| // Validate AST before lowering it to HIR. |
| // |
| // This pass is supposed to catch things that fit into AST data structures, |
| // but not permitted by the language. It runs after expansion when AST is frozen, |
| // so it can check for erroneous constructions produced by syntax extensions. |
| // This pass is supposed to perform only simple checks not requiring name resolution |
| // or type checking or some other kind of complex analysis. |
| |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_errors::{struct_span_err, Applicability, FatalError}; |
| use rustc_parse::validate_attr; |
| use rustc_session::lint::builtin::PATTERNS_IN_FNS_WITHOUT_BODY; |
| use rustc_session::lint::LintBuffer; |
| use rustc_session::Session; |
| use rustc_span::source_map::Spanned; |
| use rustc_span::symbol::{kw, sym}; |
| use rustc_span::Span; |
| use std::mem; |
| use syntax::ast::*; |
| use syntax::attr; |
| use syntax::expand::is_proc_macro_attr; |
| use syntax::print::pprust; |
| use syntax::visit::{self, Visitor}; |
| use syntax::walk_list; |
| |
| use rustc_error_codes::*; |
| |
| /// A syntactic context that disallows certain kinds of bounds (e.g., `?Trait` or `?const Trait`). |
| #[derive(Clone, Copy)] |
| enum BoundContext { |
| ImplTrait, |
| TraitBounds, |
| TraitObject, |
| } |
| |
| impl BoundContext { |
| fn description(&self) -> &'static str { |
| match self { |
| Self::ImplTrait => "`impl Trait`", |
| Self::TraitBounds => "supertraits", |
| Self::TraitObject => "trait objects", |
| } |
| } |
| } |
| |
| struct AstValidator<'a> { |
| session: &'a Session, |
| has_proc_macro_decls: bool, |
| |
| /// Used to ban nested `impl Trait`, e.g., `impl Into<impl Debug>`. |
| /// Nested `impl Trait` _is_ allowed in associated type position, |
| /// e.g., `impl Iterator<Item = impl Debug>`. |
| outer_impl_trait: Option<Span>, |
| |
| /// Keeps track of the `BoundContext` as we recurse. |
| /// |
| /// This is used to forbid `?const Trait` bounds in, e.g., |
| /// `impl Iterator<Item = Box<dyn ?const Trait>`. |
| bound_context: Option<BoundContext>, |
| |
| /// Used to ban `impl Trait` in path projections like `<impl Iterator>::Item` |
| /// or `Foo::Bar<impl Trait>` |
| is_impl_trait_banned: bool, |
| |
| /// Used to ban associated type bounds (i.e., `Type<AssocType: Bounds>`) in |
| /// certain positions. |
| is_assoc_ty_bound_banned: bool, |
| |
| lint_buffer: &'a mut LintBuffer, |
| } |
| |
| impl<'a> AstValidator<'a> { |
| fn with_banned_impl_trait(&mut self, f: impl FnOnce(&mut Self)) { |
| let old = mem::replace(&mut self.is_impl_trait_banned, true); |
| f(self); |
| self.is_impl_trait_banned = old; |
| } |
| |
| fn with_banned_assoc_ty_bound(&mut self, f: impl FnOnce(&mut Self)) { |
| let old = mem::replace(&mut self.is_assoc_ty_bound_banned, true); |
| f(self); |
| self.is_assoc_ty_bound_banned = old; |
| } |
| |
| fn with_impl_trait(&mut self, outer: Option<Span>, f: impl FnOnce(&mut Self)) { |
| let old = mem::replace(&mut self.outer_impl_trait, outer); |
| if outer.is_some() { |
| self.with_bound_context(BoundContext::ImplTrait, |this| f(this)); |
| } else { |
| f(self) |
| } |
| self.outer_impl_trait = old; |
| } |
| |
| fn with_bound_context(&mut self, ctx: BoundContext, f: impl FnOnce(&mut Self)) { |
| let old = self.bound_context.replace(ctx); |
| f(self); |
| self.bound_context = old; |
| } |
| |
| fn visit_assoc_ty_constraint_from_generic_args(&mut self, constraint: &'a AssocTyConstraint) { |
| match constraint.kind { |
| AssocTyConstraintKind::Equality { .. } => {} |
| AssocTyConstraintKind::Bound { .. } => { |
| if self.is_assoc_ty_bound_banned { |
| self.err_handler().span_err( |
| constraint.span, |
| "associated type bounds are not allowed within structs, enums, or unions", |
| ); |
| } |
| } |
| } |
| self.visit_assoc_ty_constraint(constraint); |
