clippy_lints/src/utils/internal_lints.rs

   1 use crate::consts::{constant_simple, Constant};
   2 use crate::utils::{
   3     is_expn_of, match_def_path, match_qpath, match_type, method_calls, path_to_res, paths, qpath_res, run_lints,
   4     snippet, span_lint, span_lint_and_help, span_lint_and_sugg, SpanlessEq,
   5 };
   6 use if_chain::if_chain;
   7 use rustc_ast::ast::{Crate as AstCrate, ItemKind, LitKind, NodeId};
   8 use rustc_ast::visit::FnKind;
   9 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  10 use rustc_errors::Applicability;
  11 use rustc_hir as hir;
  12 use rustc_hir::def::{DefKind, Res};
  13 use rustc_hir::hir_id::CRATE_HIR_ID;
  14 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
  15 use rustc_hir::{Crate, Expr, ExprKind, HirId, Item, MutTy, Mutability, Node, Path, StmtKind, Ty, TyKind};
  16 use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass};
  17 use rustc_middle::hir::map::Map;
  18 use rustc_middle::mir::interpret::ConstValue;
  19 use rustc_middle::ty;
  20 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
  21 use rustc_span::source_map::{Span, Spanned};
  22 use rustc_span::symbol::{Symbol, SymbolStr};
  23 use rustc_typeck::hir_ty_to_ty;
  24
  25 use std::borrow::{Borrow, Cow};
  26
  27 declare_clippy_lint! {
  28     /// **What it does:** Checks for various things we like to keep tidy in clippy.
  29     ///
  30     /// **Why is this bad?** We like to pretend we're an example of tidy code.
  31     ///
  32     /// **Known problems:** None.
  33     ///
  34     /// **Example:** Wrong ordering of the util::paths constants.
  35     pub CLIPPY_LINTS_INTERNAL,
  36     internal,
  37     "various things that will negatively affect your clippy experience"
  38 }
  39
  40 declare_clippy_lint! {
  41     /// **What it does:** Ensures every lint is associated to a `LintPass`.
  42     ///
  43     /// **Why is this bad?** The compiler only knows lints via a `LintPass`. Without
  44     /// putting a lint to a `LintPass::get_lints()`'s return, the compiler will not
  45     /// know the name of the lint.
  46     ///
  47     /// **Known problems:** Only checks for lints associated using the
  48     /// `declare_lint_pass!`, `impl_lint_pass!`, and `lint_array!` macros.
  49     ///
  50     /// **Example:**
  51     /// ```rust,ignore
  52     /// declare_lint! { pub LINT_1, ... }
  53     /// declare_lint! { pub LINT_2, ... }
  54     /// declare_lint! { pub FORGOTTEN_LINT, ... }
  55     /// // ...
  56     /// declare_lint_pass!(Pass => [LINT_1, LINT_2]);
  57     /// // missing FORGOTTEN_LINT
  58     /// ```
  59     pub LINT_WITHOUT_LINT_PASS,
  60     internal,
  61     "declaring a lint without associating it in a LintPass"
  62 }
  63
  64 declare_clippy_lint! {
  65     /// **What it does:** Checks for calls to `cx.span_lint*` and suggests to use the `utils::*`
  66     /// variant of the function.
  67     ///
  68     /// **Why is this bad?** The `utils::*` variants also add a link to the Clippy documentation to the
  69     /// warning/error messages.
  70     ///
  71     /// **Known problems:** None.
  72     ///
  73     /// **Example:**
  74     /// Bad:
  75     /// ```rust,ignore
  76     /// cx.span_lint(LINT_NAME, "message");
  77     /// ```
  78     ///
  79     /// Good:
  80     /// ```rust,ignore
  81     /// utils::span_lint(cx, LINT_NAME, "message");
  82     /// ```
  83     pub COMPILER_LINT_FUNCTIONS,
  84     internal,
  85     "usage of the lint functions of the compiler instead of the utils::* variant"
  86 }
  87
  88 declare_clippy_lint! {
  89     /// **What it does:** Checks for calls to `cx.outer().expn_data()` and suggests to use
  90     /// the `cx.outer_expn_data()`
  91     ///
  92     /// **Why is this bad?** `cx.outer_expn_data()` is faster and more concise.
  93     ///
  94     /// **Known problems:** None.
