src/librustc/front/check_attr.rs

   1 // Copyright 2015 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 use session::Session;
  12
  13 use syntax::ast;
  14 use syntax::attr::AttrMetaMethods;
  15 use syntax::visit;
  16 use syntax::visit::Visitor;
  17
  18 #[derive(Copy, Clone, PartialEq)]
  19 enum Target {
  20     Fn,
  21     Struct,
  22     Enum,
  23     Other,
  24 }
  25
  26 impl Target {
  27     fn from_item(item: &ast::Item) -> Target {
  28         match item.node {
  29             ast::ItemKind::Fn(..) => Target::Fn,
  30             ast::ItemKind::Struct(..) => Target::Struct,
  31             ast::ItemKind::Enum(..) => Target::Enum,
  32             _ => Target::Other,
  33         }
  34     }
  35 }
  36
  37 struct CheckAttrVisitor<'a> {
  38     sess: &'a Session,
  39 }
  40
  41 impl<'a> CheckAttrVisitor<'a> {
  42     fn check_inline(&self, attr: &ast::Attribute, target: Target) {
  43         if target != Target::Fn {
  44             span_err!(self.sess, attr.span, E0518, "attribute should be applied to function");
  45         }
  46     }
  47
  48     fn check_repr(&self, attr: &ast::Attribute, target: Target) {
  49         let words = match attr.meta_item_list() {
  50             Some(words) => words,
  51             None => {
  52                 return;
  53             }
  54         };
  55         for word in words {
  56             let word: &str = &word.name();
  57             let message = match word {
  58                 "C" => {
  59                     if target != Target::Struct && target != Target::Enum {
  60                             "attribute should be applied to struct or enum"
  61                     } else {
  62                         continue
  63                     }
  64                 }
  65                 "packed" |
  66                 "simd" => {
  67                     if target != Target::Struct {
  68                         "attribute should be applied to struct"
  69                     } else {
  70                         continue
  71                     }
  72                 }
  73                 "i8" | "u8" | "i16" | "u16" |
  74                 "i32" | "u32" | "i64" | "u64" |
  75                 "isize" | "usize" => {
  76                     if target != Target::Enum {
  77                             "attribute should be applied to enum"
  78                     } else {
  79                         continue
  80                     }
  81                 }
  82                 _ => continue,
  83             };
  84             span_err!(self.sess, attr.span, E0517, "{}", message);
  85         }
  86     }
  87
  88     fn check_attribute(&self, attr: &ast::Attribute, target: Target) {
  89         let name: &str = &attr.name();
  90         match name {
  91             "inline" => self.check_inline(attr, target),
  92             "repr" => self.check_repr(attr, target),
  93             _ => (),
  94         }
  95     }
  96 }
  97
  98 impl<'a, 'v> Visitor<'v> for CheckAttrVisitor<'a> {
  99     fn visit_item(&mut self, item: &ast::Item) {
 100         let target = Target::from_item(item);
 101         for attr in &item.attrs {
 102             self.check_attribute(attr, target);
 103         }
 104         visit::walk_item(self, item);
 105     }
 106 }
 107
 108 pub fn check_crate(sess: &Session, krate: &ast::Crate) {
 109     visit::walk_crate(&mut CheckAttrVisitor { sess: sess }, krate);
 110 }