From 942df064017258a92eee1a14cd613c6aec983dc8 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Mon, 6 Apr 2026 18:50:04 +0200
Subject: feat(engine): make reflection of reflected struct fields optional

---
 engine-macros/src/lib.rs | 94 +++++++++++++++++-------------------------------
 1 file changed, 33 insertions(+), 61 deletions(-)

(limited to 'engine-macros')

diff --git a/engine-macros/src/lib.rs b/engine-macros/src/lib.rs
index ad6c15f..b87acf8 100644
--- a/engine-macros/src/lib.rs
+++ b/engine-macros/src/lib.rs
@@ -2,19 +2,7 @@
 
 use proc_macro::TokenStream;
 use quote::{ToTokens, format_ident, quote};
-use syn::punctuated::Punctuated;
-use syn::{
-    Item,
-    LitStr,
-    Path as SynPath,
-    PredicateType,
-    Token,
-    TraitBound,
-    TypeParamBound,
-    WhereClause,
-    WherePredicate,
-    parse,
-};
+use syn::{Item, LitStr, Path as SynPath, parse};
 
 macro_rules! syn_path {
     ($first_segment: ident $(::$segment: ident)*) => {
@@ -57,29 +45,6 @@ pub fn reflection_derive(input: TokenStream) -> TokenStream
 
     let (impl_generics, type_generics, where_clause) = input.generics.split_for_impl();
 
-    let mut where_clause = where_clause.cloned().unwrap_or_else(|| WhereClause {
-        where_token: <Token![where]>::default(),
-        predicates: Punctuated::new(),
-    });
-
-    where_clause
-        .predicates
-        .extend(input.fields.iter().map(|field| {
-            WherePredicate::Type(PredicateType {
-                lifetimes: None,
-                bounded_ty: field.ty.clone(),
-                colon_token: <Token![:]>::default(),
-                bounds: [TypeParamBound::Trait(TraitBound {
-                    paren_token: None,
-                    modifier: syn::TraitBoundModifier::None,
-                    lifetimes: None,
-                    path: engine_crate_path.join(syn_path!(reflection::With)),
-                })]
-                .into_iter()
-                .collect(),
-            })
-        }));
-
     let fields = input.fields.into_iter().enumerate().map(|(index, field)| {
         let field_ident = field.ident.unwrap_or_else(|| format_ident!("{index}"));
 
@@ -98,10 +63,38 @@ pub fn reflection_derive(input: TokenStream) -> TokenStream
                 byte_offset: std::mem::offset_of!(Self, #field_ident),
                 type_id: std::any::TypeId::of::<#field_type>(),
                 type_name: #field_type_name,
-                reflection:
-                    #engine_crate_path::reflection::__private::get_type_reflection::<
-                        #field_type
-                    >()
+                get_reflection: #engine_crate_path::reflection::FnWithDebug::new(|| {
+                    struct SpecializationTarget<Field>(std::marker::PhantomData<Field>);
+
+                    trait FieldHasReflection
+                    {
+                        fn field_reflection(&self) -> Option<&'static #engine_crate_path::reflection::Reflection>;
+                    }
+
+                    trait FieldDoesNotHaveReflection
+                    {
+                        fn field_reflection(&self) -> Option<&'static #engine_crate_path::reflection::Reflection>;
+                    }
+
+                    impl<Field> FieldDoesNotHaveReflection for &SpecializationTarget<Field>
+                    {
+                        fn field_reflection(&self) -> Option<&'static #engine_crate_path::reflection::Reflection>
+                        {
+                            None
+                        }
+                    }
+
+                    impl<Field: #engine_crate_path::reflection::With> FieldHasReflection for SpecializationTarget<Field>
+                    {
+                        fn field_reflection(&self) -> Option<&'static #engine_crate_path::reflection::Reflection>
+                        {
+                            Some(Field::reflection())
+                        }
+                    }
+
+                    (&SpecializationTarget::<#field_type>(std::marker::PhantomData))
+                        .field_reflection()
+                })
             }
         }
     });
@@ -151,24 +144,3 @@ fn find_engine_crate_path() -> Option<SynPath>
 
     Some(syn_path!(engine))
 }
-
-trait SynPathExt
-{
-    fn join(&self, other: Self) -> Self;
-}
-
-impl SynPathExt for SynPath
-{
-    fn join(&self, other: Self) -> Self
-    {
-        Self {
-            leading_colon: self.leading_colon.clone(),
-            segments: self
-                .segments
-                .iter()
-                .chain(&other.segments)
-                .cloned()
-                .collect(),
-        }
-    }
-}
-- 
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