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, 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 /// Type used to check whether two ast are the same. This is different from the
20 /// operator `==` on ast types as this operator would compare true equality with
23 /// Note that some expressions kinds are not considered but could be added.
24 pub struct SpanlessEq<'a, 'tcx> {
25 /// Context used to evaluate constant expressions.
26 cx: &'a LateContext<'tcx>,
27 maybe_typeck_results: Option<(&'tcx TypeckResults<'tcx>, &'tcx TypeckResults<'tcx>)>,
28 allow_side_effects: bool,
29 expr_fallback: Option<Box<dyn FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a>>,
32 impl<'a, 'tcx> SpanlessEq<'a, 'tcx> {
33 pub fn new(cx: &'a LateContext<'tcx>) -> Self {
36 maybe_typeck_results: cx.maybe_typeck_results().map(|x| (x, x)),
37 allow_side_effects: true,
42 /// Consider expressions containing potential side effects as not equal.
44 pub fn deny_side_effects(self) -> Self {
46 allow_side_effects: false,
52 pub fn expr_fallback(self, expr_fallback: impl FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a) -> Self {
54 expr_fallback: Some(Box::new(expr_fallback)),
59 /// Use this method to wrap comparisons that may involve inter-expression context.
60 /// See `self.locals`.
61 pub fn inter_expr(&mut self) -> HirEqInterExpr<'_, 'a, 'tcx> {
64 locals: HirIdMap::default(),
68 pub fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
69 self.inter_expr().eq_block(left, right)
72 pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
73 self.inter_expr().eq_expr(left, right)
76 pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
77 self.inter_expr().eq_path(left, right)
80 pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
81 self.inter_expr().eq_path_segment(left, right)
84 pub fn eq_path_segments(&mut self, left: &[PathSegment<'_>], right: &[PathSegment<'_>]) -> bool {
85 self.inter_expr().eq_path_segments(left, right)
89 pub struct HirEqInterExpr<'a, 'b, 'tcx> {
90 inner: &'a mut SpanlessEq<'b, 'tcx>,
92 // When binding are declared, the binding ID in the left expression is mapped to the one on the
93 // right. For example, when comparing `{ let x = 1; x + 2 }` and `{ let y = 1; y + 2 }`,
94 // these blocks are considered equal since `x` is mapped to `y`.
95 pub locals: HirIdMap<HirId>,
98 impl HirEqInterExpr<'_, '_, '_> {
99 pub fn eq_stmt(&mut self, left: &Stmt<'_>, right: &Stmt<'_>) -> bool {
100 match (&left.kind, &right.kind) {
101 (&StmtKind::Local(l), &StmtKind::Local(r)) => {
102 // This additional check ensures that the type of the locals are equivalent even if the init
103 // expression or type have some inferred parts.
104 if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
105 let l_ty = typeck_lhs.pat_ty(l.pat);
106 let r_ty = typeck_rhs.pat_ty(r.pat);
112 // eq_pat adds the HirIds to the locals map. We therefor call it last to make sure that
113 // these only get added if the init and type is equal.
114 both(&l.init, &r.init, |l, r| self.eq_expr(l, r))
115 && both(&l.ty, &r.ty, |l, r| self.eq_ty(l, r))
116 && self.eq_pat(l.pat, r.pat)
118 (&StmtKind::Expr(l), &StmtKind::Expr(r)) | (&StmtKind::Semi(l), &StmtKind::Semi(r)) => self.eq_expr(l, r),
123 /// Checks whether two blocks are the same.
124 fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
125 if self.cannot_be_compared_block(left) || self.cannot_be_compared_block(right) {
128 match (left.stmts, left.expr, right.stmts, right.expr) {
129 ([], None, [], None) => {
130 // For empty blocks, check to see if the tokens are equal. This will catch the case where a macro
131 // expanded to nothing, or the cfg attribute was used.
