From c0dbc3389058aa24f2d672965b6acaec68bbe3de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lars=20G=C3=B6ttgens?= <lars.goettgens@rwth-aachen.de>
Date: Mon, 27 Nov 2023 17:22:07 +0100
Subject: [PATCH] Fix promotion of complex polys (#1588)

---
 src/arb/ComplexPoly.jl       | 2 ++
 src/arb/acb_poly.jl          | 2 ++
 test/arb/ComplexPoly-test.jl | 8 ++++++++
 test/arb/acb_poly-test.jl    | 8 ++++++++
 4 files changed, 20 insertions(+)

diff --git a/src/arb/ComplexPoly.jl b/src/arb/ComplexPoly.jl
index da0b9b5f35..5d95ba8f42 100644
--- a/src/arb/ComplexPoly.jl
+++ b/src/arb/ComplexPoly.jl
@@ -777,6 +777,8 @@ promote_rule(::Type{ComplexPoly}, ::Type{QQPolyRingElem}) = ComplexPoly
 
 promote_rule(::Type{ComplexPoly}, ::Type{arb_poly}) = ComplexPoly
 
+promote_rule(::Type{ComplexPoly}, ::Type{ComplexPoly}) = ComplexPoly
+
 function promote_rule(::Type{ComplexPoly}, ::Type{T}) where {T}
    return promote_rule(ComplexFieldElem, T) === ComplexFieldElem ? ComplexPoly : Union{}
 end
diff --git a/src/arb/acb_poly.jl b/src/arb/acb_poly.jl
index 0a8c8f6c86..79e375b571 100644
--- a/src/arb/acb_poly.jl
+++ b/src/arb/acb_poly.jl
@@ -774,6 +774,8 @@ promote_rule(::Type{acb_poly}, ::Type{QQPolyRingElem}) = acb_poly
 
 promote_rule(::Type{acb_poly}, ::Type{arb_poly}) = acb_poly
 
+promote_rule(::Type{acb_poly}, ::Type{acb_poly}) = acb_poly
+
 function promote_rule(::Type{acb_poly}, ::Type{T}) where {T}
    return promote_rule(acb, T) === acb ? acb_poly : Union{}
 end
diff --git a/test/arb/ComplexPoly-test.jl b/test/arb/ComplexPoly-test.jl
index 6ebe5d9d99..8ea810689e 100644
--- a/test/arb/ComplexPoly-test.jl
+++ b/test/arb/ComplexPoly-test.jl
@@ -386,3 +386,11 @@ end
       @test all([ abs(z[i] + onei(CC)) <= b for i in 1:r])
    end
 end
+
+@testset "Issue #1587" begin
+   CC = ComplexField()
+   R, t = polynomial_ring(CC, "t")
+   D, Dt = polynomial_ring(R, "Dt")
+   A_scalarform = t^3 * (32 * t^2 - 1) * (32 * t^2 + 1) * Dt^4 + 2 * t^2 * (7168 * t^4 - 3) * Dt^3 + t * (55296 * t^4 - 7) * Dt^2 + (61440 * t^4 - 1) * Dt + 12288 * t^3
+   @test A_scalarform isa PolyRingElem{ComplexPoly}
+end
diff --git a/test/arb/acb_poly-test.jl b/test/arb/acb_poly-test.jl
index 6c523ef3b7..6f1cc06a52 100644
--- a/test/arb/acb_poly-test.jl
+++ b/test/arb/acb_poly-test.jl
@@ -386,3 +386,11 @@ end
       @test all([ abs(z[i] + onei(CC)) <= b for i in 1:r])
    end
 end
+
+@testset "Issue #1587" begin
+   CC = AcbField(32)
+   R, t = polynomial_ring(CC, "t")
+   D, Dt = polynomial_ring(R, "Dt")
+   A_scalarform = t^3 * (32 * t^2 - 1) * (32 * t^2 + 1) * Dt^4 + 2 * t^2 * (7168 * t^4 - 3) * Dt^3 + t * (55296 * t^4 - 7) * Dt^2 + (61440 * t^4 - 1) * Dt + 12288 * t^3
+   @test A_scalarform isa PolyRingElem{acb_poly}
+end