1 use crate::consts::constant_simple;
2 use crate::macros::macro_backtrace;
3 use crate::source::snippet_opt;
4 use rustc_ast::ast::InlineAsmTemplatePiece;
5 use rustc_data_structures::fx::FxHasher;
6 use rustc_hir::def::Res;
7 use rustc_hir::HirIdMap;
9 ArrayLen, BinOpKind, Closure, Block, BodyId, Expr, ExprField, ExprKind, FnRetTy, GenericArg, GenericArgs, Guard, HirId,
10 InlineAsmOperand, Let, Lifetime, LifetimeName, ParamName, Pat, PatField, PatKind, Path, PathSegment, QPath, Stmt,
11 StmtKind, Ty, TyKind, TypeBinding,
13 use rustc_lexer::{tokenize, TokenKind};
14 use rustc_lint::LateContext;
15 use rustc_middle::ty::TypeckResults;
16 use rustc_span::{sym, Symbol};
17 use std::hash::{Hash, Hasher};
19 /// Callback that is called when two expressions are not equal in the sense of `SpanlessEq`, but
20 /// other conditions would make them equal.
21 type SpanlessEqCallback<'a> = dyn FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a;
23 /// Type used to check whether two ast are the same. This is different from the
24 /// operator `==` on ast types as this operator would compare true equality with
27 /// Note that some expressions kinds are not considered but could be added.
28 pub struct SpanlessEq<'a, 'tcx> {
29 /// Context used to evaluate constant expressions.
30 cx: &'a LateContext<'tcx>,
31 maybe_typeck_results: Option<(&'tcx TypeckResults<'tcx>, &'tcx TypeckResults<'tcx>)>,
32 allow_side_effects: bool,
33 expr_fallback: Option<Box<SpanlessEqCallback<'a>>>,
36 impl<'a, 'tcx> SpanlessEq<'a, 'tcx> {
37 pub fn new(cx: &'a LateContext<'tcx>) -> Self {
40 maybe_typeck_results: cx.maybe_typeck_results().map(|x| (x, x)),
41 allow_side_effects: true,
46 /// Consider expressions containing potential side effects as not equal.
48 pub fn deny_side_effects(self) -> Self {
50 allow_side_effects: false,
56 pub fn expr_fallback(self, expr_fallback: impl FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a) -> Self {
58 expr_fallback: Some(Box::new(expr_fallback)),
63 /// Use this method to wrap comparisons that may involve inter-expression context.
64 /// See `self.locals`.
65 pub fn inter_expr(&mut self) -> HirEqInterExpr<'_, 'a, 'tcx> {
68 locals: HirIdMap::default(),
72 pub fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
73 self.inter_expr().eq_block(left, right)
76 pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
77 self.inter_expr().eq_expr(left, right)
80 pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
81 self.inter_expr().eq_path(left, right)
84 pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
85 self.inter_expr().eq_path_segment(left, right)
88 pub fn eq_path_segments(&mut self, left: &[PathSegment<'_>], right: &[PathSegment<'_>]) -> bool {
89 self.inter_expr().eq_path_segments(left, right)
93 pub struct HirEqInterExpr<'a, 'b, 'tcx> {
94 inner: &'a mut SpanlessEq<'b, 'tcx>,
96 // When binding are declared, the binding ID in the left expression is mapped to the one on the
97 // right. For example, when comparing `{ let x = 1; x + 2 }` and `{ let y = 1; y + 2 }`,
98 // these blocks are considered equal since `x` is mapped to `y`.
99 pub locals: HirIdMap<HirId>,
102 impl HirEqInterExpr<'_, '_, '_> {
103 pub fn eq_stmt(&mut self, left: &Stmt<'_>, right: &Stmt<'_>) -> bool {
104 match (&left.kind, &right.kind) {
105 (&StmtKind::Local(l), &StmtKind::Local(r)) => {
106 // This additional check ensures that the type of the locals are equivalent even if the init
107 // expression or type have some inferred parts.
108 if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
109 let l_ty = typeck_lhs.pat_ty(l.pat);
110 let r_ty = typeck_rhs.pat_ty(r.pat);
116 // eq_pat adds the HirIds to the locals map. We therefor call it last to make sure that
117 // these only get added if the init and type is equal.
118 both(&l.init, &r.init, |l, r| self.eq_expr(l, r))
119 && both(&l.ty, &r.ty, |l, r| self.eq_ty(l, r))
120 && self.eq_pat(l.pat, r.pat)
122 (&StmtKind::Expr(l), &StmtKind::Expr(r)) | (&StmtKind::Semi(l), &StmtKind::Semi(r)) => self.eq_expr(l, r),
127 /// Checks whether two blocks are the same.
