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::codemap::Spanned;
  24 use syntax::parse::token::{self, keywords};
  25 use syntax::visit::{self, Visitor};
  26 use syntax_pos::Span;
  27 use errors;
  28
  29 struct AstValidator<'a> {
  30     session: &'a Session,
  31 }
  32
  33 impl<'a> AstValidator<'a> {
  34     fn err_handler(&self) -> &errors::Handler {
  35         &self.session.parse_sess.span_diagnostic
  36     }
  37
  38     fn check_label(&self, label: Ident, span: Span, id: NodeId) {
  39         if label.name == keywords::StaticLifetime.name() {
  40             self.err_handler().span_err(span, &format!("invalid label name `{}`", label.name));
  41         }
  42         if label.name.as_str() == "'_" {
  43             self.session.add_lint(lint::builtin::LIFETIME_UNDERSCORE,
  44                                   id,
  45                                   span,
  46                                   format!("invalid label name `{}`", label.name));
  47         }
  48     }
  49
  50     fn invalid_visibility(&self, vis: &Visibility, span: Span, note: Option<&str>) {
  51         if vis != &Visibility::Inherited {
  52             let mut err = struct_span_err!(self.session,
  53                                            span,
  54                                            E0449,
  55                                            "unnecessary visibility qualifier");
  56             if vis == &Visibility::Public {
  57                 err.span_label(span, &format!("`pub` not needed here"));
  58             }
  59             if let Some(note) = note {
  60                 err.note(note);
  61             }
  62             err.emit();
  63         }
  64     }
  65
  66     fn check_decl_no_pat<ReportFn: Fn(Span, bool)>(&self, decl: &FnDecl, report_err: ReportFn) {
  67         for arg in &decl.inputs {
  68             match arg.pat.node {
  69                 PatKind::Ident(BindingMode::ByValue(Mutability::Immutable), _, None) |
  70                 PatKind::Wild => {}
  71                 PatKind::Ident(..) => report_err(arg.pat.span, true),
  72                 _ => report_err(arg.pat.span, false),
  73             }
  74         }
  75     }
  76
  77     fn check_trait_fn_not_const(&self, constness: Spanned<Constness>) {
  78         match constness.node {
  79             Constness::Const => {
  80                 struct_span_err!(self.session, constness.span, E0379,
  81                                  "trait fns cannot be declared const")
  82                     .span_label(constness.span, &format!("trait fns cannot be const"))
  83                     .emit();
  84             }
  85             _ => {}
  86         }
  87     }
  88 }
  89
  90 impl<'a> Visitor for AstValidator<'a> {
  91     fn visit_lifetime(&mut self, lt: &Lifetime) {
  92         if lt.name.as_str() == "'_" {
  93             self.session.add_lint(lint::builtin::LIFETIME_UNDERSCORE,
  94                                   lt.id,
  95                                   lt.span,
  96                                   format!("invalid lifetime name `{}`", lt.name));
  97         }
  98
  99         visit::walk_lifetime(self, lt)
 100     }
 101
 102     fn visit_expr(&mut self, expr: &Expr) {
 103         match expr.node {
 104             ExprKind::While(.., Some(ident)) |
 105             ExprKind::Loop(_, Some(ident)) |
 106             ExprKind::WhileLet(.., Some(ident)) |
 107             ExprKind::ForLoop(.., Some(ident)) |
 108             ExprKind::Break(Some(ident)) |
 109             ExprKind::Continue(Some(ident)) => {
 110                 self.check_label(ident.node, ident.span, expr.id);
 111             }
 112             _ => {}
 113         }
 114
 115         visit::walk_expr(self, expr)
 116     }
 117
 118     fn visit_ty(&mut self, ty: &Ty) {
 119         match ty.node {
 120             TyKind::BareFn(ref bfty) => {
 121                 self.check_decl_no_pat(&bfty.decl, |span, _| {
 122                     let mut err = struct_span_err!(self.session,
 123                                                    span,
 124                                                    E0561,
 125                                                    "patterns aren't allowed in function pointer \
 126                                                     types");
 127                     err.span_note(span,
 128                                   "this is a recent error, see issue #35203 for more details");
 129                     err.emit();
 130                 });
 131             }
 132             _ => {}
 133         }
 134
 135         visit::walk_ty(self, ty)
 136     }
 137
 138     fn visit_path(&mut self, path: &Path, id: NodeId) {
 139         if path.global && path.segments.len() > 0 {
 140             let ident = path.segments[0].identifier;
 141             if token::Ident(ident).is_path_segment_keyword() {
 142                 self.session.add_lint(lint::builtin::SUPER_OR_SELF_IN_GLOBAL_PATH,
 143                                       id,
 144                                       path.span,
 145                                       format!("global paths cannot start with `{}`", ident));
 146             }
 147         }
 148
 149         visit::walk_path(self, path)
 150     }
 151
 152     fn visit_item(&mut self, item: &Item) {
 153         match item.node {
 154             ItemKind::Use(ref view_path) => {
 155                 let path = view_path.node.path();
