r175132 - Partially revert r175117 so that we don't break assumptions about how

John McCall rjmccall at apple.com
Thu Feb 14 11:03:17 PST 2013

On Feb 13, 2013, at 7:48 PM, Rafael EspĂ­ndola <rafael.espindola at gmail.com> wrote:
> On 13 February 2013 22:31, Rafael Espindola <rafael.espindola at gmail.com> wrote:
>> Author: rafael
>> Date: Wed Feb 13 21:31:26 2013
>> New Revision: 175132
>> URL: http://llvm.org/viewvc/llvm-project?rev=175132&view=rev
>> Log:
>> Partially revert r175117 so that we don't break assumptions about how
>> static functions in extern "C" contexts are mangled. Should fix the
>> bootstrap.
> This is really ugly, but seems to be a common assumption, so I don't
> think we can1t break it. I considered 3 options
> * Giving C language linkage to static functions in extern C contexts.
> I decided not to do this since it would then require more special
> cases in the callers. For example, without extra care we would go back
> to warning on a static returning non-POD if it defined in an extern C
> context.
> * Adding the restriction just to overloading (this patch).
> * Changing the mangling only when the function is actually overloaded.
> For example, in
> extern "C" {
>  static void foo() {
>  }
>  static void bar() {
>  }
>  static void bar(int x) {
>  }
> }
> we would produce the symbols foo, _Z3barv and _Z3bari. I still like
> the idea, but I could not find an easy way to detect in
> shouldMangleDeclName if the function was overloaded or not.

I understand what you're trying to do here, because indeed the standard
says that language linkage only applies to functions and variables with
external linkage, but I think the right thing to do is to just acknowledge
that we (AFAIK, like gcc) just give C language linkage to everything
declared in extern "C" and be done with it.  There are much more
significant ways in which we deviate from the standard's definition of
language linkage.


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