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, Closure, Expr, ExprField, ExprKind, FnRetTy, GenericArg, GenericArgs, Guard,
10 HirId, InlineAsmOperand, Let, Lifetime, LifetimeName, ParamName, Pat, PatField, PatKind, Path, PathSegment, QPath,
11 Stmt, 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 && both(&l.els, &r.els, |l, r| self.eq_block(l, r))
121 && self.eq_pat(l.pat, r.pat)
123 (&StmtKind::Expr(l), &StmtKind::Expr(r)) | (&StmtKind::Semi(l), &StmtKind::Semi(r)) => self.eq_expr(l, r),
128 /// Checks whether two blocks are the same.
129 fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
130 match (left.stmts, left.expr, right.stmts, right.expr) {
131 ([], None, [], None) => {
132 // For empty blocks, check to see if the tokens are equal. This will catch the case where a macro
133 // expanded to nothing, or the cfg attribute was used.
134 let (left, right) = match (
135 snippet_opt(self.inner.cx, left.span),
136 snippet_opt(self.inner.cx, right.span),
138 (Some(left), Some(right)) => (left, right),
141 let mut left_pos = 0;
142 let left = tokenize(&left)
144 let end = left_pos + t.len as usize;
145 let s = &left[left_pos..end];
152 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
156 let mut right_pos = 0;
157 let right = tokenize(&right)
159 let end = right_pos + t.len as usize;
160 let s = &right[right_pos..end];
167 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
174 over(left.stmts, right.stmts, |l, r| self.eq_stmt(l, r))
175 && both(&left.expr, &right.expr, |l, r| self.eq_expr(l, r))
180 fn should_ignore(&mut self, expr: &Expr<'_>) -> bool {
181 macro_backtrace(expr.span).last().map_or(false, |macro_call| {
183 &self.inner.cx.tcx.get_diagnostic_name(macro_call.def_id),
184 Some(sym::todo_macro | sym::unimplemented_macro)
189 pub fn eq_array_length(&mut self, left: ArrayLen, right: ArrayLen) -> bool {
190 match (left, right) {
191 (ArrayLen::Infer(..), ArrayLen::Infer(..)) => true,
192 (ArrayLen::Body(l_ct), ArrayLen::Body(r_ct)) => self.eq_body(l_ct.body, r_ct.body),
197 pub fn eq_body(&mut self, left: BodyId, right: BodyId) -> bool {
198 // swap out TypeckResults when hashing a body
199 let old_maybe_typeck_results = self.inner.maybe_typeck_results.replace((
200 self.inner.cx.tcx.typeck_body(left),
201 self.inner.cx.tcx.typeck_body(right),
203 let res = self.eq_expr(
204 &self.inner.cx.tcx.hir().body(left).value,
205 &self.inner.cx.tcx.hir().body(right).value,
207 self.inner.maybe_typeck_results = old_maybe_typeck_results;
211 #[expect(clippy::similar_names)]
212 pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
213 if !self.inner.allow_side_effects && left.span.ctxt() != right.span.ctxt() {
217 if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
218 if let (Some(l), Some(r)) = (
219 constant_simple(self.inner.cx, typeck_lhs, left),
220 constant_simple(self.inner.cx, typeck_rhs, right),
229 reduce_exprkind(self.inner.cx, &left.kind),
230 reduce_exprkind(self.inner.cx, &right.kind),
232 (&ExprKind::AddrOf(lb, l_mut, le), &ExprKind::AddrOf(rb, r_mut, re)) => {
233 lb == rb && l_mut == r_mut && self.eq_expr(le, re)
235 (&ExprKind::Continue(li), &ExprKind::Continue(ri)) => {
