clippy_utils/
hir_utils.rs

1use crate::consts::ConstEvalCtxt;
2use crate::macros::macro_backtrace;
3use crate::source::{SpanRange, SpanRangeExt, walk_span_to_context};
4use crate::tokenize_with_text;
5use rustc_ast::ast;
6use rustc_ast::ast::InlineAsmTemplatePiece;
7use rustc_data_structures::fx::FxHasher;
8use rustc_hir::MatchSource::TryDesugar;
9use rustc_hir::def::{DefKind, Res};
10use rustc_hir::{
11    AssocItemConstraint, BinOpKind, BindingMode, Block, BodyId, Closure, ConstArg, ConstArgKind, Expr, ExprField,
12    ExprKind, FnRetTy, GenericArg, GenericArgs, HirId, HirIdMap, InlineAsmOperand, LetExpr, Lifetime, LifetimeKind,
13    Node, Pat, PatExpr, PatExprKind, PatField, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind,
14    StructTailExpr, TraitBoundModifiers, Ty, TyKind, TyPat, TyPatKind,
15};
16use rustc_lexer::{FrontmatterAllowed, TokenKind, tokenize};
17use rustc_lint::LateContext;
18use rustc_middle::ty::TypeckResults;
19use rustc_span::{BytePos, ExpnKind, MacroKind, Symbol, SyntaxContext, sym};
20use std::hash::{Hash, Hasher};
21use std::ops::Range;
22use std::slice;
23
24/// Callback that is called when two expressions are not equal in the sense of `SpanlessEq`, but
25/// other conditions would make them equal.
26type SpanlessEqCallback<'a> = dyn FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a;
27
28/// Determines how paths are hashed and compared for equality.
29#[derive(Copy, Clone, Debug, Default)]
30pub enum PathCheck {
31    /// Paths must match exactly and are hashed by their exact HIR tree.
32    ///
33    /// Thus, `std::iter::Iterator` and `Iterator` are not considered equal even though they refer
34    /// to the same item.
35    #[default]
36    Exact,
37    /// Paths are compared and hashed based on their resolution.
38    ///
39    /// They can appear different in the HIR tree but are still considered equal
40    /// and have equal hashes as long as they refer to the same item.
41    ///
42    /// Note that this is currently only partially implemented specifically for paths that are
43    /// resolved before type-checking, i.e. the final segment must have a non-error resolution.
44    /// If a path with an error resolution is encountered, it falls back to the default exact
45    /// matching behavior.
46    Resolution,
47}
48
49/// Type used to check whether two ast are the same. This is different from the
50/// operator `==` on ast types as this operator would compare true equality with
51/// ID and span.
52///
53/// Note that some expressions kinds are not considered but could be added.
54pub struct SpanlessEq<'a, 'tcx> {
55    /// Context used to evaluate constant expressions.
56    cx: &'a LateContext<'tcx>,
57    maybe_typeck_results: Option<(&'tcx TypeckResults<'tcx>, &'tcx TypeckResults<'tcx>)>,
58    allow_side_effects: bool,
59    expr_fallback: Option<Box<SpanlessEqCallback<'a>>>,
60    path_check: PathCheck,
61}
62
63impl<'a, 'tcx> SpanlessEq<'a, 'tcx> {
64    pub fn new(cx: &'a LateContext<'tcx>) -> Self {
65        Self {
66            cx,
67            maybe_typeck_results: cx.maybe_typeck_results().map(|x| (x, x)),
68            allow_side_effects: true,
69            expr_fallback: None,
70            path_check: PathCheck::default(),
71        }
72    }
73
74    /// Consider expressions containing potential side effects as not equal.
75    #[must_use]
76    pub fn deny_side_effects(self) -> Self {
77        Self {
78            allow_side_effects: false,
79            ..self
80        }
81    }
82
83    /// Check paths by their resolution instead of exact equality. See [`PathCheck`] for more
84    /// details.
85    #[must_use]
86    pub fn paths_by_resolution(self) -> Self {
87        Self {
88            path_check: PathCheck::Resolution,
89            ..self
90        }
91    }
92
93    #[must_use]
94    pub fn expr_fallback(self, expr_fallback: impl FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a) -> Self {
95        Self {
96            expr_fallback: Some(Box::new(expr_fallback)),
97            ..self
98        }
99    }
100
101    /// Use this method to wrap comparisons that may involve inter-expression context.
102    /// See `self.locals`.
103    pub fn inter_expr(&mut self) -> HirEqInterExpr<'_, 'a, 'tcx> {
104        HirEqInterExpr {
105            inner: self,
106            left_ctxt: SyntaxContext::root(),
107            right_ctxt: SyntaxContext::root(),
108            locals: HirIdMap::default(),
109        }
110    }
111
112    pub fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
113        self.inter_expr().eq_block(left, right)
114    }
115
116    pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
117        self.inter_expr().eq_expr(left, right)
118    }
119
120    pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
121        self.inter_expr().eq_path(left, right)
122    }
123
124    pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
125        self.inter_expr().eq_path_segment(left, right)
126    }
127
128    pub fn eq_path_segments(&mut self, left: &[PathSegment<'_>], right: &[PathSegment<'_>]) -> bool {
129        self.inter_expr().eq_path_segments(left, right)
130    }
131
132    pub fn eq_modifiers(left: TraitBoundModifiers, right: TraitBoundModifiers) -> bool {
133        std::mem::discriminant(&left.constness) == std::mem::discriminant(&right.constness)
134            && std::mem::discriminant(&left.polarity) == std::mem::discriminant(&right.polarity)
135    }
136}
137
138pub struct HirEqInterExpr<'a, 'b, 'tcx> {
139    inner: &'a mut SpanlessEq<'b, 'tcx>,
140    left_ctxt: SyntaxContext,
141    right_ctxt: SyntaxContext,
142
143    // When binding are declared, the binding ID in the left expression is mapped to the one on the
144    // right. For example, when comparing `{ let x = 1; x + 2 }` and `{ let y = 1; y + 2 }`,
145    // these blocks are considered equal since `x` is mapped to `y`.
146    pub locals: HirIdMap<HirId>,
147}
148
149impl HirEqInterExpr<'_, '_, '_> {
150    pub fn eq_stmt(&mut self, left: &Stmt<'_>, right: &Stmt<'_>) -> bool {
151        match (&left.kind, &right.kind) {
152            (StmtKind::Let(l), StmtKind::Let(r)) => {
153                // This additional check ensures that the type of the locals are equivalent even if the init
154                // expression or type have some inferred parts.
155                if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
156                    let l_ty = typeck_lhs.pat_ty(l.pat);
157                    let r_ty = typeck_rhs.pat_ty(r.pat);
158                    if l_ty != r_ty {
159                        return false;
160                    }
161                }
162
163                // eq_pat adds the HirIds to the locals map. We therefore call it last to make sure that
164                // these only get added if the init and type is equal.
165                both(l.init.as_ref(), r.init.as_ref(), |l, r| self.eq_expr(l, r))
166                    && both(l.ty.as_ref(), r.ty.as_ref(), |l, r| self.eq_ty(l, r))
167                    && both(l.els.as_ref(), r.els.as_ref(), |l, r| self.eq_block(l, r))
168                    && self.eq_pat(l.pat, r.pat)
169            },
170            (StmtKind::Expr(l), StmtKind::Expr(r)) | (StmtKind::Semi(l), StmtKind::Semi(r)) => self.eq_expr(l, r),
171            _ => false,
172        }
173    }
174
175    /// Checks whether two blocks are the same.
176    fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
177        use TokenKind::{Semi, Whitespace};
178        if left.stmts.len() != right.stmts.len() {
179            return false;
180        }
181        let lspan = left.span.data();
182        let rspan = right.span.data();
183        if lspan.ctxt != SyntaxContext::root() && rspan.ctxt != SyntaxContext::root() {
184            // Don't try to check in between statements inside macros.
