src/tools/clippy/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, run_lints, snippet,
   4     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::def_id::DefId;
  14 use rustc_hir::hir_id::CRATE_HIR_ID;
  15 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
  16 use rustc_hir::{
  17     BinOpKind, Crate, Expr, ExprKind, HirId, Item, MutTy, Mutability, Node, Path, StmtKind, Ty, TyKind, UnOp,
  18 };
  19 use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass};
  20 use rustc_middle::hir::map::Map;
  21 use rustc_middle::mir::interpret::ConstValue;
  22 use rustc_middle::ty;
  23 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
  24 use rustc_span::source_map::{Span, Spanned};
  25 use rustc_span::symbol::{Symbol, SymbolStr};
  26 use rustc_typeck::hir_ty_to_ty;
  27
  28 use std::borrow::{Borrow, Cow};
  29
  30 declare_clippy_lint! {
  31     /// **What it does:** Checks for various things we like to keep tidy in clippy.
  32     ///
  33     /// **Why is this bad?** We like to pretend we're an example of tidy code.
  34     ///
  35     /// **Known problems:** None.
  36     ///
  37     /// **Example:** Wrong ordering of the util::paths constants.
  38     pub CLIPPY_LINTS_INTERNAL,
  39     internal,
  40     "various things that will negatively affect your clippy experience"
  41 }
  42
  43 declare_clippy_lint! {
  44     /// **What it does:** Ensures every lint is associated to a `LintPass`.
  45     ///
  46     /// **Why is this bad?** The compiler only knows lints via a `LintPass`. Without
  47     /// putting a lint to a `LintPass::get_lints()`'s return, the compiler will not
  48     /// know the name of the lint.
  49     ///
  50     /// **Known problems:** Only checks for lints associated using the
  51     /// `declare_lint_pass!`, `impl_lint_pass!`, and `lint_array!` macros.
  52     ///
  53     /// **Example:**
  54     /// ```rust,ignore
  55     /// declare_lint! { pub LINT_1, ... }
  56     /// declare_lint! { pub LINT_2, ... }
  57     /// declare_lint! { pub FORGOTTEN_LINT, ... }
  58     /// // ...
  59     /// declare_lint_pass!(Pass => [LINT_1, LINT_2]);
  60     /// // missing FORGOTTEN_LINT
  61     /// ```
  62     pub LINT_WITHOUT_LINT_PASS,
  63     internal,
  64     "declaring a lint without associating it in a LintPass"
  65 }
  66
  67 declare_clippy_lint! {
  68     /// **What it does:** Checks for calls to `cx.span_lint*` and suggests to use the `utils::*`
  69     /// variant of the function.
  70     ///
  71     /// **Why is this bad?** The `utils::*` variants also add a link to the Clippy documentation to the
  72     /// warning/error messages.
  73     ///
  74     /// **Known problems:** None.
  75     ///
  76     /// **Example:**
  77     /// Bad:
  78     /// ```rust,ignore
  79     /// cx.span_lint(LINT_NAME, "message");
  80     /// ```
  81     ///
  82     /// Good:
  83     /// ```rust,ignore
  84     /// utils::span_lint(cx, LINT_NAME, "message");
  85     /// ```
  86     pub COMPILER_LINT_FUNCTIONS,
  87     internal,
  88     "usage of the lint functions of the compiler instead of the utils::* variant"
  89 }
  90
  91 declare_clippy_lint! {
  92     /// **What it does:** Checks for calls to `cx.outer().expn_data()` and suggests to use
  93     /// the `cx.outer_expn_data()`
  94     ///
  95     /// **Why is this bad?** `cx.outer_expn_data()` is faster and more concise.
  96     ///
  97     /// **Known problems:** None.
  98     ///
  99     /// **Example:**
 100     /// Bad:
 101     /// ```rust,ignore
 102     /// expr.span.ctxt().outer().expn_data()
 103     /// ```
 104     ///
 105     /// Good:
 106     /// ```rust,ignore
 107     /// expr.span.ctxt().outer_expn_data()
 108     /// ```
 109     pub OUTER_EXPN_EXPN_DATA,
 110     internal,
 111     "using `cx.outer_expn().expn_data()` instead of `cx.outer_expn_data()`"
 112 }
 113
 114 declare_clippy_lint! {
 115     /// **What it does:** Not an actual lint. This lint is only meant for testing our customized internal compiler
 116     /// error message by calling `panic`.
 117     ///
 118     /// **Why is this bad?** ICE in large quantities can damage your teeth
 119     ///
 120     /// **Known problems:** None
 121     ///
 122     /// **Example:**
 123     /// Bad:
 124     /// ```rust,ignore
 125     /// 🍦🍦🍦🍦🍦
 126     /// ```
 127     pub PRODUCE_ICE,
 128     internal,
 129     "this message should not appear anywhere as we ICE before and don't emit the lint"
 130 }
 131
 132 declare_clippy_lint! {
 133     /// **What it does:** Checks for cases of an auto-generated lint without an updated description,
 134     /// i.e. `default lint description`.
 135     ///
 136     /// **Why is this bad?** Indicates that the lint is not finished.