| } |
| |
| // Mirrors `visit::walk_ty`, but tracks relevant state. |
| fn walk_ty(&mut self, t: &'a Ty) { |
| match t.kind { |
| TyKind::ImplTrait(..) => { |
| self.with_impl_trait(Some(t.span), |this| visit::walk_ty(this, t)) |
| } |
| TyKind::TraitObject(..) => { |
| self.with_bound_context(BoundContext::TraitObject, |this| visit::walk_ty(this, t)); |
| } |
| TyKind::Path(ref qself, ref path) => { |
| // We allow these: |
| // - `Option<impl Trait>` |
| // - `option::Option<impl Trait>` |
| // - `option::Option<T>::Foo<impl Trait> |
| // |
| // But not these: |
| // - `<impl Trait>::Foo` |
| // - `option::Option<impl Trait>::Foo`. |
| // |
| // To implement this, we disallow `impl Trait` from `qself` |
| // (for cases like `<impl Trait>::Foo>`) |
| // but we allow `impl Trait` in `GenericArgs` |
| // iff there are no more PathSegments. |
| if let Some(ref qself) = *qself { |
| // `impl Trait` in `qself` is always illegal |
| self.with_banned_impl_trait(|this| this.visit_ty(&qself.ty)); |
| } |
| |
| // Note that there should be a call to visit_path here, |
| // so if any logic is added to process `Path`s a call to it should be |
| // added both in visit_path and here. This code mirrors visit::walk_path. |
| for (i, segment) in path.segments.iter().enumerate() { |
| // Allow `impl Trait` iff we're on the final path segment |
| if i == path.segments.len() - 1 { |
| self.visit_path_segment(path.span, segment); |
| } else { |
| self.with_banned_impl_trait(|this| { |
| this.visit_path_segment(path.span, segment) |
| }); |
| } |
| } |
| } |
| _ => visit::walk_ty(self, t), |
| } |
| } |
| |
| fn err_handler(&self) -> &rustc_errors::Handler { |
| &self.session.diagnostic() |
| } |
| |
| fn check_lifetime(&self, ident: Ident) { |
| let valid_names = [kw::UnderscoreLifetime, kw::StaticLifetime, kw::Invalid]; |
| if !valid_names.contains(&ident.name) && ident.without_first_quote().is_reserved() { |
| self.err_handler().span_err(ident.span, "lifetimes cannot use keyword names"); |
| } |
| } |
| |
| fn check_label(&self, ident: Ident) { |
| if ident.without_first_quote().is_reserved() { |
| self.err_handler() |
| .span_err(ident.span, &format!("invalid label name `{}`", ident.name)); |
| } |
| } |
| |
| fn invalid_visibility(&self, vis: &Visibility, note: Option<&str>) { |
| if let VisibilityKind::Inherited = vis.node { |
| return; |
| } |
| |
| let mut err = |
| struct_span_err!(self.session, vis.span, E0449, "unnecessary visibility qualifier"); |
| if vis.node.is_pub() { |
| err.span_label(vis.span, "`pub` not permitted here because it's implied"); |
| } |
| if let Some(note) = note { |
| err.note(note); |
| } |
| err.emit(); |
| } |
| |
| fn check_decl_no_pat(decl: &FnDecl, mut report_err: impl FnMut(Span, bool)) { |
| for Param { pat, .. } in &decl.inputs { |
| match pat.kind { |
| PatKind::Ident(BindingMode::ByValue(Mutability::Not), _, None) | PatKind::Wild => {} |
| PatKind::Ident(BindingMode::ByValue(Mutability::Mut), _, None) => { |
| report_err(pat.span, true) |
| } |
| _ => report_err(pat.span, false), |
| } |
| } |
| } |
| |
| fn check_trait_fn_not_async(&self, span: Span, asyncness: IsAsync) { |
| if asyncness.is_async() { |
| struct_span_err!(self.session, span, E0706, "trait fns cannot be declared `async`") |
| .note("`async` trait functions are not currently supported") |
| .note( |
| "consider using the `async-trait` crate: \ |
| https://crates.io/crates/async-trait", |
| ) |
| .emit(); |
| } |
| } |
| |
| fn check_trait_fn_not_const(&self, constness: Spanned<Constness>) { |
| if constness.node == Constness::Const { |
| struct_span_err!( |
| self.session, |
| constness.span, |
| E0379, |
| "trait fns cannot be declared const" |
| ) |
| .span_label(constness.span, "trait fns cannot be const") |
| .emit(); |
| } |
| } |
| |