236 both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
238 (&ExprKind::Assign(ll, lr, _), &ExprKind::Assign(rl, rr, _)) => {
239 self.inner.allow_side_effects && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
241 (&ExprKind::AssignOp(ref lo, ll, lr), &ExprKind::AssignOp(ref ro, rl, rr)) => {
242 self.inner.allow_side_effects && lo.node == ro.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
244 (&ExprKind::Block(l, _), &ExprKind::Block(r, _)) => self.eq_block(l, r),
245 (&ExprKind::Binary(l_op, ll, lr), &ExprKind::Binary(r_op, rl, rr)) => {
246 l_op.node == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
247 || swap_binop(l_op.node, ll, lr).map_or(false, |(l_op, ll, lr)| {
248 l_op == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
251 (&ExprKind::Break(li, ref le), &ExprKind::Break(ri, ref re)) => {
252 both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
253 && both(le, re, |l, r| self.eq_expr(l, r))
255 (&ExprKind::Box(l), &ExprKind::Box(r)) => self.eq_expr(l, r),
256 (&ExprKind::Call(l_fun, l_args), &ExprKind::Call(r_fun, r_args)) => {
257 self.inner.allow_side_effects && self.eq_expr(l_fun, r_fun) && self.eq_exprs(l_args, r_args)
259 (&ExprKind::Cast(lx, lt), &ExprKind::Cast(rx, rt)) | (&ExprKind::Type(lx, lt), &ExprKind::Type(rx, rt)) => {
260 self.eq_expr(lx, rx) && self.eq_ty(lt, rt)
262 (&ExprKind::Field(l_f_exp, ref l_f_ident), &ExprKind::Field(r_f_exp, ref r_f_ident)) => {
263 l_f_ident.name == r_f_ident.name && self.eq_expr(l_f_exp, r_f_exp)
265 (&ExprKind::Index(la, li), &ExprKind::Index(ra, ri)) => self.eq_expr(la, ra) && self.eq_expr(li, ri),
266 (&ExprKind::If(lc, lt, ref le), &ExprKind::If(rc, rt, ref re)) => {
267 self.eq_expr(lc, rc) && self.eq_expr(lt, rt) && both(le, re, |l, r| self.eq_expr(l, r))
269 (&ExprKind::Let(l), &ExprKind::Let(r)) => {
270 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)
272 (&ExprKind::Lit(ref l), &ExprKind::Lit(ref r)) => l.node == r.node,
273 (&ExprKind::Loop(lb, ref ll, ref lls, _), &ExprKind::Loop(rb, ref rl, ref rls, _)) => {
274 lls == rls && self.eq_block(lb, rb) && both(ll, rl, |l, r| l.ident.name == r.ident.name)
276 (&ExprKind::Match(le, la, ref ls), &ExprKind::Match(re, ra, ref rs)) => {
278 && self.eq_expr(le, re)
279 && over(la, ra, |l, r| {
280 self.eq_pat(l.pat, r.pat)
281 && both(&l.guard, &r.guard, |l, r| self.eq_guard(l, r))
282 && self.eq_expr(l.body, r.body)
285 (&ExprKind::MethodCall(l_path, l_args, _), &ExprKind::MethodCall(r_path, r_args, _)) => {
286 self.inner.allow_side_effects && self.eq_path_segment(l_path, r_path) && self.eq_exprs(l_args, r_args)
288 (&ExprKind::Repeat(le, ll), &ExprKind::Repeat(re, rl)) => {
289 self.eq_expr(le, re) && self.eq_array_length(ll, rl)
291 (&ExprKind::Ret(ref l), &ExprKind::Ret(ref r)) => both(l, r, |l, r| self.eq_expr(l, r)),
292 (&ExprKind::Path(ref l), &ExprKind::Path(ref r)) => self.eq_qpath(l, r),
293 (&ExprKind::Struct(l_path, lf, ref lo), &ExprKind::Struct(r_path, rf, ref ro)) => {
294 self.eq_qpath(l_path, r_path)
295 && both(lo, ro, |l, r| self.eq_expr(l, r))
296 && over(lf, rf, |l, r| self.eq_expr_field(l, r))
298 (&ExprKind::Tup(l_tup), &ExprKind::Tup(r_tup)) => self.eq_exprs(l_tup, r_tup),