 137     ///
 138     /// **Known problems:** None
 139     ///
 140     /// **Example:**
 141     /// Bad:
 142     /// ```rust,ignore
 143     /// declare_lint! { pub COOL_LINT, nursery, "default lint description" }
 144     /// ```
 145     ///
 146     /// Good:
 147     /// ```rust,ignore
 148     /// declare_lint! { pub COOL_LINT, nursery, "a great new lint" }
 149     /// ```
 150     pub DEFAULT_LINT,
 151     internal,
 152     "found 'default lint description' in a lint declaration"
 153 }
 154
 155 declare_clippy_lint! {
 156     /// **What it does:** Lints `span_lint_and_then` function calls, where the
 157     /// closure argument has only one statement and that statement is a method
 158     /// call to `span_suggestion`, `span_help`, `span_note` (using the same
 159     /// span), `help` or `note`.
 160     ///
 161     /// These usages of `span_lint_and_then` should be replaced with one of the
 162     /// wrapper functions `span_lint_and_sugg`, span_lint_and_help`, or
 163     /// `span_lint_and_note`.
 164     ///
 165     /// **Why is this bad?** Using the wrapper `span_lint_and_*` functions, is more
 166     /// convenient, readable and less error prone.
 167     ///
 168     /// **Known problems:** None
 169     ///
 170     /// *Example:**
 171     /// Bad:
 172     /// ```rust,ignore
 173     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 174     ///     diag.span_suggestion(
 175     ///         expr.span,
 176     ///         help_msg,
 177     ///         sugg.to_string(),
 178     ///         Applicability::MachineApplicable,
 179     ///     );
 180     /// });
 181     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 182     ///     diag.span_help(expr.span, help_msg);
 183     /// });
 184     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 185     ///     diag.help(help_msg);
 186     /// });
 187     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 188     ///     diag.span_note(expr.span, note_msg);
 189     /// });
 190     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 191     ///     diag.note(note_msg);
 192     /// });
 193     /// ```
 194     ///
 195     /// Good:
 196     /// ```rust,ignore
 197     /// span_lint_and_sugg(
 198     ///     cx,
 199     ///     TEST_LINT,
 200     ///     expr.span,
 201     ///     lint_msg,
 202     ///     help_msg,
 203     ///     sugg.to_string(),
 204     ///     Applicability::MachineApplicable,
 205     /// );
 206     /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), help_msg);
 207     /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, None, help_msg);
 208     /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), note_msg);
 209     /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, None, note_msg);
 210     /// ```
 211     pub COLLAPSIBLE_SPAN_LINT_CALLS,
 212     internal,
 213     "found collapsible `span_lint_and_then` calls"
 214 }
 215
 216 declare_clippy_lint! {
 217     /// **What it does:** Checks for calls to `utils::match_type()` on a type diagnostic item
 218     /// and suggests to use `utils::is_type_diagnostic_item()` instead.
 219     ///
 220     /// **Why is this bad?** `utils::is_type_diagnostic_item()` does not require hardcoded paths.
 221     ///
 222     /// **Known problems:** None.
 223     ///
 224     /// **Example:**
 225     /// Bad:
 226     /// ```rust,ignore
 227     /// utils::match_type(cx, ty, &paths::VEC)
 228     /// ```
 229     ///
 230     /// Good:
 231     /// ```rust,ignore
 232     /// utils::is_type_diagnostic_item(cx, ty, sym::vec_type)
 233     /// ```
 234     pub MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
 235     internal,
 236     "using `utils::match_type()` instead of `utils::is_type_diagnostic_item()`"
 237 }
 238
 239 declare_clippy_lint! {
 240     /// **What it does:**
 241     /// Checks the paths module for invalid paths.
 242     ///
 243     /// **Why is this bad?**
 244     /// It indicates a bug in the code.
 245     ///
 246     /// **Known problems:** None.
 247     ///
 248     /// **Example:** None.
 249     pub INVALID_PATHS,
 250     internal,
 251     "invalid path"
 252 }
 253
 254 declare_clippy_lint! {
 255     /// **What it does:**
 256     /// Checks for interning symbols that have already been pre-interned and defined as constants.
 257     ///
 258     /// **Why is this bad?**
 259     /// It's faster and easier to use the symbol constant.
 260     ///
 261     /// **Known problems:** None.
 262     ///
 263     /// **Example:**
 264     /// Bad:
 265     /// ```rust,ignore
 266     /// let _ = sym!(f32);
 267     /// ```
 268     ///
 269     /// Good:
 270     /// ```rust,ignore
 271     /// let _ = sym::f32;
 272     /// ```
 273     pub INTERNING_DEFINED_SYMBOL,
 274     internal,
 275     "interning a symbol that is pre-interned and defined as a constant"
 276 }
 277
 278 declare_clippy_lint! {
 279     /// **What it does:** Checks for unnecessary conversion from Symbol to a string.
 280     ///
 281     /// **Why is this bad?** It's faster use symbols directly intead of strings.
 282     ///
 283     /// **Known problems:** None.
