src/tools/clippy/clippy_lints/src/doc.rs

   1 use clippy_utils::attrs::is_doc_hidden;
   2 use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_note, span_lint_and_then};
   3 use clippy_utils::macros::{is_panic, root_macro_call_first_node};
   4 use clippy_utils::source::{first_line_of_span, snippet_with_applicability};
   5 use clippy_utils::ty::{implements_trait, is_type_diagnostic_item};
   6 use clippy_utils::{is_entrypoint_fn, method_chain_args, return_ty};
   7 use if_chain::if_chain;
   8 use itertools::Itertools;
   9 use rustc_ast::ast::{Async, AttrKind, Attribute, Fn, FnRetTy, ItemKind};
  10 use rustc_ast::token::CommentKind;
  11 use rustc_data_structures::fx::FxHashSet;
  12 use rustc_data_structures::sync::Lrc;
  13 use rustc_errors::emitter::EmitterWriter;
  14 use rustc_errors::{Applicability, Handler, MultiSpan, SuggestionStyle};
  15 use rustc_hir as hir;
  16 use rustc_hir::intravisit::{self, Visitor};
  17 use rustc_hir::{AnonConst, Expr};
  18 use rustc_lint::{LateContext, LateLintPass};
  19 use rustc_middle::hir::nested_filter;
  20 use rustc_middle::lint::in_external_macro;
  21 use rustc_middle::ty;
  22 use rustc_parse::maybe_new_parser_from_source_str;
  23 use rustc_parse::parser::ForceCollect;
  24 use rustc_session::parse::ParseSess;
  25 use rustc_session::{declare_tool_lint, impl_lint_pass};
  26 use rustc_span::def_id::LocalDefId;
  27 use rustc_span::edition::Edition;
  28 use rustc_span::source_map::{BytePos, FilePathMapping, SourceMap, Span};
  29 use rustc_span::{sym, FileName, Pos};
  30 use std::io;
  31 use std::ops::Range;
  32 use std::thread;
  33 use url::Url;
  34
  35 declare_clippy_lint! {
  36     /// ### What it does
  37     /// Checks for the presence of `_`, `::` or camel-case words
  38     /// outside ticks in documentation.
  39     ///
  40     /// ### Why is this bad?
  41     /// *Rustdoc* supports markdown formatting, `_`, `::` and
  42     /// camel-case probably indicates some code which should be included between
  43     /// ticks. `_` can also be used for emphasis in markdown, this lint tries to
  44     /// consider that.
  45     ///
  46     /// ### Known problems
  47     /// Lots of bad docs won’t be fixed, what the lint checks
  48     /// for is limited, and there are still false positives. HTML elements and their
  49     /// content are not linted.
  50     ///
  51     /// In addition, when writing documentation comments, including `[]` brackets
  52     /// inside a link text would trip the parser. Therefore, documenting link with
  53     /// `[`SmallVec<[T; INLINE_CAPACITY]>`]` and then [`SmallVec<[T; INLINE_CAPACITY]>`]: SmallVec
  54     /// would fail.
  55     ///
  56     /// ### Examples
  57     /// ```rust
  58     /// /// Do something with the foo_bar parameter. See also
  59     /// /// that::other::module::foo.
  60     /// // ^ `foo_bar` and `that::other::module::foo` should be ticked.
  61     /// fn doit(foo_bar: usize) {}
  62     /// ```
  63     ///
  64     /// ```rust
  65     /// // Link text with `[]` brackets should be written as following:
  66     /// /// Consume the array and return the inner
  67     /// /// [`SmallVec<[T; INLINE_CAPACITY]>`][SmallVec].
  68     /// /// [SmallVec]: SmallVec
  69     /// fn main() {}
  70     /// ```
  71     #[clippy::version = "pre 1.29.0"]
  72     pub DOC_MARKDOWN,
  73     pedantic,
  74     "presence of `_`, `::` or camel-case outside backticks in documentation"
  75 }
  76
  77 declare_clippy_lint! {
  78     /// ### What it does
  79     /// Checks for the doc comments of publicly visible
  80     /// unsafe functions and warns if there is no `# Safety` section.
  81     ///
  82     /// ### Why is this bad?
  83     /// Unsafe functions should document their safety
  84     /// preconditions, so that users can be sure they are using them safely.
  85     ///
  86     /// ### Examples
  87     /// ```rust
  88     ///# type Universe = ();
  89     /// /// This function should really be documented
  90     /// pub unsafe fn start_apocalypse(u: &mut Universe) {
  91     ///     unimplemented!();
  92     /// }
  93     /// ```
  94     ///
  95     /// At least write a line about safety:
  96     ///
  97     /// ```rust
  98     ///# type Universe = ();
  99     /// /// # Safety
 100     /// ///
 101     /// /// This function should not be called before the horsemen are ready.