299 (&ExprKind::Unary(l_op, le), &ExprKind::Unary(r_op, re)) => l_op == r_op && self.eq_expr(le, re),
300 (&ExprKind::Array(l), &ExprKind::Array(r)) => self.eq_exprs(l, r),
301 (&ExprKind::DropTemps(le), &ExprKind::DropTemps(re)) => self.eq_expr(le, re),
304 (is_eq && (!self.should_ignore(left) || !self.should_ignore(right)))
305 || self.inner.expr_fallback.as_mut().map_or(false, |f| f(left, right))
308 fn eq_exprs(&mut self, left: &[Expr<'_>], right: &[Expr<'_>]) -> bool {
309 over(left, right, |l, r| self.eq_expr(l, r))
312 fn eq_expr_field(&mut self, left: &ExprField<'_>, right: &ExprField<'_>) -> bool {
313 left.ident.name == right.ident.name && self.eq_expr(left.expr, right.expr)
316 fn eq_guard(&mut self, left: &Guard<'_>, right: &Guard<'_>) -> bool {
317 match (left, right) {
318 (Guard::If(l), Guard::If(r)) => self.eq_expr(l, r),
319 (Guard::IfLet(l), Guard::IfLet(r)) => {
320 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)
326 fn eq_generic_arg(&mut self, left: &GenericArg<'_>, right: &GenericArg<'_>) -> bool {
327 match (left, right) {
328 (GenericArg::Const(l), GenericArg::Const(r)) => self.eq_body(l.value.body, r.value.body),
329 (GenericArg::Lifetime(l_lt), GenericArg::Lifetime(r_lt)) => Self::eq_lifetime(l_lt, r_lt),
330 (GenericArg::Type(l_ty), GenericArg::Type(r_ty)) => self.eq_ty(l_ty, r_ty),
331 (GenericArg::Infer(l_inf), GenericArg::Infer(r_inf)) => self.eq_ty(&l_inf.to_ty(), &r_inf.to_ty()),
336 fn eq_lifetime(left: &Lifetime, right: &Lifetime) -> bool {
337 left.name == right.name
340 fn eq_pat_field(&mut self, left: &PatField<'_>, right: &PatField<'_>) -> bool {
341 let (PatField { ident: li, pat: lp, .. }, PatField { ident: ri, pat: rp, .. }) = (&left, &right);
342 li.name == ri.name && self.eq_pat(lp, rp)
345 /// Checks whether two patterns are the same.
346 fn eq_pat(&mut self, left: &Pat<'_>, right: &Pat<'_>) -> bool {
347 match (&left.kind, &right.kind) {
348 (&PatKind::Box(l), &PatKind::Box(r)) => self.eq_pat(l, r),
349 (&PatKind::Struct(ref lp, la, ..), &PatKind::Struct(ref rp, ra, ..)) => {
350 self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat_field(l, r))
352 (&PatKind::TupleStruct(ref lp, la, ls), &PatKind::TupleStruct(ref rp, ra, rs)) => {
353 self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat(l, r)) && ls == rs
355 (&PatKind::Binding(lb, li, _, ref lp), &PatKind::Binding(rb, ri, _, ref rp)) => {
356 let eq = lb == rb && both(lp, rp, |l, r| self.eq_pat(l, r));
358 self.locals.insert(li, ri);
362 (&PatKind::Path(ref l), &PatKind::Path(ref r)) => self.eq_qpath(l, r),
363 (&PatKind::Lit(l), &PatKind::Lit(r)) => self.eq_expr(l, r),
364 (&PatKind::Tuple(l, ls), &PatKind::Tuple(r, rs)) => ls == rs && over(l, r, |l, r| self.eq_pat(l, r)),
365 (&PatKind::Range(ref ls, ref le, li), &PatKind::Range(ref rs, ref re, ri)) => {
366 both(ls, rs, |a, b| self.eq_expr(a, b)) && both(le, re, |a, b| self.eq_expr(a, b)) && (li == ri)
368 (&PatKind::Ref(le, ref lm), &PatKind::Ref(re, ref rm)) => lm == rm && self.eq_pat(le, re),
369 (&PatKind::Slice(ls, ref li, le), &PatKind::Slice(rs, ref ri, re)) => {
370 over(ls, rs, |l, r| self.eq_pat(l, r))
371 && over(le, re, |l, r| self.eq_pat(l, r))
372 && both(li, ri, |l, r| self.eq_pat(l, r))
