StackOverflow in typeintersect when using Tuple type parameters

[daanhb]

I'm making a new issue for an older issue (#22239) that was partially fixed. The problem is a StackOverflow error in the following minimal working example:

bar(::Type{Val{Tuple{Tuple{T},T}}}, ::Val{T}) where {T} = 1
bar(::Type{Val{Tuple{T,Tuple{T}}}}, ::Val{T}) where {T} = 2

The output using the current nightly build is:

ERROR: LoadError: StackOverflowError:
Stacktrace:
 [1] top-level scope
 [2] include at ./boot.jl:306 [inlined]
 [3] include_relative(::Module, ::String) at ./loading.jl:1072
 [4] include(::Module, ::String) at ./sysimg.jl:29
 [5] exec_options(::Base.JLOptions) at ./client.jl:327
 [6] _start() at ./client.jl:455
in expression starting at /tmp/mwe.jl:2

As @martinholters pointed out in #22239, the error results from typeintersect as follows:

julia> typeintersect(Tuple{Type{Tuple{T,Val{T}}}, Val{T}} where T, Tuple{Type{Tuple{Val{T},T}}, Val{T}} where T)
ERROR: StackOverflowError:
Stacktrace:
 [1] typeintersect(::Any, ::Any) at ./reflection.jl:469
 [2] top-level scope

Above examples were tested today on master:

julia> versioninfo()
Julia Version 0.7.0-DEV.4594
Commit 29a1719f95 (2018-03-15 22:41 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i5-3570 CPU @ 3.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-3.9.1 (ORCJIT, ivybridge)
Environment:

The examples do also lead to similar errors on 0.6.2.

[daanhb]

This stack overflow in typeintersect is still an issue on 0.7.0-alpha.0:

julia> typeintersect(Tuple{Type{Tuple{T,Val{T}}}, Val{T}} where T, Tuple{Type{Tuple{Val{T},T}}, Val{T}} where T)
ERROR: StackOverflowError:
Stacktrace:
 [1] typeintersect(::Any, ::Any) at ./reflection.jl:475
 [2] top-level scope
julia> versioninfo()
Julia Version 0.7.0-alpha.0
Commit 22590d529d (2018-05-31 00:07 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i5-3570 CPU @ 3.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, ivybridge)

The original MWE above also still triggers the stack overflow on v0.7.0-alpha.0, with error messages very similar to those of the nightly builds in March.

[daanhb]

I wanted to close an old issue today, but unfortunately it persists even in the 1.2 release candidate, hence a friendly bump:

julia> typeintersect(Tuple{Type{Tuple{T,Val{T}}}, Val{T}} where T, Tuple{Type{Tuple{Val{T},T}}, Val{T}} where T)
ERROR: StackOverflowError:
Stacktrace:
 [1] typeintersect(::Any, ::Any) at ./reflection.jl:560
 [2] top-level scope at REPL[1]:1

julia> versioninfo()
Julia Version 1.2.0-rc1.0
Commit 7097799cf1 (2019-05-30 02:22 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i5-3570 CPU @ 3.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, ivybridge)

I originally came to this minimal working example when working on code to convert between tuples and static arrays, in nested cases. I wanted an efficient way to identify ((1,2),3) with [1,2,3] and to convert between the two, since the former would naturally arise in constructions of domains using set operations (in DomainSets.jl), but the latter is a more efficient (and user-friendly) way of representing points in the domain. That explains my interest in nested tuples in the example.