  95     ///
  96     /// **Example:**
  97     /// Bad:
  98     /// ```rust,ignore
  99     /// expr.span.ctxt().outer().expn_data()
 100     /// ```
 101     ///
 102     /// Good:
 103     /// ```rust,ignore
 104     /// expr.span.ctxt().outer_expn_data()
 105     /// ```
 106     pub OUTER_EXPN_EXPN_DATA,
 107     internal,
 108     "using `cx.outer_expn().expn_data()` instead of `cx.outer_expn_data()`"
 109 }
 110
 111 declare_clippy_lint! {
 112     /// **What it does:** Not an actual lint. This lint is only meant for testing our customized internal compiler
 113     /// error message by calling `panic`.
 114     ///
 115     /// **Why is this bad?** ICE in large quantities can damage your teeth
 116     ///
 117     /// **Known problems:** None
 118     ///
 119     /// **Example:**
 120     /// Bad:
 121     /// ```rust,ignore
 122     /// 🍦🍦🍦🍦🍦
 123     /// ```
 124     pub PRODUCE_ICE,
 125     internal,
 126     "this message should not appear anywhere as we ICE before and don't emit the lint"
 127 }
 128
 129 declare_clippy_lint! {
 130     /// **What it does:** Checks for cases of an auto-generated lint without an updated description,
 131     /// i.e. `default lint description`.
 132     ///
 133     /// **Why is this bad?** Indicates that the lint is not finished.
 134     ///
 135     /// **Known problems:** None
 136     ///
 137     /// **Example:**
 138     /// Bad:
 139     /// ```rust,ignore
 140     /// declare_lint! { pub COOL_LINT, nursery, "default lint description" }
 141     /// ```
 142     ///
 143     /// Good:
 144     /// ```rust,ignore
 145     /// declare_lint! { pub COOL_LINT, nursery, "a great new lint" }
 146     /// ```
 147     pub DEFAULT_LINT,
 148     internal,
 149     "found 'default lint description' in a lint declaration"
 150 }
 151
 152 declare_clippy_lint! {
 153     /// **What it does:** Lints `span_lint_and_then` function calls, where the
 154     /// closure argument has only one statement and that statement is a method
 155     /// call to `span_suggestion`, `span_help`, `span_note` (using the same
 156     /// span), `help` or `note`.
 157     ///
 158     /// These usages of `span_lint_and_then` should be replaced with one of the
 159     /// wrapper functions `span_lint_and_sugg`, span_lint_and_help`, or
 160     /// `span_lint_and_note`.
 161     ///
 162     /// **Why is this bad?** Using the wrapper `span_lint_and_*` functions, is more
 163     /// convenient, readable and less error prone.
 164     ///
 165     /// **Known problems:** None
 166     ///
 167     /// *Example:**
 168     /// Bad:
 169     /// ```rust,ignore
 170     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 171     ///     diag.span_suggestion(
 172     ///         expr.span,
 173     ///         help_msg,
 174     ///         sugg.to_string(),
 175     ///         Applicability::MachineApplicable,
 176     ///     );
 177     /// });
 178     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 179     ///     diag.span_help(expr.span, help_msg);
 180     /// });
 181     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 182     ///     diag.help(help_msg);
 183     /// });
 184     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 185     ///     diag.span_note(expr.span, note_msg);
 186     /// });
 187     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 188     ///     diag.note(note_msg);
 189     /// });
 190     /// ```
 191     ///
 192     /// Good:
 193     /// ```rust,ignore
 194     /// span_lint_and_sugg(
 195     ///     cx,
 196     ///     TEST_LINT,
 197     ///     expr.span,
 198     ///     lint_msg,
 199     ///     help_msg,
 200     ///     sugg.to_string(),
 201     ///     Applicability::MachineApplicable,
 202     /// );
 203     /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), help_msg);
 204     /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, None, help_msg);
 205     /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), note_msg);
 206     /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, None, note_msg);
 207     /// ```
 208     pub COLLAPSIBLE_SPAN_LINT_CALLS,
 209     internal,
 210     "found collapsible `span_lint_and_then` calls"
 211 }
 212
 213 declare_clippy_lint! {
 214     /// **What it does:** Checks for calls to `utils::match_type()` on a type diagnostic item
 215     /// and suggests to use `utils::is_type_diagnostic_item()` instead.
 216     ///
 217     /// **Why is this bad?** `utils::is_type_diagnostic_item()` does not require hardcoded paths.
 218     ///
 219     /// **Known problems:** None.
 220     ///
 221     /// **Example:**
 222     /// Bad:
 223     /// ```rust,ignore
 224     /// utils::match_type(cx, ty, &paths::VEC)
 225     /// ```
 226     ///
 227     /// Good:
 228     /// ```rust,ignore
 229     /// utils::is_type_diagnostic_item(cx, ty, sym::vec_type)
 230     /// ```
 231     pub MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
 232     internal,
 233     "using `utils::match_type()` instead of `utils::is_type_diagnostic_item()`"
 234 }
 235
 236 declare_clippy_lint! {
 237     /// **What it does:**
 238     /// Checks the paths module for invalid paths.