185            return over(left.stmts, right.stmts, |left, right| self.eq_stmt(left, right))
186                && both(left.expr.as_ref(), right.expr.as_ref(), |left, right| {
187                    self.eq_expr(left, right)
188                });
189        }
190        if lspan.ctxt != rspan.ctxt {
191            return false;
192        }
193
194        let mut lstart = lspan.lo;
195        let mut rstart = rspan.lo;
196
197        for (left, right) in left.stmts.iter().zip(right.stmts) {
198            if !self.eq_stmt(left, right) {
199                return false;
200            }
201
202            // Try to detect any `cfg`ed statements or empty macro expansions.
203            let Some(lstmt_span) = walk_span_to_context(left.span, lspan.ctxt) else {
204                return false;
205            };
206            let Some(rstmt_span) = walk_span_to_context(right.span, rspan.ctxt) else {
207                return false;
208            };
209            let lstmt_span = lstmt_span.data();
210            let rstmt_span = rstmt_span.data();
211
212            if lstmt_span.lo < lstart && rstmt_span.lo < rstart {
213                // Can happen when macros expand to multiple statements, or rearrange statements.
214                // Nothing in between the statements to check in this case.
215                continue;
216            }
217            if lstmt_span.lo < lstart || rstmt_span.lo < rstart {
218                // Only one of the blocks had a weird macro.
219                return false;
220            }
221            if !eq_span_tokens(self.inner.cx, lstart..lstmt_span.lo, rstart..rstmt_span.lo, |t| {
222                !matches!(t, Whitespace | Semi)
223            }) {
224                return false;
225            }
226
227            lstart = lstmt_span.hi;
228            rstart = rstmt_span.hi;
229        }
230
231        let (lend, rend) = match (left.expr, right.expr) {
232            (Some(left), Some(right)) => {
233                if !self.eq_expr(left, right) {
234                    return false;
235                }
236                let Some(lexpr_span) = walk_span_to_context(left.span, lspan.ctxt) else {
237                    return false;
238                };
239                let Some(rexpr_span) = walk_span_to_context(right.span, rspan.ctxt) else {
240                    return false;
241                };
242                (lexpr_span.lo(), rexpr_span.lo())
243            },
244            (None, None) => (lspan.hi, rspan.hi),
245            (Some(_), None) | (None, Some(_)) => return false,
246        };
247
248        if lend < lstart && rend < rstart {
249            // Can happen when macros rearrange the input.
250            // Nothing in between the statements to check in this case.
251            return true;
252        } else if lend < lstart || rend < rstart {
253            // Only one of the blocks had a weird macro
254            return false;
255        }
256        eq_span_tokens(self.inner.cx, lstart..lend, rstart..rend, |t| {
257            !matches!(t, Whitespace | Semi)
258        })
259    }
260
261    fn should_ignore(&self, expr: &Expr<'_>) -> bool {
262        macro_backtrace(expr.span).last().is_some_and(|macro_call| {
263            matches!(
264                self.inner.cx.tcx.get_diagnostic_name(macro_call.def_id),
265                Some(sym::todo_macro | sym::unimplemented_macro)
266            )
267        })
268    }
269
270    pub fn eq_body(&mut self, left: BodyId, right: BodyId) -> bool {
271        // swap out TypeckResults when hashing a body
272        let old_maybe_typeck_results = self.inner.maybe_typeck_results.replace((
273            self.inner.cx.tcx.typeck_body(left),
274            self.inner.cx.tcx.typeck_body(right),
275        ));
276        let res = self.eq_expr(
277            self.inner.cx.tcx.hir_body(left).value,
278            self.inner.cx.tcx.hir_body(right).value,
279        );
280        self.inner.maybe_typeck_results = old_maybe_typeck_results;
281        res
282    }
283
284    #[expect(clippy::too_many_lines)]
285    pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
286        if !self.check_ctxt(left.span.ctxt(), right.span.ctxt()) {
287            return false;
288        }
289
290        if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results
291            && typeck_lhs.expr_ty(left) == typeck_rhs.expr_ty(right)
292            && let (Some(l), Some(r)) = (
293                ConstEvalCtxt::with_env(self.inner.cx.tcx, self.inner.cx.typing_env(), typeck_lhs)
294                    .eval_local(left, self.left_ctxt),
295                ConstEvalCtxt::with_env(self.inner.cx.tcx, self.inner.cx.typing_env(), typeck_rhs)
296                    .eval_local(right, self.right_ctxt),
297            )
298            && l == r
299        {
300            return true;
301        }
302
303        let is_eq = match (
304            reduce_exprkind(self.inner.cx, &left.kind),
305            reduce_exprkind(self.inner.cx, &right.kind),
306        ) {
307            (ExprKind::AddrOf(lb, l_mut, le), ExprKind::AddrOf(rb, r_mut, re)) => {
308                lb == rb && l_mut == r_mut && self.eq_expr(le, re)
309            },
310            (ExprKind::Array(l), ExprKind::Array(r)) => self.eq_exprs(l, r),
311            (ExprKind::Assign(ll, lr, _), ExprKind::Assign(rl, rr, _)) => {
312                self.inner.allow_side_effects && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
313            },
314            (ExprKind::AssignOp(lo, ll, lr), ExprKind::AssignOp(ro, rl, rr)) => {
315                self.inner.allow_side_effects && lo.node == ro.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
316            },
317            (ExprKind::Block(l, _), ExprKind::Block(r, _)) => self.eq_block(l, r),
318            (ExprKind::Binary(l_op, ll, lr), ExprKind::Binary(r_op, rl, rr)) => {
319                l_op.node == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
320                    || swap_binop(l_op.node, ll, lr).is_some_and(|(l_op, ll, lr)| {
321                        l_op == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
322                    })
323            },
324            (ExprKind::Break(li, le), ExprKind::Break(ri, re)) => {
325                both(li.label.as_ref(), ri.label.as_ref(), |l, r| l.ident.name == r.ident.name)
326                    && both(le.as_ref(), re.as_ref(), |l, r| self.eq_expr(l, r))
327            },
328            (ExprKind::Call(l_fun, l_args), ExprKind::Call(r_fun, r_args)) => {
329                self.inner.allow_side_effects && self.eq_expr(l_fun, r_fun) && self.eq_exprs(l_args, r_args)
330            },
331            (ExprKind::Cast(lx, lt), ExprKind::Cast(rx, rt)) => {
332                self.eq_expr(lx, rx) && self.eq_ty(lt, rt)
333            },
334            (ExprKind::Closure(_l), ExprKind::Closure(_r)) => false,
335            (ExprKind::ConstBlock(lb), ExprKind::ConstBlock(rb)) => self.eq_body(lb.body, rb.body),
336            (ExprKind::Continue(li), ExprKind::Continue(ri)) => {
337                both(li.label.as_ref(), ri.label.as_ref(), |l, r| l.ident.name == r.ident.name)
338            },
339            (ExprKind::DropTemps(le), ExprKind::DropTemps(re)) => self.eq_expr(le, re),
340            (ExprKind::Field(l_f_exp, l_f_ident), ExprKind::Field(r_f_exp, r_f_ident)) => {
341                l_f_ident.name == r_f_ident.name && self.eq_expr(l_f_exp, r_f_exp)
342            },
343            (ExprKind::Index(la, li, _), ExprKind::Index(ra, ri, _)) => self.eq_expr(la, ra) && self.eq_expr(li, ri),
344            (ExprKind::If(lc, lt, le), ExprKind::If(rc, rt, re)) => {
345                self.eq_expr(lc, rc) && self.eq_expr(lt, rt)