128 fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
129 if self.cannot_be_compared_block(left) || self.cannot_be_compared_block(right) {
132 match (left.stmts, left.expr, right.stmts, right.expr) {
133 ([], None, [], None) => {
134 // For empty blocks, check to see if the tokens are equal. This will catch the case where a macro
135 // expanded to nothing, or the cfg attribute was used.
136 let (left, right) = match (
137 snippet_opt(self.inner.cx, left.span),
138 snippet_opt(self.inner.cx, right.span),
140 (Some(left), Some(right)) => (left, right),
143 let mut left_pos = 0;
144 let left = tokenize(&left)
146 let end = left_pos + t.len;
147 let s = &left[left_pos..end];
154 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
158 let mut right_pos = 0;
159 let right = tokenize(&right)
161 let end = right_pos + t.len;
162 let s = &right[right_pos..end];
169 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
176 over(left.stmts, right.stmts, |l, r| self.eq_stmt(l, r))
177 && both(&left.expr, &right.expr, |l, r| self.eq_expr(l, r))
182 fn cannot_be_compared_block(&mut self, block: &Block<'_>) -> bool {
183 if block.stmts.last().map_or(false, |stmt| {
186 StmtKind::Semi(semi_expr) if self.should_ignore(semi_expr)
192 if let Some(block_expr) = block.expr
193 && self.should_ignore(block_expr)
201 fn should_ignore(&mut self, expr: &Expr<'_>) -> bool {
202 if macro_backtrace(expr.span).last().map_or(false, |macro_call| {
204 &self.inner.cx.tcx.get_diagnostic_name(macro_call.def_id),
205 Some(sym::todo_macro | sym::unimplemented_macro)
214 pub fn eq_array_length(&mut self, left: ArrayLen, right: ArrayLen) -> bool {
215 match (left, right) {
216 (ArrayLen::Infer(..), ArrayLen::Infer(..)) => true,
217 (ArrayLen::Body(l_ct), ArrayLen::Body(r_ct)) => self.eq_body(l_ct.body, r_ct.body),
222 pub fn eq_body(&mut self, left: BodyId, right: BodyId) -> bool {
223 // swap out TypeckResults when hashing a body
224 let old_maybe_typeck_results = self.inner.maybe_typeck_results.replace((
225 self.inner.cx.tcx.typeck_body(left),
226 self.inner.cx.tcx.typeck_body(right),
228 let res = self.eq_expr(
229 &self.inner.cx.tcx.hir().body(left).value,
230 &self.inner.cx.tcx.hir().body(right).value,
232 self.inner.maybe_typeck_results = old_maybe_typeck_results;
236 #[expect(clippy::similar_names)]
237 pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
238 if !self.inner.allow_side_effects && left.span.ctxt() != right.span.ctxt() {
242 if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
243 if let (Some(l), Some(r)) = (
244 constant_simple(self.inner.cx, typeck_lhs, left),
245 constant_simple(self.inner.cx, typeck_rhs, right),
254 reduce_exprkind(self.inner.cx, &left.kind),
255 reduce_exprkind(self.inner.cx, &right.kind),
257 (&ExprKind::AddrOf(lb, l_mut, le), &ExprKind::AddrOf(rb, r_mut, re)) => {
258 lb == rb && l_mut == r_mut && self.eq_expr(le, re)
260 (&ExprKind::Continue(li), &ExprKind::Continue(ri)) => {
261 both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
263 (&ExprKind::Assign(ll, lr, _), &ExprKind::Assign(rl, rr, _)) => {
264 self.inner.allow_side_effects && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
266 (&ExprKind::AssignOp(ref lo, ll, lr), &ExprKind::AssignOp(ref ro, rl, rr)) => {
267 self.inner.allow_side_effects && lo.node == ro.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
269 (&ExprKind::Block(l, _), &ExprKind::Block(r, _)) => self.eq_block(l, r),
270 (&ExprKind::Binary(l_op, ll, lr), &ExprKind::Binary(r_op, rl, rr)) => {
271 l_op.node == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
272 || swap_binop(l_op.node, ll, lr).map_or(false, |(l_op, ll, lr)| {
273 l_op == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
276 (&ExprKind::Break(li, ref le), &ExprKind::Break(ri, ref re)) => {
277 both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
278 && both(le, re, |l, r| self.eq_expr(l, r))
280 (&ExprKind::Box(l), &ExprKind::Box(r)) => self.eq_expr(l, r),