132 let (left, right) = match (
133 snippet_opt(self.inner.cx, left.span),
134 snippet_opt(self.inner.cx, right.span),
136 (Some(left), Some(right)) => (left, right),
139 let mut left_pos = 0;
140 let left = tokenize(&left)
142 let end = left_pos + t.len;
143 let s = &left[left_pos..end];
150 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
154 let mut right_pos = 0;
155 let right = tokenize(&right)
157 let end = right_pos + t.len;
158 let s = &right[right_pos..end];
165 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
172 over(left.stmts, right.stmts, |l, r| self.eq_stmt(l, r))
173 && both(&left.expr, &right.expr, |l, r| self.eq_expr(l, r))
178 fn cannot_be_compared_block(&mut self, block: &Block<'_>) -> bool {
179 if block.stmts.last().map_or(false, |stmt| {
182 StmtKind::Semi(semi_expr) if self.should_ignore(semi_expr)
188 if let Some(block_expr) = block.expr
189 && self.should_ignore(block_expr)
197 fn should_ignore(&mut self, expr: &Expr<'_>) -> bool {
198 if macro_backtrace(expr.span).last().map_or(false, |macro_call| {
200 &self.inner.cx.tcx.get_diagnostic_name(macro_call.def_id),
201 Some(sym::todo_macro | sym::unimplemented_macro)
210 pub fn eq_array_length(&mut self, left: ArrayLen, right: ArrayLen) -> bool {
211 match (left, right) {
212 (ArrayLen::Infer(..), ArrayLen::Infer(..)) => true,
213 (ArrayLen::Body(l_ct), ArrayLen::Body(r_ct)) => self.eq_body(l_ct.body, r_ct.body),
218 pub fn eq_body(&mut self, left: BodyId, right: BodyId) -> bool {
219 // swap out TypeckResults when hashing a body
220 let old_maybe_typeck_results = self.inner.maybe_typeck_results.replace((
221 self.inner.cx.tcx.typeck_body(left),
222 self.inner.cx.tcx.typeck_body(right),
224 let res = self.eq_expr(
225 &self.inner.cx.tcx.hir().body(left).value,
226 &self.inner.cx.tcx.hir().body(right).value,
228 self.inner.maybe_typeck_results = old_maybe_typeck_results;
232 #[expect(clippy::similar_names)]
233 pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
234 if !self.inner.allow_side_effects && left.span.ctxt() != right.span.ctxt() {
238 if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
239 if let (Some(l), Some(r)) = (
240 constant_simple(self.inner.cx, typeck_lhs, left),
241 constant_simple(self.inner.cx, typeck_rhs, right),
250 reduce_exprkind(self.inner.cx, &left.kind),
251 reduce_exprkind(self.inner.cx, &right.kind),
253 (&ExprKind::AddrOf(lb, l_mut, le), &ExprKind::AddrOf(rb, r_mut, re)) => {
254 lb == rb && l_mut == r_mut && self.eq_expr(le, re)
256 (&ExprKind::Continue(li), &ExprKind::Continue(ri)) => {
257 both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
259 (&ExprKind::Assign(ll, lr, _), &ExprKind::Assign(rl, rr, _)) => {
260 self.inner.allow_side_effects && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
262 (&ExprKind::AssignOp(ref lo, ll, lr), &ExprKind::AssignOp(ref ro, rl, rr)) => {
263 self.inner.allow_side_effects && lo.node == ro.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
265 (&ExprKind::Block(l, _), &ExprKind::Block(r, _)) => self.eq_block(l, r),
266 (&ExprKind::Binary(l_op, ll, lr), &ExprKind::Binary(r_op, rl, rr)) => {
267 l_op.node == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
268 || swap_binop(l_op.node, ll, lr).map_or(false, |(l_op, ll, lr)| {
269 l_op == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
272 (&ExprKind::Break(li, ref le), &ExprKind::Break(ri, ref re)) => {
273 both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
274 && both(le, re, |l, r| self.eq_expr(l, r))
276 (&ExprKind::Box(l), &ExprKind::Box(r)) => self.eq_expr(l, r),
277 (&ExprKind::Call(l_fun, l_args), &ExprKind::Call(r_fun, r_args)) => {
278 self.inner.allow_side_effects && self.eq_expr(l_fun, r_fun) && self.eq_exprs(l_args, r_args)