346                    && both(le.as_ref(), re.as_ref(), |l, r| self.eq_expr(l, r))
347            },
348            (ExprKind::Let(l), ExprKind::Let(r)) => {
349                self.eq_pat(l.pat, r.pat)
350                    && both(l.ty.as_ref(), r.ty.as_ref(), |l, r| self.eq_ty(l, r))
351                    && self.eq_expr(l.init, r.init)
352            },
353            (ExprKind::Lit(l), ExprKind::Lit(r)) => l.node == r.node,
354            (ExprKind::Loop(lb, ll, lls, _), ExprKind::Loop(rb, rl, rls, _)) => {
355                lls == rls && self.eq_block(lb, rb)
356                    && both(ll.as_ref(), rl.as_ref(), |l, r| l.ident.name == r.ident.name)
357            },
358            (ExprKind::Match(le, la, ls), ExprKind::Match(re, ra, rs)) => {
359                (ls == rs || (matches!((ls, rs), (TryDesugar(_), TryDesugar(_)))))
360                    && self.eq_expr(le, re)
361                    && over(la, ra, |l, r| {
362                        self.eq_pat(l.pat, r.pat)
363                            && both(l.guard.as_ref(), r.guard.as_ref(), |l, r| self.eq_expr(l, r))
364                            && self.eq_expr(l.body, r.body)
365                    })
366            },
367            (
368                ExprKind::MethodCall(l_path, l_receiver, l_args, _),
369                ExprKind::MethodCall(r_path, r_receiver, r_args, _),
370            ) => {
371                self.inner.allow_side_effects
372                    && self.eq_path_segment(l_path, r_path)
373                    && self.eq_expr(l_receiver, r_receiver)
374                    && self.eq_exprs(l_args, r_args)
375            },
376            (ExprKind::UnsafeBinderCast(lkind, le, None), ExprKind::UnsafeBinderCast(rkind, re, None)) =>
377                lkind == rkind && self.eq_expr(le, re),
378            (ExprKind::UnsafeBinderCast(lkind, le, Some(lt)), ExprKind::UnsafeBinderCast(rkind, re, Some(rt))) =>
379                lkind == rkind && self.eq_expr(le, re) && self.eq_ty(lt, rt),
380            (ExprKind::OffsetOf(l_container, l_fields), ExprKind::OffsetOf(r_container, r_fields)) => {
381                self.eq_ty(l_container, r_container) && over(l_fields, r_fields, |l, r| l.name == r.name)
382            },
383            (ExprKind::Path(l), ExprKind::Path(r)) => self.eq_qpath(l, r),
384            (ExprKind::Repeat(le, ll), ExprKind::Repeat(re, rl)) => {
385                self.eq_expr(le, re) && self.eq_const_arg(ll, rl)
386            },
387            (ExprKind::Ret(l), ExprKind::Ret(r)) => both(l.as_ref(), r.as_ref(), |l, r| self.eq_expr(l, r)),
388            (ExprKind::Struct(l_path, lf, lo), ExprKind::Struct(r_path, rf, ro)) => {
389                self.eq_qpath(l_path, r_path)
390                    && match (lo, ro) {
391                        (StructTailExpr::Base(l),StructTailExpr::Base(r)) => self.eq_expr(l, r),
392                        (StructTailExpr::None, StructTailExpr::None) |
393                        (StructTailExpr::DefaultFields(_), StructTailExpr::DefaultFields(_)) => true,
394                        _ => false,
395                    }
396                    && over(lf, rf, |l, r| self.eq_expr_field(l, r))
397            },
398            (ExprKind::Tup(l_tup), ExprKind::Tup(r_tup)) => self.eq_exprs(l_tup, r_tup),
399            (ExprKind::Use(l_expr, _), ExprKind::Use(r_expr, _)) => self.eq_expr(l_expr, r_expr),
400            (ExprKind::Type(le, lt), ExprKind::Type(re, rt)) => self.eq_expr(le, re) && self.eq_ty(lt, rt),
401            (ExprKind::Unary(l_op, le), ExprKind::Unary(r_op, re)) => l_op == r_op && self.eq_expr(le, re),
402            (ExprKind::Yield(le, _), ExprKind::Yield(re, _)) => return self.eq_expr(le, re),
403            (
404                // Else branches for branches above, grouped as per `match_same_arms`.
405                | ExprKind::AddrOf(..)
406                | ExprKind::Array(..)
407                | ExprKind::Assign(..)
408                | ExprKind::AssignOp(..)
409                | ExprKind::Binary(..)
410                | ExprKind::Become(..)
411                | ExprKind::Block(..)
412                | ExprKind::Break(..)
413                | ExprKind::Call(..)
414                | ExprKind::Cast(..)
415                | ExprKind::ConstBlock(..)
416                | ExprKind::Continue(..)
417                | ExprKind::DropTemps(..)
418                | ExprKind::Field(..)
419                | ExprKind::Index(..)
420                | ExprKind::If(..)
421                | ExprKind::Let(..)
422                | ExprKind::Lit(..)
423                | ExprKind::Loop(..)
424                | ExprKind::Match(..)
425                | ExprKind::MethodCall(..)
426                | ExprKind::OffsetOf(..)
427                | ExprKind::Path(..)
428                | ExprKind::Repeat(..)
429                | ExprKind::Ret(..)
430                | ExprKind::Struct(..)
431                | ExprKind::Tup(..)
432                | ExprKind::Use(..)
433                | ExprKind::Type(..)
434                | ExprKind::Unary(..)
435                | ExprKind::Yield(..)
436                | ExprKind::UnsafeBinderCast(..)
437
438                // --- Special cases that do not have a positive branch.
439
440                // `Err` represents an invalid expression, so let's never assume that
441                // an invalid expressions is equal to anything.
442                | ExprKind::Err(..)
443
444                // For the time being, we always consider that two closures are unequal.
445                // This behavior may change in the future.
446                | ExprKind::Closure(..)
447                // For the time being, we always consider that two instances of InlineAsm are different.
448                // This behavior may change in the future.
449                | ExprKind::InlineAsm(_)
450                , _
451            ) => false,
452        };
453        (is_eq && (!self.should_ignore(left) || !self.should_ignore(right)))
454            || self.inner.expr_fallback.as_mut().is_some_and(|f| f(left, right))
455    }
456
457    fn eq_exprs(&mut self, left: &[Expr<'_>], right: &[Expr<'_>]) -> bool {
458        over(left, right, |l, r| self.eq_expr(l, r))
459    }
460
461    fn eq_expr_field(&mut self, left: &ExprField<'_>, right: &ExprField<'_>) -> bool {
462        left.ident.name == right.ident.name && self.eq_expr(left.expr, right.expr)
463    }
464
465    fn eq_generic_arg(&mut self, left: &GenericArg<'_>, right: &GenericArg<'_>) -> bool {
466        match (left, right) {
467            (GenericArg::Const(l), GenericArg::Const(r)) => self.eq_const_arg(l.as_unambig_ct(), r.as_unambig_ct()),
468            (GenericArg::Lifetime(l_lt), GenericArg::Lifetime(r_lt)) => Self::eq_lifetime(l_lt, r_lt),
469            (GenericArg::Type(l_ty), GenericArg::Type(r_ty)) => self.eq_ty(l_ty.as_unambig_ty(), r_ty.as_unambig_ty()),
470            (GenericArg::Infer(l_inf), GenericArg::Infer(r_inf)) => self.eq_ty(&l_inf.to_ty(), &r_inf.to_ty()),
471            _ => false,
472        }
473    }
474
475    fn eq_const_arg(&mut self, left: &ConstArg<'_>, right: &ConstArg<'_>) -> bool {
476        match (&left.kind, &right.kind) {
477            (ConstArgKind::Path(l_p), ConstArgKind::Path(r_p)) => self.eq_qpath(l_p, r_p),
478            (ConstArgKind::Anon(l_an), ConstArgKind::Anon(r_an)) => self.eq_body(l_an.body, r_an.body),
479            (ConstArgKind::Infer(..), ConstArgKind::Infer(..)) => true,
480            // Use explicit match for now since ConstArg is undergoing flux.
481            (ConstArgKind::Path(..), ConstArgKind::Anon(..))
482            | (ConstArgKind::Anon(..), ConstArgKind::Path(..))