 239     ///
 240     /// **Why is this bad?**
 241     /// It indicates a bug in the code.
 242     ///
 243     /// **Known problems:** None.
 244     ///
 245     /// **Example:** None.
 246     pub INVALID_PATHS,
 247     internal,
 248     "invalid path"
 249 }
 250
 251 declare_clippy_lint! {
 252     /// **What it does:**
 253     /// Checks for interning symbols that have already been pre-interned and defined as constants.
 254     ///
 255     /// **Why is this bad?**
 256     /// It's faster and easier to use the symbol constant.
 257     ///
 258     /// **Known problems:** None.
 259     ///
 260     /// **Example:**
 261     /// Bad:
 262     /// ```rust,ignore
 263     /// let _ = sym!(f32);
 264     /// ```
 265     ///
 266     /// Good:
 267     /// ```rust,ignore
 268     /// let _ = sym::f32;
 269     /// ```
 270     pub INTERNING_DEFINED_SYMBOL,
 271     internal,
 272     "interning a symbol that is pre-interned and defined as a constant"
 273 }
 274
 275 declare_lint_pass!(ClippyLintsInternal => [CLIPPY_LINTS_INTERNAL]);
 276
 277 impl EarlyLintPass for ClippyLintsInternal {
 278     fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &AstCrate) {
 279         if let Some(utils) = krate
 280             .module
 281             .items
 282             .iter()
 283             .find(|item| item.ident.name.as_str() == "utils")
 284         {
 285             if let ItemKind::Mod(ref utils_mod) = utils.kind {
 286                 if let Some(paths) = utils_mod.items.iter().find(|item| item.ident.name.as_str() == "paths") {
 287                     if let ItemKind::Mod(ref paths_mod) = paths.kind {
 288                         let mut last_name: Option<SymbolStr> = None;
 289                         for item in &*paths_mod.items {
 290                             let name = item.ident.as_str();
 291                             if let Some(ref last_name) = last_name {
 292                                 if **last_name > *name {
 293                                     span_lint(
 294                                         cx,
 295                                         CLIPPY_LINTS_INTERNAL,
 296                                         item.span,
 297                                         "this constant should be before the previous constant due to lexical \
 298                                          ordering",
 299                                     );
 300                                 }
 301                             }
 302                             last_name = Some(name);
 303                         }
 304                     }
 305                 }
 306             }
 307         }
 308     }
 309 }
 310
 311 #[derive(Clone, Debug, Default)]
 312 pub struct LintWithoutLintPass {
 313     declared_lints: FxHashMap<Symbol, Span>,
 314     registered_lints: FxHashSet<Symbol>,
 315 }
 316
 317 impl_lint_pass!(LintWithoutLintPass => [DEFAULT_LINT, LINT_WITHOUT_LINT_PASS]);
 318
 319 impl<'tcx> LateLintPass<'tcx> for LintWithoutLintPass {
 320     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 321         if !run_lints(cx, &[DEFAULT_LINT], item.hir_id) {
 322             return;
 323         }
 324
 325         if let hir::ItemKind::Static(ref ty, Mutability::Not, body_id) = item.kind {
 326             if is_lint_ref_type(cx, ty) {
 327                 let expr = &cx.tcx.hir().body(body_id).value;
 328                 if_chain! {
 329                     if let ExprKind::AddrOf(_, _, ref inner_exp) = expr.kind;
 330                     if let ExprKind::Struct(_, ref fields, _) = inner_exp.kind;
 331                     let field = fields
 332                         .iter()
 333                         .find(|f| f.ident.as_str() == "desc")
 334                         .expect("lints must have a description field");
 335                     if let ExprKind::Lit(Spanned {
 336                         node: LitKind::Str(ref sym, _),
 337                         ..
 338                     }) = field.expr.kind;
 339                     if sym.as_str() == "default lint description";
 340
 341                     then {
 342                         span_lint(
 343                             cx,
 344                             DEFAULT_LINT,
 345                             item.span,
 346                             &format!("the lint `{}` has the default lint description", item.ident.name),
 347                         );
 348                     }
 349                 }
 350                 self.declared_lints.insert(item.ident.name, item.span);
 351             }
 352         } else if is_expn_of(item.span, "impl_lint_pass").is_some()
 353             || is_expn_of(item.span, "declare_lint_pass").is_some()
 354         {
 355             if let hir::ItemKind::Impl {
 356                 of_trait: None,
 357                 items: ref impl_item_refs,
 358                 ..
