Segmentation fault on (illegal?) type definition

[traktofon]

The following attempt at defining a recursive type (which may be illegal in the way I'm using here) immediately leads to a segmentation fault on 0.6.0-rc1 as well as on current master; it proceeds without error or segfault on 0.5.2 though.

$ julia --startup-file=no
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: https://docs.julialang.org
   _ _   _| |_  __ _   |  Type "?help" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.6.0-rc1.0 (2017-05-07 00:00 UTC)
 _/ |\__'_|_|_|\__'_|  |  Official http://julialang.org/ release
|__/                   |  x86_64-pc-linux-gnu

julia> type Foo{T,N}; v::Vector{Foo{T}}; end

signal (11): Segmentation fault
while loading no file, in expression starting on line 0
has_free_typevars at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:147
has_free_typevars at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:159 [inlined]
jl_has_free_typevars at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:178
inst_type_w_ at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:1394
inst_all at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:1240 [inlined]
inst_datatype at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:1172
inst_type_w_ at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:1400
inst_type_w_ at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:1345
jl_instantiate_unionall at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:844
jl_apply_type at /home/centos/buildbot/slave/package_tarball64/build/src/jltypes.c:794
jl_call_fptr_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:337 [inlined]
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:356 [inlined]
jl_apply_generic at /home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1930
do_call at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:75
eval at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:242
do_call at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:74
eval at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:242
do_call at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:74
eval at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:242
do_call at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:74
eval at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:242
eval at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:301
eval_body at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:624
jl_interpret_toplevel_thunk at /home/centos/buildbot/slave/package_tarball64/build/src/interpreter.c:692
jl_toplevel_eval_flex at /home/centos/buildbot/slave/package_tarball64/build/src/toplevel.c:590
jl_toplevel_eval_in at /home/centos/buildbot/slave/package_tarball64/build/src/builtins.c:496
eval at ./boot.jl:235
unknown function (ip: 0x7fb8a88b45af)
jl_call_fptr_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:337 [inlined]
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:356 [inlined]
jl_apply_generic at /home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1930
eval_user_input at ./REPL.jl:66
unknown function (ip: 0x7fb8a892f4bf)
jl_call_fptr_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:337 [inlined]
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:356 [inlined]
jl_apply_generic at /home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1930
macro expansion at ./REPL.jl:97 [inlined]
#1 at ./event.jl:73
unknown function (ip: 0x7fb8962b92af)
jl_call_fptr_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:337 [inlined]
jl_call_method_internal at /home/centos/buildbot/slave/package_tarball64/build/src/julia_internal.h:356 [inlined]
jl_apply_generic at /home/centos/buildbot/slave/package_tarball64/build/src/gf.c:1930
jl_apply at /home/centos/buildbot/slave/package_tarball64/build/src/julia.h:1422 [inlined]
start_task at /home/centos/buildbot/slave/package_tarball64/build/src/task.c:267
unknown function (ip: 0xffffffffffffffff)
Allocations: 1316512 (Pool: 1315278; Big: 1234); GC: 0
Segmentation fault

If this type definition is illegal, julia should produce an error message, but not segfault.

[fredrikekre]

FWIW it works if if all arguments are specified, e.g. type Foo{T,N}; v::Vector{Foo{T, N}}; end

[martinholters]

This should be equivalent but errors:

julia> mutable struct Foo{T,N}; v::Vector{Foo{T,M} where M}; end
ERROR: UndefVarError: Foo not defined

This errors, too:

julia> mutable struct Foo{T,N}; v::Foo{T,M} where M; end
ERROR: UndefVarError: Foo not defined

OTOH, this should be equivalent to the latter, but works:

mutable struct Foo{T,N}; v::Foo{T}; end