[Bug c++/115960] gcc throws an error when I use Optional in c++17.

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115960

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Anyways this is not a GCC issue.

The   AttrBuilder::addAllocSizeAttr is declared in the preprocessed source as:
AttrBuilder &addAllocSizeAttr(unsigned ElemSizeArg,
                                const std::optional<unsigned> &NumElemsArg);

But the upstream is defined as:

  AttrBuilder &addAllocSizeAttr(unsigned ElemSizeArg,
                                const Optional<unsigned> &NumElemsArg);


https://github.com/hdoc/llvm-project/blob/a38b25fa77bdf1437c690494ae6d61179b3bb4f8/llvm/include/llvm/IR/Attributes.h#L1188


Also note
https://github.com/llvm/llvm-project/commit/125f4457a54a550846732763ee36b1447ec8d66e


Anyways this still not a GCC bug.