# Unreachable reached at 0x7fa478093547 in Julia 1.0.5

**URL:** <https://discourse.julialang.org/t/unreachable-reached-at-0x7fa478093547-in-julia-1-0-5/36404>\
**Category:** General Usage\
**Tags:** question, error\
**Created:** [March 23, 2020, 7:44pm UTC](https://discourse.julialang.org/t/unreachable-reached-at-0x7fa478093547-in-julia-1-0-5/36404 "2020-03-23T19:44:36Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Henrique\_Becker](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/henrique_becker/32/15443_2.png) [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Post date:** [March 23, 2020, 7:44pm UTC](https://discourse.julialang.org/t/unreachable-reached-at-0x7fa478093547-in-julia-1-0-5/36404/1 "2020-03-23T19:44:36Z")

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I had the test code of a package I am developing for my PhD suddenly start crashing after a seemingly inoffensive commit.  
The complete error log is [here](https://pastebin.com/qfvqTrUx). It happens if I execute the tests in my last commit (i.e.,

```julia
git clone https://github.com/henriquebecker91/GuillotineModels.jl/
cd GuillotineModels.jl
git checkout 1f31094a 
julia
julia> activate .
julia> instantiate
julia> test

```

)  
The Julia version is 1.0.5 (the specific package versions are in the Manifest.toml file of the respository). The commit that introduced the error was [this commit](https://github.com/henriquebecker91/GuillotineModels.jl/commit/1f31094a07d2c9196a1e87b09d9fd1fa5dce5052). In other words, if I checkout `9c2e654b` instead (the previous commit) I do not have the crash. I had this problem with my Arch Linux laptop, and I used my mother’s Ubuntu laptop to reproduce it.

I do not have a MWE, but I have isolated the changes that make the problem appear, they are [those changes](https://github.com/henriquebecker91/GuillotineModels.jl/commit/1f31094a07d2c9196a1e87b09d9fd1fa5dce5052#diff-02cac12dfdf265c4db8cc6eb056a1e97R202-L240) (i.e., if I revert just those and keep the rest of the changes then the error disappear). They surprised me very much. I only changed the type of some parameters/return/literals of a single method from `Int` to the parametric type `P` that was already available in the scope, but most important, `P` is `Int` in the method call that gives the problem. (In fact, `Int64`, as `Int` is an alias for `Int64` on my system that is a 64-bit architecture). The change, therefore, should make difference only if I used a different type for `P` in the future, but it crashes in a situation in which it should have made no difference (i.e., both `Int` and `P` refer to the same type `Int64`). If the error was not consistent I would question my RAM or SSD, as it seems bizarre.

For now I will just rollback my change, as it is not essential, it only avoided unnecessary integer conversions, but I would like to know what to do to avoid hitting this problem again.

---

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**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [March 24, 2020, 6:59am UTC](https://discourse.julialang.org/t/unreachable-reached-at-0x7fa478093547-in-julia-1-0-5/36404/2 "2020-03-24T06:59:33Z")

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> [@Henrique\_Becker](#):
>
> The Julia version is 1.0.5

The first thing I would try is running on 1.4 and master. These bugs are frequently fixed in new releases.

Then, if the bug still persists, try to isolate an MWE. Also see [similar open bugs](https://github.com/JuliaLang/julia/issues?q=is%3Aissue+unreachable+reached+is%3Aopen).

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<div class="post-metadata">

**Author:** ![Henrique\_Becker](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/henrique_becker/32/15443_2.png) [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Post date:** [March 24, 2020, 2:13pm UTC](https://discourse.julialang.org/t/unreachable-reached-at-0x7fa478093547-in-julia-1-0-5/36404/3 "2020-03-24T14:13:12Z")

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Thanks Tamas, 1.4 solves the problem, so I can be sure it will be fixed for a Long Term Version (LTS) like 2.0 in the future. However, I would like to know if this kind of bug is not fixed in LTS when found (in this case, the current LTS that is v1.0). I am now using the 1.0 version because it seems to be the best option developing a long/medium term reproducibility code for my PhD. There is the possibility that I will finish my PhD before Julia 2.0 goes out. Should I not worry about using a LTS version then? (I was using it because I thought it would receive this kind of bug fixing.) The best choice for a code that takes a long time to develop and needs to be available for a long time after it is not the LTS?

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<div class="post-metadata">

**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [March 24, 2020, 2:34pm UTC](https://discourse.julialang.org/t/unreachable-reached-at-0x7fa478093547-in-julia-1-0-5/36404/4 "2020-03-24T14:34:21Z")

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> [@Henrique\_Becker](#):
>
> There is the possibility that I will finish my PhD before Julia 2.0 goes out.

That should be a possibility, especially since there is no current timeline for 2.0 😉

If you can [bisect](https://git-scm.com/docs/git-bisect) the fix you can ask for it to be backported to 1.0.x, but frankly I do not think that sticking to 1.0.x is a good idea at this point unless you are willing to live with a lot of compromises (like this one). I would always use the latest major release as it comes with a lot of benefits.

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<div class="post-metadata">

**Author:** ![Henrique\_Becker](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/henrique_becker/32/15443_2.png) [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)\
**Post date:** [March 25, 2020, 4:53am UTC](https://discourse.julialang.org/t/unreachable-reached-at-0x7fa478093547-in-julia-1-0-5/36404/5 "2020-03-25T04:53:07Z")

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Bisected it:

```julia
41c0c2f42d8beb8d1e893a4bfb21d0cfae8b9b07 is the first new commit
commit 41c0c2f42d8beb8d1e893a4bfb21d0cfae8b9b07
Author: Jeff Bezanson <jeff.bezanson@gmail.com>
Date: Wed Jan 2 15:00:08 2019 -0500

    don't use abstract_iteration for types with special cases in _apply (#30483)
    
    (cherry picked from commit 3e6f60758fd9b974972a78bbe899bb754e97a533)

 base/compiler/abstractinterpretation.jl | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

```

Tomorrow I will think about making a new issue or PR.