374 (&PatKind::Wild, &PatKind::Wild) => true,
379 #[expect(clippy::similar_names)]
380 fn eq_qpath(&mut self, left: &QPath<'_>, right: &QPath<'_>) -> bool {
381 match (left, right) {
382 (&QPath::Resolved(ref lty, lpath), &QPath::Resolved(ref rty, rpath)) => {
383 both(lty, rty, |l, r| self.eq_ty(l, r)) && self.eq_path(lpath, rpath)
385 (&QPath::TypeRelative(lty, lseg), &QPath::TypeRelative(rty, rseg)) => {
386 self.eq_ty(lty, rty) && self.eq_path_segment(lseg, rseg)
388 (&QPath::LangItem(llang_item, ..), &QPath::LangItem(rlang_item, ..)) => llang_item == rlang_item,
393 pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
394 match (left.res, right.res) {
395 (Res::Local(l), Res::Local(r)) => l == r || self.locals.get(&l) == Some(&r),
396 (Res::Local(_), _) | (_, Res::Local(_)) => false,
397 _ => over(left.segments, right.segments, |l, r| self.eq_path_segment(l, r)),
401 fn eq_path_parameters(&mut self, left: &GenericArgs<'_>, right: &GenericArgs<'_>) -> bool {
402 if !(left.parenthesized || right.parenthesized) {
403 over(left.args, right.args, |l, r| self.eq_generic_arg(l, r)) // FIXME(flip1995): may not work
404 && over(left.bindings, right.bindings, |l, r| self.eq_type_binding(l, r))
405 } else if left.parenthesized && right.parenthesized {
406 over(left.inputs(), right.inputs(), |l, r| self.eq_ty(l, r))
407 && both(&Some(&left.bindings[0].ty()), &Some(&right.bindings[0].ty()), |l, r| {
415 pub fn eq_path_segments(&mut self, left: &[PathSegment<'_>], right: &[PathSegment<'_>]) -> bool {
416 left.len() == right.len() && left.iter().zip(right).all(|(l, r)| self.eq_path_segment(l, r))
419 pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
420 // The == of idents doesn't work with different contexts,
421 // we have to be explicit about hygiene
422 left.ident.name == right.ident.name && both(&left.args, &right.args, |l, r| self.eq_path_parameters(l, r))
425 pub fn eq_ty(&mut self, left: &Ty<'_>, right: &Ty<'_>) -> bool {
426 match (&left.kind, &right.kind) {
427 (&TyKind::Slice(l_vec), &TyKind::Slice(r_vec)) => self.eq_ty(l_vec, r_vec),
428 (&TyKind::Array(lt, ll), &TyKind::Array(rt, rl)) => self.eq_ty(lt, rt) && self.eq_array_length(ll, rl),
429 (&TyKind::Ptr(ref l_mut), &TyKind::Ptr(ref r_mut)) => {
430 l_mut.mutbl == r_mut.mutbl && self.eq_ty(l_mut.ty, r_mut.ty)
432 (&TyKind::Rptr(_, ref l_rmut), &TyKind::Rptr(_, ref r_rmut)) => {
433 l_rmut.mutbl == r_rmut.mutbl && self.eq_ty(l_rmut.ty, r_rmut.ty)
435 (&TyKind::Path(ref l), &TyKind::Path(ref r)) => self.eq_qpath(l, r),
436 (&TyKind::Tup(l), &TyKind::Tup(r)) => over(l, r, |l, r| self.eq_ty(l, r)),
437 (&TyKind::Infer, &TyKind::Infer) => true,
442 fn eq_type_binding(&mut self, left: &TypeBinding<'_>, right: &TypeBinding<'_>) -> bool {
443 left.ident.name == right.ident.name && self.eq_ty(left.ty(), right.ty())
447 /// Some simple reductions like `{ return }` => `return`
448 fn reduce_exprkind<'hir>(cx: &LateContext<'_>, kind: &'hir ExprKind<'hir>) -> &'hir ExprKind<'hir> {
449 if let ExprKind::Block(block, _) = kind {
450 match (block.stmts, block.expr) {
451 // From an `if let` expression without an `else` block. The arm for the implicit wild pattern is an empty
452 // block with an empty span.
