On 1/30/21 6:22 PM, Ed Smith-Rowland wrote:
On 1/27/21 3:32 PM, Jakub Jelinek wrote:
On Sun, Oct 21, 2018 at 04:39:30PM -0400, Ed Smith-Rowland wrote:
This patch implements C++2a proposal P0330R2 Literal Suffixes for
ptrdiff_t
and size_t*. It's not official yet but looks very likely to pass.
It is
incomplete because I'm looking for some opinions. 9We also might wait
'till
it actually passes).
This paper takes the direction of a language change rather than a
library
change through C++11 literal operators. This was after feedback on that
paper after a few iterations.
As coded in this patch, integer suffixes involving 'z' are errors in
C and
warnings for C++ <= 17 (in addition to the usual warning about
implementation suffixes shadowing user-defined ones).
OTOH, the 'z' suffix is not currently legal - it can't break
currently-correct code in any C/C++ dialect. furthermore, I suspect the
language direction was chosen to accommodate a similar addition to C20.
I'm thinking of making this feature available as an extension to all of
C/C++ perhaps with appropriate pedwarn.
GCC now supports -std=c++2b and -std=gnu++2b, are you going to update
your
patch against it (and change for z/Z standing for ssize_t rather than
ptrdiff_t), plus incorporate the feedback from Joseph and Jason?
Jakub
Here is a rebased patch that is a bit leaner than the original.
Since I chose to be conservative in applying this just to C++23 I'm not
adding this to C or t earlier versions of C++ as extensions. We can add
that if people really want, maybe in stage 1.
The compat warning for C++ < 23 is not optional. since the suffixes are
not preceded by '-' I don't hav much sympathy if people tried to make a
literal 'z' operator. Which is the only reason I can see for a warning
suppression.
+ /* itk refers to fundamental types not aliased size types. */
+ if (flags & CPP_N_UNSIGNED)
+ type = size_type_node;
+ else
+ type = ptrdiff_type_node;
This is wrong if ptrdiff_t is a different size from size_t; it should be
c_common_signed_type (size_type_node).
+ | (z ? (CPP_N_SIZE_T | CPP_N_LARGE) : 0));
Why CPP_N_LARGE here? That would seem to suggest that size_t is always
the same size as unsigned long long.
Jason
