Bus error from string(typeof(x)) inside JSON.lower

[yurivish]

This is the best minimal example I've come up with so far. It happens reliably.

julia> using JSON, NamedTupleTools
julia> JSON.lower(x) = (type=string(typeof(x)), ntfromstruct(x)...)
julia> struct Foo end
julia> JSON.json(Foo())

(v1.3) pkg> status
    Status `~/.julia/environments/v1.3/Project.toml`
  ...
  [682c06a0] JSON v0.21.0
  [d9ec5142] NamedTupleTools v0.12.1
  ...

julia> versioninfo()
Julia Version 1.3.1
Commit 2d5741174c (2019-12-30 21:36 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin18.6.0)
  CPU: Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, skylake)

If you change the JSON.lower definition to the below then it no longer crashes but correctly runs forever due to the recursion (this is supposed to run forever since lower returns a NamedTuple, which itself needs to be lowered):

julia> JSON.lower(x) = (type=string(typeof(x)), fields=ntfromstruct(x))
^CERROR: InterruptException:
Stacktrace:
 [1] lower(::NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields),Tuple{String,NamedTuple{(:type, :fields), ...

[JeffBezanson]

I think this is just a stackoverflow --- I get a stack overflow error on Linux.

[yurivish]

On macOS Catalina 10.15.1 (19B2106) I definitely get a bus error:

julia> using JSON, NamedTupleTools

julia> JSON.lower(x) = (type=string(typeof(x)), ntfromstruct(x)...)

julia> struct Foo end

julia> JSON.json(Foo())
zsh: bus error  julia

[JeffBezanson]

Probably a duplicate of #17109. This appears to be a mac os issue we've never been able to resolve.