281 (&ExprKind::Call(l_fun, l_args), &ExprKind::Call(r_fun, r_args)) => {
282 self.inner.allow_side_effects && self.eq_expr(l_fun, r_fun) && self.eq_exprs(l_args, r_args)
284 (&ExprKind::Cast(lx, lt), &ExprKind::Cast(rx, rt)) | (&ExprKind::Type(lx, lt), &ExprKind::Type(rx, rt)) => {
285 self.eq_expr(lx, rx) && self.eq_ty(lt, rt)
287 (&ExprKind::Field(l_f_exp, ref l_f_ident), &ExprKind::Field(r_f_exp, ref r_f_ident)) => {
288 l_f_ident.name == r_f_ident.name && self.eq_expr(l_f_exp, r_f_exp)
290 (&ExprKind::Index(la, li), &ExprKind::Index(ra, ri)) => self.eq_expr(la, ra) && self.eq_expr(li, ri),
291 (&ExprKind::If(lc, lt, ref le), &ExprKind::If(rc, rt, ref re)) => {
292 self.eq_expr(lc, rc) && self.eq_expr(lt, rt) && both(le, re, |l, r| self.eq_expr(l, r))
294 (&ExprKind::Let(l), &ExprKind::Let(r)) => {
295 self.eq_pat(l.pat, r.pat) && both(&l.ty, &r.ty, |l, r| self.eq_ty(l, r)) && self.eq_expr(l.init, r.init)
297 (&ExprKind::Lit(ref l), &ExprKind::Lit(ref r)) => l.node == r.node,
298 (&ExprKind::Loop(lb, ref ll, ref lls, _), &ExprKind::Loop(rb, ref rl, ref rls, _)) => {
299 lls == rls && self.eq_block(lb, rb) && both(ll, rl, |l, r| l.ident.name == r.ident.name)
301 (&ExprKind::Match(le, la, ref ls), &ExprKind::Match(re, ra, ref rs)) => {
303 && self.eq_expr(le, re)
304 && over(la, ra, |l, r| {
305 self.eq_pat(l.pat, r.pat)
306 && both(&l.guard, &r.guard, |l, r| self.eq_guard(l, r))
307 && self.eq_expr(l.body, r.body)
310 (&ExprKind::MethodCall(l_path, l_args, _), &ExprKind::MethodCall(r_path, r_args, _)) => {
311 self.inner.allow_side_effects && self.eq_path_segment(l_path, r_path) && self.eq_exprs(l_args, r_args)
313 (&ExprKind::Repeat(le, ll), &ExprKind::Repeat(re, rl)) => {
314 self.eq_expr(le, re) && self.eq_array_length(ll, rl)
316 (&ExprKind::Ret(ref l), &ExprKind::Ret(ref r)) => both(l, r, |l, r| self.eq_expr(l, r)),
317 (&ExprKind::Path(ref l), &ExprKind::Path(ref r)) => self.eq_qpath(l, r),
318 (&ExprKind::Struct(l_path, lf, ref lo), &ExprKind::Struct(r_path, rf, ref ro)) => {
319 self.eq_qpath(l_path, r_path)
320 && both(lo, ro, |l, r| self.eq_expr(l, r))
321 && over(lf, rf, |l, r| self.eq_expr_field(l, r))
323 (&ExprKind::Tup(l_tup), &ExprKind::Tup(r_tup)) => self.eq_exprs(l_tup, r_tup),
324 (&ExprKind::Unary(l_op, le), &ExprKind::Unary(r_op, re)) => l_op == r_op && self.eq_expr(le, re),
325 (&ExprKind::Array(l), &ExprKind::Array(r)) => self.eq_exprs(l, r),
326 (&ExprKind::DropTemps(le), &ExprKind::DropTemps(re)) => self.eq_expr(le, re),
329 is_eq || self.inner.expr_fallback.as_mut().map_or(false, |f| f(left, right))
332 fn eq_exprs(&mut self, left: &[Expr<'_>], right: &[Expr<'_>]) -> bool {
333 over(left, right, |l, r| self.eq_expr(l, r))
336 fn eq_expr_field(&mut self, left: &ExprField<'_>, right: &ExprField<'_>) -> bool {
337 left.ident.name == right.ident.name && self.eq_expr(left.expr, right.expr)
340 fn eq_guard(&mut self, left: &Guard<'_>, right: &Guard<'_>) -> bool {
341 match (left, right) {
342 (Guard::If(l), Guard::If(r)) => self.eq_expr(l, r),
343 (Guard::IfLet(l), Guard::IfLet(r)) => {
344 self.eq_pat(l.pat, r.pat) && both(&l.ty, &r.ty, |l, r| self.eq_ty(l, r)) && self.eq_expr(l.init, r.init)
350 fn eq_generic_arg(&mut self, left: &GenericArg<'_>, right: &GenericArg<'_>) -> bool {
351 match (left, right) {
352 (GenericArg::Const(l), GenericArg::Const(r)) => self.eq_body(l.value.body, r.value.body),
353 (GenericArg::Lifetime(l_lt), GenericArg::Lifetime(r_lt)) => Self::eq_lifetime(l_lt, r_lt),
354 (GenericArg::Type(l_ty), GenericArg::Type(r_ty)) => self.eq_ty(l_ty, r_ty),
355 (GenericArg::Infer(l_inf), GenericArg::Infer(r_inf)) => self.eq_ty(&l_inf.to_ty(), &r_inf.to_ty()),
360 fn eq_lifetime(left: &Lifetime, right: &Lifetime) -> bool {
361 left.name == right.name
364 fn eq_pat_field(&mut self, left: &PatField<'_>, right: &PatField<'_>) -> bool {
365 let (PatField { ident: li, pat: lp, .. }, PatField { ident: ri, pat: rp, .. }) = (&left, &right);
366 li.name == ri.name && self.eq_pat(lp, rp)
369 /// Checks whether two patterns are the same.
