clippy_utils/
check_proc_macro.rs

1//! This module handles checking if the span given is from a proc-macro or not.
2//!
3//! Proc-macros are capable of setting the span of every token they output to a few possible spans.
4//! This includes spans we can detect easily as coming from a proc-macro (e.g. the call site
5//! or the def site), and spans we can't easily detect as such (e.g. the span of any token
6//! passed into the proc macro). This capability means proc-macros are capable of generating code
7//! with a span that looks like it was written by the user, but which should not be linted by clippy
8//! as it was generated by an external macro.
9//!
10//! That brings us to this module. The current approach is to determine a small bit of text which
11//! must exist at both the start and the end of an item (e.g. an expression or a path) assuming the
12//! code was written, and check if the span contains that text. Note this will only work correctly
13//! if the span is not from a `macro_rules` based macro.
14
15use rustc_abi::ExternAbi;
16use rustc_ast as ast;
17use rustc_ast::AttrStyle;
18use rustc_ast::ast::{
19    AttrKind, Attribute, GenericArgs, IntTy, LitIntType, LitKind, StrStyle, TraitObjectSyntax, UintTy,
20};
21use rustc_ast::token::CommentKind;
22use rustc_hir::intravisit::FnKind;
23use rustc_hir::{
24    Block, BlockCheckMode, Body, Closure, Destination, Expr, ExprKind, FieldDef, FnHeader, FnRetTy, HirId, Impl,
25    ImplItem, ImplItemImplKind, ImplItemKind, IsAuto, Item, ItemKind, Lit, LoopSource, MatchSource, MutTy, Node, Path,
26    QPath, Safety, TraitImplHeader, TraitItem, TraitItemKind, Ty, TyKind, UnOp, UnsafeSource, Variant, VariantData,
27    YieldSource,
28};
29use rustc_lint::{EarlyContext, LateContext, LintContext};
30use rustc_middle::ty::TyCtxt;
31use rustc_session::Session;
32use rustc_span::symbol::{Ident, kw};
33use rustc_span::{Span, Symbol, sym};
34
35/// The search pattern to look for. Used by `span_matches_pat`
36#[derive(Clone)]
37pub enum Pat {
38    /// A single string.
39    Str(&'static str),
40    /// Any of the given strings.
41    MultiStr(&'static [&'static str]),
42    /// Any of the given strings.
43    OwnedMultiStr(Vec<String>),
44    /// The string representation of the symbol.
45    Sym(Symbol),
46    /// Any decimal or hexadecimal digit depending on the location.
47    Num,
48}
49
50/// Checks if the start and the end of the span's text matches the patterns. This will return false
51/// if the span crosses multiple files or if source is not available.
52fn span_matches_pat(sess: &Session, span: Span, start_pat: Pat, end_pat: Pat) -> bool {
53    let pos = sess.source_map().lookup_byte_offset(span.lo());
54    let Some(ref src) = pos.sf.src else {
55        return false;
56    };
57    let end = span.hi() - pos.sf.start_pos;
58    src.get(pos.pos.0 as usize..end.0 as usize).is_some_and(|s| {
59        // Spans can be wrapped in a mixture or parenthesis, whitespace, and trailing commas.
