src/librustc_lint/nonstandard_style.rs

   1 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
   2 use rustc_ast::ast;
   3 use rustc_attr as attr;
   4 use rustc_errors::Applicability;
   5 use rustc_hir as hir;
   6 use rustc_hir::def::{DefKind, Res};
   7 use rustc_hir::intravisit::FnKind;
   8 use rustc_hir::{GenericParamKind, PatKind};
   9 use rustc_middle::ty;
  10 use rustc_span::symbol::sym;
  11 use rustc_span::{symbol::Ident, BytePos, Span};
  12 use rustc_target::spec::abi::Abi;
  13
  14 #[derive(PartialEq)]
  15 pub enum MethodLateContext {
  16     TraitAutoImpl,
  17     TraitImpl,
  18     PlainImpl,
  19 }
  20
  21 pub fn method_context(cx: &LateContext<'_, '_>, id: hir::HirId) -> MethodLateContext {
  22     let def_id = cx.tcx.hir().local_def_id(id);
  23     let item = cx.tcx.associated_item(def_id);
  24     match item.container {
  25         ty::TraitContainer(..) => MethodLateContext::TraitAutoImpl,
  26         ty::ImplContainer(cid) => match cx.tcx.impl_trait_ref(cid) {
  27             Some(_) => MethodLateContext::TraitImpl,
  28             None => MethodLateContext::PlainImpl,
  29         },
  30     }
  31 }
  32
  33 declare_lint! {
  34     pub NON_CAMEL_CASE_TYPES,
  35     Warn,
  36     "types, variants, traits and type parameters should have camel case names"
  37 }
  38
  39 declare_lint_pass!(NonCamelCaseTypes => [NON_CAMEL_CASE_TYPES]);
  40
  41 fn char_has_case(c: char) -> bool {
  42     c.is_lowercase() || c.is_uppercase()
  43 }
  44
  45 fn is_camel_case(name: &str) -> bool {
  46     let name = name.trim_matches('_');
  47     if name.is_empty() {
  48         return true;
  49     }
  50
  51     // start with a non-lowercase letter rather than non-uppercase
  52     // ones (some scripts don't have a concept of upper/lowercase)
  53     !name.chars().next().unwrap().is_lowercase()
  54         && !name.contains("__")
  55         && !name.chars().collect::<Vec<_>>().windows(2).any(|pair| {
  56             // contains a capitalisable character followed by, or preceded by, an underscore
  57             char_has_case(pair[0]) && pair[1] == '_' || char_has_case(pair[1]) && pair[0] == '_'
  58         })
  59 }
  60
  61 fn to_camel_case(s: &str) -> String {
  62     s.trim_matches('_')
  63         .split('_')
  64         .filter(|component| !component.is_empty())
  65         .map(|component| {
  66             let mut camel_cased_component = String::new();
  67
  68             let mut new_word = true;
  69             let mut prev_is_lower_case = true;
  70
  71             for c in component.chars() {
  72                 // Preserve the case if an uppercase letter follows a lowercase letter, so that
  73                 // `camelCase` is converted to `CamelCase`.
  74                 if prev_is_lower_case && c.is_uppercase() {
  75                     new_word = true;
  76                 }
  77
  78                 if new_word {
  79                     camel_cased_component.push_str(&c.to_uppercase().to_string());
  80                 } else {
  81                     camel_cased_component.push_str(&c.to_lowercase().to_string());
  82                 }
  83
  84                 prev_is_lower_case = c.is_lowercase();
  85                 new_word = false;
  86             }
  87
  88             camel_cased_component
  89         })
  90         .fold((String::new(), None), |(acc, prev): (String, Option<String>), next| {
  91             // separate two components with an underscore if their boundary cannot
  92             // be distinguished using a uppercase/lowercase case distinction
  93             let join = if let Some(prev) = prev {
  94                 let l = prev.chars().last().unwrap();
  95                 let f = next.chars().next().unwrap();
  96                 !char_has_case(l) && !char_has_case(f)
  97             } else {
  98                 false
  99             };
 100             (acc + if join { "_" } else { "" } + &next, Some(next))
 101         })
 102         .0
 103 }
 104
 105 impl NonCamelCaseTypes {
 106     fn check_case(&self, cx: &EarlyContext<'_>, sort: &str, ident: &Ident) {
 107         let name = &ident.name.as_str();
 108
 109         if !is_camel_case(name) {
 110             cx.struct_span_lint(NON_CAMEL_CASE_TYPES, ident.span, |lint| {
 111                 let msg = format!("{} `{}` should have an upper camel case name", sort, name);
 112                 lint.build(&msg)
 113                     .span_suggestion(
 114                         ident.span,
 115                         "convert the identifier to upper camel case",
 116                         to_camel_case(name),
 117                         Applicability::MaybeIncorrect,
 118                     )
 119                     .emit()
 120             })
 121         }
 122     }
 123 }
 124
 125 impl EarlyLintPass for NonCamelCaseTypes {
 126     fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) {
 127         let has_repr_c = it
 128             .attrs
 129             .iter()
 130             .any(|attr| attr::find_repr_attrs(&cx.sess.parse_sess, attr).contains(&attr::ReprC));
 131
 132         if has_repr_c {
 133             return;
 134         }
 135
 136         match it.kind {
 137             ast::ItemKind::TyAlias(..)