280 (&ExprKind::Cast(lx, lt), &ExprKind::Cast(rx, rt)) | (&ExprKind::Type(lx, lt), &ExprKind::Type(rx, rt)) => {
281 self.eq_expr(lx, rx) && self.eq_ty(lt, rt)
283 (&ExprKind::Field(l_f_exp, ref l_f_ident), &ExprKind::Field(r_f_exp, ref r_f_ident)) => {
284 l_f_ident.name == r_f_ident.name && self.eq_expr(l_f_exp, r_f_exp)
286 (&ExprKind::Index(la, li), &ExprKind::Index(ra, ri)) => self.eq_expr(la, ra) && self.eq_expr(li, ri),
287 (&ExprKind::If(lc, lt, ref le), &ExprKind::If(rc, rt, ref re)) => {
288 self.eq_expr(lc, rc) && self.eq_expr(lt, rt) && both(le, re, |l, r| self.eq_expr(l, r))
290 (&ExprKind::Let(l), &ExprKind::Let(r)) => {
291 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)
293 (&ExprKind::Lit(ref l), &ExprKind::Lit(ref r)) => l.node == r.node,
294 (&ExprKind::Loop(lb, ref ll, ref lls, _), &ExprKind::Loop(rb, ref rl, ref rls, _)) => {
295 lls == rls && self.eq_block(lb, rb) && both(ll, rl, |l, r| l.ident.name == r.ident.name)
297 (&ExprKind::Match(le, la, ref ls), &ExprKind::Match(re, ra, ref rs)) => {
299 && self.eq_expr(le, re)
300 && over(la, ra, |l, r| {
301 self.eq_pat(l.pat, r.pat)
302 && both(&l.guard, &r.guard, |l, r| self.eq_guard(l, r))
303 && self.eq_expr(l.body, r.body)
306 (&ExprKind::MethodCall(l_path, l_args, _), &ExprKind::MethodCall(r_path, r_args, _)) => {
307 self.inner.allow_side_effects && self.eq_path_segment(l_path, r_path) && self.eq_exprs(l_args, r_args)
309 (&ExprKind::Repeat(le, ll), &ExprKind::Repeat(re, rl)) => {
310 self.eq_expr(le, re) && self.eq_array_length(ll, rl)
312 (&ExprKind::Ret(ref l), &ExprKind::Ret(ref r)) => both(l, r, |l, r| self.eq_expr(l, r)),
313 (&ExprKind::Path(ref l), &ExprKind::Path(ref r)) => self.eq_qpath(l, r),
314 (&ExprKind::Struct(l_path, lf, ref lo), &ExprKind::Struct(r_path, rf, ref ro)) => {
315 self.eq_qpath(l_path, r_path)
316 && both(lo, ro, |l, r| self.eq_expr(l, r))
317 && over(lf, rf, |l, r| self.eq_expr_field(l, r))
319 (&ExprKind::Tup(l_tup), &ExprKind::Tup(r_tup)) => self.eq_exprs(l_tup, r_tup),
320 (&ExprKind::Unary(l_op, le), &ExprKind::Unary(r_op, re)) => l_op == r_op && self.eq_expr(le, re),
321 (&ExprKind::Array(l), &ExprKind::Array(r)) => self.eq_exprs(l, r),
322 (&ExprKind::DropTemps(le), &ExprKind::DropTemps(re)) => self.eq_expr(le, re),
325 is_eq || self.inner.expr_fallback.as_mut().map_or(false, |f| f(left, right))
328 fn eq_exprs(&mut self, left: &[Expr<'_>], right: &[Expr<'_>]) -> bool {
329 over(left, right, |l, r| self.eq_expr(l, r))
332 fn eq_expr_field(&mut self, left: &ExprField<'_>, right: &ExprField<'_>) -> bool {
333 left.ident.name == right.ident.name && self.eq_expr(left.expr, right.expr)
336 fn eq_guard(&mut self, left: &Guard<'_>, right: &Guard<'_>) -> bool {
337 match (left, right) {
338 (Guard::If(l), Guard::If(r)) => self.eq_expr(l, r),
339 (Guard::IfLet(l), Guard::IfLet(r)) => {
340 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)
346 fn eq_generic_arg(&mut self, left: &GenericArg<'_>, right: &GenericArg<'_>) -> bool {
347 match (left, right) {
348 (GenericArg::Const(l), GenericArg::Const(r)) => self.eq_body(l.value.body, r.value.body),
349 (GenericArg::Lifetime(l_lt), GenericArg::Lifetime(r_lt)) => Self::eq_lifetime(l_lt, r_lt),
350 (GenericArg::Type(l_ty), GenericArg::Type(r_ty)) => self.eq_ty(l_ty, r_ty),
351 (GenericArg::Infer(l_inf), GenericArg::Infer(r_inf)) => self.eq_ty(&l_inf.to_ty(), &r_inf.to_ty()),
356 fn eq_lifetime(left: &Lifetime, right: &Lifetime) -> bool {
357 left.name == right.name
360 fn eq_pat_field(&mut self, left: &PatField<'_>, right: &PatField<'_>) -> bool {
361 let (PatField { ident: li, pat: lp, .. }, PatField { ident: ri, pat: rp, .. }) = (&left, &right);
362 li.name == ri.name && self.eq_pat(lp, rp)
365 /// Checks whether two patterns are the same.