 102     /// pub unsafe fn start_apocalypse(u: &mut Universe) {
 103     ///     unimplemented!();
 104     /// }
 105     /// ```
 106     #[clippy::version = "1.39.0"]
 107     pub MISSING_SAFETY_DOC,
 108     style,
 109     "`pub unsafe fn` without `# Safety` docs"
 110 }
 111
 112 declare_clippy_lint! {
 113     /// ### What it does
 114     /// Checks the doc comments of publicly visible functions that
 115     /// return a `Result` type and warns if there is no `# Errors` section.
 116     ///
 117     /// ### Why is this bad?
 118     /// Documenting the type of errors that can be returned from a
 119     /// function can help callers write code to handle the errors appropriately.
 120     ///
 121     /// ### Examples
 122     /// Since the following function returns a `Result` it has an `# Errors` section in
 123     /// its doc comment:
 124     ///
 125     /// ```rust
 126     ///# use std::io;
 127     /// /// # Errors
 128     /// ///
 129     /// /// Will return `Err` if `filename` does not exist or the user does not have
 130     /// /// permission to read it.
 131     /// pub fn read(filename: String) -> io::Result<String> {
 132     ///     unimplemented!();
 133     /// }
 134     /// ```
 135     #[clippy::version = "1.41.0"]
 136     pub MISSING_ERRORS_DOC,
 137     pedantic,
 138     "`pub fn` returns `Result` without `# Errors` in doc comment"
 139 }
 140
 141 declare_clippy_lint! {
 142     /// ### What it does
 143     /// Checks the doc comments of publicly visible functions that
 144     /// may panic and warns if there is no `# Panics` section.
 145     ///
 146     /// ### Why is this bad?
 147     /// Documenting the scenarios in which panicking occurs
 148     /// can help callers who do not want to panic to avoid those situations.
 149     ///
 150     /// ### Examples
 151     /// Since the following function may panic it has a `# Panics` section in
 152     /// its doc comment:
 153     ///
 154     /// ```rust
 155     /// /// # Panics
 156     /// ///
 157     /// /// Will panic if y is 0
 158     /// pub fn divide_by(x: i32, y: i32) -> i32 {
 159     ///     if y == 0 {
 160     ///         panic!("Cannot divide by 0")
 161     ///     } else {
 162     ///         x / y
 163     ///     }
 164     /// }
 165     /// ```
 166     #[clippy::version = "1.51.0"]
 167     pub MISSING_PANICS_DOC,
 168     pedantic,
 169     "`pub fn` may panic without `# Panics` in doc comment"
 170 }
 171
 172 declare_clippy_lint! {
 173     /// ### What it does
 174     /// Checks for `fn main() { .. }` in doctests
 175     ///
 176     /// ### Why is this bad?
 177     /// The test can be shorter (and likely more readable)
 178     /// if the `fn main()` is left implicit.
 179     ///
 180     /// ### Examples
 181     /// ```rust
 182     /// /// An example of a doctest with a `main()` function
 183     /// ///
 184     /// /// # Examples
 185     /// ///
 186     /// /// ```
 187     /// /// fn main() {
 188     /// ///     // this needs not be in an `fn`
 189     /// /// }
 190     /// /// ```
 191     /// fn needless_main() {
 192     ///     unimplemented!();
 193     /// }
 194     /// ```
 195     #[clippy::version = "1.40.0"]
 196     pub NEEDLESS_DOCTEST_MAIN,
 197     style,
 198     "presence of `fn main() {` in code examples"
 199 }
 200
 201 declare_clippy_lint! {
 202     /// ### What it does
 203     /// Detects the syntax `['foo']` in documentation comments (notice quotes instead of backticks)
 204     /// outside of code blocks
 205     /// ### Why is this bad?