 138             | ast::ItemKind::Enum(..)
 139             | ast::ItemKind::Struct(..)
 140             | ast::ItemKind::Union(..) => self.check_case(cx, "type", &it.ident),
 141             ast::ItemKind::Trait(..) => self.check_case(cx, "trait", &it.ident),
 142             _ => (),
 143         }
 144     }
 145
 146     fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
 147         if let ast::AssocItemKind::TyAlias(..) = it.kind {
 148             self.check_case(cx, "associated type", &it.ident);
 149         }
 150     }
 151
 152     fn check_variant(&mut self, cx: &EarlyContext<'_>, v: &ast::Variant) {
 153         self.check_case(cx, "variant", &v.ident);
 154     }
 155
 156     fn check_generic_param(&mut self, cx: &EarlyContext<'_>, param: &ast::GenericParam) {
 157         if let ast::GenericParamKind::Type { .. } = param.kind {
 158             self.check_case(cx, "type parameter", &param.ident);
 159         }
 160     }
 161 }
 162
 163 declare_lint! {
 164     pub NON_SNAKE_CASE,
 165     Warn,
 166     "variables, methods, functions, lifetime parameters and modules should have snake case names"
 167 }
 168
 169 declare_lint_pass!(NonSnakeCase => [NON_SNAKE_CASE]);
 170
 171 impl NonSnakeCase {
 172     fn to_snake_case(mut str: &str) -> String {
 173         let mut words = vec![];
 174         // Preserve leading underscores
 175         str = str.trim_start_matches(|c: char| {
 176             if c == '_' {
 177                 words.push(String::new());
 178                 true
 179             } else {
 180                 false
 181             }
 182         });
 183         for s in str.split('_') {
 184             let mut last_upper = false;
 185             let mut buf = String::new();
 186             if s.is_empty() {
 187                 continue;
 188             }
 189             for ch in s.chars() {
 190                 if !buf.is_empty() && buf != "'" && ch.is_uppercase() && !last_upper {
 191                     words.push(buf);
 192                     buf = String::new();
 193                 }
 194                 last_upper = ch.is_uppercase();
 195                 buf.extend(ch.to_lowercase());
 196             }
 197             words.push(buf);
 198         }
 199         words.join("_")
 200     }
 201
 202     /// Checks if a given identifier is snake case, and reports a diagnostic if not.
 203     fn check_snake_case(&self, cx: &LateContext<'_, '_>, sort: &str, ident: &Ident) {
 204         fn is_snake_case(ident: &str) -> bool {
 205             if ident.is_empty() {
 206                 return true;
 207             }
 208             let ident = ident.trim_start_matches('\'');
 209             let ident = ident.trim_matches('_');
 210
 211             let mut allow_underscore = true;
 212             ident.chars().all(|c| {
 213                 allow_underscore = match c {
 214                     '_' if !allow_underscore => return false,
 215                     '_' => false,
 216                     // It would be more obvious to use `c.is_lowercase()`,
 217                     // but some characters do not have a lowercase form
 218                     c if !c.is_uppercase() => true,
 219                     _ => return false,
 220                 };
 221                 true
 222             })
 223         }
 224
 225         let name = &ident.name.as_str();
 226
 227         if !is_snake_case(name) {
 228             cx.struct_span_lint(NON_SNAKE_CASE, ident.span, |lint| {
 229                 let sc = NonSnakeCase::to_snake_case(name);
 230                 let msg = format!("{} `{}` should have a snake case name", sort, name);
 231                 let mut err = lint.build(&msg);
 232                 // We have a valid span in almost all cases, but we don't have one when linting a crate
 233                 // name provided via the command line.
