Issue 449b (#451)

* over_ring

* change name; special case factored polynomial

* fix issues with 449

Author: jverzani

Project.toml

@@ -2,7 +2,7 @@ name = "Polynomials"
 uuid = "f27b6e38-b328-58d1-80ce-0feddd5e7a45"
 license = "MIT"
 author = "JuliaMath"
-version = "3.2.1"
+version = "3.2.2"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/common.jl

@@ -467,14 +467,19 @@ function _eltype(P::Type{<:AbstractPolynomial}, p::AbstractPolynomial)
 end
 
 """
-    copy_with_eltype(T, [X], p::AbstractPolynomial)
+    copy_with_eltype(::Val{T}, [::Val{X}], p::AbstractPolynomial)
 
 Copy polynomial `p` changing the underlying element type and optionally the symbol.
 """
-function copy_with_eltype(::Type{T}, X, p::P) where {T, S, Y, P<:AbstractPolynomial{S, Y}}
+copy_with_eltype(::Val{T}, ::Val{X}, p::P) where {T, X, S, Y, P <:AbstractPolynomial{S,Y}} =
     ⟒(P){T, X}(p.coeffs)
-end
-copy_with_eltype(::Type{T}, p::P) where {T, S, X, P<:AbstractPolynomial{S,X}} = copy_with_eltype(T, X, p)
+copy_with_eltype(V::Val{T}, p::P) where {T, S, Y, P <:AbstractPolynomial{S,Y}} =
+    copy_with_eltype(V, Val(Y), p)
+# easier to type if performance isn't an issue, but could be dropped
+copy_with_eltype(::Type{T}, X, p::P) where {T, S, Y, P<:AbstractPolynomial{S, Y}} =
+    copy_with_eltype(Val(T), Val(X), p)
+copy_with_eltype(::Type{T}, p::P) where {T, S, X, P<:AbstractPolynomial{S,X}} =
+    copy_with_eltype(Val(T), Val(X), p)
 
 Base.iszero(p::AbstractPolynomial) = all(iszero, p)
 

src/polynomials/factored_polynomial.jl

@@ -119,7 +119,7 @@ function Base.convert(P::Type{<:FactoredPolynomial}, p::Polynomial{T,X}) where {
     ⟒(P)(coeffs(p), X)
 end
 
-function copy_with_eltype(::Type{T}, X, p::P) where {T, S, Y, P<:FactoredPolynomial{S, Y}}
+function copy_with_eltype(::Val{T}, ::Val{X}, p::P) where {T, X, S, Y, P<:FactoredPolynomial{S, Y}}
     d = convert(Dict{T, Int}, p.coeffs)
     FactoredPolynomial{T, X}(d)
 end

test/StandardBasis.jl

@@ -800,8 +800,11 @@ end
         for T in (Float64, Rational)
             xs = [1,2,3]
             p = fromroots(P,xs)
-            @test Polynomials.copy_with_eltype(T, p) == fromroots(P, T.(xs))
-            @test Polynomials.copy_with_eltype(T, :u, p) == fromroots(P, T.(xs); var=:u)
+            @test Polynomials.copy_with_eltype(Val(T), p) == fromroots(P, T.(xs))
+            @test Polynomials.copy_with_eltype(Val(T), Val(:u), p) == fromroots(P, T.(xs); var=:u)
+            P == ImmutablePolynomial && continue
+            @inferred Polynomials.copy_with_eltype(Val(T), Val(:u), p)
+            @inferred Polynomials.copy_with_eltype(Val(T), p)
         end
     end
 end