483            | (ConstArgKind::Infer(..), _)
484            | (_, ConstArgKind::Infer(..)) => false,
485        }
486    }
487
488    fn eq_lifetime(left: &Lifetime, right: &Lifetime) -> bool {
489        left.kind == right.kind
490    }
491
492    fn eq_pat_field(&mut self, left: &PatField<'_>, right: &PatField<'_>) -> bool {
493        let (PatField { ident: li, pat: lp, .. }, PatField { ident: ri, pat: rp, .. }) = (&left, &right);
494        li.name == ri.name && self.eq_pat(lp, rp)
495    }
496
497    fn eq_pat_expr(&mut self, left: &PatExpr<'_>, right: &PatExpr<'_>) -> bool {
498        match (&left.kind, &right.kind) {
499            (
500                PatExprKind::Lit {
501                    lit: left,
502                    negated: left_neg,
503                },
504                PatExprKind::Lit {
505                    lit: right,
506                    negated: right_neg,
507                },
508            ) => left_neg == right_neg && left.node == right.node,
509            (PatExprKind::ConstBlock(left), PatExprKind::ConstBlock(right)) => self.eq_body(left.body, right.body),
510            (PatExprKind::Path(left), PatExprKind::Path(right)) => self.eq_qpath(left, right),
511            (PatExprKind::Lit { .. } | PatExprKind::ConstBlock(..) | PatExprKind::Path(..), _) => false,
512        }
513    }
514
515    /// Checks whether two patterns are the same.
516    fn eq_pat(&mut self, left: &Pat<'_>, right: &Pat<'_>) -> bool {
517        match (&left.kind, &right.kind) {
518            (PatKind::Box(l), PatKind::Box(r)) => self.eq_pat(l, r),
519            (PatKind::Struct(lp, la, ..), PatKind::Struct(rp, ra, ..)) => {
520                self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat_field(l, r))
521            },
522            (PatKind::TupleStruct(lp, la, ls), PatKind::TupleStruct(rp, ra, rs)) => {
523                self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat(l, r)) && ls == rs
524            },
525            (PatKind::Binding(lb, li, _, lp), PatKind::Binding(rb, ri, _, rp)) => {
526                let eq = lb == rb && both(lp.as_ref(), rp.as_ref(), |l, r| self.eq_pat(l, r));
527                if eq {
528                    self.locals.insert(*li, *ri);
529                }
530                eq
531            },
532            (PatKind::Expr(l), PatKind::Expr(r)) => self.eq_pat_expr(l, r),
533            (PatKind::Tuple(l, ls), PatKind::Tuple(r, rs)) => ls == rs && over(l, r, |l, r| self.eq_pat(l, r)),
534            (PatKind::Range(ls, le, li), PatKind::Range(rs, re, ri)) => {
535                both(ls.as_ref(), rs.as_ref(), |a, b| self.eq_pat_expr(a, b))
536                    && both(le.as_ref(), re.as_ref(), |a, b| self.eq_pat_expr(a, b))
537                    && (li == ri)
538            },
539            (PatKind::Ref(le, lm), PatKind::Ref(re, rm)) => lm == rm && self.eq_pat(le, re),
540            (PatKind::Slice(ls, li, le), PatKind::Slice(rs, ri, re)) => {
541                over(ls, rs, |l, r| self.eq_pat(l, r))
542                    && over(le, re, |l, r| self.eq_pat(l, r))
543                    && both(li.as_ref(), ri.as_ref(), |l, r| self.eq_pat(l, r))
544            },
545            (PatKind::Wild, PatKind::Wild) => true,
546            _ => false,
547        }
548    }
549
550    fn eq_qpath(&mut self, left: &QPath<'_>, right: &QPath<'_>) -> bool {
551        match (left, right) {
552            (QPath::Resolved(lty, lpath), QPath::Resolved(rty, rpath)) => {
553                both(lty.as_ref(), rty.as_ref(), |l, r| self.eq_ty(l, r)) && self.eq_path(lpath, rpath)
554            },
555            (QPath::TypeRelative(lty, lseg), QPath::TypeRelative(rty, rseg)) => {
556                self.eq_ty(lty, rty) && self.eq_path_segment(lseg, rseg)
557            },
558            (QPath::LangItem(llang_item, ..), QPath::LangItem(rlang_item, ..)) => llang_item == rlang_item,
559            _ => false,
560        }
561    }
562
563    pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
564        match (left.res, right.res) {
565            (Res::Local(l), Res::Local(r)) => l == r || self.locals.get(&l) == Some(&r),
566            (Res::Local(_), _) | (_, Res::Local(_)) => false,
567            _ => self.eq_path_segments(left.segments, right.segments),
568        }
569    }
570
571    fn eq_path_parameters(&mut self, left: &GenericArgs<'_>, right: &GenericArgs<'_>) -> bool {
572        if left.parenthesized == right.parenthesized {
573            over(left.args, right.args, |l, r| self.eq_generic_arg(l, r)) // FIXME(flip1995): may not work
574                && over(left.constraints, right.constraints, |l, r| self.eq_assoc_eq_constraint(l, r))
575        } else {
576            false
577        }
578    }
579
580    pub fn eq_path_segments<'tcx>(
581        &mut self,
582        mut left: &'tcx [PathSegment<'tcx>],
583        mut right: &'tcx [PathSegment<'tcx>],
584    ) -> bool {
585        if let PathCheck::Resolution = self.inner.path_check
586            && let Some(left_seg) = generic_path_segments(left)
587            && let Some(right_seg) = generic_path_segments(right)
588        {
589            // If we compare by resolution, then only check the last segments that could possibly have generic
590            // arguments
591            left = left_seg;
592            right = right_seg;
593        }
594
595        over(left, right, |l, r| self.eq_path_segment(l, r))
596    }
597
598    pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
599        if !self.eq_path_parameters(left.args(), right.args()) {
600            return false;
601        }
602
603        if let PathCheck::Resolution = self.inner.path_check
604            && left.res != Res::Err
605            && right.res != Res::Err
606        {
607            left.res == right.res
608        } else {
609            // The == of idents doesn't work with different contexts,
610            // we have to be explicit about hygiene
611            left.ident.name == right.ident.name
612        }
613    }
614
615    pub fn eq_ty(&mut self, left: &Ty<'_>, right: &Ty<'_>) -> bool {
616        match (&left.kind, &right.kind) {
617            (TyKind::Slice(l_vec), TyKind::Slice(r_vec)) => self.eq_ty(l_vec, r_vec),
618            (TyKind::Array(lt, ll), TyKind::Array(rt, rl)) => self.eq_ty(lt, rt) && self.eq_const_arg(ll, rl),
619            (TyKind::Ptr(l_mut), TyKind::Ptr(r_mut)) => l_mut.mutbl == r_mut.mutbl && self.eq_ty(l_mut.ty, r_mut.ty),
620            (TyKind::Ref(_, l_rmut), TyKind::Ref(_, r_rmut)) => {
621                l_rmut.mutbl == r_rmut.mutbl && self.eq_ty(l_rmut.ty, r_rmut.ty)
622            },
623            (TyKind::Path(l), TyKind::Path(r)) => self.eq_qpath(l, r),
624            (TyKind::Tup(l), TyKind::Tup(r)) => over(l, r, |l, r| self.eq_ty(l, r)),
625            (TyKind::Infer(()), TyKind::Infer(())) => true,
626            _ => false,
627        }
628    }
629
630    /// Checks whether two constraints designate the same equality constraint (same name, and same
631    /// type or const).
632    fn eq_assoc_eq_constraint(&mut self, left: &AssocItemConstraint<'_>, right: &AssocItemConstraint<'_>) -> bool {
633        // TODO: this could be extended to check for identical associated item bound constraints
634        left.ident.name == right.ident.name
635            && (both_some_and(left.ty(), right.ty(), |l, r| self.eq_ty(l, r))
636                || both_some_and(left.ct(), right.ct(), |l, r| self.eq_const_arg(l, r)))
637    }
638
639    fn check_ctxt(&mut self, left: SyntaxContext, right: SyntaxContext) -> bool {
640        if self.left_ctxt == left && self.right_ctxt == right {
641            return true;
642        } else if self.left_ctxt == left || self.right_ctxt == right {
643            // Only one context has changed. This can only happen if the two nodes are written differently.
644            return false;
645        } else if left != SyntaxContext::root() {
646            let mut left_data = left.outer_expn_data();
647            let mut right_data = right.outer_expn_data();
648            loop {
649                use TokenKind::{BlockComment, LineComment, Whitespace};
650                if left_data.macro_def_id != right_data.macro_def_id
651                    || (matches!(
652                        left_data.kind,
653                        ExpnKind::Macro(MacroKind::Bang, name)
654                        if name == sym::cfg || name == sym::option_env
655                    ) && !eq_span_tokens(self.inner.cx, left_data.call_site, right_data.call_site, |t| {
656                        !matches!(t, Whitespace | LineComment { .. } | BlockComment { .. })
657                    }))
658                {
659                    // Either a different chain of macro calls, or different arguments to the `cfg` macro.