453 ([], None) if block.span.is_empty() => &ExprKind::Tup(&[]),
455 ([], None) => match snippet_opt(cx, block.span) {
456 // Don't reduce if there are any tokens contained in the braces
463 TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
466 .ne([TokenKind::OpenBrace, TokenKind::CloseBrace].iter().copied()) =>
470 _ => &ExprKind::Tup(&[]),
472 ([], Some(expr)) => match expr.kind {
473 // `{ return .. }` => `return ..`
474 ExprKind::Ret(..) => &expr.kind,
477 ([stmt], None) => match stmt.kind {
478 StmtKind::Expr(expr) | StmtKind::Semi(expr) => match expr.kind {
479 // `{ return ..; }` => `return ..`
480 ExprKind::Ret(..) => &expr.kind,
496 ) -> Option<(BinOpKind, &'a Expr<'a>, &'a Expr<'a>)> {
498 BinOpKind::Add | BinOpKind::Eq | BinOpKind::Ne | BinOpKind::BitAnd | BinOpKind::BitXor | BinOpKind::BitOr => {
499 Some((binop, rhs, lhs))
501 BinOpKind::Lt => Some((BinOpKind::Gt, rhs, lhs)),
502 BinOpKind::Le => Some((BinOpKind::Ge, rhs, lhs)),
503 BinOpKind::Ge => Some((BinOpKind::Le, rhs, lhs)),
504 BinOpKind::Gt => Some((BinOpKind::Lt, rhs, lhs)),
505 BinOpKind::Mul // Not always commutative, e.g. with matrices. See issue #5698
512 | BinOpKind::Or => None,
516 /// Checks if the two `Option`s are both `None` or some equal values as per
518 pub fn both<X>(l: &Option<X>, r: &Option<X>, mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
520 .map_or_else(|| r.is_none(), |x| r.as_ref().map_or(false, |y| eq_fn(x, y)))
523 /// Checks if two slices are equal as per `eq_fn`.
524 pub fn over<X>(left: &[X], right: &[X], mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
525 left.len() == right.len() && left.iter().zip(right).all(|(x, y)| eq_fn(x, y))
528 /// Counts how many elements of the slices are equal as per `eq_fn`.
529 pub fn count_eq<X: Sized>(
530 left: &mut dyn Iterator<Item = X>,
531 right: &mut dyn Iterator<Item = X>,
532 mut eq_fn: impl FnMut(&X, &X) -> bool,
534 left.zip(right).take_while(|(l, r)| eq_fn(l, r)).count()
537 /// Checks if two expressions evaluate to the same value, and don't contain any side effects.
538 pub fn eq_expr_value(cx: &LateContext<'_>, left: &Expr<'_>, right: &Expr<'_>) -> bool {
539 SpanlessEq::new(cx).deny_side_effects().eq_expr(left, right)
542 /// Type used to hash an ast element. This is different from the `Hash` trait
543 /// on ast types as this
544 /// trait would consider IDs and spans.
546 /// All expressions kind are hashed, but some might have a weaker hash.
547 pub struct SpanlessHash<'a, 'tcx> {
548 /// Context used to evaluate constant expressions.
