diff options
| -rw-r--r-- | src/librustc_ast_lowering/lib.rs | 8 | ||||
| -rw-r--r-- | src/librustc_ast_passes/ast_validation.rs | 20 | ||||
| -rw-r--r-- | src/librustc_hir/hir.rs | 1 | ||||
| -rw-r--r-- | src/librustc_parse/parser/ty.rs | 33 | ||||
| -rw-r--r-- | src/librustdoc/html/format.rs | 1 | ||||
| -rw-r--r-- | src/libsyntax/ast.rs | 11 |
6 files changed, 42 insertions, 32 deletions
diff --git a/src/librustc_ast_lowering/lib.rs b/src/librustc_ast_lowering/lib.rs index 76a0889c376..90560c371e2 100644 --- a/src/librustc_ast_lowering/lib.rs +++ b/src/librustc_ast_lowering/lib.rs @@ -1250,7 +1250,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { let bounds = this.arena.alloc_from_iter(bounds.iter().filter_map( |bound| match *bound { - GenericBound::Trait(ref ty, TraitBoundModifier::None) => { + GenericBound::Trait(ref ty, TraitBoundModifier::None) + | GenericBound::Trait(ref ty, TraitBoundModifier::MaybeConst) => { Some(this.lower_poly_trait_ref(ty, itctx.reborrow())) } GenericBound::Trait(_, TraitBoundModifier::Maybe) => None, @@ -2158,10 +2159,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { p: &PolyTraitRef, mut itctx: ImplTraitContext<'_, 'hir>, ) -> hir::PolyTraitRef<'hir> { - if p.trait_ref.constness.is_some() { - self.diagnostic().span_err(p.span, "`?const` on trait bounds is not yet implemented"); - } - let bound_generic_params = self.lower_generic_params( &p.bound_generic_params, &NodeMap::default(), @@ -2301,6 +2298,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { match f { TraitBoundModifier::None => hir::TraitBoundModifier::None, TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe, + TraitBoundModifier::MaybeConst => hir::TraitBoundModifier::MaybeConst, } } diff --git a/src/librustc_ast_passes/ast_validation.rs b/src/librustc_ast_passes/ast_validation.rs index 7dbd2362f04..23cb9734833 100644 --- a/src/librustc_ast_passes/ast_validation.rs +++ b/src/librustc_ast_passes/ast_validation.rs @@ -917,22 +917,10 @@ impl<'a> Visitor<'a> for AstValidator<'a> { } fn visit_param_bound(&mut self, bound: &'a GenericBound) { - if let GenericBound::Trait(poly, maybe_bound) = bound { - match poly.trait_ref.constness { - Some(Constness::NotConst) => { - if *maybe_bound == TraitBoundModifier::Maybe { - self.err_handler() - .span_err(bound.span(), "`?const` and `?` are mutually exclusive"); - } - - if let Some(ctx) = self.bound_context { - let msg = format!("`?const` is not permitted in {}", ctx.description()); - self.err_handler().span_err(bound.span(), &msg); - } - } - - Some(Constness::Const) => panic!("Parser should reject bare `const` on bounds"), - None => {} + if let GenericBound::Trait(_, TraitBoundModifier::MaybeConst) = bound { + if let Some(ctx) = self.bound_context { + let msg = format!("`?const` is not permitted in {}", ctx.description()); + self.err_handler().span_err(bound.span(), &msg); } } diff --git a/src/librustc_hir/hir.rs b/src/librustc_hir/hir.rs index d850cfe69ce..b62a7e413e3 100644 --- a/src/librustc_hir/hir.rs +++ b/src/librustc_hir/hir.rs @@ -364,6 +364,7 @@ impl GenericArgs<'_> { pub enum TraitBoundModifier { None, Maybe, + MaybeConst, } /// The AST represents all type param bounds as types. diff --git a/src/librustc_parse/parser/ty.rs b/src/librustc_parse/parser/ty.rs index 065a3b14428..9c9180778e5 100644 --- a/src/librustc_parse/parser/ty.rs +++ b/src/librustc_parse/parser/ty.rs @@ -27,11 +27,17 @@ struct BoundModifiers { } impl BoundModifiers { - fn trait_bound_modifier(&self) -> TraitBoundModifier { - match self.maybe { - Some(_) => TraitBoundModifier::Maybe, - None => TraitBoundModifier::None, - } + fn to_trait_bound_modifier(&self) -> Result<TraitBoundModifier, &'static str> { + let modifier = match (self.maybe, self.maybe_const) { + (None, None) => TraitBoundModifier::None, + (Some(_), None) => TraitBoundModifier::Maybe, + (None, Some(_)) => TraitBoundModifier::MaybeConst, + (Some(_), Some(_)) => { + return Err("`?const` and `?` are mutually exclusive"); + } + }; + + Ok(modifier) } } @@ -215,7 +221,7 @@ impl<'a> Parser<'a> { ) -> PResult<'a, TyKind> { assert_ne!(self.token, token::Question); - let poly_trait_ref = PolyTraitRef::new(generic_params, path, None, lo.to(self.prev_span)); + let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_span)); let mut bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)]; if parse_plus { self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded @@ -557,9 +563,18 @@ impl<'a> Parser<'a> { self.expect(&token::CloseDelim(token::Paren))?; } - let constness = modifiers.maybe_const.map(|_| ast::Constness::NotConst); - let poly_trait = PolyTraitRef::new(lifetime_defs, path, constness, lo.to(self.prev_span)); - Ok(GenericBound::Trait(poly_trait, modifiers.trait_bound_modifier())) + let modifier = match modifiers.to_trait_bound_modifier() { + Ok(m) => m, + Err(msg) => { + self.struct_span_err(lo.to(self.prev_span), msg).emit(); + + // Continue compilation as if the user had written `?Trait`. + TraitBoundModifier::Maybe + } + }; + + let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span)); + Ok(GenericBound::Trait(poly_trait, modifier)) } /// Optionally parses `for<$generic_params>`. diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs index 6434dccdfc7..79923fc3d36 100644 --- a/src/librustdoc/html/format.rs +++ b/src/librustdoc/html/format.rs @@ -361,6 +361,7 @@ impl clean::GenericBound { let modifier_str = match modifier { hir::TraitBoundModifier::None => "", hir::TraitBoundModifier::Maybe => "?", + hir::TraitBoundModifier::MaybeConst => "?const", }; if f.alternate() { write!(f, "{}{:#}", modifier_str, ty.print()) diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs index 6b54893075e..ce4d9cca81e 100644 --- a/src/libsyntax/ast.rs +++ b/src/libsyntax/ast.rs @@ -266,12 +266,19 @@ pub const CRATE_NODE_ID: NodeId = NodeId::from_u32_const(0); /// small, positive ids. pub const DUMMY_NODE_ID: NodeId = NodeId::MAX; -/// A modifier on a bound, currently this is only used for `?Sized`, where the -/// modifier is `Maybe`. Negative bounds should also be handled here. +/// A modifier on a bound, e.g., `?Sized` or `?const Trait`. +/// +/// Negative bounds should also be handled here. #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Debug)] pub enum TraitBoundModifier { + /// No modifiers None, + + /// `?Trait` Maybe, + + /// `?const Trait` + MaybeConst, } /// The AST represents all type param bounds as types. |