| // FIXME(ecstaticmorse): Instead, use `bound_context` to check this in `visit_param_bound`. |
| fn no_questions_in_bounds(&self, bounds: &GenericBounds, where_: &str, is_trait: bool) { |
| for bound in bounds { |
| if let GenericBound::Trait(ref poly, TraitBoundModifier::Maybe) = *bound { |
| let mut err = self.err_handler().struct_span_err( |
| poly.span, |
| &format!("`?Trait` is not permitted in {}", where_), |
| ); |
| if is_trait { |
| let path_str = pprust::path_to_string(&poly.trait_ref.path); |
| err.note(&format!("traits are `?{}` by default", path_str)); |
| } |
| err.emit(); |
| } |
| } |
| } |
| |
| /// Matches `'-' lit | lit (cf. parser::Parser::parse_literal_maybe_minus)`, |
| /// or paths for ranges. |
| // |
| // FIXME: do we want to allow `expr -> pattern` conversion to create path expressions? |
| // That means making this work: |
| // |
| // ```rust,ignore (FIXME) |
| // struct S; |
| // macro_rules! m { |
| // ($a:expr) => { |
| // let $a = S; |
| // } |
| // } |
| // m!(S); |
| // ``` |
| fn check_expr_within_pat(&self, expr: &Expr, allow_paths: bool) { |
| match expr.kind { |
| ExprKind::Lit(..) | ExprKind::Err => {} |
| ExprKind::Path(..) if allow_paths => {} |
| ExprKind::Unary(UnOp::Neg, ref inner) |
| if match inner.kind { |
| ExprKind::Lit(_) => true, |
| _ => false, |
| } => {} |
| _ => self.err_handler().span_err( |
| expr.span, |
| "arbitrary expressions aren't allowed \ |
| in patterns", |
| ), |
| } |
| } |
| |
| fn check_late_bound_lifetime_defs(&self, params: &[GenericParam]) { |
| // Check only lifetime parameters are present and that the lifetime |
| // parameters that are present have no bounds. |
| let non_lt_param_spans: Vec<_> = params |
| .iter() |
| .filter_map(|param| match param.kind { |
| GenericParamKind::Lifetime { .. } => { |
| if !param.bounds.is_empty() { |
| let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect(); |
| self.err_handler() |
| .span_err(spans, "lifetime bounds cannot be used in this context"); |
| } |
| None |
| } |
| _ => Some(param.ident.span), |
| }) |
| .collect(); |
| if !non_lt_param_spans.is_empty() { |
| self.err_handler().span_err( |
| non_lt_param_spans, |
| "only lifetime parameters can be used in this context", |
| ); |
| } |
| } |
| |
| fn check_fn_decl(&self, fn_decl: &FnDecl) { |
| match &*fn_decl.inputs { |
| [Param { ty, span, .. }] => { |
| if let TyKind::CVarArgs = ty.kind { |
| self.err_handler().span_err( |
| *span, |
| "C-variadic function must be declared with at least one named argument", |
| ); |
| } |
| } |
| [ps @ .., _] => { |
| for Param { ty, span, .. } in ps { |
| if let TyKind::CVarArgs = ty.kind { |
| self.err_handler().span_err( |
| *span, |
| "`...` must be the last argument of a C-variadic function", |
| ); |
| } |
| } |
| } |
| _ => {} |
| } |
| |
| fn_decl |
| .inputs |
| .iter() |
| .flat_map(|i| i.attrs.as_ref()) |
| .filter(|attr| { |
| let arr = [sym::allow, sym::cfg, sym::cfg_attr, sym::deny, sym::forbid, sym::warn]; |
| !arr.contains(&attr.name_or_empty()) && attr::is_builtin_attr(attr) |
| }) |
| .for_each(|attr| { |
| if attr.is_doc_comment() { |
| self.err_handler() |
| .struct_span_err( |
| attr.span, |
| "documentation comments cannot be applied to function parameters", |
| ) |
| .span_label(attr.span, "doc comments are not allowed here") |
| .emit(); |
| } else { |
| self.err_handler().span_err( |
| attr.span, |
| "allow, cfg, cfg_attr, deny, \ |
| forbid, and warn are the only allowed built-in attributes in function parameters", |
| ) |
| } |
| }); |
| } |
| |
| fn check_defaultness(&self, span: Span, defaultness: Defaultness) { |
| if let Defaultness::Default = defaultness { |
| self.err_handler() |
| .struct_span_err(span, "`default` is only allowed on items in `impl` definitions") |
| .emit(); |
| } |
| } |
| |
| fn check_impl_item_provided<T>(&self, sp: Span, body: &Option<T>, ctx: &str, sugg: &str) { |