60        let start_str = s.trim_start_matches(|c: char| c.is_whitespace() || c == '(');
61        let end_str = s.trim_end_matches(|c: char| c.is_whitespace() || c == ')' || c == ',');
62        (match start_pat {
63            Pat::Str(text) => start_str.starts_with(text),
64            Pat::MultiStr(texts) => texts.iter().any(|s| start_str.starts_with(s)),
65            Pat::OwnedMultiStr(texts) => texts.iter().any(|s| start_str.starts_with(s)),
66            Pat::Sym(sym) => start_str.starts_with(sym.as_str()),
67            Pat::Num => start_str.as_bytes().first().is_some_and(u8::is_ascii_digit),
68        } && match end_pat {
69            Pat::Str(text) => end_str.ends_with(text),
70            Pat::MultiStr(texts) => texts.iter().any(|s| end_str.ends_with(s)),
71            Pat::OwnedMultiStr(texts) => texts.iter().any(|s| end_str.ends_with(s)),
72            Pat::Sym(sym) => end_str.ends_with(sym.as_str()),
73            Pat::Num => end_str.as_bytes().last().is_some_and(u8::is_ascii_hexdigit),
74        })
75    })
76}
77
78/// Get the search patterns to use for the given literal
79fn lit_search_pat(lit: &LitKind) -> (Pat, Pat) {
80    match lit {
81        LitKind::Str(_, StrStyle::Cooked) => (Pat::Str("\""), Pat::Str("\"")),
82        LitKind::Str(_, StrStyle::Raw(0)) => (Pat::Str("r"), Pat::Str("\"")),
83        LitKind::Str(_, StrStyle::Raw(_)) => (Pat::Str("r#"), Pat::Str("#")),
84        LitKind::ByteStr(_, StrStyle::Cooked) => (Pat::Str("b\""), Pat::Str("\"")),
85        LitKind::ByteStr(_, StrStyle::Raw(0)) => (Pat::Str("br\""), Pat::Str("\"")),
86        LitKind::ByteStr(_, StrStyle::Raw(_)) => (Pat::Str("br#\""), Pat::Str("#")),
87        LitKind::Byte(_) => (Pat::Str("b'"), Pat::Str("'")),
88        LitKind::Char(_) => (Pat::Str("'"), Pat::Str("'")),
89        LitKind::Int(_, LitIntType::Signed(IntTy::Isize)) => (Pat::Num, Pat::Str("isize")),
90        LitKind::Int(_, LitIntType::Unsigned(UintTy::Usize)) => (Pat::Num, Pat::Str("usize")),
91        LitKind::Int(..) => (Pat::Num, Pat::Num),
92        LitKind::Float(..) => (Pat::Num, Pat::Str("")),
93        LitKind::Bool(true) => (Pat::Str("true"), Pat::Str("true")),
94        LitKind::Bool(false) => (Pat::Str("false"), Pat::Str("false")),
95        _ => (Pat::Str(""), Pat::Str("")),
96    }
97}
98
99/// Get the search patterns to use for the given path
100fn qpath_search_pat(path: &QPath<'_>) -> (Pat, Pat) {
101    match path {
102        QPath::Resolved(ty, path) => {
103            let start = if ty.is_some() {
104                Pat::Str("<")
105            } else {
106                path.segments.first().map_or(Pat::Str(""), |seg| {
107                    if seg.ident.name == kw::PathRoot {
108                        Pat::Str("::")
109                    } else {
110                        Pat::Sym(seg.ident.name)
111                    }
112                })
113            };
114            let end = path.segments.last().map_or(Pat::Str(""), |seg| {
115                if seg.args.is_some() {
116                    Pat::Str(">")
117                } else {
118                    Pat::Sym(seg.ident.name)
119                }
120            });
121            (start, end)
122        },
123        QPath::TypeRelative(_, name) => (Pat::Str(""), Pat::Sym(name.ident.name)),
124        QPath::LangItem(..) => (Pat::Str(""), Pat::Str("")),
125    }
126}
127
128fn path_search_pat(path: &Path<'_>) -> (Pat, Pat) {
129    let (head, tail) = match path.segments {
130        [] => return (Pat::Str(""), Pat::Str("")),
131        [p] => (Pat::Sym(p.ident.name), p),
132        // QPath::Resolved can have a path that looks like `<Foo as Bar>::baz` where
133        // the path (`Bar::baz`) has it's span covering the whole QPath.
134        [.., tail] => (Pat::Str(""), tail),
135    };
136    (
137        head,
138        if tail.args.is_some() {
139            Pat::Str(">")
140        } else {
141            Pat::Sym(tail.ident.name)
142        },
143    )
144}
145
146/// Get the search patterns to use for the given expression
147fn expr_search_pat(tcx: TyCtxt<'_>, e: &Expr<'_>) -> (Pat, Pat) {
148    fn expr_search_pat_inner(tcx: TyCtxt<'_>, e: &Expr<'_>, outer_span: Span) -> (Pat, Pat) {
149        // The expression can have subexpressions in different contexts, in which case
150        // building up a search pattern from the macro expansion would lead to false positives;
151        // e.g. `return format!(..)` would be considered to be from a proc macro
152        // if we build up a pattern for the macro expansion and compare it to the invocation `format!()`.
