[Patch, RFC, c*, ObjC* ] make the translation unit decl avail. via a lang hook

[IainS]

Hi Richard,

On 29 Oct 2010, at 16:28, Richard Guenther wrote:

> On Fri, Oct 29, 2010 at 3:44 PM, IainS <developer@sandoe-acoustics.co.uk 
> > wrote:
>> given that my current understanding is:
>> (a) we should make vars file-scope by setting DECL_CONTEXT =  
>> translation
>> unit decl
>> (b) there should only be one translation unit decl per TU
>> (c) at present none of the FEs export the t_u_d where other parts  
>> of the
>> machinery can see it.
>>
>> would the following patch be appropriate?
>> (it can be extended to fortran and java, I believe, fairly easily).
>
> Sounds like a hack.  Note that frontends might end up with multiple
> TUs (for example for things in fortran modules).

One would assume that a built-in that wishes to push an item to the  
'file scope' would still use 'current_translation_unit_decl'.
(to attach the decl to the 'file scope' of the current module).

[and I guess the name mangling must take care of different module  
ordering in different fortran source files?]

> It's a hack because
> it's a frontend hook that is only used by the frontend (which means
> a single global variable does do it as well,

OK, I had a global originally  (called current_translation_unit_decl)
- but that means defining it also in lto which seemed unnecessary.

> like other FEs do it

none of the FEs make the t_u_d available outside the file in which  
it's created.
and, AFAICT,  ObjC* must use the t_u_d created in c* - since they are  
sharing spaces.

If this seems reasonable
I can re-do the patch as I had it originally - with a global.

(or if I'm missing something fundamental, a pointer would be  
appreciated).

Iain

> Richard.