aaron.ballman added a comment. In D86993#4497851 <https://reviews.llvm.org/D86993#4497851>, @xbolva00 wrote:
> In D86993#4497744 <https://reviews.llvm.org/D86993#4497744>, @aaron.ballman > wrote: > >> In D86993#4477744 <https://reviews.llvm.org/D86993#4477744>, @RalfJung wrote: >> >>> It would probably be worth including all string functions that take a >>> length in such a DR. In Rust we are currently puzzling over whether calling >>> 0-length `memcmp` on something like `(char*)42` is okay or not. If not we'd >>> have to introduce a pretty pointless branch. >> >> I think the DR would be to change 7.1.4p1 where it currently says: >> >> If an argument to a function has an invalid value (such as a value outside >> the domain of the function, or a pointer outside the address space of the >> program, or a null pointer, or a pointer to non-modifiable storage when the >> corresponding parameter is not const-qualified) or a type (after default >> argument promotion) not expected by a function with a variable number of >> arguments, the behavior is undefined. >> >> "invalid value" includes null pointers and we may want to make a surgical >> repair to say something along the lines of "unless invalid value is a null >> pointer and the library function has a count parameter blah blah blah". Then >> we'd cover all the APIs taking a pointer and a count in one go, I believe. > > But not the case mentioned above, (char *)42. More like if size (count) > parameter is zero, pointer arguments are not dereferenced? Yeah, that's a good point.. I'm not certain how the committee might react to that. I think it might be an easier case for nullptr/0 than it is for invalid/0, but I do like the specification niceties that come along with "if count is zero, pointer is not dereferenced". Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D86993/new/ https://reviews.llvm.org/D86993 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
