Fix self_ handling during PascalCasification (#238)

bon-macros/src/util/ident.rs

@@ -37,7 +37,14 @@ impl IdentExt for syn::Ident {
         // https://internals.rust-lang.org/t/raw-identifiers-dont-work-for-all-identifiers/9094
         //
         // So no need to handle raw identifiers here.
-        let renamed = RenameRule::PascalCase.apply_to_field(self.raw_name());
+        let mut renamed = RenameRule::PascalCase.apply_to_field(self.raw_name());
+
+        // Make sure `Self` keyword isn't generated.
+        // This may happen if the input was `self_`, for example.
+        if renamed == "Self" {
+            renamed.push('_');
+        }
+
         Self::new(&renamed, Span::call_site())
     }
 

bon/tests/integration/builder/raw_idents.rs

@@ -92,3 +92,16 @@ fn test_fn() {
         }
     }
 }
+
+// This is based on the issue https://github.com/elastio/bon/issues/237
+#[test]
+fn test_self_underscore_bug_237() {
+    #[derive(Builder)]
+    struct Sut {
+        self_: u32,
+    }
+
+    let builder: SutBuilder<sut_builder::SetSelf_> = Sut::builder().self_(42);
+
+    assert_eq!(builder.build().self_, 42);
+}