366 fn eq_pat(&mut self, left: &Pat<'_>, right: &Pat<'_>) -> bool {
367 match (&left.kind, &right.kind) {
368 (&PatKind::Box(l), &PatKind::Box(r)) => self.eq_pat(l, r),
369 (&PatKind::Struct(ref lp, la, ..), &PatKind::Struct(ref rp, ra, ..)) => {
370 self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat_field(l, r))
372 (&PatKind::TupleStruct(ref lp, la, ls), &PatKind::TupleStruct(ref rp, ra, rs)) => {
373 self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat(l, r)) && ls == rs
375 (&PatKind::Binding(lb, li, _, ref lp), &PatKind::Binding(rb, ri, _, ref rp)) => {
376 let eq = lb == rb && both(lp, rp, |l, r| self.eq_pat(l, r));
378 self.locals.insert(li, ri);
382 (&PatKind::Path(ref l), &PatKind::Path(ref r)) => self.eq_qpath(l, r),
383 (&PatKind::Lit(l), &PatKind::Lit(r)) => self.eq_expr(l, r),
384 (&PatKind::Tuple(l, ls), &PatKind::Tuple(r, rs)) => ls == rs && over(l, r, |l, r| self.eq_pat(l, r)),
385 (&PatKind::Range(ref ls, ref le, li), &PatKind::Range(ref rs, ref re, ri)) => {
386 both(ls, rs, |a, b| self.eq_expr(a, b)) && both(le, re, |a, b| self.eq_expr(a, b)) && (li == ri)
388 (&PatKind::Ref(le, ref lm), &PatKind::Ref(re, ref rm)) => lm == rm && self.eq_pat(le, re),
389 (&PatKind::Slice(ls, ref li, le), &PatKind::Slice(rs, ref ri, re)) => {
390 over(ls, rs, |l, r| self.eq_pat(l, r))
391 && over(le, re, |l, r| self.eq_pat(l, r))
392 && both(li, ri, |l, r| self.eq_pat(l, r))
394 (&PatKind::Wild, &PatKind::Wild) => true,
399 #[expect(clippy::similar_names)]
400 fn eq_qpath(&mut self, left: &QPath<'_>, right: &QPath<'_>) -> bool {
401 match (left, right) {
402 (&QPath::Resolved(ref lty, lpath), &QPath::Resolved(ref rty, rpath)) => {
403 both(lty, rty, |l, r| self.eq_ty(l, r)) && self.eq_path(lpath, rpath)
405 (&QPath::TypeRelative(lty, lseg), &QPath::TypeRelative(rty, rseg)) => {
406 self.eq_ty(lty, rty) && self.eq_path_segment(lseg, rseg)
408 (&QPath::LangItem(llang_item, ..), &QPath::LangItem(rlang_item, ..)) => llang_item == rlang_item,
413 pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
414 match (left.res, right.res) {
415 (Res::Local(l), Res::Local(r)) => l == r || self.locals.get(&l) == Some(&r),
416 (Res::Local(_), _) | (_, Res::Local(_)) => false,
417 _ => over(left.segments, right.segments, |l, r| self.eq_path_segment(l, r)),
421 fn eq_path_parameters(&mut self, left: &GenericArgs<'_>, right: &GenericArgs<'_>) -> bool {
422 if !(left.parenthesized || right.parenthesized) {
423 over(left.args, right.args, |l, r| self.eq_generic_arg(l, r)) // FIXME(flip1995): may not work
424 && over(left.bindings, right.bindings, |l, r| self.eq_type_binding(l, r))
425 } else if left.parenthesized && right.parenthesized {
426 over(left.inputs(), right.inputs(), |l, r| self.eq_ty(l, r))
427 && both(&Some(&left.bindings[0].ty()), &Some(&right.bindings[0].ty()), |l, r| {
435 pub fn eq_path_segments(&mut self, left: &[PathSegment<'_>], right: &[PathSegment<'_>]) -> bool {
436 left.len() == right.len() && left.iter().zip(right).all(|(l, r)| self.eq_path_segment(l, r))
439 pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
440 // The == of idents doesn't work with different contexts,
441 // we have to be explicit about hygiene
