[cfe-commits] [PATCH] Ignored calling conventions

[John McCall]

On Sep 6, 2012, at 5:47 PM, Aaron Ballman wrote:
> MSDN documents that the __stdcall calling convention will be silently
> ignored if it is used when compiling for x64
> (http://msdn.microsoft.com/en-us/library/zxk0tw93(v=vs.110).aspx).
> This patch will mimic that behavior in clang as well by treating the
> calling convention as C when generating code as well as when mangling
> the convention.  This is important for Win64 support because the Win32
> APIs are all prefixed with __stdcall, even when compiling for x64.
> Currently, we cannot link against the Win64 APIs because of this
> problem.
> 
> The approach I am taking is a cautious one, so it only targets x64 in
> Microsoft mode for __stdcall.  However, I think it may make sense to
> have a more generalized approach to handling calling conventions
> because I suspect there will be other cases we wish to do this for
> more than just MSVC compatibility.  We cannot simply drop or modify
> the attribute on the function because then we would be unable to
> perform rewrites from the AST, and we don't want to foist the problem
> off on the backend either.  Thoughts are welcome as to a reasonable
> approach -- I wasn't able to find a satisfactory way to express the
> notion of a written calling convention that doesn't match what we
> actually wish to emit.
> 
> Thanks!

How ignored is it, exactly?  Is it still checked syntactically? for
redundancy? in the type system at all?

Basically, I'm asking if we can #define it. :)

John.