Deleting nothing from OrderedDict

[mforets]

Deleting nothing from OrderedDict seems to behave wildly, is it a known issue?

julia> using OrderedCollections

julia> x = OrderedDict(2 => 0.1, nothing => 0.2, 3 => 0.5)
OrderedDict{Union{Nothing, Int64}, Float64} with 3 entries:
  2       => 0.1
  nothing => 0.2
  3       => 0.5

julia> delete!(x, nothing)
OrderedDict{Union{Nothing, Int64}, Float64} with 2 entries:
  nothing => 0.1
  nothing => 0.2

julia> x
OrderedDict{Union{Nothing, Int64}, Float64} with 2 entries:
  nothing => 0.1
  nothing => 0.2

julia> x = OrderedDict(2 => 0.1, 5 => 0.4, 10 => 0.4, nothing => 0.03)
OrderedDict{Union{Nothing, Int64}, Float64} with 4 entries:
  2       => 0.1
  5       => 0.4
  10      => 0.4
  nothing => 0.03

julia> delete!(x, nothing)
OrderedDict{Union{Nothing, Int64}, Float64} with 3 entries:
  2  => 0.1
  5  => 0.4
  10 => 0.4

julia> x

signal (11): Segmentation fault
in expression starting at none:0
jl_gc_pool_alloc at /buildworker/worker/package_linux64/build/src/gc.c:1217

For the segfault, I created an upstream report: https://github.com/JuliaLang/julia/issues/45959#issue-1297699025

[serenity4]

Could this have something to do with these lines? Maybe jl_arrayunset is called with invalid arguments or something like that. But that's just a guess, I'm not familiar with these internals.

[serenity4]

Apparently an error with out of bounds indexing according to this comment

[jakobnissen]

Not too familiar with the source code, but it looks like it happens in the rehash! function, where the code assumes that if the key is not a bitstype, it contains pointers (see the definition of the ptrs variable). This assumption is violated for union bitstypes, where the union is neither a bitstype, nor stored as a pointer.