442 left.ident.name == right.ident.name && both(&left.args, &right.args, |l, r| self.eq_path_parameters(l, r))
445 pub fn eq_ty(&mut self, left: &Ty<'_>, right: &Ty<'_>) -> bool {
446 match (&left.kind, &right.kind) {
447 (&TyKind::Slice(l_vec), &TyKind::Slice(r_vec)) => self.eq_ty(l_vec, r_vec),
448 (&TyKind::Array(lt, ll), &TyKind::Array(rt, rl)) => self.eq_ty(lt, rt) && self.eq_array_length(ll, rl),
449 (&TyKind::Ptr(ref l_mut), &TyKind::Ptr(ref r_mut)) => {
450 l_mut.mutbl == r_mut.mutbl && self.eq_ty(l_mut.ty, r_mut.ty)
452 (&TyKind::Rptr(_, ref l_rmut), &TyKind::Rptr(_, ref r_rmut)) => {
453 l_rmut.mutbl == r_rmut.mutbl && self.eq_ty(l_rmut.ty, r_rmut.ty)
455 (&TyKind::Path(ref l), &TyKind::Path(ref r)) => self.eq_qpath(l, r),
456 (&TyKind::Tup(l), &TyKind::Tup(r)) => over(l, r, |l, r| self.eq_ty(l, r)),
457 (&TyKind::Infer, &TyKind::Infer) => true,
462 fn eq_type_binding(&mut self, left: &TypeBinding<'_>, right: &TypeBinding<'_>) -> bool {
463 left.ident.name == right.ident.name && self.eq_ty(left.ty(), right.ty())
467 /// Some simple reductions like `{ return }` => `return`
468 fn reduce_exprkind<'hir>(cx: &LateContext<'_>, kind: &'hir ExprKind<'hir>) -> &'hir ExprKind<'hir> {
469 if let ExprKind::Block(block, _) = kind {
470 match (block.stmts, block.expr) {
471 // From an `if let` expression without an `else` block. The arm for the implicit wild pattern is an empty
472 // block with an empty span.
473 ([], None) if block.span.is_empty() => &ExprKind::Tup(&[]),
475 ([], None) => match snippet_opt(cx, block.span) {
476 // Don't reduce if there are any tokens contained in the braces
483 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
486 .ne([TokenKind::OpenBrace, TokenKind::CloseBrace].iter().copied()) =>
490 _ => &ExprKind::Tup(&[]),
492 ([], Some(expr)) => match expr.kind {
493 // `{ return .. }` => `return ..`
494 ExprKind::Ret(..) => &expr.kind,
497 ([stmt], None) => match stmt.kind {
498 StmtKind::Expr(expr) | StmtKind::Semi(expr) => match expr.kind {
499 // `{ return ..; }` => `return ..`
500 ExprKind::Ret(..) => &expr.kind,
516 ) -> Option<(BinOpKind, &'a Expr<'a>, &'a Expr<'a>)> {
518 BinOpKind::Add | BinOpKind::Eq | BinOpKind::Ne | BinOpKind::BitAnd | BinOpKind::BitXor | BinOpKind::BitOr => {
519 Some((binop, rhs, lhs))
521 BinOpKind::Lt => Some((BinOpKind::Gt, rhs, lhs)),
522 BinOpKind::Le => Some((BinOpKind::Ge, rhs, lhs)),
523 BinOpKind::Ge => Some((BinOpKind::Le, rhs, lhs)),
524 BinOpKind::Gt => Some((BinOpKind::Lt, rhs, lhs)),
525 BinOpKind::Mul // Not always commutative, e.g. with matrices. See issue #5698
532 | BinOpKind::Or => None,
536 /// Checks if the two `Option`s are both `None` or some equal values as per
538 pub fn both<X>(l: &Option<X>, r: &Option<X>, mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
540 .map_or_else(|| r.is_none(), |x| r.as_ref().map_or(false, |y| eq_fn(x, y)))
543 /// Checks if two slices are equal as per `eq_fn`.
544 pub fn over<X>(left: &[X], right: &[X], mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
545 left.len() == right.len() && left.iter().zip(right).all(|(x, y)| eq_fn(x, y))
548 /// Counts how many elements of the slices are equal as per `eq_fn`.
