Assertion failure in jl_gf_invoke_lookup (detect_unbound_args-related)

[timholy]

On the teh/extensible_broadcast I'm getting a curious failure in test/ambiguous (this from a debug build in which I've inserted @show tuple_sig right before this line):

shell> cd test
/home/tim/src/julia-branch/test

julia> using Test

julia> include("ambiguous.jl")
Skipping Base.Distributed.cluster_manager
Skipping Base.Filesystem.JL_O_RANDOM
Skipping Base.Filesystem.JL_O_SEQUENTIAL
Skipping Base.Filesystem.JL_O_SHORT_LIVED
Skipping Base.Filesystem.JL_O_TEMPORARY
Skipping Base.dSFMT.win32_SystemFunction036!
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{typeof(Core.Inference.cat),Any}
tuple_sig = Tuple{typeof(Core.Inference.hcat)}
tuple_sig = Tuple{typeof(Core.Inference.hcat)}
tuple_sig = Tuple{typeof(Core.Inference.hcat)}
tuple_sig = Tuple{typeof(Core.Inference.hcat)}
tuple_sig = Tuple{typeof(Core.Inference.hvcat),Tuple{Vararg{Int64,N} where N}}
tuple_sig = Tuple{typeof(Core.Inference.hvcat),Tuple{Vararg{Int64,N} where N}}
tuple_sig = Tuple{typeof(Core.Inference.vcat)}
tuple_sig = Tuple{typeof(Core.Inference.vcat)}
tuple_sig = Tuple{typeof(Core.Inference.vcat)}
tuple_sig = Tuple{typeof(Core.Inference.vcat)}
tuple_sig = Tuple{typeof(Core.Inference.vcat)}
tuple_sig = Tuple{typeof(Core.Inference.vcat)}
tuple_sig = Tuple{typeof(Core.Inference.vect)}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{Dict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{Type{WeakKeyDict}}
tuple_sig = Tuple{typeof(cat),Any}
tuple_sig = Tuple{typeof(cat),Any}
tuple_sig = Tuple{typeof(hcat)}
tuple_sig = Tuple{typeof(hcat)}
tuple_sig = Tuple{typeof(hcat)}
tuple_sig = Tuple{typeof(hcat)}
tuple_sig = Tuple{typeof(hcat)}
tuple_sig = Tuple{typeof(hcat)}
tuple_sig = Tuple{typeof(hcat)}
tuple_sig = Tuple{typeof(hvcat),Tuple{Vararg{Int64,N} where N}}
tuple_sig = Tuple{typeof(hvcat),Tuple{Vararg{Int64,N} where N}}
tuple_sig = Tuple{typeof(hvcat),Tuple{Vararg{Int64,N} where N}}
tuple_sig = Tuple{typeof(Base.same_names)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(vcat)}
tuple_sig = Tuple{typeof(Base.vect)}
tuple_sig = Tuple{typeof(withenv),Function}
tuple_sig = Tuple{typeof(Base.Broadcast.broadcast_similar),Any,Base.Broadcast.DefaultArrayStyle{N},Type{Bool},Tuple{Vararg{AbstractUnitRange,N}}} where N
julia: /home/tim/src/julia-branch/src/julia.h:701: jl_svecref: Assertion `jl_typeis(t,jl_simplevector_type)' failed.

