# UndefRefError on a global constant instatiation in the stdlib

**URL:** <https://discourse.julialang.org/t/undefreferror-on-a-global-constant-instatiation-in-the-stdlib/11913>\
**Category:** Internals & Design\
**Tags:** question\
**Created:** [June 24, 2018, 8:07pm UTC](https://discourse.julialang.org/t/undefreferror-on-a-global-constant-instatiation-in-the-stdlib/11913 "2018-06-24T20:07:18Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Gaetano](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gaetano/32/4654_2.png) [@Gaetano](https://discourse.julialang.org/u/Gaetano)\
**Post date:** [June 24, 2018, 8:07pm UTC](https://discourse.julialang.org/t/undefreferror-on-a-global-constant-instatiation-in-the-stdlib/11913/1 "2018-06-24T20:07:18Z")

</div>

Running something like

```julia
init_TRNG() = init_TRNG(GLOBAL_RNG)
const threadRNG = init_TRNG()

```

in a Julia source works, the problem comes when I try to add it to the Random module in the stdlib.  
There it returns during Julia’s compilation `UndefRefError()` on the `const threadRNG` instatiation, which seems absurd to me.  
Is there some restriction to global const initialization in the stdlib or I am missing something?  
Thanks!

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<div class="post-metadata">

**Author:** ![ScottPJones](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/scottpjones/32/146_2.png) [@ScottPJones](https://discourse.julialang.org/u/ScottPJones)\
**Post date:** [June 24, 2018, 8:22pm UTC](https://discourse.julialang.org/t/undefreferror-on-a-global-constant-instatiation-in-the-stdlib/11913/2 "2018-06-24T20:22:21Z")

</div>

What version are you on, and can you copy the error message / stack trace here?

---

<div class="post-metadata">

**Author:** ![Gaetano](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gaetano/32/4654_2.png) [@Gaetano](https://discourse.julialang.org/u/Gaetano)\
**Post date:** [June 24, 2018, 8:33pm UTC](https://discourse.julialang.org/t/undefreferror-on-a-global-constant-instatiation-in-the-stdlib/11913/3 "2018-06-24T20:33:38Z")

