fix invalidations; close issue #403

Author: jverzani

Project.toml

@@ -2,7 +2,7 @@ name = "Polynomials"
 uuid = "f27b6e38-b328-58d1-80ce-0feddd5e7a45"
 license = "MIT"
 author = "JuliaMath"
-version = "3.1.0"
+version = "3.1.1"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/common.jl

@@ -430,7 +430,7 @@ function Base.convert(::Type{S}, p::P) where {S <: Number,T, P<:AbstractPolynomi
     isconstant(p) && return convert(S, constantterm(p))
     throw(ArgumentError("Can't convert a nonconstant polynomial to type $S"))
 end
-function Base.convert(::Type{T}, p::P) where {T, P<:AbstractPolynomial{T}}
+function Base.convert(::Type{T}, p::AbstractPolynomial{T,X}) where {T,X}
     isconstant(p) && return constantterm(p)
     throw(ArgumentError("Can't convert a nonconstant polynomial to type $S"))
 end