549 pub fn count_eq<X: Sized>(
550 left: &mut dyn Iterator<Item = X>,
551 right: &mut dyn Iterator<Item = X>,
552 mut eq_fn: impl FnMut(&X, &X) -> bool,
554 left.zip(right).take_while(|(l, r)| eq_fn(l, r)).count()
557 /// Checks if two expressions evaluate to the same value, and don't contain any side effects.
558 pub fn eq_expr_value(cx: &LateContext<'_>, left: &Expr<'_>, right: &Expr<'_>) -> bool {
559 SpanlessEq::new(cx).deny_side_effects().eq_expr(left, right)
562 /// Type used to hash an ast element. This is different from the `Hash` trait
563 /// on ast types as this
564 /// trait would consider IDs and spans.
566 /// All expressions kind are hashed, but some might have a weaker hash.
567 pub struct SpanlessHash<'a, 'tcx> {
568 /// Context used to evaluate constant expressions.
569 cx: &'a LateContext<'tcx>,
570 maybe_typeck_results: Option<&'tcx TypeckResults<'tcx>>,
574 impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
575 pub fn new(cx: &'a LateContext<'tcx>) -> Self {
578 maybe_typeck_results: cx.maybe_typeck_results(),
579 s: FxHasher::default(),
583 pub fn finish(self) -> u64 {
587 pub fn hash_block(&mut self, b: &Block<'_>) {
592 if let Some(e) = b.expr {
596 std::mem::discriminant(&b.rules).hash(&mut self.s);
599 #[expect(clippy::too_many_lines)]
600 pub fn hash_expr(&mut self, e: &Expr<'_>) {
601 let simple_const = self
602 .maybe_typeck_results
603 .and_then(|typeck_results| constant_simple(self.cx, typeck_results, e));
605 // const hashing may result in the same hash as some unrelated node, so add a sort of
606 // discriminant depending on which path we're choosing next
607 simple_const.hash(&mut self.s);
608 if simple_const.is_some() {
612 std::mem::discriminant(&e.kind).hash(&mut self.s);
615 ExprKind::AddrOf(kind, m, e) => {
616 std::mem::discriminant(&kind).hash(&mut self.s);
620 ExprKind::Continue(i) => {
621 if let Some(i) = i.label {
622 self.hash_name(i.ident.name);
625 ExprKind::Assign(l, r, _) => {
629 ExprKind::AssignOp(ref o, l, r) => {
630 std::mem::discriminant(&o.node).hash(&mut self.s);
634 ExprKind::Block(b, _) => {
637 ExprKind::Binary(op, l, r) => {
638 std::mem::discriminant(&op.node).hash(&mut self.s);
642 ExprKind::Break(i, ref j) => {
643 if let Some(i) = i.label {
644 self.hash_name(i.ident.name);
646 if let Some(j) = *j {
650 ExprKind::Box(e) | ExprKind::DropTemps(e) | ExprKind::Yield(e, _) => {
653 ExprKind::Call(fun, args) => {
655 self.hash_exprs(args);
657 ExprKind::Cast(e, ty) | ExprKind::Type(e, ty) => {
662 capture_clause, body, ..
664 std::mem::discriminant(&capture_clause).hash(&mut self.s);
665 // closures inherit TypeckResults
666 self.hash_expr(&self.cx.tcx.hir().body(body).value);
668 ExprKind::Field(e, ref f) => {
670 self.hash_name(f.name);
672 ExprKind::Index(a, i) => {
676 ExprKind::InlineAsm(asm) => {
677 for piece in asm.template {
679 InlineAsmTemplatePiece::String(s) => s.hash(&mut self.s),
680 InlineAsmTemplatePiece::Placeholder {
685 operand_idx.hash(&mut self.s);
686 modifier.hash(&mut self.s);
690 asm.options.hash(&mut self.s);
691 for (op, _op_sp) in asm.operands {
693 InlineAsmOperand::In { reg, expr } => {
694 reg.hash(&mut self.s);
695 self.hash_expr(expr);
697 InlineAsmOperand::Out { reg, late, expr } => {
698 reg.hash(&mut self.s);
699 late.hash(&mut self.s);
700 if let Some(expr) = expr {
701 self.hash_expr(expr);
704 InlineAsmOperand::InOut { reg, late, expr } => {
