Fix has on non-inherent fields (#2745)

crates/typst-macros/src/elem.rs

@@ -731,12 +731,18 @@ fn create_native_elem_impl(element: &Elem) -> TokenStream {
             quote! {
                 <#elem as #model::ElementFields>::Fields::#name => None,
             }
-        } else {
+        } else if field.inherent() {
             quote! {
                 <#elem as #model::ElementFields>::Fields::#name => Some(
                     ::typst::eval::IntoValue::into_value(self.#field_ident.clone())
                 ),
             }
+        } else {
+            quote! {
+                <#elem as #model::ElementFields>::Fields::#name => {
+                    self.#field_ident.clone().map(::typst::eval::IntoValue::into_value)
+                }
+            }
         }
     });
 

tests/typ/compiler/content-field.typ

@@ -1,3 +1,17 @@
+// Tests for field introspection.
+
+---
+// Verify that non-inherent fields are hidden if not set.
+#show figure: it => [
+  `repr(it)`: #repr(it) \
+  `it.has("gap"): `#repr(it.has("gap")) \
+]
+
+#figure[]
+
+#figure([], gap: 1pt)
+
+---
 // Integrated test for content fields.
 
 #let compute(equation, ..vars) = {