src/tools/clippy/clippy_utils/src/attrs.rs

   1 use rustc_ast::ast;
   2 use rustc_ast::attr;
   3 use rustc_errors::Applicability;
   4 use rustc_session::Session;
   5 use rustc_span::sym;
   6 use std::str::FromStr;
   7
   8 /// Deprecation status of attributes known by Clippy.
   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 #[rustfmt::skip]
  18 pub const BUILTIN_ATTRIBUTES: &[(&str, DeprecationStatus)] = &[
  19     ("author",                DeprecationStatus::None),
  20     ("version",               DeprecationStatus::None),
  21     ("cognitive_complexity",  DeprecationStatus::None),
  22     ("cyclomatic_complexity", DeprecationStatus::Replaced("cognitive_complexity")),
  23     ("dump",                  DeprecationStatus::None),
  24     ("msrv",                  DeprecationStatus::None),
  25     ("has_significant_drop",  DeprecationStatus::None),
  26 ];
  27
  28 pub struct LimitStack {
  29     stack: Vec<u64>,
  30 }
  31
  32 impl Drop for LimitStack {
  33     fn drop(&mut self) {
  34         assert_eq!(self.stack.len(), 1);
  35     }
  36 }
  37
  38 impl LimitStack {
  39     #[must_use]
  40     pub fn new(limit: u64) -> Self {
  41         Self { stack: vec![limit] }
  42     }
  43     pub fn limit(&self) -> u64 {
  44         *self.stack.last().expect("there should always be a value in the stack")
  45     }
  46     pub fn push_attrs(&mut self, sess: &Session, attrs: &[ast::Attribute], name: &'static str) {
  47         let stack = &mut self.stack;
  48         parse_attrs(sess, attrs, name, |val| stack.push(val));
  49     }
  50     pub fn pop_attrs(&mut self, sess: &Session, attrs: &[ast::Attribute], name: &'static str) {
  51         let stack = &mut self.stack;
  52         parse_attrs(sess, attrs, name, |val| assert_eq!(stack.pop(), Some(val)));
  53     }
  54 }
  55
  56 pub fn get_attr<'a>(
  57     sess: &'a Session,
  58     attrs: &'a [ast::Attribute],
  59     name: &'static str,
  60 ) -> impl Iterator<Item = &'a ast::Attribute> {
  61     attrs.iter().filter(move |attr| {
  62         let attr = if let ast::AttrKind::Normal(ref normal) = attr.kind {
  63             &normal.item
  64         } else {
  65             return false;
  66         };
  67         let attr_segments = &attr.path.segments;
  68         if attr_segments.len() == 2 && attr_segments[0].ident.name == sym::clippy {
  69             BUILTIN_ATTRIBUTES
  70                 .iter()
  71                 .find_map(|&(builtin_name, ref deprecation_status)| {
  72                     if attr_segments[1].ident.name.as_str() == builtin_name {
  73                         Some(deprecation_status)
  74                     } else {
  75                         None
  76                     }
  77                 })
  78                 .map_or_else(
  79                     || {
  80                         sess.span_err(attr_segments[1].ident.span, "usage of unknown attribute");
  81                         false
  82                     },
  83                     |deprecation_status| {
  84                         let mut diag =
  85                             sess.struct_span_err(attr_segments[1].ident.span, "usage of deprecated attribute");
  86                         match *deprecation_status {
  87                             DeprecationStatus::Deprecated => {
  88                                 diag.emit();
  89                                 false
  90                             },
  91                             DeprecationStatus::Replaced(new_name) => {
  92                                 diag.span_suggestion(
  93                                     attr_segments[1].ident.span,
  94                                     "consider using",
  95                                     new_name,
  96                                     Applicability::MachineApplicable,
  97                                 );
  98                                 diag.emit();
  99                                 false
 100                             },
 101                             DeprecationStatus::None => {
 102                                 diag.cancel();
 103                                 attr_segments[1].ident.name.as_str() == name
 104                             },
 105                         }
 106                     },
 107                 )
 108         } else {
 109             false
 110         }
 111     })
 112 }
 113
 114 fn parse_attrs<F: FnMut(u64)>(sess: &Session, attrs: &[ast::Attribute], name: &'static str, mut f: F) {
 115     for attr in get_attr(sess, attrs, name) {
 116         if let Some(ref value) = attr.value_str() {
 117             if let Ok(value) = FromStr::from_str(value.as_str()) {
 118                 f(value);
 119             } else {
 120                 sess.span_err(attr.span, "not a number");
 121             }
 122         } else {
 123             sess.span_err(attr.span, "bad clippy attribute");
 124         }
 125     }
 126 }
 127
 128 pub fn get_unique_inner_attr(sess: &Session, attrs: &[ast::Attribute], name: &'static str) -> Option<ast::Attribute> {
 129     let mut unique_attr = None;
 130     for attr in get_attr(sess, attrs, name) {
 131         match attr.style {
 132             ast::AttrStyle::Inner if unique_attr.is_none() => unique_attr = Some(attr.clone()),
 133             ast::AttrStyle::Inner => {
 134                 sess.struct_span_err(attr.span, &format!("`{name}` is defined multiple times"))
 135                     .span_note(unique_attr.as_ref().unwrap().span, "first definition found here")
 136                     .emit();
 137             },
 138             ast::AttrStyle::Outer => {
 139                 sess.span_err(attr.span, &format!("`{name}` cannot be an outer attribute"));
 140             },
 141         }
 142     }
 143     unique_attr
 144 }
 145
 146 /// Return true if the attributes contain any of `proc_macro`,
 147 /// `proc_macro_derive` or `proc_macro_attribute`, false otherwise
 148 pub fn is_proc_macro(sess: &Session, attrs: &[ast::Attribute]) -> bool {
 149     attrs.iter().any(|attr| sess.is_proc_macro_attr(attr))
 150 }
 151
 152 /// Return true if the attributes contain `#[doc(hidden)]`
 153 pub fn is_doc_hidden(attrs: &[ast::Attribute]) -> bool {
 154     attrs
 155         .iter()
 156         .filter(|attr| attr.has_name(sym::doc))
 157         .filter_map(ast::Attribute::meta_item_list)
 158         .any(|l| attr::list_contains_name(&l, sym::hidden))
 159 }