 234                 if !ident.span.is_dummy() {
 235                     err.span_suggestion(
 236                         ident.span,
 237                         "convert the identifier to snake case",
 238                         sc,
 239                         Applicability::MaybeIncorrect,
 240                     );
 241                 } else {
 242                     err.help(&format!("convert the identifier to snake case: `{}`", sc));
 243                 }
 244
 245                 err.emit();
 246             });
 247         }
 248     }
 249 }
 250
 251 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonSnakeCase {
 252     fn check_mod(
 253         &mut self,
 254         cx: &LateContext<'_, '_>,
 255         _: &'tcx hir::Mod<'tcx>,
 256         _: Span,
 257         id: hir::HirId,
 258     ) {
 259         if id != hir::CRATE_HIR_ID {
 260             return;
 261         }
 262
 263         let crate_ident = if let Some(name) = &cx.tcx.sess.opts.crate_name {
 264             Some(Ident::from_str(name))
 265         } else {
 266             attr::find_by_name(&cx.tcx.hir().attrs(hir::CRATE_HIR_ID), sym::crate_name)
 267                 .and_then(|attr| attr.meta())
 268                 .and_then(|meta| {
 269                     meta.name_value_literal().and_then(|lit| {
 270                         if let ast::LitKind::Str(name, ..) = lit.kind {
 271                             // Discard the double quotes surrounding the literal.
 272                             let sp = cx
 273                                 .sess()
 274                                 .source_map()
 275                                 .span_to_snippet(lit.span)
 276                                 .ok()
 277                                 .and_then(|snippet| {
 278                                     let left = snippet.find('"')?;
 279                                     let right =
 280                                         snippet.rfind('"').map(|pos| snippet.len() - pos)?;
 281
 282                                     Some(
 283                                         lit.span
 284                                             .with_lo(lit.span.lo() + BytePos(left as u32 + 1))
 285                                             .with_hi(lit.span.hi() - BytePos(right as u32)),
 286                                     )
 287                                 })
 288                                 .unwrap_or_else(|| lit.span);
 289
 290                             Some(Ident::new(name, sp))
 291                         } else {
 292                             None
 293                         }
 294                     })
 295                 })
 296         };
 297
 298         if let Some(ident) = &crate_ident {
 299             self.check_snake_case(cx, "crate", ident);
 300         }
 301     }
 302
 303     fn check_generic_param(&mut self, cx: &LateContext<'_, '_>, param: &hir::GenericParam<'_>) {
 304         if let GenericParamKind::Lifetime { .. } = param.kind {
 305             self.check_snake_case(cx, "lifetime", &param.name.ident());
 306         }
 307     }
 308
 309     fn check_fn(
 310         &mut self,
 311         cx: &LateContext<'_, '_>,
 312         fk: FnKind<'_>,
 313         _: &hir::FnDecl<'_>,
 314         _: &hir::Body<'_>,
 315         _: Span,
 316         id: hir::HirId,
 317     ) {
 318         match &fk {
 319             FnKind::Method(ident, ..) => match method_context(cx, id) {
 320                 MethodLateContext::PlainImpl => {
 321                     self.check_snake_case(cx, "method", ident);
 322                 }
 323                 MethodLateContext::TraitAutoImpl => {
 324                     self.check_snake_case(cx, "trait method", ident);
 325                 }
 326                 _ => (),
 327             },
 328             FnKind::ItemFn(ident, _, header, _, attrs) => {
 329                 // Skip foreign-ABI #[no_mangle] functions (Issue #31924)
 330                 if header.abi != Abi::Rust && attr::contains_name(attrs, sym::no_mangle) {
 331                     return;
 332                 }
 333                 self.check_snake_case(cx, "function", ident);
 334             }
 335             FnKind::Closure(_) => (),
 336         }
 337     }
 338
 339     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
 340         if let hir::ItemKind::Mod(_) = it.kind {
 341             self.check_snake_case(cx, "module", &it.ident);
 342         }
 343     }
 344
 345     fn check_trait_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::TraitItem<'_>) {
 346         if let hir::TraitItemKind::Fn(_, hir::TraitFn::Required(pnames)) = item.kind {
 347             self.check_snake_case(cx, "trait method", &item.ident);
 348             for param_name in pnames {
 349                 self.check_snake_case(cx, "variable", param_name);
 350             }
 351         }
 352     }
 353
 354     fn check_pat(&mut self, cx: &LateContext<'_, '_>, p: &hir::Pat<'_>) {
 355         if let &PatKind::Binding(_, hid, ident, _) = &p.kind {
 356             if let hir::Node::Pat(parent_pat) = cx.tcx.hir().get(cx.tcx.hir().get_parent_node(hid))
 357             {
 358                 if let PatKind::Struct(_, field_pats, _) = &parent_pat.kind {
 359                     for field in field_pats.iter() {
 360                         if field.ident != ident {
 361                             // Only check if a new name has been introduced, to avoid warning
 362                             // on both the struct definition and this pattern.