153        // So instead we return an empty pattern such that `span_matches_pat` always returns true.
154        if !e.span.eq_ctxt(outer_span) {
155            return (Pat::Str(""), Pat::Str(""));
156        }
157
158        match e.kind {
159            ExprKind::ConstBlock(_) => (Pat::Str("const"), Pat::Str("}")),
160            // Parenthesis are trimmed from the text before the search patterns are matched.
161            // See: `span_matches_pat`
162            ExprKind::Tup([]) => (Pat::Str(")"), Pat::Str("(")),
163            ExprKind::Unary(UnOp::Deref, e) => (Pat::Str("*"), expr_search_pat_inner(tcx, e, outer_span).1),
164            ExprKind::Unary(UnOp::Not, e) => (Pat::Str("!"), expr_search_pat_inner(tcx, e, outer_span).1),
165            ExprKind::Unary(UnOp::Neg, e) => (Pat::Str("-"), expr_search_pat_inner(tcx, e, outer_span).1),
166            ExprKind::Lit(lit) => lit_search_pat(&lit.node),
167            ExprKind::Array(_) | ExprKind::Repeat(..) => (Pat::Str("["), Pat::Str("]")),
168            ExprKind::Call(e, []) | ExprKind::MethodCall(_, e, [], _) => {
169                (expr_search_pat_inner(tcx, e, outer_span).0, Pat::Str("("))
170            },
171            ExprKind::Call(first, [.., last])
172            | ExprKind::MethodCall(_, first, [.., last], _)
173            | ExprKind::Binary(_, first, last)
174            | ExprKind::Tup([first, .., last])
175            | ExprKind::Assign(first, last, _)
176            | ExprKind::AssignOp(_, first, last) => (
177                expr_search_pat_inner(tcx, first, outer_span).0,
178                expr_search_pat_inner(tcx, last, outer_span).1,
179            ),
180            ExprKind::Tup([e]) | ExprKind::DropTemps(e) => expr_search_pat_inner(tcx, e, outer_span),
181            ExprKind::Cast(e, _) | ExprKind::Type(e, _) => (expr_search_pat_inner(tcx, e, outer_span).0, Pat::Str("")),
182            ExprKind::Let(let_expr) => (Pat::Str("let"), expr_search_pat_inner(tcx, let_expr.init, outer_span).1),
183            ExprKind::If(..) => (Pat::Str("if"), Pat::Str("}")),
184            ExprKind::Loop(_, Some(_), _, _) | ExprKind::Block(_, Some(_)) => (Pat::Str("'"), Pat::Str("}")),
185            ExprKind::Loop(_, None, LoopSource::Loop, _) => (Pat::Str("loop"), Pat::Str("}")),
186            ExprKind::Loop(_, None, LoopSource::While, _) => (Pat::Str("while"), Pat::Str("}")),
187            ExprKind::Loop(_, None, LoopSource::ForLoop, _) | ExprKind::Match(_, _, MatchSource::ForLoopDesugar) => {
188                (Pat::Str("for"), Pat::Str("}"))
189            },
190            ExprKind::Match(_, _, MatchSource::Normal) => (Pat::Str("match"), Pat::Str("}")),
191            ExprKind::Match(e, _, MatchSource::TryDesugar(_)) => {
192                (expr_search_pat_inner(tcx, e, outer_span).0, Pat::Str("?"))
193            },
194            ExprKind::Match(e, _, MatchSource::AwaitDesugar) | ExprKind::Yield(e, YieldSource::Await { .. }) => {
195                (expr_search_pat_inner(tcx, e, outer_span).0, Pat::Str("await"))
196            },
197            ExprKind::Closure(&Closure { body, .. }) => (
198                Pat::Str(""),
199                expr_search_pat_inner(tcx, tcx.hir_body(body).value, outer_span).1,
200            ),
201            ExprKind::Block(
202                Block {
203                    rules: BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided),
204                    ..
