Unreachable reached (1.5.0-beta1 & 1.4.0) #36443
Comments
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Seems to work on master. |
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Finally got to compiling julia from source: Yes, works on master for me too. Still failing on 1.5.0-rc1, so I guess the fix will be in 1.5.1? |
If the PR that fixes it is identified and is eligible for backporting. The best way to find it is usually to do a bisection. |
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I unfortunately don't quite have the git-fu and time to do that. I'm fine closing this and waiting for 1.6 too, I can probably work around the bug until then. |
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Bisect took me to cb41bbb, but that probably only circumvents some underlying bug here. |
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Further reduction which also crashes on master: struct Joe{N}
Joe{N}(tup::NTuple{N}, sym::Symbol) where {N} = new()
end
Joe{N}(tup::NTuple{N}) where {N} = Joe{2}(tup, :a)
function bugfunc(::Type{T}) where {T}
tup1 = Tuple{Any, Vararg}[(:a, :b)][1]
T(tup1)
end
bugfunc(Joe{2})Inference gets something wrong here: julia> @code_typed bugfunc(Joe{2})
CodeInfo(
1 ─ %1 = $(Expr(:foreigncall, :(:jl_alloc_array_1d), Array{Tuple{Any,Vararg{Any,N} where N},1}, svec(Any, Int64), 0, :(:ccall), Array{Tuple{Any,Vararg{Any,N} where N},1}, 1, 1))::Array{Tuple{Any,Vararg{Any,N} where N},1}
│ Base.arrayset(false, %1, (:a, :b), 1)::Array{Tuple{Any,Vararg{Any,N} where N},1}
│ %3 = Base.arrayref(true, %1, 1)::Tuple{Any,Vararg{Any,N} where N}
│ ($(Expr(:static_parameter, 1)))(%3)::Union{}
└── unreachable
) => Union{}
julia> code_typed(Joe{2}, (Tuple{Any,Vararg},))
1-element Array{Any,1}:
CodeInfo(
1 ─ (Joe{2})(tup, :a)::Union{}
└── unreachable
) => Union{}
julia> Joe{2}((:a, :b))
Joe{2}() |
martinholters
added
bug
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Slight further reduction: struct Joe{N}
Joe{N}(tup::NTuple{N}) where {N} = new()
end
joe(tup::NTuple) = Joe{2}(tup)
function bugfunc()
tup1 = Tuple{Any, Vararg}[(:a, :b)][1]
joe(tup1)
end
bugfunc()The problem is julia> methods(Joe{2}, Tuple{Tuple{T,Vararg{T,N}} where T where N})
# 0 methods for type constructor:due to this type intersection problem: julia> typeintersect(Tuple{Type{Joe{N}},Tuple{Vararg{T,N}} where T} where N, Tuple{Type{Joe{2}},Tuple{T,Vararg{T,N}} where T} where N)
Union{} # should be Tuple{Type{Joe{2}},Tuple{Vararg{T,2}} where T}Note that these work: julia> typeintersect(Tuple{Type{Joe{N}},Tuple{Vararg{T,N}} where T} where N, Tuple{Type{Joe{2}},Tuple{Vararg{T,N}} where T} where N)
Tuple{Type{Joe{2}},Tuple{Vararg{T,2}} where T}
julia> typeintersect(Tuple{Type{Joe{N}},Tuple{Vararg{T,N}} where T} where N, Tuple{Type{Joe{2}},Tuple{T,T,Vararg{T,N}} where T} where N)
Tuple{Type{Joe{2}},Tuple{T,T} where T} |
martinholters
added
types and dispatch
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Taking the M in MWE seriously: |
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Doesn't seem to crash now. |
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As analyzed already, the originally reported reproducer was accidentally fixed by cb41bbb, but the underlying issue is still exhibited by the reduced versions from #36443 (comment), #36443 (comment), and #36443 (comment). |
I have reached the unreachable using the following
bugscript.jl::As mentioned in the title, this happens on at least 1.4.0 and 1.5.0-beta1.
The above is pretty much the smallest example I could reduce this down to, but let me know if I can do something else to help track this down further.
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