Issue 1:
The following invalid code results in a segfault for me: Set{Array{T}}() where {T<:Float64}

Full details:

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| | |_| | | | (_| | | Version 0.6.0 (2017-06-19 13:05 UTC)
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|__/ | x86_64-suse-linux

julia> versioninfo()
Julia Version 0.6.0
Commit 903644385b* (2017-06-19 13:05 UTC)
Platform Info:
OS: Linux (x86_64-suse-linux)
CPU: Intel(R) Core(TM) i5-4200U CPU @ 1.60GHz
WORD_SIZE: 64
BLAS: libopenblas (DYNAMIC_ARCH Haswell)
LAPACK: libopenblas_openmp.so.0
LIBM: libopenlibm
LLVM: libLLVM-3.9.1 (ORCJIT, haswell)

julia> Set{Array{T}}() where {T<:Float64}

signal (11): Segmentation fault
while loading no file, in expression starting on line 0
jl_new_structv at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/datatype.c:679
Type at ./dict.jl:104
jl_call_fptr_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:339 [inlined]
jl_call_method_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:358 [inlined]
jl_apply_generic at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/gf.c:1933
Type at ./set.jl:6
jl_call_fptr_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:339 [inlined]
jl_call_method_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:358 [inlined]
jl_apply_generic at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/gf.c:1933
do_call at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/interpreter.c:75
eval at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/interpreter.c:242
do_call at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/interpreter.c:74
eval at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/interpreter.c:242
eval_body at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/interpreter.c:539
jl_interpret_toplevel_thunk at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/interpreter.c:692
jl_toplevel_eval_flex at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/toplevel.c:592
jl_toplevel_eval_in at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/builtins.c:496
eval at ./boot.jl:235
unknown function (ip: 0x7f7dad6574ff)
jl_call_fptr_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:339 [inlined]
jl_call_method_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:358 [inlined]
jl_apply_generic at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/gf.c:1933
eval_user_input at ./REPL.jl:66
unknown function (ip: 0x7f7dad6ca0ef)
jl_call_fptr_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:339 [inlined]
jl_call_method_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:358 [inlined]
jl_apply_generic at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/gf.c:1933
macro expansion at ./REPL.jl:97 [inlined]
#1 at ./event.jl:73
unknown function (ip: 0x7f7d90e3155f)
jl_call_fptr_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:339 [inlined]
jl_call_method_internal at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia_internal.h:358 [inlined]
jl_apply_generic at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/gf.c:1933
jl_apply at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/julia.h:1424 [inlined]
start_task at /home/abuild/rpmbuild/BUILD/julia-0.6.0/src/task.c:267
unknown function (ip: 0xffffffffffffffff)
Allocations: 3884938 (Pool: 3883572; Big: 1366); GC: 6
Segmentation fault (core dumped)

Issue 2:
background

Somebody in Chinese Julia community wants to implement a STMonad in Julia, and he found this bug.

And I found that this code in julia 0.6.4 only cause a error, Julia also suggest that this code use a deprecated syntax. But in Julia 1.0 this cause a crash.

Error info

v 1.0.0

minimal reproducible example

struct STMonad{A,B}
function STMonad()
new{S,Ref{S}}() where S
end
end

STMonad()

Julia info

julia> versioninfo()
Julia Version 1.0.0
Commit 5d4eaca0c9 (2018-08-08 20:58 UTC)
Platform Info:
OS: Windows (x86_64-w64-mingw32)
CPU: Intel(R) Core(TM) i7-5600U CPU @ 2.60GHz
WORD_SIZE: 64
LIBM: libopenlibm
LLVM: libLLVM-6.0.0 (ORCJIT, broadwell)

output

PS C:\Users\woclass\Desktop\`del> C:\Users\woclass\AppData\Local\Julia-1.0.0\bin\julia.exe .\STMonad.jl

Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks.
Exception: EXCEPTION_ACCESS_VIOLATION at 0x6b5cf117 -- jl_new_structv at /home/Administrator/buildbot/worker/package_win64/build/src\datatype.c:774
in expression starting at C:\Users\woclass\Desktop\`del\STMonad.jl:7
jl_set_nth_field at /home/Administrator/buildbot/worker/package_win64/build/src\datatype.c:889 [inlined]
jl_new_structv at /home/Administrator/buildbot/worker/package_win64/build/src\datatype.c:781
Type at C:\Users\woclass\Desktop\`del\STMonad.jl:3
jl_fptr_trampoline at /home/Administrator/buildbot/worker/package_win64/build/src\gf.c:1829
jl_apply_generic at /home/Administrator/buildbot/worker/package_win64/build/src\gf.c:2182
do_call at /home/Administrator/buildbot/worker/package_win64/build/src\interpreter.c:324
eval_value at /home/Administrator/buildbot/worker/package_win64/build/src\interpreter.c:428
eval_stmt_value at /home/Administrator/buildbot/worker/package_win64/build/src\interpreter.c:363 [inlined]
eval_body at /home/Administrator/buildbot/worker/package_win64/build/src\interpreter.c:682
jl_interpret_toplevel_thunk_callback at /home/Administrator/buildbot/worker/package_win64/build/src\interpreter.c:799
unknown function (ip: FFFFFFFFFFFFFFFE)
unknown function (ip: 000000000EB4522F)
unknown function (ip: FFFFFFFFFFFFFFFF)
jl_toplevel_eval_flex at /home/Administrator/buildbot/worker/package_win64/build/src\toplevel.c:787
jl_parse_eval_all at /home/Administrator/buildbot/worker/package_win64/build/src\ast.c:838
jl_load at /home/Administrator/buildbot/worker/package_win64/build/src\toplevel.c:821 [inlined]
jl_load_ at /home/Administrator/buildbot/worker/package_win64/build/src\toplevel.c:828
include at .\boot.jl:317 [inlined]
include_relative at .\loading.jl:1038
include at .\sysimg.jl:29
jl_apply_generic at /home/Administrator/buildbot/worker/package_win64/build/src\gf.c:2182
exec_options at .\client.jl:229
_start at .\client.jl:421
jl_apply_generic at /home/Administrator/buildbot/worker/package_win64/build/src\gf.c:2182
jl_apply at /home/Administrator/buildbot/worker/package_win64/build/src\julia.h:1536 [inlined]
true_main at /home/Administrator/buildbot/worker/package_win64/build/ui\repl.c:112
wmain at /home/Administrator/buildbot/worker/package_win64/build/ui\repl.c:233
__tmainCRTStartup at /usr/src/debug/mingw64-x86_64-runtime-5.0.3-1/crt\crtexe.c:329
mainCRTStartup at /usr/src/debug/mingw64-x86_64-runtime-5.0.3-1/crt\crtexe.c:212
BaseThreadInitThunk at C:\WINDOWS\System32\KERNEL32.DLL (unknown line)
RtlUserThreadStart at C:\WINDOWS\SYSTEM32\ntdll.dll (unknown line)
Allocations: 5974 (Pool: 5964; Big: 10); GC: 0

v 0.6.4

And in Juliua 0.6.4 this code just cause a MethodError, not a crash.

julia> struct STMonad{A, B}
function STMonad()
new{S, Ref{S}}() where S
end
end

WARNING: deprecated syntax "inner constructor STMonad(...) around REPL[1]:3".
Use "STMonad{A,B}(...) where {A,B}" instead.

julia> STMonad()
ERROR: MethodError: no method matching STMonad()