| // Copyright 2016 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| // 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::lint; |
| use rustc::session::Session; |
| use syntax::ast::*; |
| use syntax::attr; |
| use syntax::codemap::Spanned; |
| use syntax::parse::token; |
| use syntax::symbol::keywords; |
| use syntax::visit::{self, Visitor}; |
| use syntax_pos::Span; |
| use errors; |
| |
| struct AstValidator<'a> { |
| session: &'a Session, |
| } |
| |
| impl<'a> AstValidator<'a> { |
| fn err_handler(&self) -> &errors::Handler { |
| &self.session.parse_sess.span_diagnostic |
| } |
| |
| fn check_lifetime(&self, lifetime: &Lifetime) { |
| let valid_names = [keywords::StaticLifetime.name(), keywords::Invalid.name()]; |
| if !valid_names.contains(&lifetime.ident.name) && |
| token::Ident(lifetime.ident.without_first_quote()).is_reserved_ident() { |
| self.err_handler().span_err(lifetime.span, "lifetimes cannot use keyword names"); |
| } |
| } |
| |
| fn check_label(&self, label: Ident, span: Span) { |
| if token::Ident(label.without_first_quote()).is_reserved_ident() || label.name == "'_" { |
| self.err_handler().span_err(span, &format!("invalid label name `{}`", label.name)); |
| } |
| } |
| |
| fn invalid_non_exhaustive_attribute(&self, variant: &Variant) { |
| let has_non_exhaustive = attr::contains_name(&variant.node.attrs, "non_exhaustive"); |
| if has_non_exhaustive { |
| self.err_handler().span_err(variant.span, |
| "#[non_exhaustive] is not yet supported on variants"); |
| } |
| } |
| |
| fn invalid_visibility(&self, vis: &Visibility, span: Span, note: Option<&str>) { |
| if vis != &Visibility::Inherited { |
| let mut err = struct_span_err!(self.session, |
| span, |
| E0449, |
| "unnecessary visibility qualifier"); |
| if vis == &Visibility::Public { |
| err.span_label(span, "`pub` not needed here"); |
| } |
| if let Some(note) = note { |
| err.note(note); |
| } |
| err.emit(); |
| } |
| } |
| |
| fn check_decl_no_pat<ReportFn: Fn(Span, bool)>(&self, decl: &FnDecl, report_err: ReportFn) { |
| for arg in &decl.inputs { |
| match arg.pat.node { |
| PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), _, None) | |
| PatKind::Wild => {} |
| PatKind::Ident(BindingMode::ByValue(Mutability::Mutable), _, None) => |
| report_err(arg.pat.span, true), |
| _ => report_err(arg.pat.span, false), |
| } |
| } |
| } |
| |
| fn check_trait_fn_not_const(&self, constness: Spanned<Constness>) { |
| match 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(); |
| } |
| _ => {} |
| } |
| } |
| |
| fn no_questions_in_bounds(&self, bounds: &TyParamBounds, where_: &str, is_trait: bool) { |
| for bound in bounds { |
| if let TraitTyParamBound(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 { |
| err.note(&format!("traits are `?{}` by default", poly.trait_ref.path)); |
| } |
| err.emit(); |
| } |
| } |
| } |
| |
| /// matches '-' lit | lit (cf. parser::Parser::parse_pat_literal_maybe_minus), |
| /// or path 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.node { |
| ExprKind::Lit(..) => {} |
| ExprKind::Path(..) if allow_paths => {} |
| ExprKind::Unary(UnOp::Neg, ref inner) |
| if match inner.node { ExprKind::Lit(_) => true, _ => false } => {} |
| _ => self.err_handler().span_err(expr.span, "arbitrary expressions aren't allowed \ |
| in patterns") |
| } |
| } |
| } |
| |
| impl<'a> Visitor<'a> for AstValidator<'a> { |
| fn visit_expr(&mut self, expr: &'a Expr) { |
| match expr.node { |
| ExprKind::While(.., Some(ident)) | |
| ExprKind::Loop(_, Some(ident)) | |
| ExprKind::WhileLet(.., Some(ident)) | |
| ExprKind::ForLoop(.., Some(ident)) | |
| ExprKind::Break(Some(ident), _) | |
| ExprKind::Continue(Some(ident)) => { |
| self.check_label(ident.node, ident.span); |
| } |