705 reg.hash(&mut self.s);
706 late.hash(&mut self.s);
707 self.hash_expr(expr);
709 InlineAsmOperand::SplitInOut {
715 reg.hash(&mut self.s);
716 late.hash(&mut self.s);
717 self.hash_expr(in_expr);
718 if let Some(out_expr) = out_expr {
719 self.hash_expr(out_expr);
722 InlineAsmOperand::Const { anon_const } | InlineAsmOperand::SymFn { anon_const } => {
723 self.hash_body(anon_const.body);
725 InlineAsmOperand::SymStatic { path, def_id: _ } => self.hash_qpath(path),
729 ExprKind::Let(Let { pat, init, ty, .. }) => {
730 self.hash_expr(init);
731 if let Some(ty) = ty {
737 ExprKind::Lit(ref l) => {
738 l.node.hash(&mut self.s);
740 ExprKind::Loop(b, ref i, ..) => {
742 if let Some(i) = *i {
743 self.hash_name(i.ident.name);
746 ExprKind::If(cond, then, ref else_opt) => {
747 self.hash_expr(cond);
748 self.hash_expr(then);
749 if let Some(e) = *else_opt {
753 ExprKind::Match(e, arms, ref s) => {
757 self.hash_pat(arm.pat);
758 if let Some(ref e) = arm.guard {
761 self.hash_expr(arm.body);
766 ExprKind::MethodCall(path, args, ref _fn_span) => {
767 self.hash_name(path.ident.name);
768 self.hash_exprs(args);
770 ExprKind::ConstBlock(ref l_id) => {
771 self.hash_body(l_id.body);
773 ExprKind::Repeat(e, len) => {
775 self.hash_array_length(len);
777 ExprKind::Ret(ref e) => {
778 if let Some(e) = *e {
782 ExprKind::Path(ref qpath) => {
783 self.hash_qpath(qpath);
785 ExprKind::Struct(path, fields, ref expr) => {
786 self.hash_qpath(path);
789 self.hash_name(f.ident.name);
790 self.hash_expr(f.expr);
793 if let Some(e) = *expr {
797 ExprKind::Tup(tup) => {
798 self.hash_exprs(tup);
800 ExprKind::Array(v) => {
803 ExprKind::Unary(lop, le) => {
804 std::mem::discriminant(&lop).hash(&mut self.s);
810 pub fn hash_exprs(&mut self, e: &[Expr<'_>]) {
816 pub fn hash_name(&mut self, n: Symbol) {
820 pub fn hash_qpath(&mut self, p: &QPath<'_>) {
822 QPath::Resolved(_, path) => {
823 self.hash_path(path);
825 QPath::TypeRelative(_, path) => {
826 self.hash_name(path.ident.name);
828 QPath::LangItem(lang_item, ..) => {
829 std::mem::discriminant(&lang_item).hash(&mut self.s);
832 // self.maybe_typeck_results.unwrap().qpath_res(p, id).hash(&mut self.s);
835 pub fn hash_pat(&mut self, pat: &Pat<'_>) {
836 std::mem::discriminant(&pat.kind).hash(&mut self.s);
838 PatKind::Binding(ann, _, _, pat) => {
839 std::mem::discriminant(&ann).hash(&mut self.s);
840 if let Some(pat) = pat {
844 PatKind::Box(pat) => self.hash_pat(pat),
845 PatKind::Lit(expr) => self.hash_expr(expr),
846 PatKind::Or(pats) => {
851 PatKind::Path(ref qpath) => self.hash_qpath(qpath),
852 PatKind::Range(s, e, i) => {
859 std::mem::discriminant(&i).hash(&mut self.s);
861 PatKind::Ref(pat, mu) => {
863 std::mem::discriminant(&mu).hash(&mut self.s);
865 PatKind::Slice(l, m, r) => {
869 if let Some(pat) = m {
876 PatKind::Struct(ref qpath, fields, e) => {
877 self.hash_qpath(qpath);
879 self.hash_name(f.ident.name);
880 self.hash_pat(f.pat);
884 PatKind::Tuple(pats, e) => {
890 PatKind::TupleStruct(ref qpath, pats, e) => {
891 self.hash_qpath(qpath);
901 pub fn hash_path(&mut self, path: &Path<'_>) {
903 // constant hash since equality is dependant on inter-expression context
904 // e.g. The expressions `if let Some(x) = foo() {}` and `if let Some(y) = foo() {}` are considered equal
905 // even though the binding names are different and they have different `HirId`s.
