From 94aa51f543c70df4c410f9e4cbb7a4dea2042cb2 Mon Sep 17 00:00:00 2001
From: Guillaume Dalle <22795598+gdalle@users.noreply.github.com>
Date: Mon, 11 May 2026 09:52:47 +0200
Subject: [PATCH 1/4] fix: proper eltype in wrong-mode pushforward/pullback

---
 DifferentiationInterface/Project.toml        | 2 +-
 DifferentiationInterface/src/utils/linalg.jl | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/DifferentiationInterface/Project.toml b/DifferentiationInterface/Project.toml
index 2fd7884ce..a78e5c371 100644
--- a/DifferentiationInterface/Project.toml
+++ b/DifferentiationInterface/Project.toml
@@ -1,6 +1,6 @@
 name = "DifferentiationInterface"
 uuid = "a0c0ee7d-e4b9-4e03-894e-1c5f64a51d63"
-version = "0.7.17"
+version = "0.7.18"
 authors = ["Guillaume Dalle", "Adrian Hill"]
 
 [deps]
diff --git a/DifferentiationInterface/src/utils/linalg.jl b/DifferentiationInterface/src/utils/linalg.jl
index e11b7e266..2cb6470c3 100644
--- a/DifferentiationInterface/src/utils/linalg.jl
+++ b/DifferentiationInterface/src/utils/linalg.jl
@@ -44,5 +44,5 @@ Convert an array of tuples `tx` into a tuple of arrays, while respecting the arr
 arroftup_to_tupofarr(tx::NTuple{B, <:Number}, x::Number) where {B} = tx
 
 function arroftup_to_tupofarr(tx::AbstractArray{<:NTuple{B, <:Number}}, x::AbstractArray{<:Number}) where {B}
-    return ntuple(b -> similar(x) .= getindex.(tx, b), Val(B))
+    return ntuple(b -> similar(x, eltype(tx)) .= getindex.(tx, b), Val(B))
 end

From 323aed19da62ac760a7a54e68da86f17ab19b1af Mon Sep 17 00:00:00 2001
From: Guillaume Dalle <22795598+gdalle@users.noreply.github.com>
Date: Mon, 11 May 2026 10:10:40 +0200
Subject: [PATCH 2/4] Fix

---
 DifferentiationInterface/src/utils/linalg.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/DifferentiationInterface/src/utils/linalg.jl b/DifferentiationInterface/src/utils/linalg.jl
index 2cb6470c3..aaa22f50f 100644
--- a/DifferentiationInterface/src/utils/linalg.jl
+++ b/DifferentiationInterface/src/utils/linalg.jl
@@ -43,6 +43,6 @@ Convert an array of tuples `tx` into a tuple of arrays, while respecting the arr
 """
 arroftup_to_tupofarr(tx::NTuple{B, <:Number}, x::Number) where {B} = tx
 
-function arroftup_to_tupofarr(tx::AbstractArray{<:NTuple{B, <:Number}}, x::AbstractArray{<:Number}) where {B}
-    return ntuple(b -> similar(x, eltype(tx)) .= getindex.(tx, b), Val(B))
+function arroftup_to_tupofarr(tx::AbstractArray{<:NTuple{B, TX}}, x::AbstractArray{<:Number}) where {B, TX <: Number}
+    return ntuple(b -> similar(x, TX) .= getindex.(tx, b), Val(B))
 end

From fce7cbf127833444f3fae2476c8f6974b1e58e68 Mon Sep 17 00:00:00 2001
From: Guillaume Dalle <22795598+gdalle@users.noreply.github.com>
Date: Mon, 11 May 2026 11:44:12 +0200
Subject: [PATCH 3/4] Without type parameter to avoid angering Aqua

---
 DifferentiationInterface/src/utils/linalg.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/DifferentiationInterface/src/utils/linalg.jl b/DifferentiationInterface/src/utils/linalg.jl
index aaa22f50f..b27706a5e 100644
--- a/DifferentiationInterface/src/utils/linalg.jl
+++ b/DifferentiationInterface/src/utils/linalg.jl
@@ -43,6 +43,6 @@ Convert an array of tuples `tx` into a tuple of arrays, while respecting the arr
 """
 arroftup_to_tupofarr(tx::NTuple{B, <:Number}, x::Number) where {B} = tx
 
-function arroftup_to_tupofarr(tx::AbstractArray{<:NTuple{B, TX}}, x::AbstractArray{<:Number}) where {B, TX <: Number}
-    return ntuple(b -> similar(x, TX) .= getindex.(tx, b), Val(B))
+function arroftup_to_tupofarr(tx::AbstractArray{<:NTuple{B, <:Number}}, x::AbstractArray{<:Number}) where {B}
+    return ntuple(b -> similar(x, eltype(eltype(tx))) .= getindex.(tx, b), Val(B))
 end

From d176bc6c32884fac278b260abac8864d6e796a0e Mon Sep 17 00:00:00 2001
From: Guillaume Dalle <22795598+gdalle@users.noreply.github.com>
Date: Mon, 11 May 2026 13:25:52 +0200
Subject: [PATCH 4/4] Changelog

---
 DifferentiationInterface/CHANGELOG.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/DifferentiationInterface/CHANGELOG.md b/DifferentiationInterface/CHANGELOG.md
index 5decdf9dc..93173bf13 100644
--- a/DifferentiationInterface/CHANGELOG.md
+++ b/DifferentiationInterface/CHANGELOG.md
@@ -13,6 +13,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add support for HyperHessians backend ([#940](https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/940))
 
+### Fixed
+
+- Proper eltype in wrong-mode pushforward/pullback ([#1003](https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/1003))
+
 ## [0.7.17](https://github.com/JuliaDiff/DifferentiationInterface.jl/compare/DifferentiationInterface-v0.7.16...DifferentiationInterface-v0.7.17)
 
 ### Fixed