| if body.is_some() { |
| return; |
| } |
| |
| self.err_handler() |
| .struct_span_err(sp, &format!("associated {} in `impl` without body", ctx)) |
| .span_suggestion( |
| self.session.source_map().end_point(sp), |
| &format!("provide a definition for the {}", ctx), |
| sugg.to_string(), |
| Applicability::HasPlaceholders, |
| ) |
| .emit(); |
| } |
| |
| fn check_impl_assoc_type_no_bounds(&self, bounds: &[GenericBound]) { |
| let span = match bounds { |
| [] => return, |
| [b0] => b0.span(), |
| [b0, .., bl] => b0.span().to(bl.span()), |
| }; |
| self.err_handler() |
| .struct_span_err(span, "bounds on associated `type`s in `impl`s have no effect") |
| .emit(); |
| } |
| |
| fn check_c_varadic_type(&self, decl: &FnDecl) { |
| for Param { ty, span, .. } in &decl.inputs { |
| if let TyKind::CVarArgs = ty.kind { |
| self.err_handler() |
| .struct_span_err( |
| *span, |
| "only foreign or `unsafe extern \"C\" functions may be C-variadic", |
| ) |
| .emit(); |
| } |
| } |
| } |
| } |
| |
| enum GenericPosition { |
| Param, |
| Arg, |
| } |
| |
| fn validate_generics_order<'a>( |
| sess: &Session, |
| handler: &rustc_errors::Handler, |
| generics: impl Iterator<Item = (ParamKindOrd, Option<&'a [GenericBound]>, Span, Option<String>)>, |
| pos: GenericPosition, |
| span: Span, |
| ) { |
| let mut max_param: Option<ParamKindOrd> = None; |
| let mut out_of_order = FxHashMap::default(); |
| let mut param_idents = vec![]; |
| let mut found_type = false; |
| let mut found_const = false; |
| |
| for (kind, bounds, span, ident) in generics { |
| if let Some(ident) = ident { |
| param_idents.push((kind, bounds, param_idents.len(), ident)); |
| } |
| let max_param = &mut max_param; |
| match max_param { |
| Some(max_param) if *max_param > kind => { |
| let entry = out_of_order.entry(kind).or_insert((*max_param, vec![])); |
| entry.1.push(span); |
| } |
| Some(_) | None => *max_param = Some(kind), |
| }; |
| match kind { |
| ParamKindOrd::Type => found_type = true, |
| ParamKindOrd::Const => found_const = true, |
| _ => {} |
| } |
| } |
| |
| let mut ordered_params = "<".to_string(); |
| if !out_of_order.is_empty() { |
| param_idents.sort_by_key(|&(po, _, i, _)| (po, i)); |
| let mut first = true; |
| for (_, bounds, _, ident) in param_idents { |
| if !first { |
| ordered_params += ", "; |
| } |
| ordered_params += &ident; |
| if let Some(bounds) = bounds { |
| if !bounds.is_empty() { |
| ordered_params += ": "; |
| ordered_params += &pprust::bounds_to_string(&bounds); |
| } |
| } |
| first = false; |
| } |
| } |
| ordered_params += ">"; |
| |
| let pos_str = match pos { |
| GenericPosition::Param => "parameter", |
| GenericPosition::Arg => "argument", |
| }; |
| |
| for (param_ord, (max_param, spans)) in &out_of_order { |
| let mut err = handler.struct_span_err( |
| spans.clone(), |
| &format!( |
| "{} {pos}s must be declared prior to {} {pos}s", |
| param_ord, |
| max_param, |
| pos = pos_str, |
| ), |
| ); |
| if let GenericPosition::Param = pos { |
| err.span_suggestion( |
| span, |
| &format!( |
| "reorder the {}s: lifetimes, then types{}", |
| pos_str, |
| if sess.features_untracked().const_generics { ", then consts" } else { "" }, |
| ), |
| ordered_params.clone(), |
| Applicability::MachineApplicable, |
| ); |
| } |
| err.emit(); |
| } |
| |
| // FIXME(const_generics): we shouldn't have to abort here at all, but we currently get ICEs |
| // if we don't. Const parameters and type parameters can currently conflict if they |
| // are out-of-order. |
| if !out_of_order.is_empty() && found_type && found_const { |
| FatalError.raise(); |
| } |
| } |
| |
| impl<'a> Visitor<'a> for AstValidator<'a> { |
| fn visit_attribute(&mut self, attr: &Attribute) { |
| validate_attr::check_meta(&self.session.parse_sess, attr); |
| } |
| |