205                },
206                None,
207            ) => (Pat::Str("unsafe"), Pat::Str("}")),
208            ExprKind::Block(_, None) => (Pat::Str("{"), Pat::Str("}")),
209            ExprKind::Field(e, name) => (expr_search_pat_inner(tcx, e, outer_span).0, Pat::Sym(name.name)),
210            ExprKind::Index(e, _, _) => (expr_search_pat_inner(tcx, e, outer_span).0, Pat::Str("]")),
211            ExprKind::Path(ref path) => qpath_search_pat(path),
212            ExprKind::AddrOf(_, _, e) => (Pat::Str("&"), expr_search_pat_inner(tcx, e, outer_span).1),
213            ExprKind::Break(Destination { label: None, .. }, None) => (Pat::Str("break"), Pat::Str("break")),
214            ExprKind::Break(Destination { label: Some(name), .. }, None) => {
215                (Pat::Str("break"), Pat::Sym(name.ident.name))
216            },
217            ExprKind::Break(_, Some(e)) => (Pat::Str("break"), expr_search_pat_inner(tcx, e, outer_span).1),
218            ExprKind::Continue(Destination { label: None, .. }) => (Pat::Str("continue"), Pat::Str("continue")),
219            ExprKind::Continue(Destination { label: Some(name), .. }) => {
220                (Pat::Str("continue"), Pat::Sym(name.ident.name))
221            },
222            ExprKind::Ret(None) => (Pat::Str("return"), Pat::Str("return")),
223            ExprKind::Ret(Some(e)) => (Pat::Str("return"), expr_search_pat_inner(tcx, e, outer_span).1),
224            ExprKind::Struct(path, _, _) => (qpath_search_pat(path).0, Pat::Str("}")),
225            ExprKind::Yield(e, YieldSource::Yield) => (Pat::Str("yield"), expr_search_pat_inner(tcx, e, outer_span).1),
226            _ => (Pat::Str(""), Pat::Str("")),
227        }
228    }
229
230    expr_search_pat_inner(tcx, e, e.span)
231}
232
233fn fn_header_search_pat(header: FnHeader) -> Pat {
234    if header.is_async() {
235        Pat::Str("async")
236    } else if header.is_const() {
237        Pat::Str("const")
238    } else if header.is_unsafe() {
239        Pat::Str("unsafe")
240    } else if header.abi != ExternAbi::Rust {
241        Pat::Str("extern")
242    } else {
243        Pat::MultiStr(&["fn", "extern"])
244    }
245}
246
247fn item_search_pat(item: &Item<'_>) -> (Pat, Pat) {
248    let (start_pat, end_pat) = match &item.kind {
249        ItemKind::ExternCrate(..) => (Pat::Str("extern"), Pat::Str(";")),
250        ItemKind::Static(..) => (Pat::Str("static"), Pat::Str(";")),
251        ItemKind::Const(..) => (Pat::Str("const"), Pat::Str(";")),
252        ItemKind::Fn { sig, .. } => (fn_header_search_pat(sig.header), Pat::Str("")),
253        ItemKind::ForeignMod { .. } => (Pat::Str("extern"), Pat::Str("}")),
254        ItemKind::TyAlias(..) => (Pat::Str("type"), Pat::Str(";")),
255        ItemKind::Enum(..) => (Pat::Str("enum"), Pat::Str("}")),
256        ItemKind::Struct(_, _, VariantData::Struct { .. }) => (Pat::Str("struct"), Pat::Str("}")),
257        ItemKind::Struct(..) => (Pat::Str("struct"), Pat::Str(";")),
258        ItemKind::Union(..) => (Pat::Str("union"), Pat::Str("}")),
259        ItemKind::Trait(_, _, Safety::Unsafe, ..)
260        | ItemKind::Impl(Impl {
261            of_trait: Some(TraitImplHeader {
262                safety: Safety::Unsafe, ..
263            }),
264            ..
