diff options
Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_builtin_macros/src/deriving/default.rs | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/compiler/rustc_builtin_macros/src/deriving/default.rs b/compiler/rustc_builtin_macros/src/deriving/default.rs index a94c8a996..17df9fb27 100644 --- a/compiler/rustc_builtin_macros/src/deriving/default.rs +++ b/compiler/rustc_builtin_macros/src/deriving/default.rs @@ -24,6 +24,7 @@ pub fn expand_deriving_default( let trait_def = TraitDef { span, path: Path::new(vec![kw::Default, sym::Default]), + skip_path_as_bound: has_a_default_variant(item), additional_bounds: Vec::new(), generics: Bounds::empty(), supports_unions: false, @@ -262,3 +263,22 @@ impl<'a, 'b> rustc_ast::visit::Visitor<'a> for DetectNonVariantDefaultAttr<'a, ' } } } + +fn has_a_default_variant(item: &Annotatable) -> bool { + struct HasDefaultAttrOnVariant { + found: bool, + } + + impl<'ast> rustc_ast::visit::Visitor<'ast> for HasDefaultAttrOnVariant { + fn visit_variant(&mut self, v: &'ast rustc_ast::Variant) { + if v.attrs.iter().any(|attr| attr.has_name(kw::Default)) { + self.found = true; + } + // no need to subrecurse. + } + } + + let mut visitor = HasDefaultAttrOnVariant { found: false }; + item.visit_with(&mut visitor); + visitor.found +} |