segment fault while overwriting existing function in a module

[Roger-luo]

I got this while trying to overwrite the getindex function in BitBasis.jl, it can be re-produced by the following code

using BitBasis

struct SubBit{T, L}
    parent::BitStr{T, L}
    index::Int
end

Base.getindex(x::BitStr, index::Int) = SubBit(x, index)

Then type

bit"101"[1]

in REPL will get this segmentation fault. Not sure why, if I remove the overloading of getindex inside BitBasis then it is fine.

versioninfo

julia> versioninfo()
Julia Version 1.1.0
Commit 80516ca202 (2019-01-21 21:24 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin18.5.0)
  CPU: Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, skylake)
Environment:
  JULIA_EDITOR = code

[fredrikekre]

This is what I get on Julia 1.0, 1.1, 1.2 and master:

julia> bit"101"[1]
SubBit{Int64,3}(101 (5), 1)

[Roger-luo]

strange, I can still repeat this segmentfault on my laptop

what's your versioninfo()? maybe a Mac OS issue? Or try using BitBasis#master ?

[vtjnash]

Looks like a duplicate of #28577 (stack overflow may lead to segfault), since you appear to have defined that show(io, x::SubBit) = show(io, x)

[Roger-luo]

Oh I see. Yes, it is a dup of it. Thanks!