# Should \`convert\` include a type-assertion to ensure that the conversion succeeds?
**URL:** https://discourse.julialang.org/t/should-convert-include-a-type-assertion-to-ensure-that-the-conversion-succeeds/85577
**Category:** Internals & Design
**Tags:** base, type-stability
**Created:** [August 10, 2022, 9:05am UTC](https://discourse.julialang.org/t/should-convert-include-a-type-assertion-to-ensure-that-the-conversion-succeeds/85577 "2022-08-10T09:05:09Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@jishnub](https://discourse.julialang.org/u/jishnub)
#### Post date: [August 10, 2022, 9:05am UTC](https://discourse.julialang.org/t/should-convert-include-a-type-assertion-to-ensure-that-the-conversion-succeeds/85577/1 "2022-08-10T09:05:10Z")
>
For example, in badly inferred code, one may obtain
```julia
julia> @code_warntype (x -> convert(Int, x[1]))(Any[1])
MethodInstance for (::var"#3#4")(::Vector{Any})
from (::var"#3#4")(x) @ Main REPL[5]:1
Arguments
#self#::Core.Const(var"#3#4"())
x::Vector{Any}
Body::Any
1 ─ %1 = Base.getindex(x, 1)::Any
│ %2 = Main.convert(Main.Int, %1)::Any
└── return %2
```
However, the only sensible type that should be returned here is `Int`. With a type-assertion, we would obtain
```julia
julia> _convert(::Type{T}, x::T) where {T} = convert(T, x)::T
_convert (generic function with 1 method)
julia> @code_warntype (x -> _convert(Int, x[1]))(Any[1])
MethodInstance for (::var"#5#6")(::Vector{Any})
from (::var"#5#6")(x) @ Main REPL[8]:1
Arguments
#self#::Core.Const(var"#5#6"())
x::Vector{Any}
Body::Int64
1 ─ %1 = Base.getindex(x, 1)::Any
│ %2 = Main._convert(Main.Int, %1)::Int64
└── return %2
```
---
### Author:  [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)
#### Post date: [August 10, 2022, 9:41am UTC](https://discourse.julialang.org/t/should-convert-include-a-type-assertion-to-ensure-that-the-conversion-succeeds/85577/2 "2022-08-10T09:41:02Z")
See some discussion in [JuliaLang/julia#42372](https://github.com/JuliaLang/julia/issues/42372).