diff options
| -rw-r--r-- | compiler/rustc_typeck/src/collect.rs | 61 | ||||
| -rw-r--r-- | src/test/ui/generic-associated-types/type-param-defaults.rs | 34 | ||||
| -rw-r--r-- | src/test/ui/generic-associated-types/type-param-defaults.stderr | 20 |
3 files changed, 96 insertions, 19 deletions
diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs index 189f1f7e408..45a5eca708a 100644 --- a/compiler/rustc_typeck/src/collect.rs +++ b/compiler/rustc_typeck/src/collect.rs @@ -1606,6 +1606,13 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics { _ => None, }; + enum Defaults { + Allowed, + // See #36887 + FutureCompatDisallowed, + Deny, + } + let no_generics = hir::Generics::empty(); let ast_generics = node.generics().unwrap_or(&no_generics); let (opt_self, allow_defaults) = match node { @@ -1627,17 +1634,26 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics { }, }); - (opt_self, true) + (opt_self, Defaults::Allowed) } ItemKind::TyAlias(..) | ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::OpaqueTy(..) - | ItemKind::Union(..) => (None, true), - _ => (None, false), + | ItemKind::Union(..) => (None, Defaults::Allowed), + _ => (None, Defaults::FutureCompatDisallowed), } } - _ => (None, false), + + // GATs + Node::TraitItem(item) if matches!(item.kind, TraitItemKind::Type(..)) => { + (None, Defaults::Deny) + } + Node::ImplItem(item) if matches!(item.kind, ImplItemKind::TyAlias(..)) => { + (None, Defaults::Deny) + } + + _ => (None, Defaults::FutureCompatDisallowed), }; let has_self = opt_self.is_some(); @@ -1670,23 +1686,30 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics { let type_start = own_start - has_self as u32 + params.len() as u32; let mut i = 0; + const TYPE_DEFAULT_NOT_ALLOWED: &'static str = "defaults for type parameters are only allowed in \ + `struct`, `enum`, `type`, or `trait` definitions"; + params.extend(ast_generics.params.iter().filter_map(|param| match param.kind { GenericParamKind::Lifetime { .. } => None, GenericParamKind::Type { ref default, synthetic, .. } => { - if !allow_defaults && default.is_some() { - if !tcx.features().default_type_parameter_fallback { - tcx.struct_span_lint_hir( - lint::builtin::INVALID_TYPE_PARAM_DEFAULT, - param.hir_id, - param.span, - |lint| { - lint.build( - "defaults for type parameters are only allowed in \ - `struct`, `enum`, `type`, or `trait` definitions", - ) - .emit(); - }, - ); + if default.is_some() { + match allow_defaults { + Defaults::Allowed => {} + Defaults::FutureCompatDisallowed + if tcx.features().default_type_parameter_fallback => {} + Defaults::FutureCompatDisallowed => { + tcx.struct_span_lint_hir( + lint::builtin::INVALID_TYPE_PARAM_DEFAULT, + param.hir_id, + param.span, + |lint| { + lint.build(TYPE_DEFAULT_NOT_ALLOWED).emit(); + }, + ); + } + Defaults::Deny => { + tcx.sess.span_err(param.span, TYPE_DEFAULT_NOT_ALLOWED); + } } } @@ -1703,7 +1726,7 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics { Some(param_def) } GenericParamKind::Const { default, .. } => { - if !allow_defaults && default.is_some() { + if !matches!(allow_defaults, Defaults::Allowed) && default.is_some() { tcx.sess.span_err( param.span, "defaults for const parameters are only allowed in \ diff --git a/src/test/ui/generic-associated-types/type-param-defaults.rs b/src/test/ui/generic-associated-types/type-param-defaults.rs new file mode 100644 index 00000000000..f034076b010 --- /dev/null +++ b/src/test/ui/generic-associated-types/type-param-defaults.rs @@ -0,0 +1,34 @@ +// Check that we disallow GAT param defaults, even with `invalid_type_param_default` allowed + +#![allow(invalid_type_param_default)] + +trait Trait { + type Assoc<T = u32>; + //~^ defaults for type parameters are only allowed +} + +impl Trait for () { + type Assoc<T = u32> = u64; + //~^ defaults for type parameters are only allowed +} + +impl Trait for u32 { + type Assoc<T = u32> = T; + //~^ defaults for type parameters are only allowed +} + +trait Other {} +impl Other for u32 {} + +fn foo<T>() +where + T: Trait<Assoc = u32>, + T::Assoc: Other { + } + +fn main() { + // errors + foo::<()>(); + // works + foo::<u32>(); +} diff --git a/src/test/ui/generic-associated-types/type-param-defaults.stderr b/src/test/ui/generic-associated-types/type-param-defaults.stderr new file mode 100644 index 00000000000..85ccaba0e69 --- /dev/null +++ b/src/test/ui/generic-associated-types/type-param-defaults.stderr @@ -0,0 +1,20 @@ +error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions + --> $DIR/type-param-defaults.rs:6:16 + | +LL | type Assoc<T = u32>; + | ^^^^^^^ + +error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions + --> $DIR/type-param-defaults.rs:11:16 + | +LL | type Assoc<T = u32> = u64; + | ^^^^^^^ + +error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions + --> $DIR/type-param-defaults.rs:16:16 + | +LL | type Assoc<T = u32> = T; + | ^^^^^^^ + +error: aborting due to 3 previous errors + |