265        }) => (Pat::Str("unsafe"), Pat::Str("}")),
266        ItemKind::Trait(_, IsAuto::Yes, ..) => (Pat::Str("auto"), Pat::Str("}")),
267        ItemKind::Trait(..) => (Pat::Str("trait"), Pat::Str("}")),
268        ItemKind::Impl(_) => (Pat::Str("impl"), Pat::Str("}")),
269        _ => return (Pat::Str(""), Pat::Str("")),
270    };
271    if item.vis_span.is_empty() {
272        (start_pat, end_pat)
273    } else {
274        (Pat::Str("pub"), end_pat)
275    }
276}
277
278fn trait_item_search_pat(item: &TraitItem<'_>) -> (Pat, Pat) {
279    match &item.kind {
280        TraitItemKind::Const(..) => (Pat::Str("const"), Pat::Str(";")),
281        TraitItemKind::Type(..) => (Pat::Str("type"), Pat::Str(";")),
282        TraitItemKind::Fn(sig, ..) => (fn_header_search_pat(sig.header), Pat::Str("")),
283    }
284}
285
286fn impl_item_search_pat(item: &ImplItem<'_>) -> (Pat, Pat) {
287    let (mut start_pat, end_pat) = match &item.kind {
288        ImplItemKind::Const(..) => (Pat::Str("const"), Pat::Str(";")),
289        ImplItemKind::Type(..) => (Pat::Str("type"), Pat::Str(";")),
290        ImplItemKind::Fn(sig, ..) => (fn_header_search_pat(sig.header), Pat::Str("")),
291    };
292    if let ImplItemImplKind::Inherent { vis_span, .. } = item.impl_kind
293        && !vis_span.is_empty()
294    {
295        start_pat = Pat::Str("pub");
296    }
297    (start_pat, end_pat)
298}
299
300fn field_def_search_pat(def: &FieldDef<'_>) -> (Pat, Pat) {
301    if def.vis_span.is_empty() {
302        if def.is_positional() {
303            (Pat::Str(""), Pat::Str(""))
304        } else {
305            (Pat::Sym(def.ident.name), Pat::Str(""))
306        }
307    } else {
308        (Pat::Str("pub"), Pat::Str(""))
309    }
310}
311
312fn variant_search_pat(v: &Variant<'_>) -> (Pat, Pat) {
313    match v.data {
314        VariantData::Struct { .. } => (Pat::Sym(v.ident.name), Pat::Str("}")),
315        VariantData::Tuple(..) => (Pat::Sym(v.ident.name), Pat::Str("")),
316        VariantData::Unit(..) => (Pat::Sym(v.ident.name), Pat::Sym(v.ident.name)),
317    }
318}
319
320fn fn_kind_pat(tcx: TyCtxt<'_>, kind: &FnKind<'_>, body: &Body<'_>, hir_id: HirId) -> (Pat, Pat) {
321    let (mut start_pat, end_pat) = match kind {
322        FnKind::ItemFn(.., header) => (fn_header_search_pat(*header), Pat::Str("")),
323        FnKind::Method(.., sig) => (fn_header_search_pat(sig.header), Pat::Str("")),
324        FnKind::Closure => return (Pat::Str(""), expr_search_pat(tcx, body.value).1),
325    };
326    match tcx.hir_node(hir_id) {
327        Node::Item(Item { vis_span, .. })
328        | Node::ImplItem(ImplItem {
329            impl_kind: ImplItemImplKind::Inherent { vis_span, .. },
330            ..
