AttributeList.h Fri Jun 13 12:57:25 2014
> @@ -80,7 +80,9 @@ public:
>     /// __declspec(...)
>     AS_Declspec,
>     /// __ptr16, alignas(...), etc.
> -    AS_Keyword
> +    AS_Keyword,
> +    /// #pragma ...
> +    AS_Pragma
>   };
>
>
> Amusingly, this new enumerator overflows the bitfield used to store the
> Syntax value:
>
>   /// The number of expression arguments this attribute has.
>   /// The expressions themselves are stored after the object.
>   unsigned NumArgs : 15;
>
>   /// Corresponds to the Syntax enum.
>   unsigned SyntaxUsed : 2;

Yoiks! Good catch, Doug. It seems we need a bit more test coverage. ;-)

>
> Yet more amusingly, extending this bit-ield to three bits breaks things, as
> does replacing the one source of AS_Syntax attributes with AS_GNU :)

I will investigate, but what "things" does it break when you extend
the bit field to three bits? I modified NumArgs : 15 (down one from
16) and SyntaxUsed : 3 (up one from 2), and all tests passed for me
with MSVC on Windows (not that test coverage is the end-all, be-all).

Thanks!

~Aaron