370 fn eq_pat(&mut self, left: &Pat<'_>, right: &Pat<'_>) -> bool {
371 match (&left.kind, &right.kind) {
372 (&PatKind::Box(l), &PatKind::Box(r)) => self.eq_pat(l, r),
373 (&PatKind::Struct(ref lp, la, ..), &PatKind::Struct(ref rp, ra, ..)) => {
374 self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat_field(l, r))
376 (&PatKind::TupleStruct(ref lp, la, ls), &PatKind::TupleStruct(ref rp, ra, rs)) => {
377 self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat(l, r)) && ls == rs
379 (&PatKind::Binding(lb, li, _, ref lp), &PatKind::Binding(rb, ri, _, ref rp)) => {
380 let eq = lb == rb && both(lp, rp, |l, r| self.eq_pat(l, r));
382 self.locals.insert(li, ri);
386 (&PatKind::Path(ref l), &PatKind::Path(ref r)) => self.eq_qpath(l, r),
387 (&PatKind::Lit(l), &PatKind::Lit(r)) => self.eq_expr(l, r),
388 (&PatKind::Tuple(l, ls), &PatKind::Tuple(r, rs)) => ls == rs && over(l, r, |l, r| self.eq_pat(l, r)),
389 (&PatKind::Range(ref ls, ref le, li), &PatKind::Range(ref rs, ref re, ri)) => {
390 both(ls, rs, |a, b| self.eq_expr(a, b)) && both(le, re, |a, b| self.eq_expr(a, b)) && (li == ri)
392 (&PatKind::Ref(le, ref lm), &PatKind::Ref(re, ref rm)) => lm == rm && self.eq_pat(le, re),
393 (&PatKind::Slice(ls, ref li, le), &PatKind::Slice(rs, ref ri, re)) => {
394 over(ls, rs, |l, r| self.eq_pat(l, r))
395 && over(le, re, |l, r| self.eq_pat(l, r))
396 && both(li, ri, |l, r| self.eq_pat(l, r))
398 (&PatKind::Wild, &PatKind::Wild) => true,
403 #[expect(clippy::similar_names)]
404 fn eq_qpath(&mut self, left: &QPath<'_>, right: &QPath<'_>) -> bool {
405 match (left, right) {
406 (&QPath::Resolved(ref lty, lpath), &QPath::Resolved(ref rty, rpath)) => {
407 both(lty, rty, |l, r| self.eq_ty(l, r)) && self.eq_path(lpath, rpath)
409 (&QPath::TypeRelative(lty, lseg), &QPath::TypeRelative(rty, rseg)) => {
410 self.eq_ty(lty, rty) && self.eq_path_segment(lseg, rseg)
412 (&QPath::LangItem(llang_item, ..), &QPath::LangItem(rlang_item, ..)) => llang_item == rlang_item,
417 pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
418 match (left.res, right.res) {
419 (Res::Local(l), Res::Local(r)) => l == r || self.locals.get(&l) == Some(&r),
420 (Res::Local(_), _) | (_, Res::Local(_)) => false,
421 _ => over(left.segments, right.segments, |l, r| self.eq_path_segment(l, r)),
425 fn eq_path_parameters(&mut self, left: &GenericArgs<'_>, right: &GenericArgs<'_>) -> bool {
426 if !(left.parenthesized || right.parenthesized) {
427 over(left.args, right.args, |l, r| self.eq_generic_arg(l, r)) // FIXME(flip1995): may not work
428 && over(left.bindings, right.bindings, |l, r| self.eq_type_binding(l, r))
429 } else if left.parenthesized && right.parenthesized {
430 over(left.inputs(), right.inputs(), |l, r| self.eq_ty(l, r))
431 && both(&Some(&left.bindings[0].ty()), &Some(&right.bindings[0].ty()), |l, r| {
439 pub fn eq_path_segments(&mut self, left: &[PathSegment<'_>], right: &[PathSegment<'_>]) -> bool {
440 left.len() == right.len() && left.iter().zip(right).all(|(l, r)| self.eq_path_segment(l, r))
443 pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
