# Looks like a bug and flies like a bug, is it a bug?

**URL:** <https://discourse.julialang.org/t/looks-like-a-bug-and-flies-like-a-bug-is-it-a-bug/12485>\
**Category:** General Usage\
**Tags:** bug\
**Created:** [July 19, 2018, 9:12am UTC](https://discourse.julialang.org/t/looks-like-a-bug-and-flies-like-a-bug-is-it-a-bug/12485 "2018-07-19T09:12:42Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mohamed82008](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mohamed82008/32/18171_2.png) [@mohamed82008](https://discourse.julialang.org/u/mohamed82008)\
**Post date:** [July 19, 2018, 9:12am UTC](https://discourse.julialang.org/t/looks-like-a-bug-and-flies-like-a-bug-is-it-a-bug/12485/1 "2018-07-19T09:12:42Z")

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```julia
julia> struct T end

julia> (t::TT)(x) where {TT<:T} = x
ERROR: function type in method definition is not a type
Stacktrace:
 [1] top-level scope at none:0

```

---

<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:** [July 19, 2018, 9:24am UTC](https://discourse.julialang.org/t/looks-like-a-bug-and-flies-like-a-bug-is-it-a-bug/12485/2 "2018-07-19T09:24:41Z")

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I think this is

[https://github.com/JuliaLang/julia/issues/14919](https://github.com/JuliaLang/julia/issues/14919)

Also, please consider choosing a more specific title for your topic.