660                    return false;
661                }
662                let left_ctxt = left_data.call_site.ctxt();
663                let right_ctxt = right_data.call_site.ctxt();
664                if left_ctxt == SyntaxContext::root() && right_ctxt == SyntaxContext::root() {
665                    break;
666                }
667                if left_ctxt == SyntaxContext::root() || right_ctxt == SyntaxContext::root() {
668                    // Different lengths for the expansion stack. This can only happen if nodes are written differently,
669                    // or shouldn't be compared to start with.
670                    return false;
671                }
672                left_data = left_ctxt.outer_expn_data();
673                right_data = right_ctxt.outer_expn_data();
674            }
675        }
676        self.left_ctxt = left;
677        self.right_ctxt = right;
678        true
679    }
680}
681
682/// Some simple reductions like `{ return }` => `return`
683fn reduce_exprkind<'hir>(cx: &LateContext<'_>, kind: &'hir ExprKind<'hir>) -> &'hir ExprKind<'hir> {
684    if let ExprKind::Block(block, _) = kind {
685        match (block.stmts, block.expr) {
686            // From an `if let` expression without an `else` block. The arm for the implicit wild pattern is an empty
687            // block with an empty span.
688            ([], None) if block.span.is_empty() => &ExprKind::Tup(&[]),
689            // `{}` => `()`
690            ([], None)
691                if block.span.check_source_text(cx, |src| {
692                    tokenize(src, FrontmatterAllowed::No)
693                        .map(|t| t.kind)
694                        .filter(|t| {
695                            !matches!(
696                                t,
697                                TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
698                            )
699                        })
700                        .eq([TokenKind::OpenBrace, TokenKind::CloseBrace].iter().copied())
701                }) =>
702            {
703                &ExprKind::Tup(&[])
704            },
705            ([], Some(expr)) => match expr.kind {
706                // `{ return .. }` => `return ..`
707                ExprKind::Ret(..) => &expr.kind,
708                _ => kind,
709            },
710            ([stmt], None) => match stmt.kind {
711                StmtKind::Expr(expr) | StmtKind::Semi(expr) => match expr.kind {
712                    // `{ return ..; }` => `return ..`
713                    ExprKind::Ret(..) => &expr.kind,
714                    _ => kind,
715                },
716                _ => kind,
717            },
718            _ => kind,
719        }
720    } else {
721        kind
722    }
723}
724
725fn swap_binop<'a>(
726    binop: BinOpKind,
727    lhs: &'a Expr<'a>,
728    rhs: &'a Expr<'a>,
729) -> Option<(BinOpKind, &'a Expr<'a>, &'a Expr<'a>)> {
730    match binop {
731        BinOpKind::Add | BinOpKind::Eq | BinOpKind::Ne | BinOpKind::BitAnd | BinOpKind::BitXor | BinOpKind::BitOr => {
732            Some((binop, rhs, lhs))
733        },
734        BinOpKind::Lt => Some((BinOpKind::Gt, rhs, lhs)),
735        BinOpKind::Le => Some((BinOpKind::Ge, rhs, lhs)),
736        BinOpKind::Ge => Some((BinOpKind::Le, rhs, lhs)),
737        BinOpKind::Gt => Some((BinOpKind::Lt, rhs, lhs)),
738        BinOpKind::Mul // Not always commutative, e.g. with matrices. See issue #5698
739        | BinOpKind::Shl
740        | BinOpKind::Shr
741        | BinOpKind::Rem
742        | BinOpKind::Sub
743        | BinOpKind::Div
744        | BinOpKind::And
745        | BinOpKind::Or => None,
746    }
747}
748
749/// Checks if the two `Option`s are both `None` or some equal values as per
750/// `eq_fn`.
751pub fn both<X>(l: Option<&X>, r: Option<&X>, mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
752    l.as_ref()
753        .map_or_else(|| r.is_none(), |x| r.as_ref().is_some_and(|y| eq_fn(x, y)))
754}
755
756/// Checks if the two `Option`s are both `Some` and pass the predicate function.
757pub fn both_some_and<X, Y>(l: Option<X>, r: Option<Y>, mut pred: impl FnMut(X, Y) -> bool) -> bool {
758    l.is_some_and(|l| r.is_some_and(|r| pred(l, r)))
759}
760
761/// Checks if two slices are equal as per `eq_fn`.
762pub fn over<X, Y>(left: &[X], right: &[Y], mut eq_fn: impl FnMut(&X, &Y) -> bool) -> bool {
763    left.len() == right.len() && left.iter().zip(right).all(|(x, y)| eq_fn(x, y))
764}
765
766/// Counts how many elements of the slices are equal as per `eq_fn`.
767pub fn count_eq<X: Sized>(
768    left: &mut dyn Iterator<Item = X>,
769    right: &mut dyn Iterator<Item = X>,
770    mut eq_fn: impl FnMut(&X, &X) -> bool,
771) -> usize {
772    left.zip(right).take_while(|(l, r)| eq_fn(l, r)).count()
773}
774
775/// Checks if two expressions evaluate to the same value, and don't contain any side effects.
776pub fn eq_expr_value(cx: &LateContext<'_>, left: &Expr<'_>, right: &Expr<'_>) -> bool {
777    SpanlessEq::new(cx).deny_side_effects().eq_expr(left, right)
778}
779
780/// Returns the segments of a path that might have generic parameters.
781/// Usually just the last segment for free items, except for when the path resolves to an associated
782/// item, in which case it is the last two
783fn generic_path_segments<'tcx>(segments: &'tcx [PathSegment<'tcx>]) -> Option<&'tcx [PathSegment<'tcx>]> {
784    match segments.last()?.res {
785        Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _) => {
786            // <Ty as module::Trait<T>>::assoc::<U>
787            //        ^^^^^^^^^^^^^^^^   ^^^^^^^^^^ segments: [module, Trait<T>, assoc<U>]
788            Some(&segments[segments.len().checked_sub(2)?..])
789        },
790        Res::Err => None,
791        _ => Some(slice::from_ref(segments.last()?)),
792    }
793}
794
795/// Type used to hash an ast element. This is different from the `Hash` trait
796/// on ast types as this
797/// trait would consider IDs and spans.
798///
799/// All expressions kind are hashed, but some might have a weaker hash.
800pub struct SpanlessHash<'a, 'tcx> {
801    /// Context used to evaluate constant expressions.
802    cx: &'a LateContext<'tcx>,
803    maybe_typeck_results: Option<&'tcx TypeckResults<'tcx>>,
804    s: FxHasher,
805    path_check: PathCheck,
806}
807
808impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
809    pub fn new(cx: &'a LateContext<'tcx>) -> Self {
810        Self {
811            cx,
812            maybe_typeck_results: cx.maybe_typeck_results(),
813            s: FxHasher::default(),
814            path_check: PathCheck::default(),
815        }
816    }
817
818    /// Check paths by their resolution instead of exact equality. See [`PathCheck`] for more
819    /// details.