| fn visit_expr(&mut self, expr: &'a Expr) { |
| match &expr.kind { |
| ExprKind::Closure(_, _, _, fn_decl, _, _) => { |
| self.check_fn_decl(fn_decl); |
| } |
| ExprKind::InlineAsm(..) if !self.session.target.target.options.allow_asm => { |
| struct_span_err!( |
| self.session, |
| expr.span, |
| E0472, |
| "asm! is unsupported on this target" |
| ) |
| .emit(); |
| } |
| _ => {} |
| } |
| |
| visit::walk_expr(self, expr); |
| } |
| |
| fn visit_ty(&mut self, ty: &'a Ty) { |
| match ty.kind { |
| TyKind::BareFn(ref bfty) => { |
| self.check_fn_decl(&bfty.decl); |
| Self::check_decl_no_pat(&bfty.decl, |span, _| { |
| struct_span_err!( |
| self.session, |
| span, |
| E0561, |
| "patterns aren't allowed in function pointer types" |
| ) |
| .emit(); |
| }); |
| self.check_late_bound_lifetime_defs(&bfty.generic_params); |
| } |
| TyKind::TraitObject(ref bounds, ..) => { |
| let mut any_lifetime_bounds = false; |
| for bound in bounds { |
| if let GenericBound::Outlives(ref lifetime) = *bound { |
| if any_lifetime_bounds { |
| struct_span_err!( |
| self.session, |
| lifetime.ident.span, |
| E0226, |
| "only a single explicit lifetime bound is permitted" |
| ) |
| .emit(); |
| break; |
| } |
| any_lifetime_bounds = true; |
| } |
| } |
| self.no_questions_in_bounds(bounds, "trait object types", false); |
| } |
| TyKind::ImplTrait(_, ref bounds) => { |
| if self.is_impl_trait_banned { |
| struct_span_err!( |
| self.session, |
| ty.span, |
| E0667, |
| "`impl Trait` is not allowed in path parameters" |
| ) |
| .emit(); |
| } |
| |
| if let Some(outer_impl_trait_sp) = self.outer_impl_trait { |
| struct_span_err!( |
| self.session, |
| ty.span, |
| E0666, |
| "nested `impl Trait` is not allowed" |
| ) |
| .span_label(outer_impl_trait_sp, "outer `impl Trait`") |
| .span_label(ty.span, "nested `impl Trait` here") |
| .emit(); |
| } |
| |
| if !bounds |
| .iter() |
| .any(|b| if let GenericBound::Trait(..) = *b { true } else { false }) |
| { |
| self.err_handler().span_err(ty.span, "at least one trait must be specified"); |
| } |
| |
| self.walk_ty(ty); |
| return; |
| } |
| _ => {} |
| } |
| |
| self.walk_ty(ty) |
| } |
| |
| fn visit_label(&mut self, label: &'a Label) { |
| self.check_label(label.ident); |
| visit::walk_label(self, label); |
| } |
| |
| fn visit_lifetime(&mut self, lifetime: &'a Lifetime) { |
| self.check_lifetime(lifetime.ident); |
| visit::walk_lifetime(self, lifetime); |
| } |
| |
| fn visit_item(&mut self, item: &'a Item) { |
| if item.attrs.iter().any(|attr| is_proc_macro_attr(attr)) { |
| self.has_proc_macro_decls = true; |
| } |
| |
| match item.kind { |
| ItemKind::Impl { |
| unsafety, |
| polarity, |
| defaultness: _, |
| constness: _, |
| generics: _, |
| of_trait: Some(_), |
| ref self_ty, |
| ref items, |
| } => { |
| self.invalid_visibility(&item.vis, None); |
| if let TyKind::Err = self_ty.kind { |
| self.err_handler() |
| .struct_span_err(item.span, "`impl Trait for .. {}` is an obsolete syntax") |
| .help("use `auto trait Trait {}` instead") |
| .emit(); |
| } |
| if unsafety == Unsafety::Unsafe && polarity == ImplPolarity::Negative { |
| struct_span_err!( |
| self.session, |
| item.span, |
| E0198, |
| "negative impls cannot be unsafe" |
| ) |
| .emit(); |
| } |
| for impl_item in items { |
| self.invalid_visibility(&impl_item.vis, None); |
| if let AssocItemKind::Fn(ref sig, _) = impl_item.kind { |
| self.check_trait_fn_not_const(sig.header.constness); |
| self.check_trait_fn_not_async(impl_item.span, sig.header.asyncness.node); |
| } |
| } |
| } |
| ItemKind::Impl { |
| unsafety, |
| polarity, |
| defaultness, |
| constness, |
| generics: _, |
| of_trait: None, |
| self_ty: _, |
| items: _, |
| } => { |
| self.invalid_visibility( |
| &item.vis, |
| Some("place qualifiers on individual impl items instead"), |
| ); |
| if unsafety == Unsafety::Unsafe { |