 206     /// It is likely a typo when defining an intra-doc link
 207     ///
 208     /// ### Example
 209     /// ```rust
 210     /// /// See also: ['foo']
 211     /// fn bar() {}
 212     /// ```
 213     /// Use instead:
 214     /// ```rust
 215     /// /// See also: [`foo`]
 216     /// fn bar() {}
 217     /// ```
 218     #[clippy::version = "1.63.0"]
 219     pub DOC_LINK_WITH_QUOTES,
 220     pedantic,
 221     "possible typo for an intra-doc link"
 222 }
 223
 224 #[expect(clippy::module_name_repetitions)]
 225 #[derive(Clone)]
 226 pub struct DocMarkdown {
 227     valid_idents: FxHashSet<String>,
 228     in_trait_impl: bool,
 229 }
 230
 231 impl DocMarkdown {
 232     pub fn new(valid_idents: FxHashSet<String>) -> Self {
 233         Self {
 234             valid_idents,
 235             in_trait_impl: false,
 236         }
 237     }
 238 }
 239
 240 impl_lint_pass!(DocMarkdown => [
 241     DOC_LINK_WITH_QUOTES,
 242     DOC_MARKDOWN,
 243     MISSING_SAFETY_DOC,
 244     MISSING_ERRORS_DOC,
 245     MISSING_PANICS_DOC,
 246     NEEDLESS_DOCTEST_MAIN
 247 ]);
 248
 249 impl<'tcx> LateLintPass<'tcx> for DocMarkdown {
 250     fn check_crate(&mut self, cx: &LateContext<'tcx>) {
 251         let attrs = cx.tcx.hir().attrs(hir::CRATE_HIR_ID);
 252         check_attrs(cx, &self.valid_idents, attrs);
 253     }
 254
 255     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
 256         let attrs = cx.tcx.hir().attrs(item.hir_id());
 257         let headers = check_attrs(cx, &self.valid_idents, attrs);
 258         match item.kind {
 259             hir::ItemKind::Fn(ref sig, _, body_id) => {
 260                 if !(is_entrypoint_fn(cx, item.owner_id.to_def_id()) || in_external_macro(cx.tcx.sess, item.span)) {
 261                     let body = cx.tcx.hir().body(body_id);
 262                     let mut fpu = FindPanicUnwrap {
 263                         cx,
 264                         typeck_results: cx.tcx.typeck(item.owner_id.def_id),
 265                         panic_span: None,
 266                     };
 267                     fpu.visit_expr(body.value);
 268                     lint_for_missing_headers(
 269                         cx,
 270                         item.owner_id.def_id,
 271                         item.span,
 272                         sig,
 273                         headers,
 274                         Some(body_id),
 275                         fpu.panic_span,
 276                     );
 277                 }
 278             },
 279             hir::ItemKind::Impl(impl_) => {
 280                 self.in_trait_impl = impl_.of_trait.is_some();
 281             },
 282             hir::ItemKind::Trait(_, unsafety, ..) => {
 283                 if !headers.safety && unsafety == hir::Unsafety::Unsafe {
 284                     span_lint(
 285                         cx,
 286                         MISSING_SAFETY_DOC,
 287                         item.span,
 288                         "docs for unsafe trait missing `# Safety` section",
 289                     );
 290                 }
 291             },
 292             _ => (),
 293         }
 294     }
 295
 296     fn check_item_post(&mut self, _cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
 297         if let hir::ItemKind::Impl { .. } = item.kind {
 298             self.in_trait_impl = false;
 299         }
 300     }
 301
 302     fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::TraitItem<'_>) {
 303         let attrs = cx.tcx.hir().attrs(item.hir_id());
 304         let headers = check_attrs(cx, &self.valid_idents, attrs);
 305         if let hir::TraitItemKind::Fn(ref sig, ..) = item.kind {
 306             if !in_external_macro(cx.tcx.sess, item.span) {
 307                 lint_for_missing_headers(cx, item.owner_id.def_id, item.span, sig, headers, None, None);
 308             }
 309         }
 310     }
 311
 312     fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::ImplItem<'_>) {
 313         let attrs = cx.tcx.hir().attrs(item.hir_id());
 314         let headers = check_attrs(cx, &self.valid_idents, attrs);
 315         if self.in_trait_impl || in_external_macro(cx.tcx.sess, item.span) {
 316             return;
 317         }
 318         if let hir::ImplItemKind::Fn(ref sig, body_id) = item.kind {
 319             let body = cx.tcx.hir().body(body_id);
 320             let mut fpu = FindPanicUnwrap {
 321                 cx,
 322                 typeck_results: cx.tcx.typeck(item.owner_id.def_id),
 323                 panic_span: None,
 324             };
 325             fpu.visit_expr(body.value);
 326             lint_for_missing_headers(
 327                 cx,
 328                 item.owner_id.def_id,
 329                 item.span,
 330                 sig,
 331                 headers,
 332                 Some(body_id),
 333                 fpu.panic_span,
 334             );
 335         }
 336     }
 337 }
 338
 339 fn lint_for_missing_headers<'tcx>(
 340     cx: &LateContext<'tcx>,
 341     def_id: LocalDefId,
 342     span: impl Into<MultiSpan> + Copy,
 343     sig: &hir::FnSig<'_>,
 344     headers: DocHeaders,
 345     body_id: Option<hir::BodyId>,