549 cx: &'a LateContext<'tcx>,
550 maybe_typeck_results: Option<&'tcx TypeckResults<'tcx>>,
554 impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
555 pub fn new(cx: &'a LateContext<'tcx>) -> Self {
558 maybe_typeck_results: cx.maybe_typeck_results(),
559 s: FxHasher::default(),
563 pub fn finish(self) -> u64 {
567 pub fn hash_block(&mut self, b: &Block<'_>) {
572 if let Some(e) = b.expr {
576 std::mem::discriminant(&b.rules).hash(&mut self.s);
579 #[expect(clippy::too_many_lines)]
580 pub fn hash_expr(&mut self, e: &Expr<'_>) {
581 let simple_const = self
582 .maybe_typeck_results
583 .and_then(|typeck_results| constant_simple(self.cx, typeck_results, e));
585 // const hashing may result in the same hash as some unrelated node, so add a sort of
586 // discriminant depending on which path we're choosing next
587 simple_const.hash(&mut self.s);
588 if simple_const.is_some() {
592 std::mem::discriminant(&e.kind).hash(&mut self.s);
595 ExprKind::AddrOf(kind, m, e) => {
596 std::mem::discriminant(&kind).hash(&mut self.s);
600 ExprKind::Continue(i) => {
601 if let Some(i) = i.label {
602 self.hash_name(i.ident.name);
605 ExprKind::Assign(l, r, _) => {
609 ExprKind::AssignOp(ref o, l, r) => {
610 std::mem::discriminant(&o.node).hash(&mut self.s);
614 ExprKind::Block(b, _) => {
617 ExprKind::Binary(op, l, r) => {
618 std::mem::discriminant(&op.node).hash(&mut self.s);
622 ExprKind::Break(i, ref j) => {
623 if let Some(i) = i.label {
624 self.hash_name(i.ident.name);
626 if let Some(j) = *j {
630 ExprKind::Box(e) | ExprKind::DropTemps(e) | ExprKind::Yield(e, _) => {
633 ExprKind::Call(fun, args) => {
635 self.hash_exprs(args);
637 ExprKind::Cast(e, ty) | ExprKind::Type(e, ty) => {
641 ExprKind::Closure(&Closure {
642 capture_clause, body, ..
644 std::mem::discriminant(&capture_clause).hash(&mut self.s);
645 // closures inherit TypeckResults
646 self.hash_expr(&self.cx.tcx.hir().body(body).value);
648 ExprKind::Field(e, ref f) => {
650 self.hash_name(f.name);
652 ExprKind::Index(a, i) => {
656 ExprKind::InlineAsm(asm) => {
657 for piece in asm.template {
659 InlineAsmTemplatePiece::String(s) => s.hash(&mut self.s),
660 InlineAsmTemplatePiece::Placeholder {
665 operand_idx.hash(&mut self.s);
666 modifier.hash(&mut self.s);
670 asm.options.hash(&mut self.s);
671 for (op, _op_sp) in asm.operands {
673 InlineAsmOperand::In { reg, expr } => {
674 reg.hash(&mut self.s);
675 self.hash_expr(expr);
677 InlineAsmOperand::Out { reg, late, expr } => {
678 reg.hash(&mut self.s);
679 late.hash(&mut self.s);
680 if let Some(expr) = expr {
681 self.hash_expr(expr);
684 InlineAsmOperand::InOut { reg, late, expr } => {
685 reg.hash(&mut self.s);
686 late.hash(&mut self.s);
687 self.hash_expr(expr);
689 InlineAsmOperand::SplitInOut {
695 reg.hash(&mut self.s);
696 late.hash(&mut self.s);
697 self.hash_expr(in_expr);
698 if let Some(out_expr) = out_expr {
699 self.hash_expr(out_expr);
702 InlineAsmOperand::Const { anon_const } | InlineAsmOperand::SymFn { anon_const } => {