444 // The == of idents doesn't work with different contexts,
445 // we have to be explicit about hygiene
446 left.ident.name == right.ident.name && both(&left.args, &right.args, |l, r| self.eq_path_parameters(l, r))
449 pub fn eq_ty(&mut self, left: &Ty<'_>, right: &Ty<'_>) -> bool {
450 match (&left.kind, &right.kind) {
451 (&TyKind::Slice(l_vec), &TyKind::Slice(r_vec)) => self.eq_ty(l_vec, r_vec),
452 (&TyKind::Array(lt, ll), &TyKind::Array(rt, rl)) => self.eq_ty(lt, rt) && self.eq_array_length(ll, rl),
453 (&TyKind::Ptr(ref l_mut), &TyKind::Ptr(ref r_mut)) => {
454 l_mut.mutbl == r_mut.mutbl && self.eq_ty(l_mut.ty, r_mut.ty)
456 (&TyKind::Rptr(_, ref l_rmut), &TyKind::Rptr(_, ref r_rmut)) => {
457 l_rmut.mutbl == r_rmut.mutbl && self.eq_ty(l_rmut.ty, r_rmut.ty)
459 (&TyKind::Path(ref l), &TyKind::Path(ref r)) => self.eq_qpath(l, r),
460 (&TyKind::Tup(l), &TyKind::Tup(r)) => over(l, r, |l, r| self.eq_ty(l, r)),
461 (&TyKind::Infer, &TyKind::Infer) => true,
466 fn eq_type_binding(&mut self, left: &TypeBinding<'_>, right: &TypeBinding<'_>) -> bool {
467 left.ident.name == right.ident.name && self.eq_ty(left.ty(), right.ty())
471 /// Some simple reductions like `{ return }` => `return`
472 fn reduce_exprkind<'hir>(cx: &LateContext<'_>, kind: &'hir ExprKind<'hir>) -> &'hir ExprKind<'hir> {
473 if let ExprKind::Block(block, _) = kind {
474 match (block.stmts, block.expr) {
475 // From an `if let` expression without an `else` block. The arm for the implicit wild pattern is an empty
476 // block with an empty span.
477 ([], None) if block.span.is_empty() => &ExprKind::Tup(&[]),
479 ([], None) => match snippet_opt(cx, block.span) {
480 // Don't reduce if there are any tokens contained in the braces
487 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
490 .ne([TokenKind::OpenBrace, TokenKind::CloseBrace].iter().copied()) =>
494 _ => &ExprKind::Tup(&[]),
496 ([], Some(expr)) => match expr.kind {
497 // `{ return .. }` => `return ..`
498 ExprKind::Ret(..) => &expr.kind,
501 ([stmt], None) => match stmt.kind {
502 StmtKind::Expr(expr) | StmtKind::Semi(expr) => match expr.kind {
503 // `{ return ..; }` => `return ..`
504 ExprKind::Ret(..) => &expr.kind,
520 ) -> Option<(BinOpKind, &'a Expr<'a>, &'a Expr<'a>)> {
522 BinOpKind::Add | BinOpKind::Eq | BinOpKind::Ne | BinOpKind::BitAnd | BinOpKind::BitXor | BinOpKind::BitOr => {
523 Some((binop, rhs, lhs))
525 BinOpKind::Lt => Some((BinOpKind::Gt, rhs, lhs)),
526 BinOpKind::Le => Some((BinOpKind::Ge, rhs, lhs)),
527 BinOpKind::Ge => Some((BinOpKind::Le, rhs, lhs)),
528 BinOpKind::Gt => Some((BinOpKind::Lt, rhs, lhs)),
529 BinOpKind::Mul // Not always commutative, e.g. with matrices. See issue #5698
536 | BinOpKind::Or => None,
540 /// Checks if the two `Option`s are both `None` or some equal values as per
542 pub fn both<X>(l: &Option<X>, r: &Option<X>, mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
544 .map_or_else(|| r.is_none(), |x| r.as_ref().map_or(false, |y| eq_fn(x, y)))
547 /// Checks if two slices are equal as per `eq_fn`.
