clippy_lints/src/utils/attrs.rs

   1 use rustc_ast::ast;
   2 use rustc_ast::expand::is_proc_macro_attr;
   3 use rustc_errors::Applicability;
   4 use rustc_session::Session;
   5 use std::str::FromStr;
   6
   7 /// Deprecation status of attributes known by Clippy.
   8 #[allow(dead_code)]
   9 pub enum DeprecationStatus {
  10     /// Attribute is deprecated
  11     Deprecated,
  12     /// Attribute is deprecated and was replaced by the named attribute
  13     Replaced(&'static str),
  14     None,
  15 }
  16
  17 pub const BUILTIN_ATTRIBUTES: &[(&str, DeprecationStatus)] = &[
  18     ("author", DeprecationStatus::None),
  19     ("cognitive_complexity", DeprecationStatus::None),
  20     (
  21         "cyclomatic_complexity",
  22         DeprecationStatus::Replaced("cognitive_complexity"),
  23     ),
  24     ("dump", DeprecationStatus::None),
  25 ];
  26
  27 pub struct LimitStack {
  28     stack: Vec<u64>,
  29 }
  30
  31 impl Drop for LimitStack {
  32     fn drop(&mut self) {
  33         assert_eq!(self.stack.len(), 1);
  34     }
  35 }
  36
  37 impl LimitStack {
  38     #[must_use]
  39     pub fn new(limit: u64) -> Self {
  40         Self { stack: vec![limit] }
  41     }
  42     pub fn limit(&self) -> u64 {
  43         *self.stack.last().expect("there should always be a value in the stack")
  44     }
  45     pub fn push_attrs(&mut self, sess: &Session, attrs: &[ast::Attribute], name: &'static str) {
  46         let stack = &mut self.stack;
  47         parse_attrs(sess, attrs, name, |val| stack.push(val));
  48     }
  49     pub fn pop_attrs(&mut self, sess: &Session, attrs: &[ast::Attribute], name: &'static str) {
  50         let stack = &mut self.stack;
  51         parse_attrs(sess, attrs, name, |val| assert_eq!(stack.pop(), Some(val)));
  52     }
  53 }
  54
  55 pub fn get_attr<'a>(
  56     sess: &'a Session,
  57     attrs: &'a [ast::Attribute],
  58     name: &'static str,
  59 ) -> impl Iterator<Item = &'a ast::Attribute> {
  60     attrs.iter().filter(move |attr| {
  61         let attr = if let ast::AttrKind::Normal(ref attr) = attr.kind {
  62             attr
  63         } else {
  64             return false;
  65         };
  66         let attr_segments = &attr.path.segments;
  67         if attr_segments.len() == 2 && attr_segments[0].ident.to_string() == "clippy" {
  68             BUILTIN_ATTRIBUTES
  69                 .iter()
  70                 .find_map(|(builtin_name, deprecation_status)| {
  71                     if *builtin_name == attr_segments[1].ident.to_string() {
  72                         Some(deprecation_status)
  73                     } else {
  74                         None
  75                     }
  76                 })
  77                 .map_or_else(
  78                     || {
  79                         sess.span_err(attr_segments[1].ident.span, "Usage of unknown attribute");
  80                         false
  81                     },
  82                     |deprecation_status| {
  83                         let mut diag =
  84                             sess.struct_span_err(attr_segments[1].ident.span, "Usage of deprecated attribute");
  85                         match *deprecation_status {
  86                             DeprecationStatus::Deprecated => {
  87                                 diag.emit();
  88                                 false
  89                             },
  90                             DeprecationStatus::Replaced(new_name) => {
  91                                 diag.span_suggestion(
  92                                     attr_segments[1].ident.span,
  93                                     "consider using",
  94                                     new_name.to_string(),
  95                                     Applicability::MachineApplicable,
  96                                 );
  97                                 diag.emit();
  98                                 false
  99                             },
 100                             DeprecationStatus::None => {
 101                                 diag.cancel();
 102                                 attr_segments[1].ident.to_string() == name
 103                             },
 104                         }
 105                     },
 106                 )
 107         } else {
 108             false
 109         }
 110     })
 111 }
 112
 113 fn parse_attrs<F: FnMut(u64)>(sess: &Session, attrs: &[ast::Attribute], name: &'static str, mut f: F) {
 114     for attr in get_attr(sess, attrs, name) {
 115         if let Some(ref value) = attr.value_str() {
 116             if let Ok(value) = FromStr::from_str(&value.as_str()) {
 117                 f(value)
 118             } else {
 119                 sess.span_err(attr.span, "not a number");
 120             }
 121         } else {
 122             sess.span_err(attr.span, "bad clippy attribute");
 123         }
 124     }
 125 }
 126
 127 /// Return true if the attributes contain any of `proc_macro`,
 128 /// `proc_macro_derive` or `proc_macro_attribute`, false otherwise
 129 pub fn is_proc_macro(attrs: &[ast::Attribute]) -> bool {
 130     attrs.iter().any(is_proc_macro_attr)
 131 }