unsafe_load does not taint :noub effect

[topolarity]

do_ub() = unsafe_load(Ptr{Int}(UInt(0)))

This function executes undefined behavior, but the compiler has no idea somehow:

julia> Base.infer_effects(do_ub, ())
(!c,+e,+n,+t,+s,+m,+u,+o,+r)
julia> do_ub()
Warning: detected a stack overflow; program state may be corrupted, so further execution might be unreliable.
ERROR: StackOverflowError:

[nsajko]

Similar, perhaps:

julia> unsafe_getindex(t::Tuple, i::Int) = getfield(t, i, false)
unsafe_getindex (generic function with 1 method)

julia> InteractiveUtils.@infer_effects unsafe_getindex((), 1)
(+c,+e,+n,+t,+s,+m,+u,+o,+r)

julia> unsafe_getindex((), 1)
Unreachable reached at 0x7c963f26350f

[72487] signal 4 (2): Illegal instruction
in expression starting at REPL[3]:1
unsafe_getindex at ./REPL[1]:1
[...]