| struct_span_err!( |
| self.session, |
| item.span, |
| E0197, |
| "inherent impls cannot be unsafe" |
| ) |
| .emit(); |
| } |
| if polarity == ImplPolarity::Negative { |
| self.err_handler().span_err(item.span, "inherent impls cannot be negative"); |
| } |
| if defaultness == Defaultness::Default { |
| self.err_handler() |
| .struct_span_err(item.span, "inherent impls cannot be default") |
| .note("only trait implementations may be annotated with default") |
| .emit(); |
| } |
| if constness == Constness::Const { |
| self.err_handler() |
| .struct_span_err(item.span, "inherent impls cannot be `const`") |
| .note("only trait implementations may be annotated with `const`") |
| .emit(); |
| } |
| } |
| ItemKind::Fn(ref sig, ref generics, _) => { |
| self.visit_fn_header(&sig.header); |
| self.check_fn_decl(&sig.decl); |
| // We currently do not permit const generics in `const fn`, as |
| // this is tantamount to allowing compile-time dependent typing. |
| if sig.header.constness.node == Constness::Const { |
| // Look for const generics and error if we find any. |
| for param in &generics.params { |
| match param.kind { |
| GenericParamKind::Const { .. } => { |
| self.err_handler() |
| .struct_span_err( |
| item.span, |
| "const parameters are not permitted in `const fn`", |
| ) |
| .emit(); |
| } |
| _ => {} |
| } |
| } |
| } |
| // Reject C-varadic type unless the function is `unsafe extern "C"` semantically. |
| match sig.header.ext { |
| Extern::Explicit(StrLit { symbol_unescaped: sym::C, .. }) |
| | Extern::Implicit |
| if sig.header.unsafety == Unsafety::Unsafe => {} |
| _ => self.check_c_varadic_type(&sig.decl), |
| } |
| } |
| ItemKind::ForeignMod(..) => { |
| self.invalid_visibility( |
| &item.vis, |
| Some("place qualifiers on individual foreign items instead"), |
| ); |
| } |
| ItemKind::Enum(ref def, _) => { |
| for variant in &def.variants { |
| self.invalid_visibility(&variant.vis, None); |
| for field in variant.data.fields() { |
| self.invalid_visibility(&field.vis, None); |
| } |
| } |
| } |
| ItemKind::Trait(is_auto, _, ref generics, ref bounds, ref trait_items) => { |
| if is_auto == IsAuto::Yes { |
| // Auto traits cannot have generics, super traits nor contain items. |
| if !generics.params.is_empty() { |
| struct_span_err!( |
| self.session, |
| item.span, |
| E0567, |
| "auto traits cannot have generic parameters" |
| ) |
| .emit(); |
| } |
| if !bounds.is_empty() { |
| struct_span_err!( |
| self.session, |
| item.span, |
| E0568, |
| "auto traits cannot have super traits" |
| ) |
| .emit(); |
| } |
| if !trait_items.is_empty() { |
| struct_span_err!( |
| self.session, |
| item.span, |
| E0380, |
| "auto traits cannot have methods or associated items" |
| ) |
| .emit(); |
| } |
| } |
| self.no_questions_in_bounds(bounds, "supertraits", true); |
| |
| // Equivalent of `visit::walk_item` for `ItemKind::Trait` that inserts a bound |
| // context for the supertraits. |
| self.visit_vis(&item.vis); |
| self.visit_ident(item.ident); |
| self.visit_generics(generics); |
| self.with_bound_context(BoundContext::TraitBounds, |this| { |
| walk_list!(this, visit_param_bound, bounds); |
| }); |
| walk_list!(self, visit_trait_item, trait_items); |
| walk_list!(self, visit_attribute, &item.attrs); |
| return; |
| } |
| ItemKind::Mod(_) => { |
| // Ensure that `path` attributes on modules are recorded as used (cf. issue #35584). |
| attr::first_attr_value_str_by_name(&item.attrs, sym::path); |
| } |
| ItemKind::Union(ref vdata, _) => { |
| if let VariantData::Tuple(..) | VariantData::Unit(..) = vdata { |
| self.err_handler() |
| .span_err(item.span, "tuple and unit unions are not permitted"); |
| } |
| if vdata.fields().is_empty() { |
| self.err_handler().span_err(item.span, "unions cannot have zero fields"); |
| } |
| } |
| _ => {} |
| } |