 359             } = item.kind
 360             {
 361                 let mut collector = LintCollector {
 362                     output: &mut self.registered_lints,
 363                     cx,
 364                 };
 365                 let body_id = cx.tcx.hir().body_owned_by(
 366                     impl_item_refs
 367                         .iter()
 368                         .find(|iiref| iiref.ident.as_str() == "get_lints")
 369                         .expect("LintPass needs to implement get_lints")
 370                         .id
 371                         .hir_id,
 372                 );
 373                 collector.visit_expr(&cx.tcx.hir().body(body_id).value);
 374             }
 375         }
 376     }
 377
 378     fn check_crate_post(&mut self, cx: &LateContext<'tcx>, _: &'tcx Crate<'_>) {
 379         if !run_lints(cx, &[LINT_WITHOUT_LINT_PASS], CRATE_HIR_ID) {
 380             return;
 381         }
 382
 383         for (lint_name, &lint_span) in &self.declared_lints {
 384             // When using the `declare_tool_lint!` macro, the original `lint_span`'s
 385             // file points to "<rustc macros>".
 386             // `compiletest-rs` thinks that's an error in a different file and
 387             // just ignores it. This causes the test in compile-fail/lint_pass
 388             // not able to capture the error.
 389             // Therefore, we need to climb the macro expansion tree and find the
 390             // actual span that invoked `declare_tool_lint!`:
 391             let lint_span = lint_span.ctxt().outer_expn_data().call_site;
 392
 393             if !self.registered_lints.contains(lint_name) {
 394                 span_lint(
 395                     cx,
 396                     LINT_WITHOUT_LINT_PASS,
 397                     lint_span,
 398                     &format!("the lint `{}` is not added to any `LintPass`", lint_name),
 399                 );
 400             }
 401         }
 402     }
 403 }
 404
 405 fn is_lint_ref_type<'tcx>(cx: &LateContext<'tcx>, ty: &Ty<'_>) -> bool {
 406     if let TyKind::Rptr(
 407         _,
 408         MutTy {
 409             ty: ref inner,
 410             mutbl: Mutability::Not,
 411         },
 412     ) = ty.kind
 413     {
 414         if let TyKind::Path(ref path) = inner.kind {
 415             if let Res::Def(DefKind::Struct, def_id) = cx.qpath_res(path, inner.hir_id) {
 416                 return match_def_path(cx, def_id, &paths::LINT);
 417             }
 418         }
 419     }
 420
 421     false
 422 }
 423
 424 struct LintCollector<'a, 'tcx> {
 425     output: &'a mut FxHashSet<Symbol>,
 426     cx: &'a LateContext<'tcx>,
 427 }
 428
 429 impl<'a, 'tcx> Visitor<'tcx> for LintCollector<'a, 'tcx> {
 430     type Map = Map<'tcx>;
 431
 432     fn visit_path(&mut self, path: &'tcx Path<'_>, _: HirId) {
 433         if path.segments.len() == 1 {
 434             self.output.insert(path.segments[0].ident.name);
 435         }
 436     }
 437
 438     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
 439         NestedVisitorMap::All(self.cx.tcx.hir())
 440     }
 441 }
 442
 443 #[derive(Clone, Default)]
 444 pub struct CompilerLintFunctions {
 445     map: FxHashMap<&'static str, &'static str>,
 446 }
 447
 448 impl CompilerLintFunctions {
 449     #[must_use]
 450     pub fn new() -> Self {
 451         let mut map = FxHashMap::default();
 452         map.insert("span_lint", "utils::span_lint");
 453         map.insert("struct_span_lint", "utils::span_lint");
 454         map.insert("lint", "utils::span_lint");
 455         map.insert("span_lint_note", "utils::span_lint_and_note");
 456         map.insert("span_lint_help", "utils::span_lint_and_help");
 457         Self { map }
 458     }
 459 }
 460
 461 impl_lint_pass!(CompilerLintFunctions => [COMPILER_LINT_FUNCTIONS]);
 462
 463 impl<'tcx> LateLintPass<'tcx> for CompilerLintFunctions {
 464     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 465         if !run_lints(cx, &[COMPILER_LINT_FUNCTIONS], expr.hir_id) {
 466             return;
 467         }
 468
 469         if_chain! {
 470             if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind;
 471             let fn_name = path.ident;
 472             if let Some(sugg) = self.map.get(&*fn_name.as_str());
 473             let ty = cx.typeck_results().expr_ty(&args[0]).peel_refs();
 474             if match_type(cx, ty, &paths::EARLY_CONTEXT)
 475                 || match_type(cx, ty, &paths::LATE_CONTEXT);
 476             then {
 477                 span_lint_and_help(