548 pub fn over<X>(left: &[X], right: &[X], mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
549 left.len() == right.len() && left.iter().zip(right).all(|(x, y)| eq_fn(x, y))
552 /// Counts how many elements of the slices are equal as per `eq_fn`.
553 pub fn count_eq<X: Sized>(
554 left: &mut dyn Iterator<Item = X>,
555 right: &mut dyn Iterator<Item = X>,
556 mut eq_fn: impl FnMut(&X, &X) -> bool,
558 left.zip(right).take_while(|(l, r)| eq_fn(l, r)).count()
561 /// Checks if two expressions evaluate to the same value, and don't contain any side effects.
562 pub fn eq_expr_value(cx: &LateContext<'_>, left: &Expr<'_>, right: &Expr<'_>) -> bool {
563 SpanlessEq::new(cx).deny_side_effects().eq_expr(left, right)
566 /// Type used to hash an ast element. This is different from the `Hash` trait
567 /// on ast types as this
568 /// trait would consider IDs and spans.
570 /// All expressions kind are hashed, but some might have a weaker hash.
571 pub struct SpanlessHash<'a, 'tcx> {
572 /// Context used to evaluate constant expressions.
573 cx: &'a LateContext<'tcx>,
574 maybe_typeck_results: Option<&'tcx TypeckResults<'tcx>>,
578 impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
579 pub fn new(cx: &'a LateContext<'tcx>) -> Self {
582 maybe_typeck_results: cx.maybe_typeck_results(),
583 s: FxHasher::default(),
587 pub fn finish(self) -> u64 {
591 pub fn hash_block(&mut self, b: &Block<'_>) {
596 if let Some(e) = b.expr {
600 std::mem::discriminant(&b.rules).hash(&mut self.s);
603 #[expect(clippy::too_many_lines)]
604 pub fn hash_expr(&mut self, e: &Expr<'_>) {
605 let simple_const = self
606 .maybe_typeck_results
607 .and_then(|typeck_results| constant_simple(self.cx, typeck_results, e));
609 // const hashing may result in the same hash as some unrelated node, so add a sort of
610 // discriminant depending on which path we're choosing next
611 simple_const.hash(&mut self.s);
612 if simple_const.is_some() {
616 std::mem::discriminant(&e.kind).hash(&mut self.s);
619 ExprKind::AddrOf(kind, m, e) => {
620 std::mem::discriminant(&kind).hash(&mut self.s);
624 ExprKind::Continue(i) => {
625 if let Some(i) = i.label {
626 self.hash_name(i.ident.name);
629 ExprKind::Assign(l, r, _) => {
633 ExprKind::AssignOp(ref o, l, r) => {
634 std::mem::discriminant(&o.node).hash(&mut self.s);
638 ExprKind::Block(b, _) => {
641 ExprKind::Binary(op, l, r) => {
642 std::mem::discriminant(&op.node).hash(&mut self.s);
646 ExprKind::Break(i, ref j) => {
647 if let Some(i) = i.label {
648 self.hash_name(i.ident.name);
650 if let Some(j) = *j {
654 ExprKind::Box(e) | ExprKind::DropTemps(e) | ExprKind::Yield(e, _) => {
657 ExprKind::Call(fun, args) => {
659 self.hash_exprs(args);
661 ExprKind::Cast(e, ty) | ExprKind::Type(e, ty) => {
665 ExprKind::Closure(&Closure {
666 capture_clause, body, ..