Thread 1 "julia" received signal SIGABRT, Aborted.
0x00007ffff6b21428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54
54      ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  0x00007ffff6b21428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54
#1  0x00007ffff6b2302a in __GI_abort () at abort.c:89
#2  0x00007ffff6b19bd7 in __assert_fail_base (fmt=<optimized out>, assertion=assertion@entry=0x7ffff7790b48 "jl_typeis(t,jl_simplevector_type)", 
    file=file@entry=0x7ffff7790b20 "/home/tim/src/julia-branch/src/julia.h", line=line@entry=701, 
    function=function@entry=0x7ffff77914e0 <__PRETTY_FUNCTION__.27486> "jl_svecref") at assert.c:92
#3  0x00007ffff6b19c82 in __GI___assert_fail (assertion=0x7ffff7790b48 "jl_typeis(t,jl_simplevector_type)", 
    file=0x7ffff7790b20 "/home/tim/src/julia-branch/src/julia.h", line=701, function=0x7ffff77914e0 <__PRETTY_FUNCTION__.27486> "jl_svecref") at assert.c:101
#4  0x00007ffff75170ec in jl_svecref (t=0x7fffebb87a90, i=0) at /home/tim/src/julia-branch/src/julia.h:701
#5  0x00007ffff751edeb in jl_gf_invoke_lookup (types=0x7fffeb66f8f0, world=18446744073709551615) at /home/tim/src/julia-branch/src/gf.c:2009
#6  0x00007fffbb5ba410 in japi1_#detect_unbound_args#28_62734 (imported=0 '\000', recursive=1 '\001', mods...=<optimized out>)
    at /home/tim/src/julia-branch/usr/share/julia/site/v0.7/Test/src/Test.jl:1303
#7  0x00007ffff75181e9 in jl_call_fptr_internal (fptr=0x7fffffffbc30, meth=0x7fffe9fd1990, args=0x7fffffffbcf0, nargs=5)
    at /home/tim/src/julia-branch/src/julia_internal.h:366
#8  0x00007ffff75182fa in jl_call_method_internal (meth=0x7fffe9fd1990, args=0x7fffffffbcf0, nargs=5) at /home/tim/src/julia-branch/src/julia_internal.h:385
#9  0x00007ffff751ed8b in jl_apply_generic (args=0x7fffffffbcf0, nargs=5) at /home/tim/src/julia-branch/src/gf.c:2003
#10 0x00007ffff752b184 in jl_apply (args=0x7fffffffbcf0, nargs=5) at /home/tim/src/julia-branch/src/julia.h:1471
#11 0x00007ffff752e14a in jl_f__apply (F=0x0, args=0x7fffffffbe88, nargs=3) at /home/tim/src/julia-branch/src/builtins.c:556
#12 0x00007fffbb5b9b01 in japi1_#detect_unbound_args_62733 (mods...=0x7fffee58bec0 <jl_system_image_data+2007168>)
#13 0x00007ffff75181e9 in jl_call_fptr_internal (fptr=0x7fffffffbf50, meth=0x7fffea160810, args=0x7fffffffc070, nargs=4)
    at /home/tim/src/julia-branch/src/julia_internal.h:366
#14 0x00007ffff75182fa in jl_call_method_internal (meth=0x7fffea160810, args=0x7fffffffc070, nargs=4) at /home/tim/src/julia-branch/src/julia_internal.h:385
#15 0x00007ffff751ed8b in jl_apply_generic (args=0x7fffffffc070, nargs=4) at /home/tim/src/julia-branch/src/gf.c:2003
#16 0x00007fffbb5ba6ba in japi1_#detect_unbound_args#28_62734 (imported=0 '\000', recursive=1 '\001', mods...=<optimized out>)
    at /home/tim/src/julia-branch/usr/share/julia/site/v0.7/Test/src/Test.jl:1292
#17 0x00007ffff75181e9 in jl_call_fptr_internal (fptr=0x7fffffffc140, meth=0x7fffe9fd1990, args=0x7fffffffc200, nargs=5)
    at /home/tim/src/julia-branch/src/julia_internal.h:366
#18 0x00007ffff75182fa in jl_call_method_internal (meth=0x7fffe9fd1990, args=0x7fffffffc200, nargs=5) at /home/tim/src/julia-branch/src/julia_internal.h:385
#19 0x00007ffff751ed8b in jl_apply_generic (args=0x7fffffffc200, nargs=5) at /home/tim/src/julia-branch/src/gf.c:2003
#20 0x00007ffff752b184 in jl_apply (args=0x7fffffffc200, nargs=5) at /home/tim/src/julia-branch/src/julia.h:1471
#21 0x00007ffff752e14a in jl_f__apply (F=0x0, args=0x7fffffffc398, nargs=3) at /home/tim/src/julia-branch/src/builtins.c:556
#22 0x00007fffbb5b9b01 in japi1_#detect_unbound_args_62733 (mods...=0x7fffee3a4a30 <jl_system_image_data+11248>)
#23 0x00007ffff75181e9 in jl_call_fptr_internal (fptr=0x7fffffffc460, meth=0x7fffea160810, args=0x7fffffffc770, nargs=4)
    at /home/tim/src/julia-branch/src/julia_internal.h:366
#24 0x00007ffff75182fa in jl_call_method_internal (meth=0x7fffea160810, args=0x7fffffffc770, nargs=4) at /home/tim/src/julia-branch/src/julia_internal.h:385
#25 0x00007ffff7518485 in jl_invoke (meth=0x7fffea160810, args=0x7fffffffc770, nargs=4) at /home/tim/src/julia-branch/src/gf.c:41
#26 0x00007fffbb5b574f in macro expansion () at /home/tim/src/julia-branch/test/ambiguous.jl:268
#27 macro expansion () at /home/tim/src/julia-branch/usr/share/julia/site/v0.7/Test/src/Test.jl:950
#28 japi1_anonymous_62715 () at <missing>:65535
---Type <return> to continue, or q <return> to quit---q
Quit
(gdb) f 5
#5  0x00007ffff751edeb in jl_gf_invoke_lookup (types=0x7fffeb66f8f0, world=18446744073709551615) at /home/tim/src/julia-branch/src/gf.c:2009
2009        jl_methtable_t *mt = ((jl_datatype_t*)jl_tparam0(types))->name->mt;
(gdb) call jl_(types)
Tuple{typeof(Base.Broadcast.broadcast_similar), Any, Base.Broadcast.DefaultArrayStyle{N}, Type{Bool}, Tuple{Vararg{Base.AbstractUnitRange{T} where T, N}}} where N
(gdb) call jl_(types)
Tuple{typeof(Base.Broadcast.broadcast_similar), Any, Base.Broadcast.DefaultArrayStyle{N}, Type{Bool}, Tuple{Vararg{Base.AbstractUnitRange{T} where T, N}}} where N
(gdb) call jl_(types.parameters)
String
(gdb) 

Memory corruption?

[timholy]

I should add that this failure seems to be deterministic, with the exception of the type reported by jl_(types.parameters) (on different runs I get at least String or Any).

[timholy]

This still happens on current master. It blocks the merger of #23939, and with impending feature freeze it risks sticking us with the old API.

This appears to be some form of memory corruption, and I worry that I lack the time to track it down myself.