| ExprKind::InlineAsm(..) if !self.session.target.target.options.allow_asm => { |
| span_err!(self.session, expr.span, E0472, "asm! is unsupported on this target"); |
| } |
| _ => {} |
| } |
| |
| visit::walk_expr(self, expr) |
| } |
| |
| fn visit_ty(&mut self, ty: &'a Ty) { |
| match ty.node { |
| TyKind::BareFn(ref bfty) => { |
| self.check_decl_no_pat(&bfty.decl, |span, _| { |
| struct_span_err!(self.session, span, E0561, |
| "patterns aren't allowed in function pointer types").emit(); |
| }); |
| } |
| TyKind::TraitObject(ref bounds, ..) => { |
| let mut any_lifetime_bounds = false; |
| for bound in bounds { |
| if let RegionTyParamBound(ref lifetime) = *bound { |
| if any_lifetime_bounds { |
| span_err!(self.session, lifetime.span, E0226, |
| "only a single explicit lifetime bound is permitted"); |
| break; |
| } |
| any_lifetime_bounds = true; |
| } |
| } |
| self.no_questions_in_bounds(bounds, "trait object types", false); |
| } |
| TyKind::ImplTrait(ref bounds) => { |
| if !bounds.iter() |
| .any(|b| if let TraitTyParamBound(..) = *b { true } else { false }) { |
| self.err_handler().span_err(ty.span, "at least one trait must be specified"); |
| } |
| } |
| _ => {} |
| } |
| |
| visit::walk_ty(self, ty) |
| } |
| |
| fn visit_use_tree(&mut self, use_tree: &'a UseTree, id: NodeId, _nested: bool) { |
| // Check if the path in this `use` is not generic, such as `use foo::bar<T>;` While this |
| // can't happen normally thanks to the parser, a generic might sneak in if the `use` is |
| // built using a macro. |
| // |
| // macro_use foo { |
| // ($p:path) => { use $p; } |
| // } |
| // foo!(bar::baz<T>); |
| use_tree.prefix.segments.iter().find(|segment| { |
| segment.parameters.is_some() |
| }).map(|segment| { |
| self.err_handler().span_err(segment.parameters.as_ref().unwrap().span(), |
| "generic arguments in import path"); |
| }); |
| |
| visit::walk_use_tree(self, use_tree, id); |
| } |
| |
| fn visit_lifetime(&mut self, lifetime: &'a Lifetime) { |
| self.check_lifetime(lifetime); |
| visit::walk_lifetime(self, lifetime); |
| } |
| |
| fn visit_item(&mut self, item: &'a Item) { |
| match item.node { |
| ItemKind::Impl(unsafety, polarity, _, _, Some(..), ref ty, ref impl_items) => { |
| self.invalid_visibility(&item.vis, item.span, None); |
| if ty.node == TyKind::Err { |
| 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 { |
| span_err!(self.session, item.span, E0198, "negative impls cannot be unsafe"); |
| } |
| for impl_item in impl_items { |
| self.invalid_visibility(&impl_item.vis, impl_item.span, None); |
| if let ImplItemKind::Method(ref sig, _) = impl_item.node { |
| self.check_trait_fn_not_const(sig.constness); |
| } |
| } |
| } |
| ItemKind::Impl(unsafety, polarity, defaultness, _, None, _, _) => { |
| self.invalid_visibility(&item.vis, |
| item.span, |
| Some("place qualifiers on individual impl items instead")); |
| if unsafety == Unsafety::Unsafe { |
| span_err!(self.session, item.span, E0197, "inherent impls cannot be unsafe"); |
| } |
| if polarity == ImplPolarity::Negative { |
| self.err_handler().span_err(item.span, "inherent impls cannot be negative"); |
| } |
| if defaultness == Defaultness::Default { |
| self.err_handler().span_err(item.span, "inherent impls cannot be default"); |
| } |
| } |
| ItemKind::ForeignMod(..) => { |
| self.invalid_visibility(&item.vis, |
| item.span, |
| Some("place qualifiers on individual foreign items \ |
| instead")); |
| } |
| ItemKind::Enum(ref def, _) => { |
| for variant in &def.variants { |
| self.invalid_non_exhaustive_attribute(variant); |
| for field in variant.node.data.fields() { |
| self.invalid_visibility(&field.vis, field.span, 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.is_parameterized() { |
| 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); |