| |
| visit::walk_item(self, item) |
| } |
| |
| fn visit_foreign_item(&mut self, fi: &'a ForeignItem) { |
| match fi.kind { |
| ForeignItemKind::Fn(ref decl, _) => { |
| self.check_fn_decl(decl); |
| Self::check_decl_no_pat(decl, |span, _| { |
| struct_span_err!( |
| self.session, |
| span, |
| E0130, |
| "patterns aren't allowed in foreign function declarations" |
| ) |
| .span_label(span, "pattern not allowed in foreign function") |
| .emit(); |
| }); |
| } |
| ForeignItemKind::Static(..) | ForeignItemKind::Ty | ForeignItemKind::Macro(..) => {} |
| } |
| |
| visit::walk_foreign_item(self, fi) |
| } |
| |
| // Mirrors `visit::walk_generic_args`, but tracks relevant state. |
| fn visit_generic_args(&mut self, _: Span, generic_args: &'a GenericArgs) { |
| match *generic_args { |
| GenericArgs::AngleBracketed(ref data) => { |
| walk_list!(self, visit_generic_arg, &data.args); |
| validate_generics_order( |
| self.session, |
| self.err_handler(), |
| data.args.iter().map(|arg| { |
| ( |
| match arg { |
| GenericArg::Lifetime(..) => ParamKindOrd::Lifetime, |
| GenericArg::Type(..) => ParamKindOrd::Type, |
| GenericArg::Const(..) => ParamKindOrd::Const, |
| }, |
| None, |
| arg.span(), |
| None, |
| ) |
| }), |
| GenericPosition::Arg, |
| generic_args.span(), |
| ); |
| |
| // Type bindings such as `Item = impl Debug` in `Iterator<Item = Debug>` |
| // are allowed to contain nested `impl Trait`. |
| self.with_impl_trait(None, |this| { |
| walk_list!( |
| this, |
| visit_assoc_ty_constraint_from_generic_args, |
| &data.constraints |
| ); |
| }); |
| } |
| GenericArgs::Parenthesized(ref data) => { |
| walk_list!(self, visit_ty, &data.inputs); |
| if let FunctionRetTy::Ty(ty) = &data.output { |
| // `-> Foo` syntax is essentially an associated type binding, |
| // so it is also allowed to contain nested `impl Trait`. |
| self.with_impl_trait(None, |this| this.visit_ty(ty)); |
| } |
| } |
| } |
| } |
| |
| fn visit_generics(&mut self, generics: &'a Generics) { |
| let mut prev_ty_default = None; |
| for param in &generics.params { |
| if let GenericParamKind::Type { ref default, .. } = param.kind { |
| if default.is_some() { |
| prev_ty_default = Some(param.ident.span); |
| } else if let Some(span) = prev_ty_default { |
| self.err_handler() |
| .span_err(span, "type parameters with a default must be trailing"); |
| break; |
| } |
| } |
| } |
| |
| validate_generics_order( |
| self.session, |
| self.err_handler(), |
| generics.params.iter().map(|param| { |
| let ident = Some(param.ident.to_string()); |
| let (kind, ident) = match ¶m.kind { |
| GenericParamKind::Lifetime { .. } => (ParamKindOrd::Lifetime, ident), |
| GenericParamKind::Type { .. } => (ParamKindOrd::Type, ident), |
| GenericParamKind::Const { ref ty } => { |
| let ty = pprust::ty_to_string(ty); |
| (ParamKindOrd::Const, Some(format!("const {}: {}", param.ident, ty))) |
| } |
| }; |
| (kind, Some(&*param.bounds), param.ident.span, ident) |
| }), |
| GenericPosition::Param, |
| generics.span, |
| ); |
| |
| for predicate in &generics.where_clause.predicates { |
| if let WherePredicate::EqPredicate(ref predicate) = *predicate { |
| self.err_handler() |
| .struct_span_err( |
| predicate.span, |
| "equality constraints are not yet supported in `where` clauses", |
| ) |
| .span_label(predicate.span, "not supported") |
| .note( |
| "for more information, see https://github.com/rust-lang/rust/issues/20041", |
| ) |
| .emit(); |
| } |
| } |
| |
| visit::walk_generics(self, generics) |
| } |
| |
| fn visit_generic_param(&mut self, param: &'a GenericParam) { |
| if let GenericParamKind::Lifetime { .. } = param.kind { |
| self.check_lifetime(param.ident); |
| } |
| visit::walk_generic_param(self, param); |
| } |
| |
| fn visit_param_bound(&mut self, bound: &'a GenericBound) { |
| match bound { |