 284     ///
 285     /// **Example:**
 286     /// Bad:
 287     /// ```rust,ignore
 288     /// symbol.as_str() == "clippy";
 289     /// ```
 290     ///
 291     /// Good:
 292     /// ```rust,ignore
 293     /// symbol == sym::clippy;
 294     /// ```
 295     pub UNNECESSARY_SYMBOL_STR,
 296     internal,
 297     "unnecessary conversion between Symbol and string"
 298 }
 299
 300 declare_lint_pass!(ClippyLintsInternal => [CLIPPY_LINTS_INTERNAL]);
 301
 302 impl EarlyLintPass for ClippyLintsInternal {
 303     fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &AstCrate) {
 304         if let Some(utils) = krate
 305             .module
 306             .items
 307             .iter()
 308             .find(|item| item.ident.name.as_str() == "utils")
 309         {
 310             if let ItemKind::Mod(ref utils_mod) = utils.kind {
 311                 if let Some(paths) = utils_mod.items.iter().find(|item| item.ident.name.as_str() == "paths") {
 312                     if let ItemKind::Mod(ref paths_mod) = paths.kind {
 313                         let mut last_name: Option<SymbolStr> = None;
 314                         for item in &*paths_mod.items {
 315                             let name = item.ident.as_str();
 316                             if let Some(ref last_name) = last_name {
 317                                 if **last_name > *name {
 318                                     span_lint(
 319                                         cx,
 320                                         CLIPPY_LINTS_INTERNAL,
 321                                         item.span,
 322                                         "this constant should be before the previous constant due to lexical \
 323                                          ordering",
 324                                     );
 325                                 }
 326                             }
 327                             last_name = Some(name);
 328                         }
 329                     }
 330                 }
 331             }
 332         }
 333     }
 334 }
 335
 336 #[derive(Clone, Debug, Default)]
 337 pub struct LintWithoutLintPass {
 338     declared_lints: FxHashMap<Symbol, Span>,
 339     registered_lints: FxHashSet<Symbol>,
 340 }
 341
 342 impl_lint_pass!(LintWithoutLintPass => [DEFAULT_LINT, LINT_WITHOUT_LINT_PASS]);
 343
 344 impl<'tcx> LateLintPass<'tcx> for LintWithoutLintPass {
 345     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 346         if !run_lints(cx, &[DEFAULT_LINT], item.hir_id) {
 347             return;
 348         }
 349
 350         if let hir::ItemKind::Static(ref ty, Mutability::Not, body_id) = item.kind {
 351             if is_lint_ref_type(cx, ty) {
 352                 let expr = &cx.tcx.hir().body(body_id).value;
 353                 if_chain! {
 354                     if let ExprKind::AddrOf(_, _, ref inner_exp) = expr.kind;
 355                     if let ExprKind::Struct(_, ref fields, _) = inner_exp.kind;
 356                     let field = fields
 357                         .iter()
 358                         .find(|f| f.ident.as_str() == "desc")
 359                         .expect("lints must have a description field");
 360                     if let ExprKind::Lit(Spanned {
 361                         node: LitKind::Str(ref sym, _),
 362                         ..
 363                     }) = field.expr.kind;
 364                     if sym.as_str() == "default lint description";
 365
 366                     then {
 367                         span_lint(
 368                             cx,
 369                             DEFAULT_LINT,
 370                             item.span,
 371                             &format!("the lint `{}` has the default lint description", item.ident.name),
 372                         );
 373                     }
 374                 }
 375                 self.declared_lints.insert(item.ident.name, item.span);
 376             }
 377         } else if is_expn_of(item.span, "impl_lint_pass").is_some()
 378             || is_expn_of(item.span, "declare_lint_pass").is_some()
 379         {
 380             if let hir::ItemKind::Impl(hir::Impl {
 381                 of_trait: None,
 382                 items: ref impl_item_refs,
 383                 ..
 384             }) = item.kind
 385             {
 386                 let mut collector = LintCollector {
 387                     output: &mut self.registered_lints,
 388                     cx,
 389                 };
 390                 let body_id = cx.tcx.hir().body_owned_by(
 391                     impl_item_refs
 392                         .iter()
 393                         .find(|iiref| iiref.ident.as_str() == "get_lints")
 394                         .expect("LintPass needs to implement get_lints")
 395                         .id
 396                         .hir_id,
 397                 );
 398                 collector.visit_expr(&cx.tcx.hir().body(body_id).value);
 399             }
 400         }
 401     }
 402
 403     fn check_crate_post(&mut self, cx: &LateContext<'tcx>, _: &'tcx Crate<'_>) {
 404         if !run_lints(cx, &[LINT_WITHOUT_LINT_PASS], CRATE_HIR_ID) {
 405             return;
 406         }
 407
 408         for (lint_name, &lint_span) in &self.declared_lints {
 409             // When using the `declare_tool_lint!` macro, the original `lint_span`'s
 410             // file points to "<rustc macros>".
 411             // `compiletest-rs` thinks that's an error in a different file and
 412             // just ignores it. This causes the test in compile-fail/lint_pass
 413             // not able to capture the error.