 156                 if !path.segments.iter().all(|segment| segment.parameters.is_empty()) {
 157                     self.err_handler()
 158                         .span_err(path.span, "type or lifetime parameters in import path");
 159                 }
 160             }
 161             ItemKind::Impl(.., Some(..), _, ref impl_items) => {
 162                 self.invalid_visibility(&item.vis, item.span, None);
 163                 for impl_item in impl_items {
 164                     self.invalid_visibility(&impl_item.vis, impl_item.span, None);
 165                     if let ImplItemKind::Method(ref sig, _) = impl_item.node {
 166                         self.check_trait_fn_not_const(sig.constness);
 167                     }
 168                 }
 169             }
 170             ItemKind::Impl(.., None, _, _) => {
 171                 self.invalid_visibility(&item.vis,
 172                                         item.span,
 173                                         Some("place qualifiers on individual impl items instead"));
 174             }
 175             ItemKind::DefaultImpl(..) => {
 176                 self.invalid_visibility(&item.vis, item.span, None);
 177             }
 178             ItemKind::ForeignMod(..) => {
 179                 self.invalid_visibility(&item.vis,
 180                                         item.span,
 181                                         Some("place qualifiers on individual foreign items \
 182                                               instead"));
 183             }
 184             ItemKind::Enum(ref def, _) => {
 185                 for variant in &def.variants {
 186                     for field in variant.node.data.fields() {
 187                         self.invalid_visibility(&field.vis, field.span, None);
 188                     }
 189                 }
 190             }
 191             ItemKind::Trait(.., ref trait_items) => {
 192                 for trait_item in trait_items {
 193                     if let TraitItemKind::Method(ref sig, ref block) = trait_item.node {
 194                         self.check_trait_fn_not_const(sig.constness);
 195                         if block.is_none() {
 196                             self.check_decl_no_pat(&sig.decl, |span, _| {
 197                                 self.session.add_lint(lint::builtin::PATTERNS_IN_FNS_WITHOUT_BODY,
 198                                                       trait_item.id, span,
 199                                                       "patterns aren't allowed in methods \
 200                                                        without bodies".to_string());
 201                             });
 202                         }
 203                     }
 204                 }
 205             }
 206             ItemKind::Mod(_) => {
 207                 // Ensure that `path` attributes on modules are recorded as used (c.f. #35584).
 208                 attr::first_attr_value_str_by_name(&item.attrs, "path");
 209             }
 210             ItemKind::Union(ref vdata, _) => {
 211                 if !vdata.is_struct() {
 212                     self.err_handler().span_err(item.span,
 213                                                 "tuple and unit unions are not permitted");
 214                 }
 215                 if vdata.fields().len() == 0 {
 216                     self.err_handler().span_err(item.span,
 217                                                 "unions cannot have zero fields");
 218                 }
 219             }
 220             _ => {}
 221         }
 222
 223         visit::walk_item(self, item)
 224     }
 225
 226     fn visit_foreign_item(&mut self, fi: &ForeignItem) {
 227         match fi.node {
 228             ForeignItemKind::Fn(ref decl, _) => {
 229                 self.check_decl_no_pat(decl, |span, is_recent| {
 230                     let mut err = struct_span_err!(self.session,
 231                                                    span,
 232                                                    E0130,
 233                                                    "patterns aren't allowed in foreign function \
 234                                                     declarations");
 235                     err.span_label(span, &format!("pattern not allowed in foreign function"));
 236                     if is_recent {
 237                         err.span_note(span,
 238                                       "this is a recent error, see issue #35203 for more details");
 239                     }
 240                     err.emit();
 241                 });
 242             }
 243             ForeignItemKind::Static(..) => {}
 244         }
 245
 246         visit::walk_foreign_item(self, fi)
 247     }
 248
 249     fn visit_vis(&mut self, vis: &Visibility) {
 250         match *vis {
 251             Visibility::Restricted { ref path, .. } => {
 252                 if !path.segments.iter().all(|segment| segment.parameters.is_empty()) {
 253                     self.err_handler()
 254                         .span_err(path.span, "type or lifetime parameters in visibility path");
 255                 }
 256             }
 257             _ => {}
 258         }
 259
 260         visit::walk_vis(self, vis)
 261     }
 262 }
 263
 264 pub fn check_crate(session: &Session, krate: &Crate) {
 265     visit::walk_crate(&mut AstValidator { session: session }, krate)
 266 }