# Strange inference problem in v0.6.2

**URL:** <https://discourse.julialang.org/t/strange-inference-problem-in-v0-6-2/10662>\
**Category:** General Usage\
**Created:** [May 2, 2018, 6:13pm UTC](https://discourse.julialang.org/t/strange-inference-problem-in-v0-6-2/10662 "2018-05-02T18:13:33Z")\
**Posts on this page:** 1\
**Page:** 1

<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:** [May 2, 2018, 6:13pm UTC](https://discourse.julialang.org/t/strange-inference-problem-in-v0-6-2/10662/1 "2018-05-02T18:13:33Z")

</div>

I have been running into a very strange bug, only on v0.6.2.  
This code has worked in the past, but apparently some of the changes to make things more generic, and handle conversions to substring types, may have provoked this.

This only happens when the `convert` call is in a macro, and sometimes, when it is executed more than once, the error goes away.

In this example, `LatinStr` is really an alias for the type `Str{LatinCSE,Nothing,Nothing,Nothing}`.  
`LatinCSE` is an alias for the type `CSE{CharSet{:Latin}, Encoding{:Byte}}`

```julia
julia> using Base.Test,Strs ; @test convert(LatinStr, "|") == "|"
ERROR: TypeError: issubtype: expected Type, got TypeVar
Stacktrace:
 [1] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:2005
 [2] (::Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState})(::Expr) at ./<missing>:0
 [3] next(::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}, ::Int64) at ./generator.jl:45
 [4] copy!(::Array{Any,1}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}) at ./abstractarray.jl:573
 [5] _collect(::Type{Any}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}, ::Core.Inference.HasShape) at ./array.jl:396
 [6] collect(::Type{Any}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}) at ./array.jl:393
 [7] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1901
 [8] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [9] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2722
 [10] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [11] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [12] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [13] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [14] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [15] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [16] (::Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState})(::Expr) at ./<missing>:0
 [17] next(::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}, ::Int64) at ./generator.jl:45
 [18] copy!(::Array{Any,1}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}) at ./abstractarray.jl:573
 [19] _collect(::Type{Any}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}, ::Core.Inference.HasShape) at ./array.jl:396
 [20] collect(::Type{Any}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}) at ./array.jl:393
 [21] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1901
 [22] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [23] (::Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState})(::Expr) at ./<missing>:0
 [24] next(::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}, ::Int64) at ./generator.jl:45
 [25] copy!(::Array{Any,1}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}) at ./abstractarray.jl:573
 [26] _collect(::Type{Any}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}, ::Core.Inference.HasShape) at ./array.jl:396
 [27] collect(::Type{Any}, ::Core.Inference.Generator{Array{Any,1},Core.Inference.##189#190{Array{Any,1},Core.Inference.InferenceState}}) at ./array.jl:393
 [28] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1901
 [29] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [30] abstract_interpret(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:2076
 [31] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2669
 [32] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [33] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [34] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [35] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [36] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [37] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [38] abstract_interpret(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:2076
 [39] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2669
 [40] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [41] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [42] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [43] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [44] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [45] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [46] abstract_interpret(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:2076
 [47] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2669
 [48] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [49] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [50] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [51] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [52] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [53] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [54] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2722
 [55] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [56] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [57] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [58] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [59] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [60] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [61] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2722
 [62] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [63] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [64] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [65] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [66] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [67] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [68] abstract_interpret(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:2076
 [69] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2669
 [70] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [71] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [72] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [73] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [74] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [75] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [76] abstract_interpret(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:2076
 [77] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2669
 [78] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [79] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [80] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [81] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [82] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [83] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [84] abstract_interpret(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:2084
 [85] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2669
 [86] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [87] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [88] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [89] abstract_call(::Any, ::Tuple{}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [90] abstract_apply(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1561
 [91] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1689
 [92] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [93] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [94] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2722
 [95] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [96] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [97] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [98] abstract_call(::Any, ::Tuple{}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [99] abstract_apply(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1561
 [100] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1689
 [101] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [102] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [103] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2722
 [104] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [105] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [106] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [107] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [108] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [109] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [110] abstract_interpret(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:2084
 [111] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2669
 [112] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [113] typeinf_edge(::Method, ::Any, ::SimpleVector, ::Core.Inference.InferenceState) at ./inference.jl:2535
 [114] abstract_call_gf_by_type(::Any, ::Any, ::Core.Inference.InferenceState) at ./inference.jl:1420
 [115] abstract_call(::Any, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1897
 [116] abstract_eval_call(::Expr, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1927
 [117] abstract_eval(::Any, ::Array{Any,1}, ::Core.Inference.InferenceState) at ./inference.jl:1950
 [118] typeinf_work(::Core.Inference.InferenceState) at ./inference.jl:2722
 [119] typeinf(::Core.Inference.InferenceState) at ./inference.jl:2787
 [120] typeinf_frame(::Core.MethodInstance, ::Bool, ::Bool, ::Core.Inference.InferenceParams) at ./inference.jl:2504
 [121] typeinf_code(::Core.MethodInstance, ::Bool, ::Bool, ::Core.Inference.InferenceParams) at ./inference.jl:2583
 [122] typeinf_ext(::Core.MethodInstance, ::UInt64) at ./inference.jl:2622

julia> @test convert(LatinStr, "|") == "|"
Test Passed

```