906 Res::Local(_) => 1_usize.hash(&mut self.s),
908 for seg in path.segments {
909 self.hash_name(seg.ident.name);
910 self.hash_generic_args(seg.args().args);
916 pub fn hash_stmt(&mut self, b: &Stmt<'_>) {
917 std::mem::discriminant(&b.kind).hash(&mut self.s);
920 StmtKind::Local(local) => {
921 self.hash_pat(local.pat);
922 if let Some(init) = local.init {
923 self.hash_expr(init);
926 StmtKind::Item(..) => {},
927 StmtKind::Expr(expr) | StmtKind::Semi(expr) => {
928 self.hash_expr(expr);
933 pub fn hash_guard(&mut self, g: &Guard<'_>) {
935 Guard::If(expr) | Guard::IfLet(Let { init: expr, .. }) => {
936 self.hash_expr(expr);
941 pub fn hash_lifetime(&mut self, lifetime: Lifetime) {
942 std::mem::discriminant(&lifetime.name).hash(&mut self.s);
943 if let LifetimeName::Param(param_id, ref name) = lifetime.name {
944 std::mem::discriminant(name).hash(&mut self.s);
945 param_id.hash(&mut self.s);
947 ParamName::Plain(ref ident) => {
948 ident.name.hash(&mut self.s);
950 ParamName::Fresh | ParamName::Error => {},
955 pub fn hash_ty(&mut self, ty: &Ty<'_>) {
956 std::mem::discriminant(&ty.kind).hash(&mut self.s);
957 self.hash_tykind(&ty.kind);
960 pub fn hash_tykind(&mut self, ty: &TyKind<'_>) {
962 TyKind::Slice(ty) => {
965 &TyKind::Array(ty, len) => {
967 self.hash_array_length(len);
969 TyKind::Ptr(ref mut_ty) => {
970 self.hash_ty(mut_ty.ty);
971 mut_ty.mutbl.hash(&mut self.s);
973 TyKind::Rptr(lifetime, ref mut_ty) => {
974 self.hash_lifetime(*lifetime);
975 self.hash_ty(mut_ty.ty);
976 mut_ty.mutbl.hash(&mut self.s);
978 TyKind::BareFn(bfn) => {
979 bfn.unsafety.hash(&mut self.s);
980 bfn.abi.hash(&mut self.s);
981 for arg in bfn.decl.inputs {
984 std::mem::discriminant(&bfn.decl.output).hash(&mut self.s);
985 match bfn.decl.output {
986 FnRetTy::DefaultReturn(_) => {},
987 FnRetTy::Return(ty) => {
991 bfn.decl.c_variadic.hash(&mut self.s);
993 TyKind::Tup(ty_list) => {
998 TyKind::Path(ref qpath) => self.hash_qpath(qpath),
999 TyKind::OpaqueDef(_, arg_list) => {
1000 self.hash_generic_args(arg_list);
1002 TyKind::TraitObject(_, lifetime, _) => {
1003 self.hash_lifetime(*lifetime);
1005 TyKind::Typeof(anon_const) => {
1006 self.hash_body(anon_const.body);
1008 TyKind::Err | TyKind::Infer | TyKind::Never => {},
1012 pub fn hash_array_length(&mut self, length: ArrayLen) {
1014 ArrayLen::Infer(..) => {},
1015 ArrayLen::Body(anon_const) => self.hash_body(anon_const.body),
1019 pub fn hash_body(&mut self, body_id: BodyId) {
1020 // swap out TypeckResults when hashing a body
1021 let old_maybe_typeck_results = self.maybe_typeck_results.replace(self.cx.tcx.typeck_body(body_id));
1022 self.hash_expr(&self.cx.tcx.hir().body(body_id).value);
1023 self.maybe_typeck_results = old_maybe_typeck_results;
1026 fn hash_generic_args(&mut self, arg_list: &[GenericArg<'_>]) {
1027 for arg in arg_list {
1029 GenericArg::Lifetime(l) => self.hash_lifetime(l),
1030 GenericArg::Type(ref ty) => self.hash_ty(ty),
1031 GenericArg::Const(ref ca) => self.hash_body(ca.value.body),
1032 GenericArg::Infer(ref inf) => self.hash_ty(&inf.to_ty()),
1038 pub fn hash_stmt(cx: &LateContext<'_>, s: &Stmt<'_>) -> u64 {
1039 let mut h = SpanlessHash::new(cx);
1044 pub fn hash_expr(cx: &LateContext<'_>, e: &Expr<'_>) -> u64 {
1045 let mut h = SpanlessHash::new(cx);