331        }) => {
332            if !vis_span.is_empty() {
333                start_pat = Pat::Str("pub");
334            }
335        },
336        Node::ImplItem(_) | Node::TraitItem(_) => {},
337        _ => start_pat = Pat::Str(""),
338    }
339    (start_pat, end_pat)
340}
341
342fn attr_search_pat(attr: &Attribute) -> (Pat, Pat) {
343    match attr.kind {
344        AttrKind::Normal(..) => {
345            if let Some(ident) = attr.ident() {
346                // NOTE: This will likely have false positives, like `allow = 1`
347                let ident_string = ident.to_string();
348                if attr.style == AttrStyle::Outer {
349                    (
350                        Pat::OwnedMultiStr(vec!["#[".to_owned() + &ident_string, ident_string]),
351                        Pat::Str(""),
352                    )
353                } else {
354                    (
355                        Pat::OwnedMultiStr(vec!["#![".to_owned() + &ident_string, ident_string]),
356                        Pat::Str(""),
357                    )
358                }
359            } else {
360                (Pat::Str("#"), Pat::Str("]"))
361            }
362        },
363        AttrKind::DocComment(_kind @ CommentKind::Line, ..) => {
364            if attr.style == AttrStyle::Outer {
365                (Pat::Str("///"), Pat::Str(""))
366            } else {
367                (Pat::Str("//!"), Pat::Str(""))
368            }
369        },
370        AttrKind::DocComment(_kind @ CommentKind::Block, ..) => {
371            if attr.style == AttrStyle::Outer {
372                (Pat::Str("/**"), Pat::Str("*/"))
373            } else {
374                (Pat::Str("/*!"), Pat::Str("*/"))
375            }
376        },
377    }
378}
379
380fn ty_search_pat(ty: &Ty<'_>) -> (Pat, Pat) {
381    match ty.kind {
382        TyKind::Slice(..) | TyKind::Array(..) => (Pat::Str("["), Pat::Str("]")),
383        TyKind::Ptr(MutTy { ty, .. }) => (Pat::Str("*"), ty_search_pat(ty).1),
384        TyKind::Ref(_, MutTy { ty, .. }) => (Pat::Str("&"), ty_search_pat(ty).1),
385        TyKind::FnPtr(fn_ptr) => (
386            if fn_ptr.safety.is_unsafe() {
387                Pat::Str("unsafe")
388            } else if fn_ptr.abi != ExternAbi::Rust {
389                Pat::Str("extern")
390            } else {
391                Pat::MultiStr(&["fn", "extern"])
392            },
393            match fn_ptr.decl.output {
394                FnRetTy::DefaultReturn(_) => {
395                    if let [.., ty] = fn_ptr.decl.inputs {
396                        ty_search_pat(ty).1
397                    } else {
398                        Pat::Str("(")
399                    }
400                },
401                FnRetTy::Return(ty) => ty_search_pat(ty).1,
402            },
403        ),
404        TyKind::Never => (Pat::Str("!"), Pat::Str("!")),
405        // Parenthesis are trimmed from the text before the search patterns are matched.
406        // See: `span_matches_pat`
407        TyKind::Tup([]) => (Pat::Str(")"), Pat::Str("(")),
408        TyKind::Tup([ty]) => ty_search_pat(ty),
409        TyKind::Tup([head, .., tail]) => (ty_search_pat(head).0, ty_search_pat(tail).1),
410        TyKind::OpaqueDef(..) => (Pat::Str("impl"), Pat::Str("")),
411        TyKind::Path(qpath) => qpath_search_pat(&qpath),
412        TyKind::Infer(()) => (Pat::Str("_"), Pat::Str("_")),
413        TyKind::UnsafeBinder(binder_ty) => (Pat::Str("unsafe"), ty_search_pat(binder_ty.inner_ty).1),
414        TyKind::TraitObject(_, tagged_ptr) if let TraitObjectSyntax::Dyn = tagged_ptr.tag() => {
415            (Pat::Str("dyn"), Pat::Str(""))
416        },
417        // NOTE: `TraitObject` is incomplete. It will always return true then.
418        _ => (Pat::Str(""), Pat::Str("")),
419    }
420}
421
422fn ast_ty_search_pat(ty: &ast::Ty) -> (Pat, Pat) {
423    use ast::{Extern, FnRetTy, MutTy, Safety, TraitObjectSyntax, TyKind};
424
425    match &ty.kind {
426        TyKind::Slice(..) | TyKind::Array(..) => (Pat::Str("["), Pat::Str("]")),
427        TyKind::Ptr(MutTy { ty, .. }) => (Pat::Str("*"), ast_ty_search_pat(ty).1),
428        TyKind::Ref(_, MutTy { ty, .. }) | TyKind::PinnedRef(_, MutTy { ty, .. }) => {
429            (Pat::Str("&"), ast_ty_search_pat(ty).1)
430        },
431        TyKind::FnPtr(fn_ptr) => (
432            if let Safety::Unsafe(_) = fn_ptr.safety {
433                Pat::Str("unsafe")
434            } else if let Extern::Explicit(strlit, _) = fn_ptr.ext
435                && strlit.symbol == sym::rust
436            {
437                Pat::MultiStr(&["fn", "extern"])
438            } else {
439                Pat::Str("extern")
440            },
441            match &fn_ptr.decl.output {
442                FnRetTy::Default(_) => {
443                    if let [.., param] = &*fn_ptr.decl.inputs {
444                        ast_ty_search_pat(&param.ty).1
445                    } else {
446                        Pat::Str("(")
447                    }
448                },
449                FnRetTy::Ty(ty) => ast_ty_search_pat(ty).1,
450            },
451        ),
452        TyKind::Never => (Pat::Str("!"), Pat::Str("!")),
453        // Parenthesis are trimmed from the text before the search patterns are matched.