820    #[must_use]
821    pub fn paths_by_resolution(self) -> Self {
822        Self {
823            path_check: PathCheck::Resolution,
824            ..self
825        }
826    }
827
828    pub fn finish(self) -> u64 {
829        self.s.finish()
830    }
831
832    pub fn hash_block(&mut self, b: &Block<'_>) {
833        for s in b.stmts {
834            self.hash_stmt(s);
835        }
836
837        if let Some(e) = b.expr {
838            self.hash_expr(e);
839        }
840
841        std::mem::discriminant(&b.rules).hash(&mut self.s);
842    }
843
844    #[expect(clippy::too_many_lines)]
845    pub fn hash_expr(&mut self, e: &Expr<'_>) {
846        let simple_const = self.maybe_typeck_results.and_then(|typeck_results| {
847            ConstEvalCtxt::with_env(self.cx.tcx, self.cx.typing_env(), typeck_results).eval_local(e, e.span.ctxt())
848        });
849
850        // const hashing may result in the same hash as some unrelated node, so add a sort of
851        // discriminant depending on which path we're choosing next
852        simple_const.hash(&mut self.s);
853        if simple_const.is_some() {
854            return;
855        }
856
857        std::mem::discriminant(&e.kind).hash(&mut self.s);
858
859        match &e.kind {
860            ExprKind::AddrOf(kind, m, e) => {
861                std::mem::discriminant(kind).hash(&mut self.s);
862                m.hash(&mut self.s);
863                self.hash_expr(e);
864            },
865            ExprKind::Continue(i) => {
866                if let Some(i) = i.label {
867                    self.hash_name(i.ident.name);
868                }
869            },
870            ExprKind::Array(v) => {
871                self.hash_exprs(v);
872            },
873            ExprKind::Assign(l, r, _) => {
874                self.hash_expr(l);
875                self.hash_expr(r);
876            },
877            ExprKind::AssignOp(o, l, r) => {
878                std::mem::discriminant(&o.node).hash(&mut self.s);
879                self.hash_expr(l);
880                self.hash_expr(r);
881            },
882            ExprKind::Become(f) => {
883                self.hash_expr(f);
884            },
885            ExprKind::Block(b, _) => {
886                self.hash_block(b);
887            },
888            ExprKind::Binary(op, l, r) => {
889                std::mem::discriminant(&op.node).hash(&mut self.s);
890                self.hash_expr(l);
891                self.hash_expr(r);
892            },
893            ExprKind::Break(i, j) => {
894                if let Some(i) = i.label {
895                    self.hash_name(i.ident.name);
896                }
897                if let Some(j) = j {
898                    self.hash_expr(j);
899                }
900            },
901            ExprKind::Call(fun, args) => {
902                self.hash_expr(fun);
903                self.hash_exprs(args);
904            },
905            ExprKind::Cast(e, ty) | ExprKind::Type(e, ty) => {
906                self.hash_expr(e);
907                self.hash_ty(ty);
908            },
909            ExprKind::Closure(Closure {
910                capture_clause, body, ..
911            }) => {
912                std::mem::discriminant(capture_clause).hash(&mut self.s);
913                // closures inherit TypeckResults
914                self.hash_expr(self.cx.tcx.hir_body(*body).value);
915            },
916            ExprKind::ConstBlock(l_id) => {
917                self.hash_body(l_id.body);
918            },
919            ExprKind::DropTemps(e) | ExprKind::Yield(e, _) => {
920                self.hash_expr(e);
921            },
922            ExprKind::Field(e, f) => {
923                self.hash_expr(e);
924                self.hash_name(f.name);
925            },
926            ExprKind::Index(a, i, _) => {
927                self.hash_expr(a);
928                self.hash_expr(i);
929            },
930            ExprKind::InlineAsm(asm) => {
931                for piece in asm.template {
932                    match piece {
933                        InlineAsmTemplatePiece::String(s) => s.hash(&mut self.s),
934                        InlineAsmTemplatePiece::Placeholder {
935                            operand_idx,
936                            modifier,
937                            span: _,
938                        } => {
939                            operand_idx.hash(&mut self.s);
940                            modifier.hash(&mut self.s);
941                        },
942                    }
943                }
944                asm.options.hash(&mut self.s);
945                for (op, _op_sp) in asm.operands {
946                    match op {
947                        InlineAsmOperand::In { reg, expr } => {
948                            reg.hash(&mut self.s);
949                            self.hash_expr(expr);
950                        },
951                        InlineAsmOperand::Out { reg, late, expr } => {
952                            reg.hash(&mut self.s);
953                            late.hash(&mut self.s);
954                            if let Some(expr) = expr {
955                                self.hash_expr(expr);
956                            }
957                        },
958                        InlineAsmOperand::InOut { reg, late, expr } => {
959                            reg.hash(&mut self.s);
960                            late.hash(&mut self.s);
961                            self.hash_expr(expr);
962                        },
963                        InlineAsmOperand::SplitInOut {
964                            reg,
965                            late,
966                            in_expr,
967                            out_expr,
968                        } => {
969                            reg.hash(&mut self.s);
970                            late.hash(&mut self.s);
971                            self.hash_expr(in_expr);
972                            if let Some(out_expr) = out_expr {
973                                self.hash_expr(out_expr);
974                            }
975                        },
976                        InlineAsmOperand::SymFn { expr } => {
977                            self.hash_expr(expr);
978                        },
979                        InlineAsmOperand::Const { anon_const } => {
980                            self.hash_body(anon_const.body);
981                        },
982                        InlineAsmOperand::SymStatic { path, def_id: _ } => self.hash_qpath(path),
983                        InlineAsmOperand::Label { block } => self.hash_block(block),
984                    }
985                }
986            },
987            ExprKind::Let(LetExpr { pat, init, ty, .. }) => {
988                self.hash_expr(init);
989                if let Some(ty) = ty {
990                    self.hash_ty(ty);
991                }
992                self.hash_pat(pat);
993            },
994            ExprKind::Lit(l) => {
995                l.node.hash(&mut self.s);
996            },
997            ExprKind::Loop(b, i, ..) => {
998                self.hash_block(b);
999                if let Some(i) = i {
1000                    self.hash_name(i.ident.name);
1001                }
1002            },
1003            ExprKind::If(cond, then, else_opt) => {
1004                self.hash_expr(cond);
1005                self.hash_expr(then);
1006                if let Some(e) = else_opt {
1007                    self.hash_expr(e);
1008                }
1009            },
1010            ExprKind::Match(scrutinee, arms, _) => {
1011                self.hash_expr(scrutinee);
1012
1013                for arm in *arms {
1014                    self.hash_pat(arm.pat);
1015                    if let Some(e) = arm.guard {
1016                        self.hash_expr(e);
1017                    }
1018                    self.hash_expr(arm.body);
1019                }
1020            },
1021            ExprKind::MethodCall(path, receiver, args, _fn_span) => {
1022                self.hash_name(path.ident.name);
1023                self.hash_expr(receiver);
1024                self.hash_exprs(args);
1025            },
1026            ExprKind::OffsetOf(container, fields) => {
1027                self.hash_ty(container);
1028                for field in *fields {
1029                    self.hash_name(field.name);
1030                }
1031            },
1032            ExprKind::Path(qpath) => {
1033                self.hash_qpath(qpath);
1034            },
1035            ExprKind::Repeat(e, len) => {
1036                self.hash_expr(e);
1037                self.hash_const_arg(len);
1038            },
1039            ExprKind::Ret(e) => {
1040                if let Some(e) = e {
1041                    self.hash_expr(e);
1042                }
1043            },
1044            ExprKind::Struct(path, fields, expr) => {
1045                self.hash_qpath(path);
1046
1047                for f in *fields {
1048                    self.hash_name(f.ident.name);
1049                    self.hash_expr(f.expr);
1050                }
1051
1052                if let StructTailExpr::Base(e) = expr {
1053                    self.hash_expr(e);
1054                }
1055            },
1056            ExprKind::Tup(tup) => {
1057                self.hash_exprs(tup);
1058            },
1059            ExprKind::Use(expr, _) => {
1060                self.hash_expr(expr);
1061            },
1062            ExprKind::Unary(l_op, le) => {
1063                std::mem::discriminant(l_op).hash(&mut self.s);
1064                self.hash_expr(le);
1065            },
1066            ExprKind::UnsafeBinderCast(kind, expr, ty) => {
1067                std::mem::discriminant(kind).hash(&mut self.s);
1068                self.hash_expr(expr);