 478                     cx,
 479                     COMPILER_LINT_FUNCTIONS,
 480                     path.ident.span,
 481                     "usage of a compiler lint function",
 482                     None,
 483                     &format!("please use the Clippy variant of this function: `{}`", sugg),
 484                 );
 485             }
 486         }
 487     }
 488 }
 489
 490 declare_lint_pass!(OuterExpnDataPass => [OUTER_EXPN_EXPN_DATA]);
 491
 492 impl<'tcx> LateLintPass<'tcx> for OuterExpnDataPass {
 493     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 494         if !run_lints(cx, &[OUTER_EXPN_EXPN_DATA], expr.hir_id) {
 495             return;
 496         }
 497
 498         let (method_names, arg_lists, spans) = method_calls(expr, 2);
 499         let method_names: Vec<SymbolStr> = method_names.iter().map(|s| s.as_str()).collect();
 500         let method_names: Vec<&str> = method_names.iter().map(|s| &**s).collect();
 501         if_chain! {
 502             if let ["expn_data", "outer_expn"] = method_names.as_slice();
 503             let args = arg_lists[1];
 504             if args.len() == 1;
 505             let self_arg = &args[0];
 506             let self_ty = cx.typeck_results().expr_ty(self_arg).peel_refs();
 507             if match_type(cx, self_ty, &paths::SYNTAX_CONTEXT);
 508             then {
 509                 span_lint_and_sugg(
 510                     cx,
 511                     OUTER_EXPN_EXPN_DATA,
 512                     spans[1].with_hi(expr.span.hi()),
 513                     "usage of `outer_expn().expn_data()`",
 514                     "try",
 515                     "outer_expn_data()".to_string(),
 516                     Applicability::MachineApplicable,
 517                 );
 518             }
 519         }
 520     }
 521 }
 522
 523 declare_lint_pass!(ProduceIce => [PRODUCE_ICE]);
 524
 525 impl EarlyLintPass for ProduceIce {
 526     fn check_fn(&mut self, _: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
 527         if is_trigger_fn(fn_kind) {
 528             panic!("Would you like some help with that?");
 529         }
 530     }
 531 }
 532
 533 fn is_trigger_fn(fn_kind: FnKind<'_>) -> bool {
 534     match fn_kind {
 535         FnKind::Fn(_, ident, ..) => ident.name.as_str() == "it_looks_like_you_are_trying_to_kill_clippy",
 536         FnKind::Closure(..) => false,
 537     }
 538 }
 539
 540 declare_lint_pass!(CollapsibleCalls => [COLLAPSIBLE_SPAN_LINT_CALLS]);
 541
 542 impl<'tcx> LateLintPass<'tcx> for CollapsibleCalls {
 543     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 544         if !run_lints(cx, &[COLLAPSIBLE_SPAN_LINT_CALLS], expr.hir_id) {
 545             return;
 546         }
 547
 548         if_chain! {
 549             if let ExprKind::Call(ref func, ref and_then_args) = expr.kind;
 550             if let ExprKind::Path(ref path) = func.kind;
 551             if match_qpath(path, &["span_lint_and_then"]);
 552             if and_then_args.len() == 5;
 553             if let ExprKind::Closure(_, _, body_id, _, _) = &and_then_args[4].kind;
 554             let body = cx.tcx.hir().body(*body_id);
 555             if let ExprKind::Block(block, _) = &body.value.kind;
 556             let stmts = &block.stmts;
 557             if stmts.len() == 1 && block.expr.is_none();
 558             if let StmtKind::Semi(only_expr) = &stmts[0].kind;
 559             if let ExprKind::MethodCall(ref ps, _, ref span_call_args, _) = &only_expr.kind;
 560             let and_then_snippets = get_and_then_snippets(cx, and_then_args);
 561             let mut sle = SpanlessEq::new(cx).deny_side_effects();
 562             then {
 563                 match &*ps.ident.as_str() {
 564                     "span_suggestion" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 565                         suggest_suggestion(cx, expr, &and_then_snippets, &span_suggestion_snippets(cx, span_call_args));
 566                     },
 567                     "span_help" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 568                         let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 569                         suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), true);
 570                     },
 571                     "span_note" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 572                         let note_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 573                         suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), true);
 574                     },
 575                     "help" => {
