From 55c35d90c8a36217b353daa0d540feac88ae3e60 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lars=20G=C3=B6ttgens?= <lars.goettgens@rwth-aachen.de>
Date: Wed, 2 Oct 2024 22:51:35 +0200
Subject: [PATCH] Correct mutating op fallbacks (#1823)

* Fix docstrings of `inv!` and `div!`

* Move methods from `AA.*` to `Base.*`

the `AA.*` should only implement methods for julia types and delegate everything else
---
 src/Fields.jl                    |  2 +-
 src/Poly.jl                      |  5 -----
 src/fundamental_interface.jl     | 27 ++++++++++++++++++++++++---
 src/generic/LaurentMPoly.jl      |  4 ++--
 src/generic/Misc/Localization.jl |  4 ----
 5 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/src/Fields.jl b/src/Fields.jl
index b659bb650f..68961924b5 100644
--- a/src/Fields.jl
+++ b/src/Fields.jl
@@ -16,7 +16,7 @@ is_zero_divisor(a::T) where T <: FieldElem = is_zero(a)
 
 Base.divrem(a::T, b::T) where {T <: FieldElem} = divexact(a, b), zero(parent(a))
 
-div(a::T, b::T) where {T <: FieldElem} = divexact(a, b)
+Base.div(a::T, b::T) where {T <: FieldElem} = divexact(a, b)
 
 function gcd(x::T, y::T) where {T <: FieldElem}
    check_parent(x, y)
diff --git a/src/Poly.jl b/src/Poly.jl
index 2bacc1643f..f87db58c39 100644
--- a/src/Poly.jl
+++ b/src/Poly.jl
@@ -1479,11 +1479,6 @@ function Base.divrem(f::PolyRingElem{T}, g::PolyRingElem{T}) where T <: RingElem
    return q, f
 end
 
-function Base.div(f::PolyRingElem{T}, g::PolyRingElem{T}) where T <: RingElement
-   q, r = divrem(f, g)
-   return q
-end
-
 ##############################################################################
 #
 #  Ad hoc Euclidean division
diff --git a/src/fundamental_interface.jl b/src/fundamental_interface.jl
index 45124af686..38187c0128 100644
--- a/src/fundamental_interface.jl
+++ b/src/fundamental_interface.jl
@@ -328,11 +328,16 @@ neg!(a) = neg!(a, a)
     inv!(z, a)
     inv!(a)
 
-Return `inv(a)`, possibly modifying the object `z` in the process.
+Return `AbstractAlgebra.inv(a)`, possibly modifying the object `z` in the process.
 Aliasing is permitted.
 The unary version is a shorthand for `inv!(a, a)`.
+
+!!! note
+    `AbstractAlgebra.inv` and `Base.inv` differ only in their behavior on julia
+    types like `Integer` and `Rational{Int}`. The former makes it adhere to the
+    Ring interface.
 """
-inv!(z, a) = inv(a)
+inv!(z, a) = AbstractAlgebra.inv(a)
 inv!(a) = inv!(a, a)
 
 for (name, op) in ((:add!, :+), (:sub!, :-), (:mul!, :*))
@@ -378,7 +383,7 @@ submul!(z, a, b) = submul!(z, a, b, parent(z)())
 
 function divexact end
 
-for name in (:divexact, :div, :rem, :mod, :gcd, :lcm)
+for name in (:divexact, :rem, :mod, :gcd, :lcm)
   name_bang = Symbol(name, "!")
   @eval begin
     @doc """
@@ -394,6 +399,22 @@ for name in (:divexact, :div, :rem, :mod, :gcd, :lcm)
   end
 end
 
+@doc """
+    div!(z, a, b)
+    div!(a, b)
+
+Return `div(a, b)`, possibly modifying the object `z` in the process.
+Aliasing is permitted.
+The two argument version is a shorthand for `div(a, a, b)`.
+
+!!! note
+    `AbstractAlgebra.div` and `Base.div` differ only in their behavior on julia
+    types like `Integer` and `Rational{Int}`. The former makes it adhere to the
+    Ring interface.
+"""
+div!(z, a, b) = AbstractAlgebra.div(a, b)
+div!(a, b) = div!(a, a, b)
+
 @doc raw"""
     canonical_injection(D, i)
 
diff --git a/src/generic/LaurentMPoly.jl b/src/generic/LaurentMPoly.jl
index 04396a3bb3..62fb1c1a2f 100644
--- a/src/generic/LaurentMPoly.jl
+++ b/src/generic/LaurentMPoly.jl
@@ -106,7 +106,7 @@ function is_gen(a::LaurentMPolyWrap)
     return !iszero(_var_index(a))
 end
 
-function inv(a::LaurentMPolyWrap)
+function Base.inv(a::LaurentMPolyWrap)
     (ap, ad) = _normalize(a)
     return LaurentMPolyWrap(parent(a), inv(ap), neg!(ad, ad))
 end
@@ -204,7 +204,7 @@ function gcd(a::LaurentMPolyWrap, b::LaurentMPolyWrap)
     return LaurentMPolyWrap(parent(a), gcd(ap, bp), zero!(ad))
 end
 
-function divrem(a::LaurentMPolyWrap, b::LaurentMPolyWrap)
+function Base.divrem(a::LaurentMPolyWrap, b::LaurentMPolyWrap)
     check_parent(a, b)
     error("divrem not implemented for LaurentMPoly")
 end
diff --git a/src/generic/Misc/Localization.jl b/src/generic/Misc/Localization.jl
index 1f7c27a466..490f768b67 100644
--- a/src/generic/Misc/Localization.jl
+++ b/src/generic/Misc/Localization.jl
@@ -263,10 +263,6 @@ function Base.divrem(a::LocalizedEuclideanRingElem{T}, b::LocalizedEuclideanRing
   end
 end
 
-function Base.div(a::LocalizedEuclideanRingElem{T}, b::LocalizedEuclideanRingElem{T}) where {T}
-  return divrem(a, b)[1]
-end
-
 function rem(a::LocalizedEuclideanRingElem{T}, b::LocalizedEuclideanRingElem{T}) where {T}
   return divrem(a, b)[2]
 end