454        // See: `span_matches_pat`
455        TyKind::Tup(tup) => match &**tup {
456            [] => (Pat::Str(")"), Pat::Str("(")),
457            [ty] => ast_ty_search_pat(ty),
458            [head, .., tail] => (ast_ty_search_pat(head).0, ast_ty_search_pat(tail).1),
459        },
460        TyKind::ImplTrait(..) => (Pat::Str("impl"), Pat::Str("")),
461        TyKind::Path(qself_path, path) => {
462            let start = if qself_path.is_some() {
463                Pat::Str("<")
464            } else if let Some(first) = path.segments.first() {
465                ident_search_pat(first.ident).0
466            } else {
467                // this shouldn't be possible, but sure
468                Pat::Str("")
469            };
470            let end = if let Some(last) = path.segments.last() {
471                match last.args.as_deref() {
472                    // last `>` in `std::foo::Bar<T>`
473                    Some(GenericArgs::AngleBracketed(_)) => Pat::Str(">"),
474                    Some(GenericArgs::Parenthesized(par_args)) => match &par_args.output {
475                        FnRetTy::Default(_) => {
476                            if let Some(last) = par_args.inputs.last() {
477                                // `B` in `(A, B)` -- `)` gets stripped
478                                ast_ty_search_pat(last).1
479                            } else {
480                                // `(` in `()` -- `)` gets stripped
481                                Pat::Str("(")
482                            }
483                        },
484                        // `C` in `(A, B) -> C`
485                        FnRetTy::Ty(ty) => ast_ty_search_pat(ty).1,
486                    },
487                    // last `..` in `(..)` -- `)` gets stripped
488                    Some(GenericArgs::ParenthesizedElided(_)) => Pat::Str(".."),
489                    // `bar` in `std::foo::bar`
490                    None => ident_search_pat(last.ident).1,
491                }
492            } else {
493                // this shouldn't be possible
494                Pat::Str(
495                    if qself_path.is_some() {
496                        ">"  // last `>` in `<Vec as IntoIterator>`
497                    } else {
498                        ""
499                    }
500                )
501            };
502            (start, end)
503        },
504        TyKind::Infer => (Pat::Str("_"), Pat::Str("_")),
505        TyKind::Paren(ty) => ast_ty_search_pat(ty),
506        TyKind::UnsafeBinder(binder_ty) => (Pat::Str("unsafe"), ast_ty_search_pat(&binder_ty.inner_ty).1),
507        TyKind::TraitObject(_, trait_obj_syntax) => {
508            if let TraitObjectSyntax::Dyn = trait_obj_syntax {
509                (Pat::Str("dyn"), Pat::Str(""))
510            } else {
511                // NOTE: `TraitObject` is incomplete. It will always return true then.
512                (Pat::Str(""), Pat::Str(""))
513            }
514        },
515        TyKind::MacCall(mac_call) => {
516            let start = if let Some(first) = mac_call.path.segments.first() {
517                ident_search_pat(first.ident).0
518            } else {
519                Pat::Str("")
520            };
521            (start, Pat::Str(""))
522        },
523
524        // implicit, so has no contents to match against
525        TyKind::ImplicitSelf
526
527        // experimental
528        |TyKind::Pat(..)