 576                         let help_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
 577                         suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), false);
 578                     }
 579                     "note" => {
 580                         let note_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
 581                         suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), false);
 582                     }
 583                     _  => (),
 584                 }
 585             }
 586         }
 587     }
 588 }
 589
 590 struct AndThenSnippets<'a> {
 591     cx: Cow<'a, str>,
 592     lint: Cow<'a, str>,
 593     span: Cow<'a, str>,
 594     msg: Cow<'a, str>,
 595 }
 596
 597 fn get_and_then_snippets<'a, 'hir>(cx: &LateContext<'_>, and_then_snippets: &'hir [Expr<'hir>]) -> AndThenSnippets<'a> {
 598     let cx_snippet = snippet(cx, and_then_snippets[0].span, "cx");
 599     let lint_snippet = snippet(cx, and_then_snippets[1].span, "..");
 600     let span_snippet = snippet(cx, and_then_snippets[2].span, "span");
 601     let msg_snippet = snippet(cx, and_then_snippets[3].span, r#""...""#);
 602
 603     AndThenSnippets {
 604         cx: cx_snippet,
 605         lint: lint_snippet,
 606         span: span_snippet,
 607         msg: msg_snippet,
 608     }
 609 }
 610
 611 struct SpanSuggestionSnippets<'a> {
 612     help: Cow<'a, str>,
 613     sugg: Cow<'a, str>,
 614     applicability: Cow<'a, str>,
 615 }
 616
 617 fn span_suggestion_snippets<'a, 'hir>(
 618     cx: &LateContext<'_>,
 619     span_call_args: &'hir [Expr<'hir>],
 620 ) -> SpanSuggestionSnippets<'a> {
 621     let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 622     let sugg_snippet = snippet(cx, span_call_args[3].span, "..");
 623     let applicability_snippet = snippet(cx, span_call_args[4].span, "Applicability::MachineApplicable");
 624
 625     SpanSuggestionSnippets {
 626         help: help_snippet,
 627         sugg: sugg_snippet,
 628         applicability: applicability_snippet,
 629     }
 630 }
 631
 632 fn suggest_suggestion(
 633     cx: &LateContext<'_>,
 634     expr: &Expr<'_>,
 635     and_then_snippets: &AndThenSnippets<'_>,
 636     span_suggestion_snippets: &SpanSuggestionSnippets<'_>,
 637 ) {
 638     span_lint_and_sugg(
 639         cx,
 640         COLLAPSIBLE_SPAN_LINT_CALLS,
 641         expr.span,
 642         "this call is collapsible",
 643         "collapse into",
 644         format!(
 645             "span_lint_and_sugg({}, {}, {}, {}, {}, {}, {})",
 646             and_then_snippets.cx,
 647             and_then_snippets.lint,
 648             and_then_snippets.span,
 649             and_then_snippets.msg,
 650             span_suggestion_snippets.help,
 651             span_suggestion_snippets.sugg,
 652             span_suggestion_snippets.applicability
 653         ),
 654         Applicability::MachineApplicable,
 655     );
 656 }
 657
 658 fn suggest_help(
 659     cx: &LateContext<'_>,
 660     expr: &Expr<'_>,
 661     and_then_snippets: &AndThenSnippets<'_>,
 662     help: &str,
 663     with_span: bool,
 664 ) {
 665     let option_span = if with_span {
 666         format!("Some({})", and_then_snippets.span)
 667     } else {
 668         "None".to_string()
 669     };
 670
 671     span_lint_and_sugg(
 672         cx,
 673         COLLAPSIBLE_SPAN_LINT_CALLS,
 674         expr.span,
 675         "this call is collapsible",
 676         "collapse into",
 677         format!(
 678             "span_lint_and_help({}, {}, {}, {}, {}, {})",
 679             and_then_snippets.cx,
 680             and_then_snippets.lint,
 681             and_then_snippets.span,
 682             and_then_snippets.msg,
 683             &option_span,
 684             help
 685         ),
 686         Applicability::MachineApplicable,
 687     );
 688 }
 689
 690 fn suggest_note(
 691     cx: &LateContext<'_>,
 692     expr: &Expr<'_>,
 693     and_then_snippets: &AndThenSnippets<'_>,
 694     note: &str,
 695     with_span: bool,
 696 ) {
 697     let note_span = if with_span {
 698         format!("Some({})", and_then_snippets.span)
 699     } else {
 700         "None".to_string()
 701     };
 702
 703     span_lint_and_sugg(
 704         cx,
 705         COLLAPSIBLE_SPAN_LINT_CALLS,
 706         expr.span,
 707         "this call is collspible",
 708         "collapse into",
 709         format!(
 710             "span_lint_and_note({}, {}, {}, {}, {}, {})",
 711             and_then_snippets.cx,
 712             and_then_snippets.lint,