 414             // Therefore, we need to climb the macro expansion tree and find the
 415             // actual span that invoked `declare_tool_lint!`:
 416             let lint_span = lint_span.ctxt().outer_expn_data().call_site;
 417
 418             if !self.registered_lints.contains(lint_name) {
 419                 span_lint(
 420                     cx,
 421                     LINT_WITHOUT_LINT_PASS,
 422                     lint_span,
 423                     &format!("the lint `{}` is not added to any `LintPass`", lint_name),
 424                 );
 425             }
 426         }
 427     }
 428 }
 429
 430 fn is_lint_ref_type<'tcx>(cx: &LateContext<'tcx>, ty: &Ty<'_>) -> bool {
 431     if let TyKind::Rptr(
 432         _,
 433         MutTy {
 434             ty: ref inner,
 435             mutbl: Mutability::Not,
 436         },
 437     ) = ty.kind
 438     {
 439         if let TyKind::Path(ref path) = inner.kind {
 440             if let Res::Def(DefKind::Struct, def_id) = cx.qpath_res(path, inner.hir_id) {
 441                 return match_def_path(cx, def_id, &paths::LINT);
 442             }
 443         }
 444     }
 445
 446     false
 447 }
 448
 449 struct LintCollector<'a, 'tcx> {
 450     output: &'a mut FxHashSet<Symbol>,
 451     cx: &'a LateContext<'tcx>,
 452 }
 453
 454 impl<'a, 'tcx> Visitor<'tcx> for LintCollector<'a, 'tcx> {
 455     type Map = Map<'tcx>;
 456
 457     fn visit_path(&mut self, path: &'tcx Path<'_>, _: HirId) {
 458         if path.segments.len() == 1 {
 459             self.output.insert(path.segments[0].ident.name);
 460         }
 461     }
 462
 463     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
 464         NestedVisitorMap::All(self.cx.tcx.hir())
 465     }
 466 }
 467
 468 #[derive(Clone, Default)]
 469 pub struct CompilerLintFunctions {
 470     map: FxHashMap<&'static str, &'static str>,
 471 }
 472
 473 impl CompilerLintFunctions {
 474     #[must_use]
 475     pub fn new() -> Self {
 476         let mut map = FxHashMap::default();
 477         map.insert("span_lint", "utils::span_lint");
 478         map.insert("struct_span_lint", "utils::span_lint");
 479         map.insert("lint", "utils::span_lint");
 480         map.insert("span_lint_note", "utils::span_lint_and_note");
 481         map.insert("span_lint_help", "utils::span_lint_and_help");
 482         Self { map }
 483     }
 484 }
 485
 486 impl_lint_pass!(CompilerLintFunctions => [COMPILER_LINT_FUNCTIONS]);
 487
 488 impl<'tcx> LateLintPass<'tcx> for CompilerLintFunctions {
 489     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 490         if !run_lints(cx, &[COMPILER_LINT_FUNCTIONS], expr.hir_id) {
 491             return;
 492         }
 493
 494         if_chain! {
 495             if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind;
 496             let fn_name = path.ident;
 497             if let Some(sugg) = self.map.get(&*fn_name.as_str());
 498             let ty = cx.typeck_results().expr_ty(&args[0]).peel_refs();
 499             if match_type(cx, ty, &paths::EARLY_CONTEXT)
 500                 || match_type(cx, ty, &paths::LATE_CONTEXT);
 501             then {
 502                 span_lint_and_help(
 503                     cx,
 504                     COMPILER_LINT_FUNCTIONS,
 505                     path.ident.span,
 506                     "usage of a compiler lint function",
 507                     None,
 508                     &format!("please use the Clippy variant of this function: `{}`", sugg),
 509                 );
 510             }
 511         }
 512     }
 513 }
 514
 515 declare_lint_pass!(OuterExpnDataPass => [OUTER_EXPN_EXPN_DATA]);
 516
 517 impl<'tcx> LateLintPass<'tcx> for OuterExpnDataPass {
 518     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 519         if !run_lints(cx, &[OUTER_EXPN_EXPN_DATA], expr.hir_id) {
 520             return;
 521         }
 522
 523         let (method_names, arg_lists, spans) = method_calls(expr, 2);
 524         let method_names: Vec<SymbolStr> = method_names.iter().map(|s| s.as_str()).collect();
 525         let method_names: Vec<&str> = method_names.iter().map(|s| &**s).collect();
 526         if_chain! {
 527             if let ["expn_data", "outer_expn"] = method_names.as_slice();
 528             let args = arg_lists[1];
 529             if args.len() == 1;
 530             let self_arg = &args[0];
 531             let self_ty = cx.typeck_results().expr_ty(self_arg).peel_refs();
 532             if match_type(cx, self_ty, &paths::SYNTAX_CONTEXT);
 533             then {
 534                 span_lint_and_sugg(
 535                     cx,
 536                     OUTER_EXPN_EXPN_DATA,
 537                     spans[1].with_hi(expr.span.hi()),
 538                     "usage of `outer_expn().expn_data()`",
 539                     "try",
 540                     "outer_expn_data()".to_string(),
 541                     Applicability::MachineApplicable,
 542                 );
 543             }
 544         }
 545     }
 546 }
 547
 548 declare_lint_pass!(ProduceIce => [PRODUCE_ICE]);
 549
 550 impl EarlyLintPass for ProduceIce {
 551     fn check_fn(&mut self, _: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
 552         if is_trigger_fn(fn_kind) {
 553             panic!("Would you like some help with that?");
 554         }
 555     }
 556 }
 557
 558 fn is_trigger_fn(fn_kind: FnKind<'_>) -> bool {
 559     match fn_kind {
 560         FnKind::Fn(_, ident, ..) => ident.name.as_str() == "it_looks_like_you_are_trying_to_kill_clippy",