 346     panic_span: Option<Span>,
 347 ) {
 348     if !cx.effective_visibilities.is_exported(def_id) {
 349         return; // Private functions do not require doc comments
 350     }
 351
 352     // do not lint if any parent has `#[doc(hidden)]` attribute (#7347)
 353     if cx
 354         .tcx
 355         .hir()
 356         .parent_iter(cx.tcx.hir().local_def_id_to_hir_id(def_id))
 357         .any(|(id, _node)| is_doc_hidden(cx.tcx.hir().attrs(id)))
 358     {
 359         return;
 360     }
 361
 362     if !headers.safety && sig.header.unsafety == hir::Unsafety::Unsafe {
 363         span_lint(
 364             cx,
 365             MISSING_SAFETY_DOC,
 366             span,
 367             "unsafe function's docs miss `# Safety` section",
 368         );
 369     }
 370     if !headers.panics && panic_span.is_some() {
 371         span_lint_and_note(
 372             cx,
 373             MISSING_PANICS_DOC,
 374             span,
 375             "docs for function which may panic missing `# Panics` section",
 376             panic_span,
 377             "first possible panic found here",
 378         );
 379     }
 380     if !headers.errors {
 381         let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
 382         if is_type_diagnostic_item(cx, return_ty(cx, hir_id), sym::Result) {
 383             span_lint(
 384                 cx,
 385                 MISSING_ERRORS_DOC,
 386                 span,
 387                 "docs for function returning `Result` missing `# Errors` section",
 388             );
 389         } else {
 390             if_chain! {
 391                 if let Some(body_id) = body_id;
 392                 if let Some(future) = cx.tcx.lang_items().future_trait();
 393                 let typeck = cx.tcx.typeck_body(body_id);
 394                 let body = cx.tcx.hir().body(body_id);
 395                 let ret_ty = typeck.expr_ty(body.value);
 396                 if implements_trait(cx, ret_ty, future, &[]);
 397                 if let ty::Opaque(_, subs) = ret_ty.kind();
 398                 if let Some(gen) = subs.types().next();
 399                 if let ty::Generator(_, subs, _) = gen.kind();
 400                 if is_type_diagnostic_item(cx, subs.as_generator().return_ty(), sym::Result);
 401                 then {
 402                     span_lint(
 403                         cx,
 404                         MISSING_ERRORS_DOC,
 405                         span,
 406                         "docs for function returning `Result` missing `# Errors` section",
 407                     );
 408                 }
 409             }
 410         }
 411     }
 412 }
 413
 414 /// Cleanup documentation decoration.
 415 ///
 416 /// We can't use `rustc_ast::attr::AttributeMethods::with_desugared_doc` or
 417 /// `rustc_ast::parse::lexer::comments::strip_doc_comment_decoration` because we
 418 /// need to keep track of
 419 /// the spans but this function is inspired from the later.
 420 #[expect(clippy::cast_possible_truncation)]
 421 #[must_use]
 422 pub fn strip_doc_comment_decoration(doc: &str, comment_kind: CommentKind, span: Span) -> (String, Vec<(usize, Span)>) {
 423     // one-line comments lose their prefix
 424     if comment_kind == CommentKind::Line {
 425         let mut doc = doc.to_owned();
 426         doc.push('\n');
 427         let len = doc.len();
 428         // +3 skips the opening delimiter
 429         return (doc, vec![(len, span.with_lo(span.lo() + BytePos(3)))]);
 430     }
 431
 432     let mut sizes = vec![];
 433     let mut contains_initial_stars = false;
 434     for line in doc.lines() {
 435         let offset = line.as_ptr() as usize - doc.as_ptr() as usize;
 436         debug_assert_eq!(offset as u32 as usize, offset);
 437         contains_initial_stars |= line.trim_start().starts_with('*');
 438         // +1 adds the newline, +3 skips the opening delimiter
 439         sizes.push((line.len() + 1, span.with_lo(span.lo() + BytePos(3 + offset as u32))));
 440     }
 441     if !contains_initial_stars {
 442         return (doc.to_string(), sizes);
 443     }
 444     // remove the initial '*'s if any
 445     let mut no_stars = String::with_capacity(doc.len());
 446     for line in doc.lines() {
 447         let mut chars = line.chars();
 448         for c in &mut chars {
 449             if c.is_whitespace() {
 450                 no_stars.push(c);
 451             } else {
 452                 no_stars.push(if c == '*' { ' ' } else { c });
 453                 break;
 454             }
 455         }
 456         no_stars.push_str(chars.as_str());
 457         no_stars.push('\n');
 458     }
 459
 460     (no_stars, sizes)
 461 }
 462
 463 #[derive(Copy, Clone, Default)]
 464 struct DocHeaders {
 465     safety: bool,
 466     errors: bool,
 467     panics: bool,
 468 }
 469
 470 fn check_attrs<'a>(cx: &LateContext<'_>, valid_idents: &FxHashSet<String>, attrs: &'a [Attribute]) -> DocHeaders {
 471     use pulldown_cmark::{BrokenLink, CowStr, Options};
 472     /// We don't want the parser to choke on intra doc links. Since we don't
 473     /// actually care about rendering them, just pretend that all broken links are
 474     /// point to a fake address.