 713             and_then_snippets.span,
 714             and_then_snippets.msg,
 715             note_span,
 716             note
 717         ),
 718         Applicability::MachineApplicable,
 719     );
 720 }
 721
 722 declare_lint_pass!(MatchTypeOnDiagItem => [MATCH_TYPE_ON_DIAGNOSTIC_ITEM]);
 723
 724 impl<'tcx> LateLintPass<'tcx> for MatchTypeOnDiagItem {
 725     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 726         if !run_lints(cx, &[MATCH_TYPE_ON_DIAGNOSTIC_ITEM], expr.hir_id) {
 727             return;
 728         }
 729
 730         if_chain! {
 731             // Check if this is a call to utils::match_type()
 732             if let ExprKind::Call(fn_path, [context, ty, ty_path]) = expr.kind;
 733             if let ExprKind::Path(fn_qpath) = &fn_path.kind;
 734             if match_qpath(&fn_qpath, &["utils", "match_type"]);
 735             // Extract the path to the matched type
 736             if let Some(segments) = path_to_matched_type(cx, ty_path);
 737             let segments: Vec<&str> = segments.iter().map(|sym| &**sym).collect();
 738             if let Some(ty_did) = path_to_res(cx, &segments[..]).and_then(|res| res.opt_def_id());
 739             // Check if the matched type is a diagnostic item
 740             let diag_items = cx.tcx.diagnostic_items(ty_did.krate);
 741             if let Some(item_name) = diag_items.iter().find_map(|(k, v)| if *v == ty_did { Some(k) } else { None });
 742             then {
 743                 let cx_snippet = snippet(cx, context.span, "_");
 744                 let ty_snippet = snippet(cx, ty.span, "_");
 745
 746                 span_lint_and_sugg(
 747                     cx,
 748                     MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
 749                     expr.span,
 750                     "usage of `utils::match_type()` on a type diagnostic item",
 751                     "try",
 752                     format!("utils::is_type_diagnostic_item({}, {}, sym::{})", cx_snippet, ty_snippet, item_name),
 753                     Applicability::MaybeIncorrect,
 754                 );
 755             }
 756         }
 757     }
 758 }
 759
 760 fn path_to_matched_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Vec<SymbolStr>> {
 761     use rustc_hir::ItemKind;
 762
 763     match &expr.kind {
 764         ExprKind::AddrOf(.., expr) => return path_to_matched_type(cx, expr),
 765         ExprKind::Path(qpath) => match qpath_res(cx, qpath, expr.hir_id) {
 766             Res::Local(hir_id) => {
 767                 let parent_id = cx.tcx.hir().get_parent_node(hir_id);
 768                 if let Some(Node::Local(local)) = cx.tcx.hir().find(parent_id) {
 769                     if let Some(init) = local.init {
 770                         return path_to_matched_type(cx, init);
 771                     }
 772                 }
 773             },
 774             Res::Def(DefKind::Const | DefKind::Static, def_id) => {
 775                 if let Some(Node::Item(item)) = cx.tcx.hir().get_if_local(def_id) {
 776                     if let ItemKind::Const(.., body_id) | ItemKind::Static(.., body_id) = item.kind {
 777                         let body = cx.tcx.hir().body(body_id);
 778                         return path_to_matched_type(cx, &body.value);
 779                     }
 780                 }
 781             },
 782             _ => {},
 783         },
 784         ExprKind::Array(exprs) => {
 785             let segments: Vec<SymbolStr> = exprs
 786                 .iter()
 787                 .filter_map(|expr| {
 788                     if let ExprKind::Lit(lit) = &expr.kind {
 789                         if let LitKind::Str(sym, _) = lit.node {
 790                             return Some(sym.as_str());
 791                         }
 792                     }
 793
 794                     None
 795                 })
 796                 .collect();
 797
 798             if segments.len() == exprs.len() {
 799                 return Some(segments);
 800             }
 801         },
 802         _ => {},
 803     }
 804
 805     None
 806 }
 807
 808 // This is not a complete resolver for paths. It works on all the paths currently used in the paths
 809 // module.  That's all it does and all it needs to do.
 810 pub fn check_path(cx: &LateContext<'_>, path: &[&str]) -> bool {
 811     if path_to_res(cx, path).is_some() {
 812         return true;
 813     }
 814
 815     // Some implementations can't be found by `path_to_res`, particularly inherent
 816     // implementations of native types. Check lang items.
