feat: handle overrides in element group derivation

Author: scootermon

svd-rs/CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+- Allow overriding `dimElementGroup` fields when deriving.
+
 ## [v0.14.12] - 2025-03-11
 
 - Bump MSRV to 1.70.0

svd-rs/src/derive_from.rs

@@ -1,6 +1,6 @@
 //! Implementations of DeriveFrom, setting non-explicit fields.
 use crate::{
-    ClusterInfo, EnumeratedValues, FieldInfo, MaybeArray, PeripheralInfo, RegisterInfo,
+    ClusterInfo, DimElement, EnumeratedValues, FieldInfo, MaybeArray, PeripheralInfo, RegisterInfo,
     RegisterProperties,
 };
 
@@ -110,6 +110,27 @@ impl DeriveFrom for FieldInfo {
     }
 }
 
+impl DeriveFrom for DimElement {
+    fn derive_from(&self, other: &Self) -> Self {
+        let Self {
+            dim,              // mandatory
+            dim_increment: _, // mandatory
+            dim_index,
+            dim_name,
+            dim_array_index,
+        } = other;
+
+        let mut derived = self.clone();
+        derived.dim_name = derived.dim_name.or_else(|| dim_name.clone());
+        if derived.dim == *dim {
+            // Only derive dimIndex and dimArrayIndex if the dimensions are the same.
+            derived.dim_index = derived.dim_index.or_else(|| dim_index.clone());
+            derived.dim_array_index = derived.dim_array_index.or_else(|| dim_array_index.clone());
+        }
+        derived
+    }
+}
+
 impl<T> DeriveFrom for MaybeArray<T>
 where
     T: DeriveFrom + crate::Name,
@@ -128,9 +149,12 @@ where
                     Self::Single(info.derive_from(other_info))
                 }
             }
-            (Self::Array(info, dim), Self::Single(other_info) | Self::Array(other_info, _)) => {
+            (Self::Array(info, dim), Self::Single(other_info)) => {
                 Self::Array(info.derive_from(other_info), dim.clone())
             }
+            (Self::Array(info, dim), Self::Array(other_info, other_dim)) => {
+                Self::Array(info.derive_from(other_info), dim.derive_from(other_dim))
+            }
         }
     }
 }