</div>

Julia 0.7.0 - master The error is in full

```julia
DelimitedFiles ─ 2.354190 seconds
error during bootstrap:
LoadError("sysimg.jl", 493, LoadError("/home/rodia/dev/RNG-julia/usr/share/julia/stdlib/v0.7/Random/src/Random.jl", 254, LoadError("/home/rodia/dev/RNG-julia/usr/share/julia/stdlib/v0.7/Random/src/RNGs.jl", 586, UndefRefError())))
rec_backtrace at /home/rodia/dev/RNG-julia/src/stackwalk.c:94
record_backtrace at /home/rodia/dev/RNG-julia/src/task.c:246
jl_throw at /home/rodia/dev/RNG-julia/src/task.c:577
getproperty at ./sysimg.jl:18 [inlined]
getindex at ./refvalue.jl:32 [inlined]
calc_jump at /home/rodia/dev/RNG-julia/usr/share/julia/stdlib/v0.7/Random/src/DSFMT.jl:176 [inlined]
randjump at /home/rodia/dev/RNG-julia/usr/share/julia/stdlib/v0.7/Random/src/RNGs.jl:561 [inlined]
init_TRNG at /home/rodia/dev/RNG-julia/usr/share/julia/stdlib/v0.7/Random/src/RNGs.jl:580 [inlined]
init_TRNG at /home/rodia/dev/RNG-julia/usr/share/julia/stdlib/v0.7/Random/src/RNGs.jl:584
jl_fptr_trampoline at /home/rodia/dev/RNG-julia/src/gf.c:1813
jl_apply_generic at /home/rodia/dev/RNG-julia/src/gf.c:2142
do_call at /home/rodia/dev/RNG-julia/src/interpreter.c:324
eval_value at /home/rodia/dev/RNG-julia/src/interpreter.c:428
eval_stmt_value at /home/rodia/dev/RNG-julia/src/interpreter.c:363 [inlined]
eval_body at /home/rodia/dev/RNG-julia/src/interpreter.c:671
jl_interpret_toplevel_thunk_callback at /home/rodia/dev/RNG-julia/src/interpreter.c:788
unknown function (ip: 0xfffffffffffffffe)
unknown function (ip: 0x7fb65625f7ef)
unknown function (ip: (nil))
jl_interpret_toplevel_thunk at /home/rodia/dev/RNG-julia/src/interpreter.c:797
jl_toplevel_eval_flex at /home/rodia/dev/RNG-julia/src/toplevel.c:814
jl_parse_eval_all at /home/rodia/dev/RNG-julia/src/ast.c:854
jl_load at /home/rodia/dev/RNG-julia/src/toplevel.c:848
include at ./boot.jl:317 [inlined]
include_relative at ./loading.jl:1075
include at ./sysimg.jl:29 [inlined]
include at /home/rodia/dev/RNG-julia/usr/share/julia/stdlib/v0.7/Random/src/Random.jl:5
jl_apply_generic at /home/rodia/dev/RNG-julia/src/gf.c:2142
do_call at /home/rodia/dev/RNG-julia/src/interpreter.c:324
eval_value at /home/rodia/dev/RNG-julia/src/interpreter.c:428
eval_stmt_value at /home/rodia/dev/RNG-julia/src/interpreter.c:363 [inlined]
eval_body at /home/rodia/dev/RNG-julia/src/interpreter.c:671
jl_interpret_toplevel_thunk_callback at /home/rodia/dev/RNG-julia/src/interpreter.c:788
unknown function (ip: 0xfffffffffffffffe)
unknown function (ip: 0x7fb657524fcf)
unknown function (ip: 0xffffffffffffffff)
jl_interpret_toplevel_thunk at /home/rodia/dev/RNG-julia/src/interpreter.c:797
jl_toplevel_eval_flex at /home/rodia/dev/RNG-julia/src/toplevel.c:814
jl_eval_module_expr at /home/rodia/dev/RNG-julia/src/toplevel.c:233
jl_toplevel_eval_flex at /home/rodia/dev/RNG-julia/src/toplevel.c:605
jl_parse_eval_all at /home/rodia/dev/RNG-julia/src/ast.c:854
jl_load at /home/rodia/dev/RNG-julia/src/toplevel.c:848
include at ./boot.jl:317 [inlined]
include_relative at ./loading.jl:1075
_require at ./loading.jl:998
require at ./loading.jl:879
require at ./loading.jl:874
jl_apply_generic at /home/rodia/dev/RNG-julia/src/gf.c:2142
do_call at /home/rodia/dev/RNG-julia/src/interpreter.c:324
eval_value at /home/rodia/dev/RNG-julia/src/interpreter.c:428
eval_body at /home/rodia/dev/RNG-julia/src/interpreter.c:554
jl_interpret_toplevel_thunk_callback at /home/rodia/dev/RNG-julia/src/interpreter.c:788
unknown function (ip: 0xfffffffffffffffe)
unknown function (ip: 0x7fb6578a68ef)
unknown function (ip: 0x26)
jl_interpret_toplevel_thunk at /home/rodia/dev/RNG-julia/src/interpreter.c:797
jl_toplevel_eval_flex at /home/rodia/dev/RNG-julia/src/toplevel.c:814
jl_parse_eval_all at /home/rodia/dev/RNG-julia/src/ast.c:854
jl_load at /home/rodia/dev/RNG-julia/src/toplevel.c:848
exec_program at /home/rodia/dev/RNG-julia/ui/repl.c:36
true_main at /home/rodia/dev/RNG-julia/ui/repl.c:124
main at /home/rodia/dev/RNG-julia/ui/repl.c:243
__libc_start_main at /usr/lib/libc.so.6 (unknown line)
_start at /home/rodia/dev/RNG-julia/usr/bin/julia (unknown line)

***This error is usually fixed by running `make clean`. If the error persists, try `make cleanall`.***
make[1]: *** [Makefile:201: /home/rodia/dev/RNG-julia/usr/lib/julia/sys-o.a] Error 1
make: *** [Makefile:78: julia-sysimg-release] Error 2

```

Obviously `make cleanall` does not resolve the issue.

---

<div class="post-metadata">

**Author:** ![Gaetano](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gaetano/32/4654_2.png) [@Gaetano](https://discourse.julialang.org/u/Gaetano)\
**Post date:** [June 25, 2018, 3:05pm UTC](https://discourse.julialang.org/t/undefreferror-on-a-global-constant-instatiation-in-the-stdlib/11913/4 "2018-06-25T15:05:19Z")

</div>

Wwll actually it seems that the problem comes whenever calling `init_TRNG`, which is simply defined as  
`init_TRNG(r::MersenneTwister) = randjump(r, big(10)^20, Threads.nthreads())`  
`randjump` does nothing more than returing an n-array of MersenneTwister. So I still do not get why it goes to a UndefRefError, should I instatiate it as a type or something?