src/librustc_passes/ast_validation.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Validate AST before lowering it to HIR
  12 //
  13 // This pass is supposed to catch things that fit into AST data structures,
  14 // but not permitted by the language. It runs after expansion when AST is frozen,
  15 // so it can check for erroneous constructions produced by syntax extensions.
  16 // This pass is supposed to perform only simple checks not requiring name resolution
  17 // or type checking or some other kind of complex analysis.
  18
  19 use rustc::lint;
  20 use rustc::session::Session;
  21 use syntax::ast::*;
  22 use syntax::attr;
  23 use syntax::parse::token::{self, keywords};
  24 use syntax::visit::{self, Visitor};
  25 use syntax_pos::Span;
  26 use errors;
  27
  28 struct AstValidator<'a> {
  29     session: &'a Session,
  30 }
  31
  32 impl<'a> AstValidator<'a> {
  33     fn err_handler(&self) -> &errors::Handler {
  34         &self.session.parse_sess.span_diagnostic
  35     }
  36
  37     fn check_label(&self, label: Ident, span: Span, id: NodeId) {
  38         if label.name == keywords::StaticLifetime.name() {
  39             self.err_handler().span_err(span, &format!("invalid label name `{}`", label.name));
  40         }
  41         if label.name.as_str() == "'_" {
  42             self.session.add_lint(lint::builtin::LIFETIME_UNDERSCORE,
  43                                   id,
  44                                   span,
  45                                   format!("invalid label name `{}`", label.name));
  46         }
  47     }
  48
  49     fn invalid_visibility(&self, vis: &Visibility, span: Span, note: Option<&str>) {
  50         if vis != &Visibility::Inherited {
  51             let mut err = struct_span_err!(self.session,
  52                                            span,
  53                                            E0449,
  54                                            "unnecessary visibility qualifier");
  55             if let Some(note) = note {
  56                 err.span_note(span, note);
  57             }
  58             err.emit();
  59         }
  60     }
  61
  62     fn check_decl_no_pat<ReportFn: Fn(Span, bool)>(&self, decl: &FnDecl, report_err: ReportFn) {
  63         for arg in &decl.inputs {
  64             match arg.pat.node {
  65                 PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), _, None) |
  66                 PatKind::Wild => {}
  67                 PatKind::Ident(..) => report_err(arg.pat.span, true),
  68                 _ => report_err(arg.pat.span, false),
  69             }
  70         }
  71     }
  72 }
  73
  74 impl<'a> Visitor for AstValidator<'a> {
  75     fn visit_lifetime(&mut self, lt: &Lifetime) {
  76         if lt.name.as_str() == "'_" {
  77             self.session.add_lint(lint::builtin::LIFETIME_UNDERSCORE,
  78                                   lt.id,
  79                                   lt.span,
  80                                   format!("invalid lifetime name `{}`", lt.name));
  81         }
  82
  83         visit::walk_lifetime(self, lt)
  84     }
  85
  86     fn visit_expr(&mut self, expr: &Expr) {
  87         match expr.node {
  88             ExprKind::While(_, _, Some(ident)) |
  89             ExprKind::Loop(_, Some(ident)) |
  90             ExprKind::WhileLet(_, _, _, Some(ident)) |
  91             ExprKind::ForLoop(_, _, _, Some(ident)) |
  92             ExprKind::Break(Some(ident)) |
  93             ExprKind::Continue(Some(ident)) => {
  94                 self.check_label(ident.node, ident.span, expr.id);
  95             }
  96             _ => {}
  97         }
  98
  99         visit::walk_expr(self, expr)
 100     }
 101
 102     fn visit_ty(&mut self, ty: &Ty) {
 103         match ty.node {
 104             TyKind::BareFn(ref bfty) => {
 105                 self.check_decl_no_pat(&bfty.decl, |span, _| {
 106                     let mut err = struct_span_err!(self.session,
 107                                                    span,
 108                                                    E0561,
 109                                                    "patterns aren't allowed in function pointer \
 110                                                     types");
 111                     err.span_note(span,
 112                                   "this is a recent error, see issue #35203 for more details");
 113                     err.emit();
 114                 });
 115             }
 116             _ => {}
 117         }
 118
 119         visit::walk_ty(self, ty)
 120     }
 121
