327 lines
13 KiB
Rust
327 lines
13 KiB
Rust
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Validate AST before lowering it to HIR
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//
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// This pass is supposed to catch things that fit into AST data structures,
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// but not permitted by the language. It runs after expansion when AST is frozen,
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// so it can check for erroneous constructions produced by syntax extensions.
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// This pass is supposed to perform only simple checks not requiring name resolution
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// or type checking or some other kind of complex analysis.
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use rustc::lint;
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use rustc::session::Session;
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use syntax::ast::*;
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use syntax::attr;
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use syntax::codemap::Spanned;
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use syntax::parse::token;
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use syntax::symbol::keywords;
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use syntax::visit::{self, Visitor};
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use syntax_pos::Span;
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use errors;
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struct AstValidator<'a> {
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session: &'a Session,
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}
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impl<'a> AstValidator<'a> {
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fn err_handler(&self) -> &errors::Handler {
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&self.session.parse_sess.span_diagnostic
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}
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fn check_label(&self, label: Ident, span: Span, id: NodeId) {
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if label.name == keywords::StaticLifetime.name() {
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self.err_handler().span_err(span, &format!("invalid label name `{}`", label.name));
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}
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if label.name == "'_" {
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self.session.add_lint(lint::builtin::LIFETIME_UNDERSCORE,
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id,
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span,
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format!("invalid label name `{}`", label.name));
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}
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}
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fn invalid_visibility(&self, vis: &Visibility, span: Span, note: Option<&str>) {
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if vis != &Visibility::Inherited {
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let mut err = struct_span_err!(self.session,
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span,
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E0449,
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"unnecessary visibility qualifier");
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if vis == &Visibility::Public {
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err.span_label(span, &format!("`pub` not needed here"));
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}
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if let Some(note) = note {
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err.note(note);
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}
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err.emit();
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}
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}
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fn check_decl_no_pat<ReportFn: Fn(Span, bool)>(&self, decl: &FnDecl, report_err: ReportFn) {
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for arg in &decl.inputs {
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match arg.pat.node {
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PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), _, None) |
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PatKind::Wild => {}
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PatKind::Ident(..) => report_err(arg.pat.span, true),
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_ => report_err(arg.pat.span, false),
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}
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}
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}
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fn check_trait_fn_not_const(&self, constness: Spanned<Constness>) {
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match constness.node {
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Constness::Const => {
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struct_span_err!(self.session, constness.span, E0379,
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"trait fns cannot be declared const")
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.span_label(constness.span, &format!("trait fns cannot be const"))
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.emit();
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}
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_ => {}
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}
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}
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fn no_questions_in_bounds(&self, bounds: &TyParamBounds, where_: &str, is_trait: bool) {
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for bound in bounds {
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if let TraitTyParamBound(ref poly, TraitBoundModifier::Maybe) = *bound {
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let mut err = self.err_handler().struct_span_err(poly.span,
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&format!("`?Trait` is not permitted in {}", where_));
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if is_trait {
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err.note(&format!("traits are `?{}` by default", poly.trait_ref.path));
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}
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err.emit();
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}
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}
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}
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}
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impl<'a> Visitor<'a> for AstValidator<'a> {
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fn visit_lifetime(&mut self, lt: &'a Lifetime) {
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if lt.name == "'_" {
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self.session.add_lint(lint::builtin::LIFETIME_UNDERSCORE,
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lt.id,
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lt.span,
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format!("invalid lifetime name `{}`", lt.name));
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}
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visit::walk_lifetime(self, lt)
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}
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fn visit_expr(&mut self, expr: &'a Expr) {
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match expr.node {
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ExprKind::While(.., Some(ident)) |
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ExprKind::Loop(_, Some(ident)) |
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ExprKind::WhileLet(.., Some(ident)) |
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ExprKind::ForLoop(.., Some(ident)) |
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ExprKind::Break(Some(ident), _) |
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ExprKind::Continue(Some(ident)) => {
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self.check_label(ident.node, ident.span, expr.id);
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}
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_ => {}
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}
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visit::walk_expr(self, expr)
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}
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fn visit_ty(&mut self, ty: &'a Ty) {
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match ty.node {
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TyKind::BareFn(ref bfty) => {
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self.check_decl_no_pat(&bfty.decl, |span, _| {
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let mut err = struct_span_err!(self.session,
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span,
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E0561,
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"patterns aren't allowed in function pointer \
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types");
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err.span_note(span,
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"this is a recent error, see issue #35203 for more details");
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err.emit();
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});
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}
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TyKind::TraitObject(ref bounds) => {
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let mut any_lifetime_bounds = false;
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for bound in bounds {
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if let RegionTyParamBound(ref lifetime) = *bound {
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if any_lifetime_bounds {
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span_err!(self.session, lifetime.span, E0226,
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"only a single explicit lifetime bound is permitted");
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break;
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}
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any_lifetime_bounds = true;
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}
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}
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self.no_questions_in_bounds(bounds, "trait object types", false);
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}
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TyKind::ImplTrait(ref bounds) => {
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if !bounds.iter()
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.any(|b| if let TraitTyParamBound(..) = *b { true } else { false }) {
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self.err_handler().span_err(ty.span, "at least one trait must be specified");
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}
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}
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_ => {}
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}
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visit::walk_ty(self, ty)
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}
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fn visit_path(&mut self, path: &'a Path, id: NodeId) {