 363                             self.check_snake_case(cx, "variable", &ident);
 364                         }
 365                     }
 366                     return;
 367                 }
 368             }
 369             self.check_snake_case(cx, "variable", &ident);
 370         }
 371     }
 372
 373     fn check_struct_def(&mut self, cx: &LateContext<'_, '_>, s: &hir::VariantData<'_>) {
 374         for sf in s.fields() {
 375             self.check_snake_case(cx, "structure field", &sf.ident);
 376         }
 377     }
 378 }
 379
 380 declare_lint! {
 381     pub NON_UPPER_CASE_GLOBALS,
 382     Warn,
 383     "static constants should have uppercase identifiers"
 384 }
 385
 386 declare_lint_pass!(NonUpperCaseGlobals => [NON_UPPER_CASE_GLOBALS]);
 387
 388 impl NonUpperCaseGlobals {
 389     fn check_upper_case(cx: &LateContext<'_, '_>, sort: &str, ident: &Ident) {
 390         let name = &ident.name.as_str();
 391         if name.chars().any(|c| c.is_lowercase()) {
 392             cx.struct_span_lint(NON_UPPER_CASE_GLOBALS, ident.span, |lint| {
 393                 let uc = NonSnakeCase::to_snake_case(&name).to_uppercase();
 394                 lint.build(&format!("{} `{}` should have an upper case name", sort, name))
 395                     .span_suggestion(
 396                         ident.span,
 397                         "convert the identifier to upper case",
 398                         uc,
 399                         Applicability::MaybeIncorrect,
 400                     )
 401                     .emit();
 402             })
 403         }
 404     }
 405 }
 406
 407 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonUpperCaseGlobals {
 408     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
 409         match it.kind {
 410             hir::ItemKind::Static(..) if !attr::contains_name(&it.attrs, sym::no_mangle) => {
 411                 NonUpperCaseGlobals::check_upper_case(cx, "static variable", &it.ident);
 412             }
 413             hir::ItemKind::Const(..) => {
 414                 NonUpperCaseGlobals::check_upper_case(cx, "constant", &it.ident);
 415             }
 416             _ => {}
 417         }
 418     }
 419
 420     fn check_trait_item(&mut self, cx: &LateContext<'_, '_>, ti: &hir::TraitItem<'_>) {
 421         if let hir::TraitItemKind::Const(..) = ti.kind {
 422             NonUpperCaseGlobals::check_upper_case(cx, "associated constant", &ti.ident);
 423         }
 424     }
 425
 426     fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, ii: &hir::ImplItem<'_>) {
 427         if let hir::ImplItemKind::Const(..) = ii.kind {
 428             NonUpperCaseGlobals::check_upper_case(cx, "associated constant", &ii.ident);
 429         }
 430     }
 431
 432     fn check_pat(&mut self, cx: &LateContext<'_, '_>, p: &hir::Pat<'_>) {
 433         // Lint for constants that look like binding identifiers (#7526)
 434         if let PatKind::Path(hir::QPath::Resolved(None, ref path)) = p.kind {
 435             if let Res::Def(DefKind::Const, _) = path.res {
 436                 if path.segments.len() == 1 {
 437                     NonUpperCaseGlobals::check_upper_case(
 438                         cx,
 439                         "constant in pattern",
 440                         &path.segments[0].ident,
 441                     );
 442                 }
 443             }
 444         }
 445     }
 446
 447     fn check_generic_param(&mut self, cx: &LateContext<'_, '_>, param: &hir::GenericParam<'_>) {
 448         if let GenericParamKind::Const { .. } = param.kind {
 449             NonUpperCaseGlobals::check_upper_case(cx, "const parameter", &param.name.ident());
 450         }
 451     }
 452 }
 453
 454 #[cfg(test)]
 455 mod tests;