 475     #[expect(clippy::unnecessary_wraps)] // we're following a type signature
 476     fn fake_broken_link_callback<'a>(_: BrokenLink<'_>) -> Option<(CowStr<'a>, CowStr<'a>)> {
 477         Some(("fake".into(), "fake".into()))
 478     }
 479
 480     let mut doc = String::new();
 481     let mut spans = vec![];
 482
 483     for attr in attrs {
 484         if let AttrKind::DocComment(comment_kind, comment) = attr.kind {
 485             let (comment, current_spans) = strip_doc_comment_decoration(comment.as_str(), comment_kind, attr.span);
 486             spans.extend_from_slice(&current_spans);
 487             doc.push_str(&comment);
 488         } else if attr.has_name(sym::doc) {
 489             // ignore mix of sugared and non-sugared doc
 490             // don't trigger the safety or errors check
 491             return DocHeaders {
 492                 safety: true,
 493                 errors: true,
 494                 panics: true,
 495             };
 496         }
 497     }
 498
 499     let mut current = 0;
 500     for &mut (ref mut offset, _) in &mut spans {
 501         let offset_copy = *offset;
 502         *offset = current;
 503         current += offset_copy;
 504     }
 505
 506     if doc.is_empty() {
 507         return DocHeaders::default();
 508     }
 509
 510     let mut cb = fake_broken_link_callback;
 511
 512     let parser =
 513         pulldown_cmark::Parser::new_with_broken_link_callback(&doc, Options::empty(), Some(&mut cb)).into_offset_iter();
 514     // Iterate over all `Events` and combine consecutive events into one
 515     let events = parser.coalesce(|previous, current| {
 516         use pulldown_cmark::Event::Text;
 517
 518         let previous_range = previous.1;
 519         let current_range = current.1;
 520
 521         match (previous.0, current.0) {
 522             (Text(previous), Text(current)) => {
 523                 let mut previous = previous.to_string();
 524                 previous.push_str(&current);
 525                 Ok((Text(previous.into()), previous_range))
 526             },
 527             (previous, current) => Err(((previous, previous_range), (current, current_range))),
 528         }
 529     });
 530     check_doc(cx, valid_idents, events, &spans)
 531 }
 532
 533 const RUST_CODE: &[&str] = &["rust", "no_run", "should_panic", "compile_fail"];
 534
 535 fn check_doc<'a, Events: Iterator<Item = (pulldown_cmark::Event<'a>, Range<usize>)>>(
 536     cx: &LateContext<'_>,
 537     valid_idents: &FxHashSet<String>,
 538     events: Events,
 539     spans: &[(usize, Span)],
 540 ) -> DocHeaders {
 541     // true if a safety header was found
 542     use pulldown_cmark::Event::{
 543         Code, End, FootnoteReference, HardBreak, Html, Rule, SoftBreak, Start, TaskListMarker, Text,
 544     };
 545     use pulldown_cmark::Tag::{CodeBlock, Heading, Item, Link, Paragraph};
 546     use pulldown_cmark::{CodeBlockKind, CowStr};
 547
 548     let mut headers = DocHeaders::default();
 549     let mut in_code = false;
 550     let mut in_link = None;
 551     let mut in_heading = false;
 552     let mut is_rust = false;
 553     let mut edition = None;
 554     let mut ticks_unbalanced = false;
 555     let mut text_to_check: Vec<(CowStr<'_>, Span)> = Vec::new();
 556     let mut paragraph_span = spans.get(0).expect("function isn't called if doc comment is empty").1;
 557     for (event, range) in events {
 558         match event {
 559             Start(CodeBlock(ref kind)) => {
 560                 in_code = true;
 561                 if let CodeBlockKind::Fenced(lang) = kind {
 562                     for item in lang.split(',') {
 563                         if item == "ignore" {
 564                             is_rust = false;
 565                             break;
 566                         }
 567                         if let Some(stripped) = item.strip_prefix("edition") {
 568                             is_rust = true;
 569                             edition = stripped.parse::<Edition>().ok();
 570                         } else if item.is_empty() || RUST_CODE.contains(&item) {
 571                             is_rust = true;
 572                         }
 573                     }
 574                 }
 575             },
 576             End(CodeBlock(_)) => {
 577                 in_code = false;
 578                 is_rust = false;
 579             },
 580             Start(Link(_, url, _)) => in_link = Some(url),
 581             End(Link(..)) => in_link = None,
 582             Start(Heading(_, _, _) | Paragraph | Item) => {