529
530        // unused
531        | TyKind::CVarArgs
532        | TyKind::Typeof(_)
533
534        // placeholder
535        | TyKind::Dummy
536        | TyKind::Err(_) => (Pat::Str(""), Pat::Str("")),
537    }
538}
539
540fn ident_search_pat(ident: Ident) -> (Pat, Pat) {
541    (Pat::Sym(ident.name), Pat::Sym(ident.name))
542}
543
544pub trait WithSearchPat<'cx> {
545    type Context: LintContext;
546    fn search_pat(&self, cx: &Self::Context) -> (Pat, Pat);
547    fn span(&self) -> Span;
548}
549macro_rules! impl_with_search_pat {
550    (($cx_ident:ident: $cx_ty:ident<$cx_lt:lifetime>, $self:tt: $ty:ty) => $fn:ident($($args:tt)*)) => {
551        impl<$cx_lt> WithSearchPat<$cx_lt> for $ty {
552            type Context = $cx_ty<$cx_lt>;
553            fn search_pat(&$self, $cx_ident: &Self::Context) -> (Pat, Pat) {
554                $fn($($args)*)
555            }
556            fn span(&self) -> Span {
557                self.span
558            }
559        }
560    };
561}
562impl_with_search_pat!((cx: LateContext<'tcx>, self: Expr<'tcx>) => expr_search_pat(cx.tcx, self));
563impl_with_search_pat!((_cx: LateContext<'tcx>, self: Item<'_>) => item_search_pat(self));
564impl_with_search_pat!((_cx: LateContext<'tcx>, self: TraitItem<'_>) => trait_item_search_pat(self));
565impl_with_search_pat!((_cx: LateContext<'tcx>, self: ImplItem<'_>) => impl_item_search_pat(self));
566impl_with_search_pat!((_cx: LateContext<'tcx>, self: FieldDef<'_>) => field_def_search_pat(self));
567impl_with_search_pat!((_cx: LateContext<'tcx>, self: Variant<'_>) => variant_search_pat(self));
568impl_with_search_pat!((_cx: LateContext<'tcx>, self: Ty<'_>) => ty_search_pat(self));
569impl_with_search_pat!((_cx: LateContext<'tcx>, self: Ident) => ident_search_pat(*self));
570impl_with_search_pat!((_cx: LateContext<'tcx>, self: Lit) => lit_search_pat(&self.node));
571impl_with_search_pat!((_cx: LateContext<'tcx>, self: Path<'_>) => path_search_pat(self));
572
573impl_with_search_pat!((_cx: EarlyContext<'tcx>, self: Attribute) => attr_search_pat(self));
574impl_with_search_pat!((_cx: EarlyContext<'tcx>, self: ast::Ty) => ast_ty_search_pat(self));
575
576impl<'cx> WithSearchPat<'cx> for (&FnKind<'cx>, &Body<'cx>, HirId, Span) {
577    type Context = LateContext<'cx>;
578
579    fn search_pat(&self, cx: &Self::Context) -> (Pat, Pat) {
580        fn_kind_pat(cx.tcx, self.0, self.1, self.2)
581    }
582
583    fn span(&self) -> Span {
584        self.3
585    }
586}
587
588/// Checks if the item likely came from a proc-macro.
589///
590/// This should be called after `in_external_macro` and the initial pattern matching of the ast as
591/// it is significantly slower than both of those.
592pub fn is_from_proc_macro<'cx, T: WithSearchPat<'cx>>(cx: &T::Context, item: &T) -> bool {
593    let (start_pat, end_pat) = item.search_pat(cx);
594    !span_matches_pat(cx.sess(), item.span(), start_pat, end_pat)
595}
596
597/// Checks if the span actually refers to a match expression
598pub fn is_span_match(cx: &impl LintContext, span: Span) -> bool {
599    span_matches_pat(cx.sess(), span, Pat::Str("match"), Pat::Str("}"))
600}
601
602/// Checks if the span actually refers to an if expression
603pub fn is_span_if(cx: &impl LintContext, span: Span) -> bool {
604    span_matches_pat(cx.sess(), span, Pat::Str("if"), Pat::Str("}"))
605}
clippy_utils/check_proc_macro.rs

clippy_utils/
check_proc_macro.rs