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if path.segments.len() >= 2 && path.is_global() {
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let ident = path.segments[1].identifier;
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if token::Ident(ident).is_path_segment_keyword() {
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self.session.add_lint(lint::builtin::SUPER_OR_SELF_IN_GLOBAL_PATH,
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id,
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path.span,
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format!("global paths cannot start with `{}`", ident));
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}
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}
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visit::walk_path(self, path)
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}
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fn visit_item(&mut self, item: &'a Item) {
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match item.node {
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ItemKind::Use(ref view_path) => {
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let path = view_path.node.path();
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if path.segments.iter().any(|segment| segment.parameters.is_some()) {
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self.err_handler()
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.span_err(path.span, "type or lifetime parameters in import path");
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}
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}
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ItemKind::Impl(.., Some(..), _, ref impl_items) => {
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self.invalid_visibility(&item.vis, item.span, None);
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for impl_item in impl_items {
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self.invalid_visibility(&impl_item.vis, impl_item.span, None);
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if let ImplItemKind::Method(ref sig, _) = impl_item.node {
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self.check_trait_fn_not_const(sig.constness);
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}
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}
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}
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ItemKind::Impl(.., None, _, _) => {
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self.invalid_visibility(&item.vis,
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item.span,
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Some("place qualifiers on individual impl items instead"));
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}
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ItemKind::DefaultImpl(..) => {
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self.invalid_visibility(&item.vis, item.span, None);
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}
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ItemKind::ForeignMod(..) => {
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self.invalid_visibility(&item.vis,
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item.span,
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Some("place qualifiers on individual foreign items \
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instead"));
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}
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ItemKind::Enum(ref def, _) => {
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for variant in &def.variants {
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for field in variant.node.data.fields() {
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self.invalid_visibility(&field.vis, field.span, None);
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}
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}
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}
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ItemKind::Trait(.., ref bounds, ref trait_items) => {
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self.no_questions_in_bounds(bounds, "supertraits", true);
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for trait_item in trait_items {
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if let TraitItemKind::Method(ref sig, ref block) = trait_item.node {
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self.check_trait_fn_not_const(sig.constness);
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if block.is_none() {
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self.check_decl_no_pat(&sig.decl, |span, _| {
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self.session.add_lint(lint::builtin::PATTERNS_IN_FNS_WITHOUT_BODY,
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trait_item.id, span,
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"patterns aren't allowed in methods \
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without bodies".to_string());
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});
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}
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}
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}
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}
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ItemKind::Mod(_) => {
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// Ensure that `path` attributes on modules are recorded as used (c.f. #35584).
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attr::first_attr_value_str_by_name(&item.attrs, "path");
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if item.attrs.iter().any(|attr| attr.check_name("warn_directory_ownership")) {
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let lint = lint::builtin::LEGACY_DIRECTORY_OWNERSHIP;
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let msg = "cannot declare a new module at this location";
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self.session.add_lint(lint, item.id, item.span, msg.to_string());
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}
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}
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ItemKind::Union(ref vdata, _) => {
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if !vdata.is_struct() {
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self.err_handler().span_err(item.span,
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"tuple and unit unions are not permitted");
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}
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if vdata.fields().len() == 0 {
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self.err_handler().span_err(item.span,
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"unions cannot have zero fields");
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}
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}
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_ => {}
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}
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visit::walk_item(self, item)
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}
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fn visit_foreign_item(&mut self, fi: &'a ForeignItem) {
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match fi.node {
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ForeignItemKind::Fn(ref decl, _) => {
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self.check_decl_no_pat(decl, |span, is_recent| {
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let mut err = struct_span_err!(self.session,
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span,
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E0130,
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"patterns aren't allowed in foreign function \
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declarations");
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err.span_label(span, &format!("pattern not allowed in foreign function"));
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if is_recent {
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err.span_note(span,
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"this is a recent error, see issue #35203 for more details");
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}
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err.emit();
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});
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}
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ForeignItemKind::Static(..) => {}
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}
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visit::walk_foreign_item(self, fi)
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}
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fn visit_vis(&mut self, vis: &'a Visibility) {
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match *vis {
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Visibility::Restricted { ref path, .. } => {
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if !path.segments.iter().all(|segment| segment.parameters.is_none()) {
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self.err_handler()
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.span_err(path.span, "type or lifetime parameters in visibility path");
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}
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}
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_ => {}
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}
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visit::walk_vis(self, vis)
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}
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fn visit_generics(&mut self, g: &'a Generics) {
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let mut seen_default = None;
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for ty_param in &g.ty_params {
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if ty_param.default.is_some() {
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seen_default = Some(ty_param.span);
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} else if let Some(span) = seen_default {
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self.err_handler()
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.span_err(span, "type parameters with a default must be trailing");
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break
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}
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}
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for predicate in &g.where_clause.predicates {
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if let WherePredicate::EqPredicate(ref predicate) = *predicate {
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self.err_handler().span_err(predicate.span, "equality constraints are not yet \
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supported in where clauses (#20041)");
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}
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}
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visit::walk_generics(self, g)
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}
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}
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pub fn check_crate(session: &Session, krate: &Crate) {
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visit::walk_crate(&mut AstValidator { session: session }, krate)
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}
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