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rust/clippy_utils/src/hir_utils.rs
Jason Newcomb 58132cb3b0 Improve SpanlessEq 
* Don't consider expansions of different macros to be the same, even if they expand to the same tokens
* Don't consider `cfg!` expansions to be equal if they check different configs.
2023-05-18 16:42:13 -04:00

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use crate::consts::constant_simple;
use crate::macros::macro_backtrace;
use crate::source::{get_source_text, snippet_opt, walk_span_to_context, SpanRange};
use crate::tokenize_with_text;
use rustc_ast::ast::InlineAsmTemplatePiece;
use rustc_data_structures::fx::FxHasher;
use rustc_hir::def::Res;
use rustc_hir::HirIdMap;
use rustc_hir::{
ArrayLen, BinOpKind, BindingAnnotation, Block, BodyId, Closure, Expr, ExprField, ExprKind, FnRetTy, GenericArg,
GenericArgs, Guard, HirId, InlineAsmOperand, Let, Lifetime, LifetimeName, Pat, PatField, PatKind, Path,
PathSegment, PrimTy, QPath, Stmt, StmtKind, Ty, TyKind, TypeBinding,
};
use rustc_lexer::{tokenize, TokenKind};
use rustc_lint::LateContext;
use rustc_middle::ty::TypeckResults;
use rustc_span::{sym, BytePos, ExpnKind, MacroKind, Symbol, SyntaxContext};
use std::hash::{Hash, Hasher};
use std::ops::Range;
/// Callback that is called when two expressions are not equal in the sense of `SpanlessEq`, but
/// other conditions would make them equal.
type SpanlessEqCallback<'a> = dyn FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a;
/// Type used to check whether two ast are the same. This is different from the
/// operator `==` on ast types as this operator would compare true equality with
/// ID and span.
///
/// Note that some expressions kinds are not considered but could be added.
pub struct SpanlessEq<'a, 'tcx> {
/// Context used to evaluate constant expressions.
cx: &'a LateContext<'tcx>,
maybe_typeck_results: Option<(&'tcx TypeckResults<'tcx>, &'tcx TypeckResults<'tcx>)>,
allow_side_effects: bool,
expr_fallback: Option<Box<SpanlessEqCallback<'a>>>,
}
impl<'a, 'tcx> SpanlessEq<'a, 'tcx> {
pub fn new(cx: &'a LateContext<'tcx>) -> Self {
Self {
cx,
maybe_typeck_results: cx.maybe_typeck_results().map(|x| (x, x)),
allow_side_effects: true,
expr_fallback: None,
}
}
/// Consider expressions containing potential side effects as not equal.
#[must_use]
pub fn deny_side_effects(self) -> Self {
Self {
allow_side_effects: false,
..self
}
}
#[must_use]
pub fn expr_fallback(self, expr_fallback: impl FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a) -> Self {
Self {
expr_fallback: Some(Box::new(expr_fallback)),
..self
}
}
/// Use this method to wrap comparisons that may involve inter-expression context.
/// See `self.locals`.
pub fn inter_expr(&mut self) -> HirEqInterExpr<'_, 'a, 'tcx> {
HirEqInterExpr {
inner: self,
left_ctxt: SyntaxContext::root(),
right_ctxt: SyntaxContext::root(),
locals: HirIdMap::default(),
}
}
pub fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
self.inter_expr().eq_block(left, right)
}
pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
self.inter_expr().eq_expr(left, right)
}
pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
self.inter_expr().eq_path(left, right)
}
pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
self.inter_expr().eq_path_segment(left, right)
}
pub fn eq_path_segments(&mut self, left: &[PathSegment<'_>], right: &[PathSegment<'_>]) -> bool {
self.inter_expr().eq_path_segments(left, right)
}
}
pub struct HirEqInterExpr<'a, 'b, 'tcx> {
inner: &'a mut SpanlessEq<'b, 'tcx>,
left_ctxt: SyntaxContext,
right_ctxt: SyntaxContext,
// When binding are declared, the binding ID in the left expression is mapped to the one on the
// right. For example, when comparing `{ let x = 1; x + 2 }` and `{ let y = 1; y + 2 }`,
// these blocks are considered equal since `x` is mapped to `y`.
pub locals: HirIdMap<HirId>,
}
impl HirEqInterExpr<'_, '_, '_> {
pub fn eq_stmt(&mut self, left: &Stmt<'_>, right: &Stmt<'_>) -> bool {
match (&left.kind, &right.kind) {
(&StmtKind::Local(l), &StmtKind::Local(r)) => {
// This additional check ensures that the type of the locals are equivalent even if the init
// expression or type have some inferred parts.