1069                if let Some(ty) = ty {
1070                    self.hash_ty(ty);
1071                }
1072            },
1073            ExprKind::Err(_) => {},
1074        }
1075    }
1076
1077    pub fn hash_exprs(&mut self, e: &[Expr<'_>]) {
1078        for e in e {
1079            self.hash_expr(e);
1080        }
1081    }
1082
1083    pub fn hash_name(&mut self, n: Symbol) {
1084        n.hash(&mut self.s);
1085    }
1086
1087    pub fn hash_qpath(&mut self, p: &QPath<'_>) {
1088        match p {
1089            QPath::Resolved(_, path) => {
1090                self.hash_path(path);
1091            },
1092            QPath::TypeRelative(_, path) => {
1093                self.hash_name(path.ident.name);
1094            },
1095            QPath::LangItem(lang_item, ..) => {
1096                std::mem::discriminant(lang_item).hash(&mut self.s);
1097            },
1098        }
1099        // self.maybe_typeck_results.unwrap().qpath_res(p, id).hash(&mut self.s);
1100    }
1101
1102    pub fn hash_pat_expr(&mut self, lit: &PatExpr<'_>) {
1103        std::mem::discriminant(&lit.kind).hash(&mut self.s);
1104        match &lit.kind {
1105            PatExprKind::Lit { lit, negated } => {
1106                lit.node.hash(&mut self.s);
1107                negated.hash(&mut self.s);
1108            },
1109            PatExprKind::ConstBlock(c) => self.hash_body(c.body),
1110            PatExprKind::Path(qpath) => self.hash_qpath(qpath),
1111        }
1112    }
1113
1114    pub fn hash_ty_pat(&mut self, pat: &TyPat<'_>) {
1115        std::mem::discriminant(&pat.kind).hash(&mut self.s);
1116        match pat.kind {
1117            TyPatKind::Range(s, e) => {
1118                self.hash_const_arg(s);
1119                self.hash_const_arg(e);
1120            },
1121            TyPatKind::Or(variants) => {
1122                for variant in variants {
1123                    self.hash_ty_pat(variant);
1124                }
1125            },
1126            TyPatKind::NotNull | TyPatKind::Err(_) => {},
1127        }
1128    }
1129
1130    pub fn hash_pat(&mut self, pat: &Pat<'_>) {
1131        std::mem::discriminant(&pat.kind).hash(&mut self.s);
1132        match &pat.kind {
1133            PatKind::Missing => unreachable!(),
1134            PatKind::Binding(BindingMode(by_ref, mutability), _, _, pat) => {
1135                std::mem::discriminant(by_ref).hash(&mut self.s);
1136                std::mem::discriminant(mutability).hash(&mut self.s);
1137                if let Some(pat) = pat {
1138                    self.hash_pat(pat);
1139                }
1140            },
1141            PatKind::Box(pat) | PatKind::Deref(pat) => self.hash_pat(pat),
1142            PatKind::Expr(expr) => self.hash_pat_expr(expr),
1143            PatKind::Or(pats) => {
1144                for pat in *pats {
1145                    self.hash_pat(pat);
1146                }
1147            },
1148            PatKind::Range(s, e, i) => {
1149                if let Some(s) = s {
1150                    self.hash_pat_expr(s);
1151                }
1152                if let Some(e) = e {
1153                    self.hash_pat_expr(e);
1154                }
1155                std::mem::discriminant(i).hash(&mut self.s);
1156            },
1157            PatKind::Ref(pat, mu) => {
1158                self.hash_pat(pat);
1159                std::mem::discriminant(mu).hash(&mut self.s);
1160            },
1161            PatKind::Guard(pat, guard) => {
1162                self.hash_pat(pat);
1163                self.hash_expr(guard);
1164            },
1165            PatKind::Slice(l, m, r) => {
1166                for pat in *l {
1167                    self.hash_pat(pat);
1168                }
1169                if let Some(pat) = m {
1170                    self.hash_pat(pat);
1171                }
1172                for pat in *r {
1173                    self.hash_pat(pat);
1174                }
1175            },
1176            PatKind::Struct(qpath, fields, e) => {
1177                self.hash_qpath(qpath);
1178                for f in *fields {
1179                    self.hash_name(f.ident.name);
1180                    self.hash_pat(f.pat);
1181                }
1182                e.hash(&mut self.s);
1183            },
1184            PatKind::Tuple(pats, e) => {
1185                for pat in *pats {
1186                    self.hash_pat(pat);
1187                }
1188                e.hash(&mut self.s);
1189            },
1190            PatKind::TupleStruct(qpath, pats, e) => {
1191                self.hash_qpath(qpath);
1192                for pat in *pats {
1193                    self.hash_pat(pat);
1194                }
1195                e.hash(&mut self.s);
1196            },
1197            PatKind::Never | PatKind::Wild | PatKind::Err(_) => {},
1198        }
1199    }
1200
1201    pub fn hash_path(&mut self, path: &Path<'_>) {
1202        match path.res {
1203            // constant hash since equality is dependant on inter-expression context
1204            // e.g. The expressions `if let Some(x) = foo() {}` and `if let Some(y) = foo() {}` are considered equal
1205            // even though the binding names are different and they have different `HirId`s.
1206            Res::Local(_) => 1_usize.hash(&mut self.s),
1207            _ => {
1208                if let PathCheck::Resolution = self.path_check
1209                    && let [.., last] = path.segments
1210                    && let Some(segments) = generic_path_segments(path.segments)
1211                {
1212                    for seg in segments {
1213                        self.hash_generic_args(seg.args().args);
1214                    }
1215                    last.res.hash(&mut self.s);
1216                } else {
1217                    for seg in path.segments {
1218                        self.hash_name(seg.ident.name);
1219                        self.hash_generic_args(seg.args().args);
1220                    }
1221                }
1222            },
1223        }
1224    }
1225
1226    pub fn hash_modifiers(&mut self, modifiers: TraitBoundModifiers) {
1227        let TraitBoundModifiers { constness, polarity } = modifiers;
1228        std::mem::discriminant(&polarity).hash(&mut self.s);
1229        std::mem::discriminant(&constness).hash(&mut self.s);
1230    }
1231
1232    pub fn hash_stmt(&mut self, b: &Stmt<'_>) {
1233        std::mem::discriminant(&b.kind).hash(&mut self.s);
1234
1235        match &b.kind {
1236            StmtKind::Let(local) => {
1237                self.hash_pat(local.pat);
1238                if let Some(init) = local.init {
1239                    self.hash_expr(init);
1240                }
1241                if let Some(els) = local.els {
1242                    self.hash_block(els);
1243                }
1244            },
1245            StmtKind::Item(..) => {},
1246            StmtKind::Expr(expr) | StmtKind::Semi(expr) => {
1247                self.hash_expr(expr);
1248            },
1249        }
1250    }
1251
1252    pub fn hash_lifetime(&mut self, lifetime: &Lifetime) {
1253        lifetime.ident.name.hash(&mut self.s);
1254        std::mem::discriminant(&lifetime.kind).hash(&mut self.s);
1255        if let LifetimeKind::Param(param_id) = lifetime.kind {
1256            param_id.hash(&mut self.s);
1257        }
1258    }
1259
1260    pub fn hash_ty(&mut self, ty: &Ty<'_>) {
1261        std::mem::discriminant(&ty.kind).hash(&mut self.s);
1262        self.hash_tykind(&ty.kind);
1263    }
1264
1265    pub fn hash_tykind(&mut self, ty: &TyKind<'_>) {
1266        match ty {
1267            TyKind::Slice(ty) => {
1268                self.hash_ty(ty);
1269            },
1270            TyKind::Array(ty, len) => {
1271                self.hash_ty(ty);
1272                self.hash_const_arg(len);
1273            },
1274            TyKind::Pat(ty, pat) => {
1275                self.hash_ty(ty);
1276                self.hash_ty_pat(pat);
1277            },
1278            TyKind::Ptr(mut_ty) => {
1279                self.hash_ty(mut_ty.ty);
1280                mut_ty.mutbl.hash(&mut self.s);
1281            },
1282            TyKind::Ref(lifetime, mut_ty) => {
1283                self.hash_lifetime(lifetime);
1284                self.hash_ty(mut_ty.ty);
1285                mut_ty.mutbl.hash(&mut self.s);
1286            },
1287            TyKind::FnPtr(fn_ptr) => {
1288                fn_ptr.safety.hash(&mut self.s);
1289                fn_ptr.abi.hash(&mut self.s);
1290                for arg in fn_ptr.decl.inputs {
1291                    self.hash_ty(arg);
1292                }
1293                std::mem::discriminant(&fn_ptr.decl.output).hash(&mut self.s);
1294                match fn_ptr.decl.output {
1295                    FnRetTy::DefaultReturn(_) => {},
1296                    FnRetTy::Return(ty) => {
1297                        self.hash_ty(ty);
1298                    },
1299                }
1300                fn_ptr.decl.c_variadic.hash(&mut self.s);
1301            },
1302            TyKind::Tup(ty_list) => {
1303                for ty in *ty_list {
1304                    self.hash_ty(ty);
1305                }
1306            },
1307            TyKind::Path(qpath) => self.hash_qpath(qpath),
1308            TyKind::TraitObject(_, lifetime) => {
1309                self.hash_lifetime(lifetime);
1310            },
1311            TyKind::Typeof(anon_const) => {
1312                self.hash_body(anon_const.body);
1313            },
1314            TyKind::UnsafeBinder(binder) => {
1315                self.hash_ty(binder.inner_ty);
1316            },
1317            TyKind::Err(_)
1318            | TyKind::Infer(())
1319            | TyKind::Never
1320            | TyKind::InferDelegation(..)