 122     fn visit_path(&mut self, path: &Path, id: NodeId) {
 123         if path.global && path.segments.len() > 0 {
 124             let ident = path.segments[0].identifier;
 125             if token::Ident(ident).is_path_segment_keyword() {
 126                 self.session.add_lint(lint::builtin::SUPER_OR_SELF_IN_GLOBAL_PATH,
 127                                       id,
 128                                       path.span,
 129                                       format!("global paths cannot start with `{}`", ident));
 130             }
 131         }
 132
 133         visit::walk_path(self, path)
 134     }
 135
 136     fn visit_item(&mut self, item: &Item) {
 137         match item.node {
 138             ItemKind::Use(ref view_path) => {
 139                 let path = view_path.node.path();
 140                 if !path.segments.iter().all(|segment| segment.parameters.is_empty()) {
 141                     self.err_handler()
 142                         .span_err(path.span, "type or lifetime parameters in import path");
 143                 }
 144             }
 145             ItemKind::Impl(_, _, _, Some(..), _, ref impl_items) => {
 146                 self.invalid_visibility(&item.vis, item.span, None);
 147                 for impl_item in impl_items {
 148                     self.invalid_visibility(&impl_item.vis, impl_item.span, None);
 149                 }
 150             }
 151             ItemKind::Impl(_, _, _, None, _, _) => {
 152                 self.invalid_visibility(&item.vis,
 153                                         item.span,
 154                                         Some("place qualifiers on individual impl items instead"));
 155             }
 156             ItemKind::DefaultImpl(..) => {
 157                 self.invalid_visibility(&item.vis, item.span, None);
 158             }
 159             ItemKind::ForeignMod(..) => {
 160                 self.invalid_visibility(&item.vis,
 161                                         item.span,
 162                                         Some("place qualifiers on individual foreign items \
 163                                               instead"));
 164             }
 165             ItemKind::Enum(ref def, _) => {
 166                 for variant in &def.variants {
 167                     for field in variant.node.data.fields() {
 168                         self.invalid_visibility(&field.vis, field.span, None);
 169                     }
 170                 }
 171             }
 172             ItemKind::Mod(_) => {
 173                 // Ensure that `path` attributes on modules are recorded as used (c.f. #35584).
 174                 attr::first_attr_value_str_by_name(&item.attrs, "path");
 175             }
 176             _ => {}
 177         }
 178
 179         visit::walk_item(self, item)
 180     }
 181
 182     fn visit_foreign_item(&mut self, fi: &ForeignItem) {
 183         match fi.node {
 184             ForeignItemKind::Fn(ref decl, _) => {
 185                 self.check_decl_no_pat(decl, |span, is_recent| {
 186                     let mut err = struct_span_err!(self.session,
 187                                                    span,
 188                                                    E0130,
 189                                                    "patterns aren't allowed in foreign function \
 190                                                     declarations");
 191                     err.span_label(span, &format!("pattern not allowed in foreign function"));
 192                     if is_recent {
 193                         err.span_note(span,
 194                                       "this is a recent error, see issue #35203 for more details");
 195                     }
 196                     err.emit();
 197                 });
 198             }
 199             ForeignItemKind::Static(..) => {}
 200         }
 201
 202         visit::walk_foreign_item(self, fi)
 203     }
 204
 205     fn visit_vis(&mut self, vis: &Visibility) {
 206         match *vis {
 207             Visibility::Restricted { ref path, .. } => {
 208                 if !path.segments.iter().all(|segment| segment.parameters.is_empty()) {
 209                     self.err_handler()
 210                         .span_err(path.span, "type or lifetime parameters in visibility path");
 211                 }
 212             }
 213             _ => {}
 214         }
 215
 216         visit::walk_vis(self, vis)
 217     }
 218 }
 219
 220 pub fn check_crate(session: &Session, krate: &Crate) {
 221     visit::walk_crate(&mut AstValidator { session: session }, krate)
 222 }