if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
let l_ty = typeck_lhs.pat_ty(l.pat);
let r_ty = typeck_rhs.pat_ty(r.pat);
if l_ty != r_ty {
return false;
}
}
// eq_pat adds the HirIds to the locals map. We therefore call it last to make sure that
// these only get added if the init and type is equal.
both(&l.init, &r.init, |l, r| self.eq_expr(l, r))
&& both(&l.ty, &r.ty, |l, r| self.eq_ty(l, r))
&& both(&l.els, &r.els, |l, r| self.eq_block(l, r))
&& self.eq_pat(l.pat, r.pat)
},
(&StmtKind::Expr(l), &StmtKind::Expr(r)) | (&StmtKind::Semi(l), &StmtKind::Semi(r)) => self.eq_expr(l, r),
_ => false,
}
}
/// Checks whether two blocks are the same.
#[expect(clippy::similar_names)]
fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
use TokenKind::{BlockComment, LineComment, Semi, Whitespace};
if left.stmts.len() != right.stmts.len() {
return false;
}
let lspan = left.span.data();
let rspan = right.span.data();
if lspan.ctxt != SyntaxContext::root() && rspan.ctxt != SyntaxContext::root() {
// Don't try to check in between statements inside macros.
return over(left.stmts, right.stmts, |left, right| self.eq_stmt(left, right))
&& both(&left.expr, &right.expr, |left, right| self.eq_expr(left, right));
}
if lspan.ctxt != rspan.ctxt {
return false;
}
let mut lstart = lspan.lo;
let mut rstart = rspan.lo;
for (left, right) in left.stmts.iter().zip(right.stmts) {
if !self.eq_stmt(left, right) {
return false;
}
// Try to detect any `cfg`ed statements or empty macro expansions.
let Some(lstmt_span) = walk_span_to_context(left.span, lspan.ctxt) else {
return false;
};
let Some(rstmt_span) = walk_span_to_context(right.span, rspan.ctxt) else {
return false;
};
let lstmt_span = lstmt_span.data();
let rstmt_span = rstmt_span.data();
if lstmt_span.lo < lstart && rstmt_span.lo < rstart {
// Can happen when macros expand to multiple statements, or rearrange statements.
// Nothing in between the statements to check in this case.
continue;
}
if lstmt_span.lo < lstart || rstmt_span.lo < rstart {
// Only one of the blocks had a weird macro.
return false;
}
if !eq_span_tokens(self.inner.cx, lstart..lstmt_span.lo, rstart..rstmt_span.lo, |t| {
!matches!(t, Whitespace | LineComment { .. } | BlockComment { .. } | Semi)
}) {
return false;
}
lstart = lstmt_span.hi;
rstart = rstmt_span.hi;
}
let (lend, rend) = match (left.expr, right.expr) {
(Some(left), Some(right)) => {
if !self.eq_expr(left, right) {
return false;
}
let Some(lexpr_span) = walk_span_to_context(left.span, lspan.ctxt) else {
return false;
};
let Some(rexpr_span) = walk_span_to_context(right.span, rspan.ctxt) else {
return false;
};
(lexpr_span.lo(), rexpr_span.lo())
},
(None, None) => (lspan.hi, rspan.hi),
(Some(_), None) | (None, Some(_)) => return false,
};
if lend < lstart && rend < rstart {
// Can happen when macros rearrange the input.
// Nothing in between the statements to check in this case.
