[PATCH] Remove support for pnaclcall attribute

[Aaron Ballman]

On Tue, Jan 27, 2015 at 2:50 PM, Derek Schuff <dschuff at google.com> wrote:
> Hi jvoung,
>
> It was used for interoperability with PNaCl's calling conventions, but
> it's no longer needed.
>
> http://reviews.llvm.org/D7206
>
> Files:
>   include/clang-c/Index.h
>   include/clang/AST/Type.h
>   include/clang/Basic/Attr.td
>   include/clang/Basic/Specifiers.h
>   lib/AST/Type.cpp
>   lib/AST/TypePrinter.cpp
>   lib/Basic/Targets.cpp
>   lib/CodeGen/CGCall.cpp
>   lib/CodeGen/TargetInfo.cpp
>   lib/Sema/SemaDeclAttr.cpp
>   lib/Sema/SemaType.cpp
>   test/CodeGen/arm-pnaclcall.c
>   test/CodeGen/x86_64-arguments-nacl.c
>   test/Sema/callingconv.c
>   tools/libclang/CXType.cpp

Quick question:

> Index: include/clang-c/Index.h
> ===================================================================
> --- include/clang-c/Index.h
> +++ include/clang-c/Index.h
> @@ -2854,7 +2854,7 @@
>    CXCallingConv_X86Pascal = 5,
>    CXCallingConv_AAPCS = 6,
>    CXCallingConv_AAPCS_VFP = 7,
> -  CXCallingConv_PnaclCall = 8,
> +  CXCallingConv_PnaclCall = 8, /* unused */

Do we have to worry about backwards compatibility for this? If so,
it's not really unused, but reserved.
We may want to rename the identifier to something else as well, since
we don't want people using it. If it truly is unused, we could remove
the enumerator entirely and simply have a comment stating that 8 is
free, but was PnaclCall.

 ~Aaron