On Tue, Mar 15, 2022 at 11:57:22AM -0400, Jason Merrill wrote:
> > The intent of r11-6729 is that it prints something that helps user to figure
> > out what exactly is being accessed.
> > When we find a unique non-static data member that is being accessed, even
> > when we can't fold it nicely, IMNSHO it is better to print
> > ((sometype *)&var)->field
> > or
> > (*(sometype *)&var).field
> > instead of
> > *(fieldtype *)((char *)&var + 56)
> > because the user doesn't know what is at offset 56, we shouldn't ask user
> > to decipher structure layout etc.
>
> The problem is that the reference is *not* to any non-static data member,
> it's to the PMF as a whole. But c_fold_indirect_ref_for_warn wrongly turns
> it into a reference to the first non-static data member.
>
> We asked c_fold_indirect_ref_warn to fold a MEM_REF with RECORD_TYPE, and it
> gave us back a COMPONENT_REF with POINTER_TYPE. That seems clearly wrong.
That is not what I see on the testcase.
I see the outer c_fold_indirect_ref_for_warn call with type ptrmemfunc
which is a 64-bit RECORD_TYPE containing a single ptr member which has
pointer to function type, and op which is the x VAR_DECL with sp type which
is 128-bit RECORD_TYPE containing 64-bit __pfn member and 64-bit __delta
member.
As all the bits of the ptrmemfunc RECORD_TYPE fit within the __pfn member
(they are equal size), it wants to print (cast)(something.__pfn).
Jakub
