r218006 - Sema: Diagnose undefined structs used as Microsoft anonymous structs

[jahanian]

On Sep 18, 2014, at 9:33 AM, jahanian <fjahanian at apple.com> wrote:

> 
> On Sep 17, 2014, at 5:42 PM, David Majnemer <david.majnemer at gmail.com> wrote:
> 
>> Author: majnemer
>> Date: Wed Sep 17 19:42:05 2014
>> New Revision: 218006
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=218006&view=rev
>> Log:
>> Sema: Diagnose undefined structs used as Microsoft anonymous structs
>> 
>> Previously, we would not mark structs containing anonymous structs as
>> invalid.  Later, horrific things would occur when trying to determine
>> the size of the parent record.
>> 
>> Instead, require the struct to be a complete type when used as an
>> anonymous struct.  Mark both the anonymous field for the struct and the
>> parent context as invalid (this is similar to what we do when a struct
>> contains a field with an incomplete type.)
> 
> 
> Thank you David for working on this. Will this test case continue to work without error. This was the behavior before:
> 
> struct anon_fault {
> 	struct undefined;
> };
> 
> struct undefined {
>   int ii;
> };
> 
> int main()
> {
>   return sizeof(struct anon_fault);
> }
> 

We get the error with your patch:

t.c:2:2: error: field has incomplete type 'struct undefined'
t.c:2:9: note: forward declaration of 'struct undefined'
        struct undefined;
               ^
I am not familiar with details of microsoft’s anonymous structs. Is this the expected behavior?

- Thanks, Fariborz



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