 561         FnKind::Closure(..) => false,
 562     }
 563 }
 564
 565 declare_lint_pass!(CollapsibleCalls => [COLLAPSIBLE_SPAN_LINT_CALLS]);
 566
 567 impl<'tcx> LateLintPass<'tcx> for CollapsibleCalls {
 568     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 569         if !run_lints(cx, &[COLLAPSIBLE_SPAN_LINT_CALLS], expr.hir_id) {
 570             return;
 571         }
 572
 573         if_chain! {
 574             if let ExprKind::Call(ref func, ref and_then_args) = expr.kind;
 575             if let ExprKind::Path(ref path) = func.kind;
 576             if match_qpath(path, &["span_lint_and_then"]);
 577             if and_then_args.len() == 5;
 578             if let ExprKind::Closure(_, _, body_id, _, _) = &and_then_args[4].kind;
 579             let body = cx.tcx.hir().body(*body_id);
 580             if let ExprKind::Block(block, _) = &body.value.kind;
 581             let stmts = &block.stmts;
 582             if stmts.len() == 1 && block.expr.is_none();
 583             if let StmtKind::Semi(only_expr) = &stmts[0].kind;
 584             if let ExprKind::MethodCall(ref ps, _, ref span_call_args, _) = &only_expr.kind;
 585             let and_then_snippets = get_and_then_snippets(cx, and_then_args);
 586             let mut sle = SpanlessEq::new(cx).deny_side_effects();
 587             then {
 588                 match &*ps.ident.as_str() {
 589                     "span_suggestion" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 590                         suggest_suggestion(cx, expr, &and_then_snippets, &span_suggestion_snippets(cx, span_call_args));
 591                     },
 592                     "span_help" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 593                         let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 594                         suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), true);
 595                     },
 596                     "span_note" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 597                         let note_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 598                         suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), true);
 599                     },
 600                     "help" => {
 601                         let help_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
 602                         suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), false);
 603                     }
 604                     "note" => {
 605                         let note_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
 606                         suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), false);
 607                     }
 608                     _  => (),
 609                 }
 610             }
 611         }
 612     }
 613 }
 614
 615 struct AndThenSnippets<'a> {
 616     cx: Cow<'a, str>,
 617     lint: Cow<'a, str>,
 618     span: Cow<'a, str>,
 619     msg: Cow<'a, str>,
 620 }
 621
 622 fn get_and_then_snippets<'a, 'hir>(cx: &LateContext<'_>, and_then_snippets: &'hir [Expr<'hir>]) -> AndThenSnippets<'a> {
 623     let cx_snippet = snippet(cx, and_then_snippets[0].span, "cx");
 624     let lint_snippet = snippet(cx, and_then_snippets[1].span, "..");
 625     let span_snippet = snippet(cx, and_then_snippets[2].span, "span");
 626     let msg_snippet = snippet(cx, and_then_snippets[3].span, r#""...""#);
 627
 628     AndThenSnippets {
 629         cx: cx_snippet,
 630         lint: lint_snippet,
 631         span: span_snippet,
 632         msg: msg_snippet,
 633     }
 634 }
 635
 636 struct SpanSuggestionSnippets<'a> {
 637     help: Cow<'a, str>,
 638     sugg: Cow<'a, str>,
 639     applicability: Cow<'a, str>,
 640 }
 641
 642 fn span_suggestion_snippets<'a, 'hir>(
 643     cx: &LateContext<'_>,
 644     span_call_args: &'hir [Expr<'hir>],
 645 ) -> SpanSuggestionSnippets<'a> {
 646     let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 647     let sugg_snippet = snippet(cx, span_call_args[3].span, "..");
 648     let applicability_snippet = snippet(cx, span_call_args[4].span, "Applicability::MachineApplicable");
 649
 650     SpanSuggestionSnippets {
 651         help: help_snippet,
 652         sugg: sugg_snippet,
 653         applicability: applicability_snippet,
 654     }
 655 }
 656
 657 fn suggest_suggestion(
 658     cx: &LateContext<'_>,
 659     expr: &Expr<'_>,
 660     and_then_snippets: &AndThenSnippets<'_>,
 661     span_suggestion_snippets: &SpanSuggestionSnippets<'_>,
 662 ) {
 663     span_lint_and_sugg(
 664         cx,
 665         COLLAPSIBLE_SPAN_LINT_CALLS,
 666         expr.span,
 667         "this call is collapsible",
 668         "collapse into",
 669         format!(
 670             "span_lint_and_sugg({}, {}, {}, {}, {}, {}, {})",
 671             and_then_snippets.cx,
 672             and_then_snippets.lint,
 673             and_then_snippets.span,
 674             and_then_snippets.msg,
 675             span_suggestion_snippets.help,
 676             span_suggestion_snippets.sugg,
 677             span_suggestion_snippets.applicability
 678         ),
 679         Applicability::MachineApplicable,
 680     );
 681 }
 682
 683 fn suggest_help(
 684     cx: &LateContext<'_>,
 685     expr: &Expr<'_>,
 686     and_then_snippets: &AndThenSnippets<'_>,
 687     help: &str,
 688     with_span: bool,
 689 ) {
 690     let option_span = if with_span {
 691         format!("Some({})", and_then_snippets.span)
 692     } else {
 693         "None".to_string()
 694     };
