Deduce the template parameter KEY from the value_type of the initializer_list supplied to the constructor of set. This deduction guide does not participate unless the specified ALLOC is convertible to bsl::allocator<KEY>.
Declared in <bslstl_set.h>
template<
class KEY,
class ALLOC,
class DEFAULT_ALLOCATOR = bsl::allocator<KEY>>
requires bsl::is_convertible_v<ALLOC *, DEFAULT_ALLOCATOR>
set<KEY>(
std::initializer_list<KEY>,
ALLOC*) -> set<KEY>;