 583                 if let Start(Heading(_, _, _)) = event {
 584                     in_heading = true;
 585                 }
 586                 ticks_unbalanced = false;
 587                 let (_, span) = get_current_span(spans, range.start);
 588                 paragraph_span = first_line_of_span(cx, span);
 589             },
 590             End(Heading(_, _, _) | Paragraph | Item) => {
 591                 if let End(Heading(_, _, _)) = event {
 592                     in_heading = false;
 593                 }
 594                 if ticks_unbalanced {
 595                     span_lint_and_help(
 596                         cx,
 597                         DOC_MARKDOWN,
 598                         paragraph_span,
 599                         "backticks are unbalanced",
 600                         None,
 601                         "a backtick may be missing a pair",
 602                     );
 603                 } else {
 604                     for (text, span) in text_to_check {
 605                         check_text(cx, valid_idents, &text, span);
 606                     }
 607                 }
 608                 text_to_check = Vec::new();
 609             },
 610             Start(_tag) | End(_tag) => (), // We don't care about other tags
 611             Html(_html) => (),             // HTML is weird, just ignore it
 612             SoftBreak | HardBreak | TaskListMarker(_) | Code(_) | Rule => (),
 613             FootnoteReference(text) | Text(text) => {
 614                 let (begin, span) = get_current_span(spans, range.start);
 615                 paragraph_span = paragraph_span.with_hi(span.hi());
 616                 ticks_unbalanced |= text.contains('`') && !in_code;
 617                 if Some(&text) == in_link.as_ref() || ticks_unbalanced {
 618                     // Probably a link of the form `<http://example.com>`
 619                     // Which are represented as a link to "http://example.com" with
 620                     // text "http://example.com" by pulldown-cmark
 621                     continue;
 622                 }
 623                 let trimmed_text = text.trim();
 624                 headers.safety |= in_heading && trimmed_text == "Safety";
 625                 headers.safety |= in_heading && trimmed_text == "Implementation safety";
 626                 headers.safety |= in_heading && trimmed_text == "Implementation Safety";
 627                 headers.errors |= in_heading && trimmed_text == "Errors";
 628                 headers.panics |= in_heading && trimmed_text == "Panics";
 629                 if in_code {
 630                     if is_rust {
 631                         let edition = edition.unwrap_or_else(|| cx.tcx.sess.edition());
 632                         check_code(cx, &text, edition, span);
 633                     }
 634                 } else {
 635                     check_link_quotes(cx, in_link.is_some(), trimmed_text, span, &range, begin, text.len());
 636                     // Adjust for the beginning of the current `Event`
 637                     let span = span.with_lo(span.lo() + BytePos::from_usize(range.start - begin));
 638                     text_to_check.push((text, span));
 639                 }
 640             },
 641         }
 642     }
 643     headers
 644 }
 645
 646 fn check_link_quotes(
 647     cx: &LateContext<'_>,
 648     in_link: bool,
 649     trimmed_text: &str,
 650     span: Span,
 651     range: &Range<usize>,
 652     begin: usize,
 653     text_len: usize,
 654 ) {
 655     if in_link && trimmed_text.starts_with('\'') && trimmed_text.ends_with('\'') {
 656         // fix the span to only point at the text within the link
 657         let lo = span.lo() + BytePos::from_usize(range.start - begin);
 658         span_lint(
 659             cx,
 660             DOC_LINK_WITH_QUOTES,
 661             span.with_lo(lo).with_hi(lo + BytePos::from_usize(text_len)),
 662             "possible intra-doc link using quotes instead of backticks",
 663         );
 664     }
 665 }
 666
 667 fn get_current_span(spans: &[(usize, Span)], idx: usize) -> (usize, Span) {
 668     let index = match spans.binary_search_by(|c| c.0.cmp(&idx)) {
 669         Ok(o) => o,
 670         Err(e) => e - 1,
 671     };
 672     spans[index]
 673 }
 674
 675 fn check_code(cx: &LateContext<'_>, text: &str, edition: Edition, span: Span) {
 676     fn has_needless_main(code: String, edition: Edition) -> bool {
 677         rustc_driver::catch_fatal_errors(|| {
 678             rustc_span::create_session_globals_then(edition, || {