| for trait_item in trait_items { |
| if let TraitItemKind::Method(ref sig, ref block) = trait_item.node { |
| self.check_trait_fn_not_const(sig.constness); |
| if block.is_none() { |
| self.check_decl_no_pat(&sig.decl, |span, mut_ident| { |
| if mut_ident { |
| self.session.buffer_lint( |
| lint::builtin::PATTERNS_IN_FNS_WITHOUT_BODY, |
| trait_item.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(); |
| } |
| }); |
| } |
| } |
| } |
| } |
| ItemKind::TraitAlias(Generics { ref params, .. }, ..) => { |
| for param in params { |
| if let GenericParam::Type(TyParam { |
| ref bounds, |
| ref default, |
| span, |
| .. |
| }) = *param |
| { |
| if !bounds.is_empty() { |
| self.err_handler().span_err(span, |
| "type parameters on the left side of a \ |
| trait alias cannot be bounded"); |
| } |
| if !default.is_none() { |
| self.err_handler().span_err(span, |
| "type parameters on the left side of a \ |
| trait alias cannot have defaults"); |
| } |
| } |
| } |
| } |
| ItemKind::Mod(_) => { |
| // Ensure that `path` attributes on modules are recorded as used (c.f. #35584). |
| attr::first_attr_value_str_by_name(&item.attrs, "path"); |
| if attr::contains_name(&item.attrs, "warn_directory_ownership") { |
| let lint = lint::builtin::LEGACY_DIRECTORY_OWNERSHIP; |
| let msg = "cannot declare a new module at this location"; |
| self.session.buffer_lint(lint, item.id, item.span, msg); |
| } |
| } |
| ItemKind::Union(ref vdata, _) => { |
| if !vdata.is_struct() { |
| self.err_handler().span_err(item.span, |
| "tuple and unit unions are not permitted"); |
| } |
| if vdata.fields().len() == 0 { |
| 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.node { |
| ForeignItemKind::Fn(ref 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 => {} |
| } |
| |
| visit::walk_foreign_item(self, fi) |
| } |
| |
| fn visit_vis(&mut self, vis: &'a Visibility) { |
| match *vis { |
| Visibility::Restricted { ref path, .. } => { |
| path.segments.iter().find(|segment| segment.parameters.is_some()).map(|segment| { |
| self.err_handler().span_err(segment.parameters.as_ref().unwrap().span(), |
| "generic arguments in visibility path"); |
| }); |
| } |
| _ => {} |
| } |
| |
| visit::walk_vis(self, vis) |
| } |
| |
| fn visit_generics(&mut self, g: &'a Generics) { |
| let mut seen_non_lifetime_param = false; |
| let mut seen_default = None; |
| for param in &g.params { |
| match (param, seen_non_lifetime_param) { |
| (&GenericParam::Lifetime(ref ld), true) => { |
| self.err_handler() |
| .span_err(ld.lifetime.span, "lifetime parameters must be leading"); |
| }, |
| (&GenericParam::Lifetime(_), false) => {} |
| _ => { |
| seen_non_lifetime_param = true; |
| } |
| } |
| |
| if let GenericParam::Type(ref ty_param @ TyParam { default: Some(_), .. }) = *param { |
| seen_default = Some(ty_param.span); |
| } else if let Some(span) = seen_default { |
| self.err_handler() |
| .span_err(span, "type parameters with a default must be trailing"); |
| break |
| } |
| } |
| for predicate in &g.where_clause.predicates { |
| if let WherePredicate::EqPredicate(ref predicate) = *predicate { |
| self.err_handler().span_err(predicate.span, "equality constraints are not yet \ |
| supported in where clauses (#20041)"); |
| } |
| } |
| visit::walk_generics(self, g) |
| } |
| |
| fn visit_pat(&mut self, pat: &'a Pat) { |
| match pat.node { |
| PatKind::Lit(ref expr) => { |
| self.check_expr_within_pat(expr, false); |
| } |
| PatKind::Range(ref start, ref end, _) => { |
| self.check_expr_within_pat(start, true); |
| self.check_expr_within_pat(end, true); |
| } |
| _ => {} |
| } |
| |
| visit::walk_pat(self, pat) |
| } |
| } |
| |
| pub fn check_crate(session: &Session, krate: &Crate) { |
| visit::walk_crate(&mut AstValidator { session: session }, krate) |
| } |