| GenericBound::Trait(_, TraitBoundModifier::MaybeConst) => { |
| 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); |
| } |
| } |
| |
| GenericBound::Trait(_, TraitBoundModifier::MaybeConstMaybe) => { |
| self.err_handler() |
| .span_err(bound.span(), "`?const` and `?` are mutually exclusive"); |
| } |
| |
| _ => {} |
| } |
| |
| visit::walk_param_bound(self, bound) |
| } |
| |
| fn visit_pat(&mut self, pat: &'a Pat) { |
| match pat.kind { |
| PatKind::Lit(ref expr) => { |
| self.check_expr_within_pat(expr, false); |
| } |
| PatKind::Range(ref start, ref end, _) => { |
| if let Some(expr) = start { |
| self.check_expr_within_pat(expr, true); |
| } |
| if let Some(expr) = end { |
| self.check_expr_within_pat(expr, true); |
| } |
| } |
| _ => {} |
| } |
| |
| visit::walk_pat(self, pat) |
| } |
| |
| fn visit_where_predicate(&mut self, p: &'a WherePredicate) { |
| if let &WherePredicate::BoundPredicate(ref bound_predicate) = p { |
| // A type binding, eg `for<'c> Foo: Send+Clone+'c` |
| self.check_late_bound_lifetime_defs(&bound_predicate.bound_generic_params); |
| } |
| visit::walk_where_predicate(self, p); |
| } |
| |
| fn visit_poly_trait_ref(&mut self, t: &'a PolyTraitRef, m: &'a TraitBoundModifier) { |
| self.check_late_bound_lifetime_defs(&t.bound_generic_params); |
| visit::walk_poly_trait_ref(self, t, m); |
| } |
| |
| fn visit_variant_data(&mut self, s: &'a VariantData) { |
| self.with_banned_assoc_ty_bound(|this| visit::walk_struct_def(this, s)) |
| } |
| |
| fn visit_enum_def( |
| &mut self, |
| enum_definition: &'a EnumDef, |
| generics: &'a Generics, |
| item_id: NodeId, |
| _: Span, |
| ) { |
| self.with_banned_assoc_ty_bound(|this| { |
| visit::walk_enum_def(this, enum_definition, generics, item_id) |
| }) |
| } |
| |
| fn visit_impl_item(&mut self, ii: &'a AssocItem) { |
| match &ii.kind { |
| AssocItemKind::Const(_, body) => { |
| self.check_impl_item_provided(ii.span, body, "constant", " = <expr>;"); |
| } |
| AssocItemKind::Fn(sig, body) => { |
| self.check_impl_item_provided(ii.span, body, "function", " { <body> }"); |
| self.check_fn_decl(&sig.decl); |
| } |
| AssocItemKind::TyAlias(bounds, body) => { |
| self.check_impl_item_provided(ii.span, body, "type", " = <type>;"); |
| self.check_impl_assoc_type_no_bounds(bounds); |
| } |
| _ => {} |
| } |
| visit::walk_impl_item(self, ii); |
| } |
| |
| fn visit_trait_item(&mut self, ti: &'a AssocItem) { |
| self.invalid_visibility(&ti.vis, None); |
| self.check_defaultness(ti.span, ti.defaultness); |
| |
| if let AssocItemKind::Fn(sig, block) = &ti.kind { |
| self.check_fn_decl(&sig.decl); |
| self.check_trait_fn_not_async(ti.span, sig.header.asyncness.node); |
| self.check_trait_fn_not_const(sig.header.constness); |
| if block.is_none() { |
| Self::check_decl_no_pat(&sig.decl, |span, mut_ident| { |
| if mut_ident { |
| self.lint_buffer.buffer_lint( |
| PATTERNS_IN_FNS_WITHOUT_BODY, |
| ti.id, |
| span, |
| "patterns aren't allowed in methods without bodies", |
| ); |
| } else { |
| struct_span_err!( |
| self.session, |
| span, |
| E0642, |
| "patterns aren't allowed in methods without bodies" |
| ) |
| .emit(); |
| } |
| }); |
| } |
| } |
| |
| visit::walk_trait_item(self, ti); |
| } |
| |
| fn visit_assoc_item(&mut self, item: &'a AssocItem) { |
| if let AssocItemKind::Fn(sig, _) = &item.kind { |
| self.check_c_varadic_type(&sig.decl); |
| } |
| visit::walk_assoc_item(self, item); |
| } |
| } |
| |
| pub fn check_crate(session: &Session, krate: &Crate, lints: &mut LintBuffer) -> bool { |
| let mut validator = AstValidator { |
| session, |
| has_proc_macro_decls: false, |
| outer_impl_trait: None, |
| bound_context: None, |
| is_impl_trait_banned: false, |
| is_assoc_ty_bound_banned: false, |
| lint_buffer: lints, |
| }; |
| visit::walk_crate(&mut validator, krate); |
| |
| validator.has_proc_macro_decls |
| } |