 817     let path_syms: Vec<_> = path.iter().map(|p| Symbol::intern(p)).collect();
 818     let lang_items = cx.tcx.lang_items();
 819     for lang_item in lang_items.items() {
 820         if let Some(def_id) = lang_item {
 821             let lang_item_path = cx.get_def_path(*def_id);
 822             if path_syms.starts_with(&lang_item_path) {
 823                 if let [item] = &path_syms[lang_item_path.len()..] {
 824                     for child in cx.tcx.item_children(*def_id) {
 825                         if child.ident.name == *item {
 826                             return true;
 827                         }
 828                     }
 829                 }
 830             }
 831         }
 832     }
 833
 834     false
 835 }
 836
 837 declare_lint_pass!(InvalidPaths => [INVALID_PATHS]);
 838
 839 impl<'tcx> LateLintPass<'tcx> for InvalidPaths {
 840     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 841         let local_def_id = &cx.tcx.parent_module(item.hir_id);
 842         let mod_name = &cx.tcx.item_name(local_def_id.to_def_id());
 843         if_chain! {
 844             if mod_name.as_str() == "paths";
 845             if let hir::ItemKind::Const(ty, body_id) = item.kind;
 846             let ty = hir_ty_to_ty(cx.tcx, ty);
 847             if let ty::Array(el_ty, _) = &ty.kind();
 848             if let ty::Ref(_, el_ty, _) = &el_ty.kind();
 849             if el_ty.is_str();
 850             let body = cx.tcx.hir().body(body_id);
 851             let typeck_results = cx.tcx.typeck_body(body_id);
 852             if let Some(Constant::Vec(path)) = constant_simple(cx, typeck_results, &body.value);
 853             let path: Vec<&str> = path.iter().map(|x| {
 854                     if let Constant::Str(s) = x {
 855                         s.as_str()
 856                     } else {
 857                         // We checked the type of the constant above
 858                         unreachable!()
 859                     }
 860                 }).collect();
 861             if !check_path(cx, &path[..]);
 862             then {
 863                 span_lint(cx, CLIPPY_LINTS_INTERNAL, item.span, "invalid path");
 864             }
 865         }
 866     }
 867 }
 868
 869 #[derive(Default)]
 870 pub struct InterningDefinedSymbol {
 871     // Maps the symbol value to the constant name.
 872     symbol_map: FxHashMap<u32, String>,
 873 }
 874
 875 impl_lint_pass!(InterningDefinedSymbol => [INTERNING_DEFINED_SYMBOL]);
 876
 877 impl<'tcx> LateLintPass<'tcx> for InterningDefinedSymbol {
 878     fn check_crate(&mut self, cx: &LateContext<'_>, _: &Crate<'_>) {
 879         if !self.symbol_map.is_empty() {
 880             return;
 881         }
 882
 883         if let Some(Res::Def(_, def_id)) = path_to_res(cx, &paths::SYM_MODULE) {
 884             for item in cx.tcx.item_children(def_id).iter() {
 885                 if_chain! {
 886                     if let Res::Def(DefKind::Const, item_def_id) = item.res;
 887                     let ty = cx.tcx.type_of(item_def_id);
 888                     if match_type(cx, ty, &paths::SYMBOL);
 889                     if let Ok(ConstValue::Scalar(value)) = cx.tcx.const_eval_poly(item_def_id);
 890                     if let Ok(value) = value.to_u32();
 891                     then {
 892                         self.symbol_map.insert(value, item.ident.to_string());
 893                     }
 894                 }
 895             }
 896         }
 897     }
 898
 899     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 900         if_chain! {
 901             if let ExprKind::Call(func, [arg]) = &expr.kind;
 902             if let ty::FnDef(def_id, _) = cx.typeck_results().expr_ty(func).kind();
 903             if match_def_path(cx, *def_id, &paths::SYMBOL_INTERN);
 904             if let Some(Constant::Str(arg)) = constant_simple(cx, cx.typeck_results(), arg);
 905             let value = Symbol::intern(&arg).as_u32();
 906             if let Some(symbol_const) = self.symbol_map.get(&value);
 907             then {
 908                 span_lint_and_sugg(
 909                     cx,
 910                     INTERNING_DEFINED_SYMBOL,
 911                     is_expn_of(expr.span, "sym").unwrap_or(expr.span),
 912                     "interning a defined symbol",
 913                     "try",
 914                     format!("rustc_span::symbol::sym::{}", symbol_const),
 915                     Applicability::MachineApplicable,
 916                 );
 917             }
 918         }
 919     }
 920 }