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ast_validation.rs
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// 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::codemap::Span;
use syntax::errors;
use syntax::parse::token::{self, keywords};
use syntax::visit::{self, Visitor};
struct AstValidator<'a> {
session: &'a Session,
}
impl<'a> AstValidator<'a> {
fn err_handler(&self) -> &errors::Handler {
&self.session.parse_sess.span_diagnostic
}
fn check_label(&self, label: Ident, span: Span, id: NodeId) {
if label.name == keywords::StaticLifetime.name() {
self.err_handler().span_err(span, &format!("invalid label name `{}`", label.name));
}
if label.name.as_str() == "'_" {
self.session.add_lint(
lint::builtin::LIFETIME_UNDERSCORE, id, span,
format!("invalid label name `{}`", label.name)
);
}
}
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 let Some(note) = note {
err.span_note(span, note);
}
err.emit();
}
}
}
impl<'a, 'v> Visitor<'v> for AstValidator<'a> {
fn visit_lifetime(&mut self, lt: &Lifetime) {
if lt.name.as_str() == "'_" {
self.session.add_lint(
lint::builtin::LIFETIME_UNDERSCORE, lt.id, lt.span,
format!("invalid lifetime name `{}`", lt.name)
);
}
visit::walk_lifetime(self, lt)
}
fn visit_expr(&mut self, expr: &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, expr.id);
}
_ => {}
}
visit::walk_expr(self, expr)
}
fn visit_path(&mut self, path: &Path, id: NodeId) {
if path.global && path.segments.len() > 0 {
let ident = path.segments[0].identifier;
if token::Ident(ident).is_path_segment_keyword() {
self.session.add_lint(
lint::builtin::SUPER_OR_SELF_IN_GLOBAL_PATH, id, path.span,
format!("global paths cannot start with `{}`", ident)
);
}
}
visit::walk_path(self, path)
}
fn visit_item(&mut self, item: &Item) {
match item.node {
ItemKind::Use(ref view_path) => {
let path = view_path.node.path();
if !path.segments.iter().all(|segment| segment.parameters.is_empty()) {
self.err_handler().span_err(path.span, "type or lifetime parameters \
in import path");
}
}
ItemKind::Impl(_, _, _, Some(..), _, ref impl_items) => {
self.invalid_visibility(&item.vis, item.span, None);
for impl_item in impl_items {
self.invalid_visibility(&impl_item.vis, impl_item.span, None);
}
}
ItemKind::Impl(_, _, _, None, _, _) => {
self.invalid_visibility(&item.vis, item.span, Some("place qualifiers on individual \
impl items instead"));
}
ItemKind::DefaultImpl(..) => {
self.invalid_visibility(&item.vis, item.span, None);
}
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 {
for field in variant.node.data.fields() {
self.invalid_visibility(&field.vis, field.span, None);
}
}
}
_ => {}
}
visit::walk_item(self, item)
}
fn visit_variant_data(&mut self, vdata: &VariantData, _: Ident,
_: &Generics, _: NodeId, span: Span) {
if vdata.fields().is_empty() {
if vdata.is_tuple() {
self.err_handler().struct_span_err(span, "empty tuple structs and enum variants \
are not allowed, use unit structs and \
enum variants instead")
.span_help(span, "remove trailing `()` to make a unit \
struct or unit enum variant")
.emit();
}
}
visit::walk_struct_def(self, vdata)
}
fn visit_vis(&mut self, vis: &Visibility) {
match *vis {
Visibility::Restricted{ref path, ..} => {
if !path.segments.iter().all(|segment| segment.parameters.is_empty()) {
self.err_handler().span_err(path.span, "type or lifetime parameters \
in visibility path");
}
}
_ => {}
}
visit::walk_vis(self, vis)
}
}
pub fn check_crate(session: &Session, krate: &Crate) {
visit::walk_crate(&mut AstValidator { session: session }, krate)
}