668 std::mem::discriminant(&capture_clause).hash(&mut self.s);
669 // closures inherit TypeckResults
670 self.hash_expr(&self.cx.tcx.hir().body(body).value);
672 ExprKind::Field(e, ref f) => {
674 self.hash_name(f.name);
676 ExprKind::Index(a, i) => {
680 ExprKind::InlineAsm(asm) => {
681 for piece in asm.template {
683 InlineAsmTemplatePiece::String(s) => s.hash(&mut self.s),
684 InlineAsmTemplatePiece::Placeholder {
689 operand_idx.hash(&mut self.s);
690 modifier.hash(&mut self.s);
694 asm.options.hash(&mut self.s);
695 for (op, _op_sp) in asm.operands {
697 InlineAsmOperand::In { reg, expr } => {
698 reg.hash(&mut self.s);
699 self.hash_expr(expr);
701 InlineAsmOperand::Out { reg, late, expr } => {
702 reg.hash(&mut self.s);
703 late.hash(&mut self.s);
704 if let Some(expr) = expr {
705 self.hash_expr(expr);
708 InlineAsmOperand::InOut { reg, late, expr } => {
709 reg.hash(&mut self.s);
710 late.hash(&mut self.s);
711 self.hash_expr(expr);
713 InlineAsmOperand::SplitInOut {
719 reg.hash(&mut self.s);
720 late.hash(&mut self.s);
721 self.hash_expr(in_expr);
722 if let Some(out_expr) = out_expr {
723 self.hash_expr(out_expr);
726 InlineAsmOperand::Const { anon_const } | InlineAsmOperand::SymFn { anon_const } => {
727 self.hash_body(anon_const.body);
729 InlineAsmOperand::SymStatic { path, def_id: _ } => self.hash_qpath(path),
733 ExprKind::Let(Let { pat, init, ty, .. }) => {
734 self.hash_expr(init);
735 if let Some(ty) = ty {
741 ExprKind::Lit(ref l) => {
742 l.node.hash(&mut self.s);
744 ExprKind::Loop(b, ref i, ..) => {
746 if let Some(i) = *i {
747 self.hash_name(i.ident.name);
750 ExprKind::If(cond, then, ref else_opt) => {
751 self.hash_expr(cond);
752 self.hash_expr(then);
753 if let Some(e) = *else_opt {
757 ExprKind::Match(e, arms, ref s) => {
761 self.hash_pat(arm.pat);
762 if let Some(ref e) = arm.guard {
765 self.hash_expr(arm.body);
770 ExprKind::MethodCall(path, args, ref _fn_span) => {
771 self.hash_name(path.ident.name);
772 self.hash_exprs(args);
774 ExprKind::ConstBlock(ref l_id) => {
775 self.hash_body(l_id.body);
777 ExprKind::Repeat(e, len) => {
779 self.hash_array_length(len);
781 ExprKind::Ret(ref e) => {
782 if let Some(e) = *e {
786 ExprKind::Path(ref qpath) => {
787 self.hash_qpath(qpath);
789 ExprKind::Struct(path, fields, ref expr) => {
790 self.hash_qpath(path);
793 self.hash_name(f.ident.name);
794 self.hash_expr(f.expr);
797 if let Some(e) = *expr {
801 ExprKind::Tup(tup) => {
802 self.hash_exprs(tup);
804 ExprKind::Array(v) => {
807 ExprKind::Unary(lop, le) => {
808 std::mem::discriminant(&lop).hash(&mut self.s);
814 pub fn hash_exprs(&mut self, e: &[Expr<'_>]) {
820 pub fn hash_name(&mut self, n: Symbol) {
824 pub fn hash_qpath(&mut self, p: &QPath<'_>) {
826 QPath::Resolved(_, path) => {
827 self.hash_path(path);
829 QPath::TypeRelative(_, path) => {
830 self.hash_name(path.ident.name);
832 QPath::LangItem(lang_item, ..) => {
833 std::mem::discriminant(&lang_item).hash(&mut self.s);
836 // self.maybe_typeck_results.unwrap().qpath_res(p, id).hash(&mut self.s);
839 pub fn hash_pat(&mut self, pat: &Pat<'_>) {
840 std::mem::discriminant(&pat.kind).hash(&mut self.s);
842 PatKind::Binding(ann, _, _, pat) => {
843 std::mem::discriminant(&ann).hash(&mut self.s);
844 if let Some(pat) = pat {
848 PatKind::Box(pat) => self.hash_pat(pat),
849 PatKind::Lit(expr) => self.hash_expr(expr),
850 PatKind::Or(pats) => {
855 PatKind::Path(ref qpath) => self.hash_qpath(qpath),
856 PatKind::Range(s, e, i) => {
863 std::mem::discriminant(&i).hash(&mut self.s);
865 PatKind::Ref(pat, mu) => {
867 std::mem::discriminant(&mu).hash(&mut self.s);
869 PatKind::Slice(l, m, r) => {
873 if let Some(pat) = m {
880 PatKind::Struct(ref qpath, fields, e) => {
881 self.hash_qpath(qpath);
883 self.hash_name(f.ident.name);
884 self.hash_pat(f.pat);
888 PatKind::Tuple(pats, e) => {
894 PatKind::TupleStruct(ref qpath, pats, e) => {
895 self.hash_qpath(qpath);
905 pub fn hash_path(&mut self, path: &Path<'_>) {
907 // constant hash since equality is dependant on inter-expression context
908 // e.g. The expressions `if let Some(x) = foo() {}` and `if let Some(y) = foo() {}` are considered equal
909 // even though the binding names are different and they have different `HirId`s.