 695
 696     span_lint_and_sugg(
 697         cx,
 698         COLLAPSIBLE_SPAN_LINT_CALLS,
 699         expr.span,
 700         "this call is collapsible",
 701         "collapse into",
 702         format!(
 703             "span_lint_and_help({}, {}, {}, {}, {}, {})",
 704             and_then_snippets.cx,
 705             and_then_snippets.lint,
 706             and_then_snippets.span,
 707             and_then_snippets.msg,
 708             &option_span,
 709             help
 710         ),
 711         Applicability::MachineApplicable,
 712     );
 713 }
 714
 715 fn suggest_note(
 716     cx: &LateContext<'_>,
 717     expr: &Expr<'_>,
 718     and_then_snippets: &AndThenSnippets<'_>,
 719     note: &str,
 720     with_span: bool,
 721 ) {
 722     let note_span = if with_span {
 723         format!("Some({})", and_then_snippets.span)
 724     } else {
 725         "None".to_string()
 726     };
 727
 728     span_lint_and_sugg(
 729         cx,
 730         COLLAPSIBLE_SPAN_LINT_CALLS,
 731         expr.span,
 732         "this call is collspible",
 733         "collapse into",
 734         format!(
 735             "span_lint_and_note({}, {}, {}, {}, {}, {})",
 736             and_then_snippets.cx,
 737             and_then_snippets.lint,
 738             and_then_snippets.span,
 739             and_then_snippets.msg,
 740             note_span,
 741             note
 742         ),
 743         Applicability::MachineApplicable,
 744     );
 745 }
 746
 747 declare_lint_pass!(MatchTypeOnDiagItem => [MATCH_TYPE_ON_DIAGNOSTIC_ITEM]);
 748
 749 impl<'tcx> LateLintPass<'tcx> for MatchTypeOnDiagItem {
 750     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 751         if !run_lints(cx, &[MATCH_TYPE_ON_DIAGNOSTIC_ITEM], expr.hir_id) {
 752             return;
 753         }
 754
 755         if_chain! {
 756             // Check if this is a call to utils::match_type()
 757             if let ExprKind::Call(fn_path, [context, ty, ty_path]) = expr.kind;
 758             if let ExprKind::Path(fn_qpath) = &fn_path.kind;
 759             if match_qpath(&fn_qpath, &["utils", "match_type"]);
 760             // Extract the path to the matched type
 761             if let Some(segments) = path_to_matched_type(cx, ty_path);
 762             let segments: Vec<&str> = segments.iter().map(|sym| &**sym).collect();
 763             if let Some(ty_did) = path_to_res(cx, &segments[..]).and_then(|res| res.opt_def_id());
 764             // Check if the matched type is a diagnostic item
 765             let diag_items = cx.tcx.diagnostic_items(ty_did.krate);
 766             if let Some(item_name) = diag_items.iter().find_map(|(k, v)| if *v == ty_did { Some(k) } else { None });
 767             then {
 768                 let cx_snippet = snippet(cx, context.span, "_");
 769                 let ty_snippet = snippet(cx, ty.span, "_");
 770
 771                 span_lint_and_sugg(
 772                     cx,
 773                     MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
 774                     expr.span,
 775                     "usage of `utils::match_type()` on a type diagnostic item",
 776                     "try",
 777                     format!("utils::is_type_diagnostic_item({}, {}, sym::{})", cx_snippet, ty_snippet, item_name),
 778                     Applicability::MaybeIncorrect,
 779                 );
 780             }
 781         }
 782     }
 783 }
 784
 785 fn path_to_matched_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Vec<SymbolStr>> {
 786     use rustc_hir::ItemKind;
 787
 788     match &expr.kind {
 789         ExprKind::AddrOf(.., expr) => return path_to_matched_type(cx, expr),
 790         ExprKind::Path(qpath) => match cx.qpath_res(qpath, expr.hir_id) {
 791             Res::Local(hir_id) => {
 792                 let parent_id = cx.tcx.hir().get_parent_node(hir_id);
 793                 if let Some(Node::Local(local)) = cx.tcx.hir().find(parent_id) {
 794                     if let Some(init) = local.init {
 795                         return path_to_matched_type(cx, init);
 796                     }
 797                 }
 798             },
 799             Res::Def(DefKind::Const | DefKind::Static, def_id) => {
 800                 if let Some(Node::Item(item)) = cx.tcx.hir().get_if_local(def_id) {
 801                     if let ItemKind::Const(.., body_id) | ItemKind::Static(.., body_id) = item.kind {
 802                         let body = cx.tcx.hir().body(body_id);
 803                         return path_to_matched_type(cx, &body.value);
 804                     }
 805                 }
 806             },
 807             _ => {},
 808         },
 809         ExprKind::Array(exprs) => {
 810             let segments: Vec<SymbolStr> = exprs
 811                 .iter()
 812                 .filter_map(|expr| {
 813                     if let ExprKind::Lit(lit) = &expr.kind {
 814                         if let LitKind::Str(sym, _) = lit.node {
 815                             return Some(sym.as_str());
 816                         }
 817                     }
 818
 819                     None
 820                 })
 821                 .collect();
 822
 823             if segments.len() == exprs.len() {
 824                 return Some(segments);
 825             }
 826         },
 827         _ => {},
 828     }
 829
 830     None
 831 }
 832
 833 // This is not a complete resolver for paths. It works on all the paths currently used in the paths
 834 // module.  That's all it does and all it needs to do.