1321            | TyKind::OpaqueDef(_)
1322            | TyKind::TraitAscription(_) => {},
1323        }
1324    }
1325
1326    pub fn hash_body(&mut self, body_id: BodyId) {
1327        // swap out TypeckResults when hashing a body
1328        let old_maybe_typeck_results = self.maybe_typeck_results.replace(self.cx.tcx.typeck_body(body_id));
1329        self.hash_expr(self.cx.tcx.hir_body(body_id).value);
1330        self.maybe_typeck_results = old_maybe_typeck_results;
1331    }
1332
1333    fn hash_const_arg(&mut self, const_arg: &ConstArg<'_>) {
1334        match &const_arg.kind {
1335            ConstArgKind::Path(path) => self.hash_qpath(path),
1336            ConstArgKind::Anon(anon) => self.hash_body(anon.body),
1337            ConstArgKind::Infer(..) => {},
1338        }
1339    }
1340
1341    fn hash_generic_args(&mut self, arg_list: &[GenericArg<'_>]) {
1342        for arg in arg_list {
1343            match arg {
1344                GenericArg::Lifetime(l) => self.hash_lifetime(l),
1345                GenericArg::Type(ty) => self.hash_ty(ty.as_unambig_ty()),
1346                GenericArg::Const(ca) => self.hash_const_arg(ca.as_unambig_ct()),
1347                GenericArg::Infer(inf) => self.hash_ty(&inf.to_ty()),
1348            }
1349        }
1350    }
1351}
1352
1353pub fn hash_stmt(cx: &LateContext<'_>, s: &Stmt<'_>) -> u64 {
1354    let mut h = SpanlessHash::new(cx);
1355    h.hash_stmt(s);
1356    h.finish()
1357}
1358
1359pub fn is_bool(ty: &Ty<'_>) -> bool {
1360    if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
1361        matches!(path.res, Res::PrimTy(PrimTy::Bool))
1362    } else {
1363        false
1364    }
1365}
1366
1367pub fn hash_expr(cx: &LateContext<'_>, e: &Expr<'_>) -> u64 {
1368    let mut h = SpanlessHash::new(cx);
1369    h.hash_expr(e);
1370    h.finish()
1371}
1372
1373fn eq_span_tokens(
1374    cx: &LateContext<'_>,
1375    left: impl SpanRange,
1376    right: impl SpanRange,
1377    pred: impl Fn(TokenKind) -> bool,
1378) -> bool {
1379    fn f(cx: &LateContext<'_>, left: Range<BytePos>, right: Range<BytePos>, pred: impl Fn(TokenKind) -> bool) -> bool {
1380        if let Some(lsrc) = left.get_source_range(cx)
1381            && let Some(lsrc) = lsrc.as_str()
1382            && let Some(rsrc) = right.get_source_range(cx)
1383            && let Some(rsrc) = rsrc.as_str()
1384        {
1385            let pred = |&(token, ..): &(TokenKind, _, _)| pred(token);
1386            let map = |(_, source, _)| source;
1387
1388            let ltok = tokenize_with_text(lsrc).filter(pred).map(map);
1389            let rtok = tokenize_with_text(rsrc).filter(pred).map(map);
1390            ltok.eq(rtok)
1391        } else {
1392            // Unable to access the source. Conservatively assume the blocks aren't equal.
1393            false
1394        }
1395    }
1396    f(cx, left.into_range(), right.into_range(), pred)
1397}
1398
1399/// Returns true if the expression contains ambiguous literals (unsuffixed float or int literals)
1400/// that could be interpreted as either f32/f64 or i32/i64 depending on context.
1401pub fn has_ambiguous_literal_in_expr(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
1402    match expr.kind {
1403        ExprKind::Path(ref qpath) => {
1404            if let Res::Local(hir_id) = cx.qpath_res(qpath, expr.hir_id)
1405                && let Node::LetStmt(local) = cx.tcx.parent_hir_node(hir_id)
1406                && local.ty.is_none()
1407                && let Some(init) = local.init
1408            {
1409                return has_ambiguous_literal_in_expr(cx, init);
1410            }
1411            false
1412        },
1413        ExprKind::Lit(lit) => matches!(
1414            lit.node,
1415            ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) | ast::LitKind::Int(_, ast::LitIntType::Unsuffixed)
1416        ),
1417
1418        ExprKind::Array(exprs) | ExprKind::Tup(exprs) => exprs.iter().any(|e| has_ambiguous_literal_in_expr(cx, e)),
1419
1420        ExprKind::Assign(lhs, rhs, _) | ExprKind::AssignOp(_, lhs, rhs) | ExprKind::Binary(_, lhs, rhs) => {
1421            has_ambiguous_literal_in_expr(cx, lhs) || has_ambiguous_literal_in_expr(cx, rhs)
1422        },
1423
1424        ExprKind::Unary(_, e)
1425        | ExprKind::Cast(e, _)
1426        | ExprKind::Type(e, _)
1427        | ExprKind::DropTemps(e)
1428        | ExprKind::AddrOf(_, _, e)
1429        | ExprKind::Field(e, _)
1430        | ExprKind::Index(e, _, _)
1431        | ExprKind::Yield(e, _) => has_ambiguous_literal_in_expr(cx, e),
1432
1433        ExprKind::MethodCall(_, receiver, args, _) | ExprKind::Call(receiver, args) => {
1434            has_ambiguous_literal_in_expr(cx, receiver) || args.iter().any(|e| has_ambiguous_literal_in_expr(cx, e))
1435        },
1436
1437        ExprKind::Closure(Closure { body, .. }) => {
1438            let body = cx.tcx.hir_body(*body);
1439            let closure_expr = crate::peel_blocks(body.value);
1440            has_ambiguous_literal_in_expr(cx, closure_expr)
1441        },
1442
1443        ExprKind::Block(blk, _) => blk.expr.as_ref().is_some_and(|e| has_ambiguous_literal_in_expr(cx, e)),
1444
1445        ExprKind::If(cond, then_expr, else_expr) => {
1446            has_ambiguous_literal_in_expr(cx, cond)
1447                || has_ambiguous_literal_in_expr(cx, then_expr)
1448                || else_expr.as_ref().is_some_and(|e| has_ambiguous_literal_in_expr(cx, e))
1449        },
1450
1451        ExprKind::Match(scrutinee, arms, _) => {
1452            has_ambiguous_literal_in_expr(cx, scrutinee)
1453                || arms.iter().any(|arm| has_ambiguous_literal_in_expr(cx, arm.body))
1454        },
1455
1456        ExprKind::Loop(body, ..) => body.expr.is_some_and(|e| has_ambiguous_literal_in_expr(cx, e)),
1457
1458        ExprKind::Ret(opt_expr) | ExprKind::Break(_, opt_expr) => {
1459            opt_expr.as_ref().is_some_and(|e| has_ambiguous_literal_in_expr(cx, e))
1460        },
1461
1462        _ => false,
1463    }
1464}