 679                 let filename = FileName::anon_source_code(&code);
 680
 681                 let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
 682                 let fallback_bundle =
 683                     rustc_errors::fallback_fluent_bundle(rustc_errors::DEFAULT_LOCALE_RESOURCES, false);
 684                 let emitter = EmitterWriter::new(
 685                     Box::new(io::sink()),
 686                     None,
 687                     None,
 688                     fallback_bundle,
 689                     false,
 690                     false,
 691                     false,
 692                     None,
 693                     false,
 694                 );
 695                 let handler = Handler::with_emitter(false, None, Box::new(emitter));
 696                 let sess = ParseSess::with_span_handler(handler, sm);
 697
 698                 let mut parser = match maybe_new_parser_from_source_str(&sess, filename, code) {
 699                     Ok(p) => p,
 700                     Err(errs) => {
 701                         drop(errs);
 702                         return false;
 703                     },
 704                 };
 705
 706                 let mut relevant_main_found = false;
 707                 loop {
 708                     match parser.parse_item(ForceCollect::No) {
 709                         Ok(Some(item)) => match &item.kind {
 710                             ItemKind::Fn(box Fn {
 711                                 sig, body: Some(block), ..
 712                             }) if item.ident.name == sym::main => {
 713                                 let is_async = matches!(sig.header.asyncness, Async::Yes { .. });
 714                                 let returns_nothing = match &sig.decl.output {
 715                                     FnRetTy::Default(..) => true,
 716                                     FnRetTy::Ty(ty) if ty.kind.is_unit() => true,
 717                                     FnRetTy::Ty(_) => false,
 718                                 };
 719
 720                                 if returns_nothing && !is_async && !block.stmts.is_empty() {
 721                                     // This main function should be linted, but only if there are no other functions
 722                                     relevant_main_found = true;
 723                                 } else {
 724                                     // This main function should not be linted, we're done
 725                                     return false;
 726                                 }
 727                             },
 728                             // Tests with one of these items are ignored
 729                             ItemKind::Static(..)
 730                             | ItemKind::Const(..)
 731                             | ItemKind::ExternCrate(..)
 732                             | ItemKind::ForeignMod(..)
 733                             // Another function was found; this case is ignored
 734                             | ItemKind::Fn(..) => return false,
 735                             _ => {},
 736                         },
 737                         Ok(None) => break,
 738                         Err(e) => {
 739                             e.cancel();
 740                             return false;
 741                         },
 742                     }
 743                 }
 744
 745                 relevant_main_found
 746             })
 747         })
 748         .ok()
 749         .unwrap_or_default()
 750     }
 751
 752     // Because of the global session, we need to create a new session in a different thread with
 753     // the edition we need.
 754     let text = text.to_owned();
 755     if thread::spawn(move || has_needless_main(text, edition))
 756         .join()
 757         .expect("thread::spawn failed")
 758     {
 759         span_lint(cx, NEEDLESS_DOCTEST_MAIN, span, "needless `fn main` in doctest");
 760     }
 761 }
 762
 763 fn check_text(cx: &LateContext<'_>, valid_idents: &FxHashSet<String>, text: &str, span: Span) {
 764     for word in text.split(|c: char| c.is_whitespace() || c == '\'') {
 765         // Trim punctuation as in `some comment (see foo::bar).`
 766         //                                                   ^^
 767         // Or even as in `_foo bar_` which is emphasized. Also preserve `::` as a prefix/suffix.
 768         let mut word = word.trim_matches(|c: char| !c.is_alphanumeric() && c != ':');
 769
 770         // Remove leading or trailing single `:` which may be part of a sentence.
