Fix dangling implicit derives

Author: n8tlarsen

CHANGELOG.md

@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
+- Fix dangling implicit derives
 
 ## [v0.28.0] - 2022-12-25
 

src/generate/peripheral.rs

@@ -859,7 +859,7 @@ fn compare_this_against_prev(
     Ok(None)
 }
 
-/// Compare the given type name against previous regexs, then inspect fields
+/// Compare previous type names against the given regex, then inspect fields
 fn compare_prev_against_this(
     reg: &MaybeArray<RegisterInfo>,
     ty_name: &str,
@@ -913,6 +913,21 @@ fn compare_prev_against_this(
                     }
                 }
             }
+            if let DeriveInfo::Implicit(my_rpath) = &my_derive_info {
+                match prev_derive_info {
+                    DeriveInfo::Implicit(their_rpath) => {
+                        if their_rpath.name == ty_name {
+                            (_, *their_rpath) = find_root(&my_rpath.name, path, index)?;
+                        }
+                    }
+                    DeriveInfo::Explicit(their_rpath) => {
+                        if their_rpath.name == ty_name {
+                            (_, *their_rpath) = find_root(&my_rpath.name, path, index)?;
+                        }
+                    }
+                    _ => {}
+                }
+            }
         }
     }
     Ok(my_derive_info)