From 92d86ce1bb28d383a8eed63d50e58451a0636e0c Mon Sep 17 00:00:00 2001
From: Max Horn <max@quendi.de>
Date: Thu, 5 Dec 2024 20:30:17 +0100
Subject: [PATCH] Add some convert method to/from QQBarFieldElem

---
 src/calcium/qqbar.jl       | 11 +++++++++++
 test/calcium/qqbar-test.jl | 31 +++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/src/calcium/qqbar.jl b/src/calcium/qqbar.jl
index 30bc1e75e..7998915b6 100644
--- a/src/calcium/qqbar.jl
+++ b/src/calcium/qqbar.jl
@@ -1414,6 +1414,17 @@ function (::Type{Float64})(a::QQBarFieldElem)
   return Float64(x)
 end
 
+function (::Type{T})(a::QQBarFieldElem) where {T <: Integer}
+  return T(ZZRingElem(a))
+end
+
+function (::Type{T})(a::QQBarFieldElem) where {T <: Rational}
+  return T(QQFieldElem(a))
+end
+
+convert(::Type{QQBarFieldElem}, a::RationalUnion) = QQBarFieldElem(a)
+convert(::Type{T}, a::QQBarFieldElem) where {T <: RationalUnion} = T(a)
+
 ###############################################################################
 #
 #   Unsafe functions
diff --git a/test/calcium/qqbar-test.jl b/test/calcium/qqbar-test.jl
index d435c5a14..1590fd1c2 100644
--- a/test/calcium/qqbar-test.jl
+++ b/test/calcium/qqbar-test.jl
@@ -418,4 +418,35 @@ end
   x = sqrt(R(-2))
   @test_throws InexactError Float64(x)
   @test isapprox(ComplexF64(x),sqrt(complex(-2)))
+
+
+  x = R(2)
+  for T in [Int16, UInt32, Int, BigInt, Rational{Int}, Rational{BigInt}, ZZRingElem, QQFieldElem]
+    y = convert(T, x)
+    @test y::T == 2
+
+    y = T(x)
+    @test y::T == 2
+
+    z = convert(QQBarFieldElem, y)
+    @test z::QQBarFieldElem == x
+
+    z = QQBarFieldElem(y)
+    @test z::QQBarFieldElem == x
+  end
+
+  x = R(2//3)
+  for T in [Rational{Int}, Rational{BigInt}, QQFieldElem]
+    y = convert(T, x)
+    @test y::T == 2//3
+
+    y = T(x)
+    @test y::T == 2//3
+
+    z = convert(QQBarFieldElem, y)
+    @test z::QQBarFieldElem == x
+
+    z = QQBarFieldElem(y)
+    @test z::QQBarFieldElem == x
+  end
 end