910 Res::Local(_) => 1_usize.hash(&mut self.s),
912 for seg in path.segments {
913 self.hash_name(seg.ident.name);
914 self.hash_generic_args(seg.args().args);
920 pub fn hash_stmt(&mut self, b: &Stmt<'_>) {
921 std::mem::discriminant(&b.kind).hash(&mut self.s);
924 StmtKind::Local(local) => {
925 self.hash_pat(local.pat);
926 if let Some(init) = local.init {
927 self.hash_expr(init);
930 StmtKind::Item(..) => {},
931 StmtKind::Expr(expr) | StmtKind::Semi(expr) => {
932 self.hash_expr(expr);
937 pub fn hash_guard(&mut self, g: &Guard<'_>) {
939 Guard::If(expr) | Guard::IfLet(Let { init: expr, .. }) => {
940 self.hash_expr(expr);
945 pub fn hash_lifetime(&mut self, lifetime: Lifetime) {
946 std::mem::discriminant(&lifetime.name).hash(&mut self.s);
947 if let LifetimeName::Param(param_id, ref name) = lifetime.name {
948 std::mem::discriminant(name).hash(&mut self.s);
949 param_id.hash(&mut self.s);
951 ParamName::Plain(ref ident) => {
952 ident.name.hash(&mut self.s);
954 ParamName::Fresh | ParamName::Error => {},
959 pub fn hash_ty(&mut self, ty: &Ty<'_>) {
960 std::mem::discriminant(&ty.kind).hash(&mut self.s);
961 self.hash_tykind(&ty.kind);
964 pub fn hash_tykind(&mut self, ty: &TyKind<'_>) {
966 TyKind::Slice(ty) => {
969 &TyKind::Array(ty, len) => {
971 self.hash_array_length(len);
973 TyKind::Ptr(ref mut_ty) => {
974 self.hash_ty(mut_ty.ty);
975 mut_ty.mutbl.hash(&mut self.s);
977 TyKind::Rptr(lifetime, ref mut_ty) => {
978 self.hash_lifetime(*lifetime);
979 self.hash_ty(mut_ty.ty);
980 mut_ty.mutbl.hash(&mut self.s);
982 TyKind::BareFn(bfn) => {
983 bfn.unsafety.hash(&mut self.s);
984 bfn.abi.hash(&mut self.s);
985 for arg in bfn.decl.inputs {
988 std::mem::discriminant(&bfn.decl.output).hash(&mut self.s);
989 match bfn.decl.output {
990 FnRetTy::DefaultReturn(_) => {},
991 FnRetTy::Return(ty) => {
995 bfn.decl.c_variadic.hash(&mut self.s);
997 TyKind::Tup(ty_list) => {
1002 TyKind::Path(ref qpath) => self.hash_qpath(qpath),
1003 TyKind::OpaqueDef(_, arg_list) => {
1004 self.hash_generic_args(arg_list);
1006 TyKind::TraitObject(_, lifetime, _) => {
1007 self.hash_lifetime(*lifetime);
1009 TyKind::Typeof(anon_const) => {
1010 self.hash_body(anon_const.body);
1012 TyKind::Err | TyKind::Infer | TyKind::Never => {},
1016 pub fn hash_array_length(&mut self, length: ArrayLen) {
1018 ArrayLen::Infer(..) => {},
1019 ArrayLen::Body(anon_const) => self.hash_body(anon_const.body),
1023 pub fn hash_body(&mut self, body_id: BodyId) {
1024 // swap out TypeckResults when hashing a body
1025 let old_maybe_typeck_results = self.maybe_typeck_results.replace(self.cx.tcx.typeck_body(body_id));
1026 self.hash_expr(&self.cx.tcx.hir().body(body_id).value);
1027 self.maybe_typeck_results = old_maybe_typeck_results;
1030 fn hash_generic_args(&mut self, arg_list: &[GenericArg<'_>]) {
1031 for arg in arg_list {
1033 GenericArg::Lifetime(l) => self.hash_lifetime(l),
1034 GenericArg::Type(ref ty) => self.hash_ty(ty),
1035 GenericArg::Const(ref ca) => self.hash_body(ca.value.body),
1036 GenericArg::Infer(ref inf) => self.hash_ty(&inf.to_ty()),
1042 pub fn hash_stmt(cx: &LateContext<'_>, s: &Stmt<'_>) -> u64 {
1043 let mut h = SpanlessHash::new(cx);
1048 pub fn hash_expr(cx: &LateContext<'_>, e: &Expr<'_>) -> u64 {
1049 let mut h = SpanlessHash::new(cx);