On 10/29/20 1:40 PM, Richard Biener wrote:
On Thu, 29 Oct 2020, Jakub Jelinek wrote:
On Thu, Oct 29, 2020 at 05:00:40PM +0100, Jan Hubicka wrote:
That's ugly and will for sure defeat warning / access code
when we access this as char[], no? I mean, we could
as well use 'int str[1];' here?
Well, we always get char pointer via macro that is IMO OK, but I am also
not very much in love with this.
Do we treat signed char [...]; as typeless storage too, or just
what the C++ standard requires (i.e. char, unsigned char and std::byte
where the last one is enum type with unsigned char underlying type)?
All that is covered by is_byte_access_type which includes all
character types (including char16_t and wchar it seems) and std::byte.
Well, that's a bug, apparently from the PR94923 patch (r11-499);
previously it was char, signed char, and unsigned char. And even that
is too much; even C++98 said just char and unsigned char could be used
for bytewise access.
When C++17 clarified this with the notion of "provides storage", it
applied to only unsigned char and std::byte, not even the full set of
byte-access types. We still need to allow bytewise access using plain
char, but perhaps we don't need to treat plain char arrays as typeless.
Attributes to say that a particular array does or does not provide
storage for objects of other types do sound useful.
Jason