 771         if word.starts_with(':') && !word.starts_with("::") {
 772             word = word.trim_start_matches(':');
 773         }
 774         if word.ends_with(':') && !word.ends_with("::") {
 775             word = word.trim_end_matches(':');
 776         }
 777
 778         if valid_idents.contains(word) || word.chars().all(|c| c == ':') {
 779             continue;
 780         }
 781
 782         // Adjust for the current word
 783         let offset = word.as_ptr() as usize - text.as_ptr() as usize;
 784         let span = Span::new(
 785             span.lo() + BytePos::from_usize(offset),
 786             span.lo() + BytePos::from_usize(offset + word.len()),
 787             span.ctxt(),
 788             span.parent(),
 789         );
 790
 791         check_word(cx, word, span);
 792     }
 793 }
 794
 795 fn check_word(cx: &LateContext<'_>, word: &str, span: Span) {
 796     /// Checks if a string is camel-case, i.e., contains at least two uppercase
 797     /// letters (`Clippy` is ok) and one lower-case letter (`NASA` is ok).
 798     /// Plurals are also excluded (`IDs` is ok).
 799     fn is_camel_case(s: &str) -> bool {
 800         if s.starts_with(|c: char| c.is_ascii_digit()) {
 801             return false;
 802         }
 803
 804         let s = s.strip_suffix('s').unwrap_or(s);
 805
 806         s.chars().all(char::is_alphanumeric)
 807             && s.chars().filter(|&c| c.is_uppercase()).take(2).count() > 1
 808             && s.chars().filter(|&c| c.is_lowercase()).take(1).count() > 0
 809     }
 810
 811     fn has_underscore(s: &str) -> bool {
 812         s != "_" && !s.contains("\\_") && s.contains('_')
 813     }
 814
 815     fn has_hyphen(s: &str) -> bool {
 816         s != "-" && s.contains('-')
 817     }
 818
 819     if let Ok(url) = Url::parse(word) {
 820         // try to get around the fact that `foo::bar` parses as a valid URL
 821         if !url.cannot_be_a_base() {
 822             span_lint(
 823                 cx,
 824                 DOC_MARKDOWN,
 825                 span,
 826                 "you should put bare URLs between `<`/`>` or make a proper Markdown link",
 827             );
 828
 829             return;
 830         }
 831     }
 832
 833     // We assume that mixed-case words are not meant to be put inside backticks. (Issue #2343)
 834     if has_underscore(word) && has_hyphen(word) {
 835         return;
 836     }
 837
 838     if has_underscore(word) || word.contains("::") || is_camel_case(word) {
 839         let mut applicability = Applicability::MachineApplicable;
 840
 841         span_lint_and_then(
 842             cx,
 843             DOC_MARKDOWN,
 844             span,
 845             "item in documentation is missing backticks",
 846             |diag| {
 847                 let snippet = snippet_with_applicability(cx, span, "..", &mut applicability);
 848                 diag.span_suggestion_with_style(
 849                     span,
 850                     "try",
 851                     format!("`{snippet}`"),
 852                     applicability,
 853                     // always show the suggestion in a separate line, since the
 854                     // inline presentation adds another pair of backticks
 855                     SuggestionStyle::ShowAlways,
 856                 );
 857             },
 858         );
 859     }
 860 }
 861
 862 struct FindPanicUnwrap<'a, 'tcx> {
 863     cx: &'a LateContext<'tcx>,
 864     panic_span: Option<Span>,
 865     typeck_results: &'tcx ty::TypeckResults<'tcx>,
 866 }
 867
 868 impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
 869     type NestedFilter = nested_filter::OnlyBodies;
 870
 871     fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
 872         if self.panic_span.is_some() {
 873             return;
 874         }
 875
 876         if let Some(macro_call) = root_macro_call_first_node(self.cx, expr) {
 877             if is_panic(self.cx, macro_call.def_id)
 878                 || matches!(
 879                     self.cx.tcx.item_name(macro_call.def_id).as_str(),
 880                     "assert" | "assert_eq" | "assert_ne" | "todo"
 881                 )
 882             {
 883                 self.panic_span = Some(macro_call.span);
 884             }
 885         }
 886
 887         // check for `unwrap`
 888         if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
 889             let receiver_ty = self.typeck_results.expr_ty(arglists[0].0).peel_refs();
 890             if is_type_diagnostic_item(self.cx, receiver_ty, sym::Option)
 891                 || is_type_diagnostic_item(self.cx, receiver_ty, sym::Result)
 892             {
 893                 self.panic_span = Some(expr.span);
 894             }
 895         }
 896
 897         // and check sub-expressions
 898         intravisit::walk_expr(self, expr);
 899     }
 900
 901     // Panics in const blocks will cause compilation to fail.
 902     fn visit_anon_const(&mut self, _: &'tcx AnonConst) {}
 903
 904     fn nested_visit_map(&mut self) -> Self::Map {
 905         self.cx.tcx.hir()
 906     }
 907 }