 835 pub fn check_path(cx: &LateContext<'_>, path: &[&str]) -> bool {
 836     if path_to_res(cx, path).is_some() {
 837         return true;
 838     }
 839
 840     // Some implementations can't be found by `path_to_res`, particularly inherent
 841     // implementations of native types. Check lang items.
 842     let path_syms: Vec<_> = path.iter().map(|p| Symbol::intern(p)).collect();
 843     let lang_items = cx.tcx.lang_items();
 844     for lang_item in lang_items.items() {
 845         if let Some(def_id) = lang_item {
 846             let lang_item_path = cx.get_def_path(*def_id);
 847             if path_syms.starts_with(&lang_item_path) {
 848                 if let [item] = &path_syms[lang_item_path.len()..] {
 849                     for child in cx.tcx.item_children(*def_id) {
 850                         if child.ident.name == *item {
 851                             return true;
 852                         }
 853                     }
 854                 }
 855             }
 856         }
 857     }
 858
 859     false
 860 }
 861
 862 declare_lint_pass!(InvalidPaths => [INVALID_PATHS]);
 863
 864 impl<'tcx> LateLintPass<'tcx> for InvalidPaths {
 865     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 866         let local_def_id = &cx.tcx.parent_module(item.hir_id);
 867         let mod_name = &cx.tcx.item_name(local_def_id.to_def_id());
 868         if_chain! {
 869             if mod_name.as_str() == "paths";
 870             if let hir::ItemKind::Const(ty, body_id) = item.kind;
 871             let ty = hir_ty_to_ty(cx.tcx, ty);
 872             if let ty::Array(el_ty, _) = &ty.kind();
 873             if let ty::Ref(_, el_ty, _) = &el_ty.kind();
 874             if el_ty.is_str();
 875             let body = cx.tcx.hir().body(body_id);
 876             let typeck_results = cx.tcx.typeck_body(body_id);
 877             if let Some(Constant::Vec(path)) = constant_simple(cx, typeck_results, &body.value);
 878             let path: Vec<&str> = path.iter().map(|x| {
 879                     if let Constant::Str(s) = x {
 880                         s.as_str()
 881                     } else {
 882                         // We checked the type of the constant above
 883                         unreachable!()
 884                     }
 885                 }).collect();
 886             if !check_path(cx, &path[..]);
 887             then {
 888                 span_lint(cx, CLIPPY_LINTS_INTERNAL, item.span, "invalid path");
 889             }
 890         }
 891     }
 892 }
 893
 894 #[derive(Default)]
 895 pub struct InterningDefinedSymbol {
 896     // Maps the symbol value to the constant DefId.
 897     symbol_map: FxHashMap<u32, DefId>,
 898 }
 899
 900 impl_lint_pass!(InterningDefinedSymbol => [INTERNING_DEFINED_SYMBOL, UNNECESSARY_SYMBOL_STR]);
 901
 902 impl<'tcx> LateLintPass<'tcx> for InterningDefinedSymbol {
 903     fn check_crate(&mut self, cx: &LateContext<'_>, _: &Crate<'_>) {
 904         if !self.symbol_map.is_empty() {
 905             return;
 906         }
 907
 908         for &module in &[&paths::KW_MODULE, &paths::SYM_MODULE] {
 909             if let Some(Res::Def(_, def_id)) = path_to_res(cx, module) {
 910                 for item in cx.tcx.item_children(def_id).iter() {
 911                     if_chain! {
 912                         if let Res::Def(DefKind::Const, item_def_id) = item.res;
 913                         let ty = cx.tcx.type_of(item_def_id);
 914                         if match_type(cx, ty, &paths::SYMBOL);
 915                         if let Ok(ConstValue::Scalar(value)) = cx.tcx.const_eval_poly(item_def_id);
 916                         if let Ok(value) = value.to_u32();
 917                         then {
 918                             self.symbol_map.insert(value, item_def_id);
 919                         }
 920                     }
 921                 }
 922             }
 923         }
 924     }
 925
 926     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 927         if_chain! {
 928             if let ExprKind::Call(func, [arg]) = &expr.kind;
 929             if let ty::FnDef(def_id, _) = cx.typeck_results().expr_ty(func).kind();
 930             if match_def_path(cx, *def_id, &paths::SYMBOL_INTERN);
 931             if let Some(Constant::Str(arg)) = constant_simple(cx, cx.typeck_results(), arg);
 932             let value = Symbol::intern(&arg).as_u32();
 933             if let Some(&def_id) = self.symbol_map.get(&value);
 934             then {
 935                 span_lint_and_sugg(
 936                     cx,
 937                     INTERNING_DEFINED_SYMBOL,
 938                     is_expn_of(expr.span, "sym").unwrap_or(expr.span),
 939                     "interning a defined symbol",
 940                     "try",
 941                     cx.tcx.def_path_str(def_id),
 942                     Applicability::MachineApplicable,
 943                 );
 944             }
 945         }
 946         if let ExprKind::Binary(op, left, right) = expr.kind {
 947             if matches!(op.node, BinOpKind::Eq | BinOpKind::Ne) {
 948                 let data = [
 949                     (left, self.symbol_str_expr(left, cx)),
 950                     (right, self.symbol_str_expr(right, cx)),
 951                 ];
 952                 match data {
 953                     // both operands are a symbol string
