Support builder(overwritable) with builder(getter) (#369)

Author: Veetaha

bon-macros/src/builder/builder_gen/getters.rs

@@ -60,6 +60,13 @@ impl<'a> GettersCtx<'a> {
         // be treated as totally different symbols due to the hygiene rules.
         let self_ = quote!(self);
 
+        let where_clause = self.member.is_stateful().then(|| {
+            quote! {
+                where
+                    #state_var::#member_pascal: #state_mod::IsSet,
+            }
+        });
+
         Ok(quote_spanned! {self.member.span=>
             #( #docs )*
             #[allow(
@@ -70,8 +77,7 @@ impl<'a> GettersCtx<'a> {
             #[inline(always)]
             #[must_use = "this method has no side effects; it only returns a value"]
             #(#fn_modifiers)* fn #name(&#self_) -> #return_ty
-            where
-                #state_var::#member_pascal: #state_mod::IsSet,
+            #where_clause
             {
                 #body
             }

bon-macros/src/builder/builder_gen/member/config/mod.rs

@@ -231,14 +231,6 @@ impl MemberConfig {
             );
         }
 
-        if let Some(getter) = &self.getter {
-            self.validate_mutually_exclusive(
-                ParamName::Getter,
-                getter.key.span(),
-                &[ParamName::Overwritable],
-            )?;
-        }
-
         if self.start_fn.is_present() {
             self.validate_mutually_allowed(
                 ParamName::StartFn,

bon/tests/integration/builder/attr_overwritable.rs

@@ -93,11 +93,24 @@ mod on {
 
             #[builder(default)]
             c: u32,
+
+            #[builder(getter)]
+            d: u32,
+
+            #[builder(getter)]
+            e: Option<u32>,
         }
 
+        let builder = Sut::builder().a(1).a(2).b(3).b(4).c(5).c(6).d(7).e(8);
+
+        assert_debug_eq(builder.get_d(), expect!["7"]);
+        assert_debug_eq(builder.get_e(), expect!["Some(8)"]);
+
+        let value = builder.build();
+
         assert_debug_eq(
-            Sut::builder().a(1).a(2).b(3).b(4).c(5).c(6).build(),
-            expect!["Sut { a: 2, b: Some(4), c: 6 }"],
+            value,
+            expect!["Sut { a: 2, b: Some(4), c: 6, d: 7, e: Some(8) }"],
         );
     }
 }