703 self.hash_body(anon_const.body);
705 InlineAsmOperand::SymStatic { path, def_id: _ } => self.hash_qpath(path),
709 ExprKind::Let(Let { pat, init, ty, .. }) => {
710 self.hash_expr(init);
711 if let Some(ty) = ty {
717 ExprKind::Lit(ref l) => {
718 l.node.hash(&mut self.s);
720 ExprKind::Loop(b, ref i, ..) => {
722 if let Some(i) = *i {
723 self.hash_name(i.ident.name);
726 ExprKind::If(cond, then, ref else_opt) => {
727 self.hash_expr(cond);
728 self.hash_expr(then);
729 if let Some(e) = *else_opt {
733 ExprKind::Match(e, arms, ref s) => {
737 self.hash_pat(arm.pat);
738 if let Some(ref e) = arm.guard {
741 self.hash_expr(arm.body);
746 ExprKind::MethodCall(path, args, ref _fn_span) => {
747 self.hash_name(path.ident.name);
748 self.hash_exprs(args);
750 ExprKind::ConstBlock(ref l_id) => {
751 self.hash_body(l_id.body);
753 ExprKind::Repeat(e, len) => {
755 self.hash_array_length(len);
757 ExprKind::Ret(ref e) => {
758 if let Some(e) = *e {
762 ExprKind::Path(ref qpath) => {
763 self.hash_qpath(qpath);
765 ExprKind::Struct(path, fields, ref expr) => {
766 self.hash_qpath(path);
769 self.hash_name(f.ident.name);
770 self.hash_expr(f.expr);
773 if let Some(e) = *expr {
777 ExprKind::Tup(tup) => {
778 self.hash_exprs(tup);
780 ExprKind::Array(v) => {
783 ExprKind::Unary(lop, le) => {
784 std::mem::discriminant(&lop).hash(&mut self.s);
790 pub fn hash_exprs(&mut self, e: &[Expr<'_>]) {
796 pub fn hash_name(&mut self, n: Symbol) {
800 pub fn hash_qpath(&mut self, p: &QPath<'_>) {
802 QPath::Resolved(_, path) => {
803 self.hash_path(path);
805 QPath::TypeRelative(_, path) => {
806 self.hash_name(path.ident.name);
808 QPath::LangItem(lang_item, ..) => {
809 std::mem::discriminant(&lang_item).hash(&mut self.s);
812 // self.maybe_typeck_results.unwrap().qpath_res(p, id).hash(&mut self.s);
815 pub fn hash_pat(&mut self, pat: &Pat<'_>) {
816 std::mem::discriminant(&pat.kind).hash(&mut self.s);
818 PatKind::Binding(ann, _, _, pat) => {
819 std::mem::discriminant(&ann).hash(&mut self.s);
820 if let Some(pat) = pat {
824 PatKind::Box(pat) => self.hash_pat(pat),
825 PatKind::Lit(expr) => self.hash_expr(expr),
826 PatKind::Or(pats) => {
831 PatKind::Path(ref qpath) => self.hash_qpath(qpath),
832 PatKind::Range(s, e, i) => {
839 std::mem::discriminant(&i).hash(&mut self.s);
841 PatKind::Ref(pat, mu) => {
843 std::mem::discriminant(&mu).hash(&mut self.s);
845 PatKind::Slice(l, m, r) => {
849 if let Some(pat) = m {
856 PatKind::Struct(ref qpath, fields, e) => {
857 self.hash_qpath(qpath);
859 self.hash_name(f.ident.name);
860 self.hash_pat(f.pat);
864 PatKind::Tuple(pats, e) => {
870 PatKind::TupleStruct(ref qpath, pats, e) => {
871 self.hash_qpath(qpath);
881 pub fn hash_path(&mut self, path: &Path<'_>) {
883 // constant hash since equality is dependant on inter-expression context
884 // e.g. The expressions `if let Some(x) = foo() {}` and `if let Some(y) = foo() {}` are considered equal
885 // even though the binding names are different and they have different `HirId`s.