 954                     [(_, Some(left)), (_, Some(right))] => {
 955                         span_lint_and_sugg(
 956                             cx,
 957                             UNNECESSARY_SYMBOL_STR,
 958                             expr.span,
 959                             "unnecessary `Symbol` to string conversion",
 960                             "try",
 961                             format!(
 962                                 "{} {} {}",
 963                                 left.as_symbol_snippet(cx),
 964                                 op.node.as_str(),
 965                                 right.as_symbol_snippet(cx),
 966                             ),
 967                             Applicability::MachineApplicable,
 968                         );
 969                     },
 970                     // one of the operands is a symbol string
 971                     [(expr, Some(symbol)), _] | [_, (expr, Some(symbol))] => {
 972                         // creating an owned string for comparison
 973                         if matches!(symbol, SymbolStrExpr::Expr { is_to_owned: true, .. }) {
 974                             span_lint_and_sugg(
 975                                 cx,
 976                                 UNNECESSARY_SYMBOL_STR,
 977                                 expr.span,
 978                                 "unnecessary string allocation",
 979                                 "try",
 980                                 format!("{}.as_str()", symbol.as_symbol_snippet(cx)),
 981                                 Applicability::MachineApplicable,
 982                             );
 983                         }
 984                     },
 985                     // nothing found
 986                     [(_, None), (_, None)] => {},
 987                 }
 988             }
 989         }
 990     }
 991 }
 992
 993 impl InterningDefinedSymbol {
 994     fn symbol_str_expr<'tcx>(&self, expr: &'tcx Expr<'tcx>, cx: &LateContext<'tcx>) -> Option<SymbolStrExpr<'tcx>> {
 995         static IDENT_STR_PATHS: &[&[&str]] = &[&paths::IDENT_AS_STR, &paths::TO_STRING_METHOD];
 996         static SYMBOL_STR_PATHS: &[&[&str]] = &[
 997             &paths::SYMBOL_AS_STR,
 998             &paths::SYMBOL_TO_IDENT_STRING,
 999             &paths::TO_STRING_METHOD,
1000         ];
1001         // SymbolStr might be de-referenced: `&*symbol.as_str()`
1002         let call = if_chain! {
1003             if let ExprKind::AddrOf(_, _, e) = expr.kind;
1004             if let ExprKind::Unary(UnOp::UnDeref, e) = e.kind;
1005             then { e } else { expr }
1006         };
1007         if_chain! {
1008             // is a method call
1009             if let ExprKind::MethodCall(_, _, [item], _) = call.kind;
1010             if let Some(did) = cx.typeck_results().type_dependent_def_id(call.hir_id);
1011             let ty = cx.typeck_results().expr_ty(item);
1012             // ...on either an Ident or a Symbol
1013             if let Some(is_ident) = if match_type(cx, ty, &paths::SYMBOL) {
1014                 Some(false)
1015             } else if match_type(cx, ty, &paths::IDENT) {
1016                 Some(true)
1017             } else {
1018                 None
1019             };
1020             // ...which converts it to a string
1021             let paths = if is_ident { IDENT_STR_PATHS } else { SYMBOL_STR_PATHS };
1022             if let Some(path) = paths.iter().find(|path| match_def_path(cx, did, path));
1023             then {
1024                 let is_to_owned = path.last().unwrap().ends_with("string");
1025                 return Some(SymbolStrExpr::Expr {
1026                     item,
1027                     is_ident,
1028                     is_to_owned,
1029                 });
1030             }
1031         }
1032         // is a string constant
1033         if let Some(Constant::Str(s)) = constant_simple(cx, cx.typeck_results(), expr) {
1034             let value = Symbol::intern(&s).as_u32();
1035             // ...which matches a symbol constant
1036             if let Some(&def_id) = self.symbol_map.get(&value) {
1037                 return Some(SymbolStrExpr::Const(def_id));
1038             }
1039         }
1040         None
1041     }
1042 }
1043
1044 enum SymbolStrExpr<'tcx> {
1045     /// a string constant with a corresponding symbol constant
1046     Const(DefId),
1047     /// a "symbol to string" expression like `symbol.as_str()`
1048     Expr {
1049         /// part that evaluates to `Symbol` or `Ident`
1050         item: &'tcx Expr<'tcx>,
1051         is_ident: bool,
1052         /// whether an owned `String` is created like `to_ident_string()`
1053         is_to_owned: bool,
1054     },
1055 }
1056
1057 impl<'tcx> SymbolStrExpr<'tcx> {
1058     /// Returns a snippet that evaluates to a `Symbol` and is const if possible
1059     fn as_symbol_snippet(&self, cx: &LateContext<'_>) -> Cow<'tcx, str> {
1060         match *self {
1061             Self::Const(def_id) => cx.tcx.def_path_str(def_id).into(),
1062             Self::Expr { item, is_ident, .. } => {
1063                 let mut snip = snippet(cx, item.span.source_callsite(), "..");
1064                 if is_ident {
1065                     // get `Ident.name`
1066                     snip.to_mut().push_str(".name");
1067                 }
1068                 snip
1069             },
1070         }
1071     }
1072 }