886 Res::Local(_) => 1_usize.hash(&mut self.s),
888 for seg in path.segments {
889 self.hash_name(seg.ident.name);
890 self.hash_generic_args(seg.args().args);
896 pub fn hash_stmt(&mut self, b: &Stmt<'_>) {
897 std::mem::discriminant(&b.kind).hash(&mut self.s);
900 StmtKind::Local(local) => {
901 self.hash_pat(local.pat);
902 if let Some(init) = local.init {
903 self.hash_expr(init);
905 if let Some(els) = local.els {
906 self.hash_block(els);
909 StmtKind::Item(..) => {},
910 StmtKind::Expr(expr) | StmtKind::Semi(expr) => {
911 self.hash_expr(expr);
916 pub fn hash_guard(&mut self, g: &Guard<'_>) {
918 Guard::If(expr) | Guard::IfLet(Let { init: expr, .. }) => {
919 self.hash_expr(expr);
924 pub fn hash_lifetime(&mut self, lifetime: Lifetime) {
925 std::mem::discriminant(&lifetime.name).hash(&mut self.s);
926 if let LifetimeName::Param(param_id, ref name) = lifetime.name {
927 std::mem::discriminant(name).hash(&mut self.s);
928 param_id.hash(&mut self.s);
930 ParamName::Plain(ref ident) => {
931 ident.name.hash(&mut self.s);
933 ParamName::Fresh | ParamName::Error => {},
938 pub fn hash_ty(&mut self, ty: &Ty<'_>) {
939 std::mem::discriminant(&ty.kind).hash(&mut self.s);
940 self.hash_tykind(&ty.kind);
943 pub fn hash_tykind(&mut self, ty: &TyKind<'_>) {
945 TyKind::Slice(ty) => {
948 &TyKind::Array(ty, len) => {
950 self.hash_array_length(len);
952 TyKind::Ptr(ref mut_ty) => {
953 self.hash_ty(mut_ty.ty);
954 mut_ty.mutbl.hash(&mut self.s);
956 TyKind::Rptr(lifetime, ref mut_ty) => {
957 self.hash_lifetime(*lifetime);
958 self.hash_ty(mut_ty.ty);
959 mut_ty.mutbl.hash(&mut self.s);
961 TyKind::BareFn(bfn) => {
962 bfn.unsafety.hash(&mut self.s);
963 bfn.abi.hash(&mut self.s);
964 for arg in bfn.decl.inputs {
967 std::mem::discriminant(&bfn.decl.output).hash(&mut self.s);
968 match bfn.decl.output {
969 FnRetTy::DefaultReturn(_) => {},
970 FnRetTy::Return(ty) => {
974 bfn.decl.c_variadic.hash(&mut self.s);
976 TyKind::Tup(ty_list) => {
981 TyKind::Path(ref qpath) => self.hash_qpath(qpath),
982 TyKind::OpaqueDef(_, arg_list) => {
983 self.hash_generic_args(arg_list);
985 TyKind::TraitObject(_, lifetime, _) => {
986 self.hash_lifetime(*lifetime);
988 TyKind::Typeof(anon_const) => {
989 self.hash_body(anon_const.body);
991 TyKind::Err | TyKind::Infer | TyKind::Never => {},
995 pub fn hash_array_length(&mut self, length: ArrayLen) {
997 ArrayLen::Infer(..) => {},
998 ArrayLen::Body(anon_const) => self.hash_body(anon_const.body),
1002 pub fn hash_body(&mut self, body_id: BodyId) {
1003 // swap out TypeckResults when hashing a body
1004 let old_maybe_typeck_results = self.maybe_typeck_results.replace(self.cx.tcx.typeck_body(body_id));
1005 self.hash_expr(&self.cx.tcx.hir().body(body_id).value);
1006 self.maybe_typeck_results = old_maybe_typeck_results;
1009 fn hash_generic_args(&mut self, arg_list: &[GenericArg<'_>]) {
1010 for arg in arg_list {
1012 GenericArg::Lifetime(l) => self.hash_lifetime(l),
1013 GenericArg::Type(ref ty) => self.hash_ty(ty),
1014 GenericArg::Const(ref ca) => self.hash_body(ca.value.body),
1015 GenericArg::Infer(ref inf) => self.hash_ty(&inf.to_ty()),
1021 pub fn hash_stmt(cx: &LateContext<'_>, s: &Stmt<'_>) -> u64 {
1022 let mut h = SpanlessHash::new(cx);
1027 pub fn hash_expr(cx: &LateContext<'_>, e: &Expr<'_>) -> u64 {
1028 let mut h = SpanlessHash::new(cx);