return true;
} else if lend < lstart || rend < rstart {
// Only one of the blocks had a weird macro
return false;
}
eq_span_tokens(self.inner.cx, lstart..lend, rstart..rend, |t| {
!matches!(t, Whitespace | LineComment { .. } | BlockComment { .. } | Semi)
})
}
fn should_ignore(&mut self, expr: &Expr<'_>) -> bool {
macro_backtrace(expr.span).last().map_or(false, |macro_call| {
matches!(
&self.inner.cx.tcx.get_diagnostic_name(macro_call.def_id),
Some(sym::todo_macro | sym::unimplemented_macro)
)
})
}
pub fn eq_array_length(&mut self, left: ArrayLen, right: ArrayLen) -> bool {
match (left, right) {
(ArrayLen::Infer(..), ArrayLen::Infer(..)) => true,
(ArrayLen::Body(l_ct), ArrayLen::Body(r_ct)) => self.eq_body(l_ct.body, r_ct.body),
(_, _) => false,
}
}
pub fn eq_body(&mut self, left: BodyId, right: BodyId) -> bool {
// swap out TypeckResults when hashing a body
let old_maybe_typeck_results = self.inner.maybe_typeck_results.replace((
self.inner.cx.tcx.typeck_body(left),
self.inner.cx.tcx.typeck_body(right),
));
let res = self.eq_expr(
self.inner.cx.tcx.hir().body(left).value,
self.inner.cx.tcx.hir().body(right).value,
);
self.inner.maybe_typeck_results = old_maybe_typeck_results;
res
}
#[expect(clippy::similar_names)]
pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
if !self.check_ctxt(left.span.ctxt(), right.span.ctxt()) {
return false;
}
if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
if let (Some(l), Some(r)) = (
constant_simple(self.inner.cx, typeck_lhs, left),
constant_simple(self.inner.cx, typeck_rhs, right),
) {
if l == r {
return true;
}
}
}
let is_eq = match (
reduce_exprkind(self.inner.cx, &left.kind),
reduce_exprkind(self.inner.cx, &right.kind),
) {
(&ExprKind::AddrOf(lb, l_mut, le), &ExprKind::AddrOf(rb, r_mut, re)) => {
lb == rb && l_mut == r_mut && self.eq_expr(le, re)
},
(&ExprKind::Continue(li), &ExprKind::Continue(ri)) => {
both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
},
(&ExprKind::Assign(ll, lr, _), &ExprKind::Assign(rl, rr, _)) => {
self.inner.allow_side_effects && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
},
(&ExprKind::AssignOp(ref lo, ll, lr), &ExprKind::AssignOp(ref ro, rl, rr)) => {
self.inner.allow_side_effects && lo.node == ro.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
},
(&ExprKind::Block(l, _), &ExprKind::Block(r, _)) => self.eq_block(l, r),
(&ExprKind::Binary(l_op, ll, lr), &ExprKind::Binary(r_op, rl, rr)) => {
l_op.node == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
|| swap_binop(l_op.node, ll, lr).map_or(false, |(l_op, ll, lr)| {
l_op == r_op.node && self.eq_expr(ll, rl) && self.eq_expr(lr, rr)
})
},
(&ExprKind::Break(li, ref le), &ExprKind::Break(ri, ref re)) => {
both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
&& both(le, re, |l, r| self.eq_expr(l, r))
},
(&ExprKind::Call(l_fun, l_args), &ExprKind::Call(r_fun, r_args)) => {
self.inner.allow_side_effects && self.eq_expr(l_fun, r_fun) && self.eq_exprs(l_args, r_args)
},
(&ExprKind::Cast(lx, lt), &ExprKind::Cast(rx, rt)) | (&ExprKind::Type(lx, lt), &ExprKind::Type(rx, rt)) => {
self.eq_expr(lx, rx) && self.eq_ty(lt, rt)
},
(&ExprKind::Field(l_f_exp, ref l_f_ident), &ExprKind::Field(r_f_exp, ref r_f_ident)) => {
l_f_ident.name == r_f_ident.name && self.eq_expr(l_f_exp, r_f_exp)
},
(&ExprKind::Index(la, li), &ExprKind::Index(ra, ri)) => self.eq_expr(la, ra) && self.eq_expr(li, ri),
(&ExprKind::If(lc, lt, ref le), &ExprKind::If(rc, rt, ref re)) => {
self.eq_expr(lc, rc) && self.eq_expr(lt, rt) && both(le, re, |l, r| self.eq_expr(l, r))
},
(&ExprKind::Let(l), &ExprKind::Let(r)) => {
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)
},
(ExprKind::Lit(l), ExprKind::Lit(r)) => l.node == r.node,
(&ExprKind::Loop(lb, ref ll, ref lls, _), &ExprKind::Loop(rb, ref rl, ref rls, _)) => {
lls == rls && self.eq_block(lb, rb) && both(ll, rl, |l, r| l.ident.name == r.ident.name)
},
(&ExprKind::Match(le, la, ref ls), &ExprKind::Match(re, ra, ref rs)) => {
ls == rs
&& self.eq_expr(le, re)
&& over(la, ra, |l, r| {
self.eq_pat(l.pat, r.pat)
&& both(&l.guard, &r.guard, |l, r| self.eq_guard(l, r))
&& self.eq_expr(l.body, r.body)
})
},
(
&ExprKind::MethodCall(l_path, l_receiver, l_args, _),
&ExprKind::MethodCall(r_path, r_receiver, r_args, _),
) => {
self.inner.allow_side_effects
&& self.eq_path_segment(l_path, r_path)
&& self.eq_expr(l_receiver, r_receiver)
&& self.eq_exprs(l_args, r_args)
},
(&ExprKind::Repeat(le, ll), &ExprKind::Repeat(re, rl)) => {
self.eq_expr(le, re) && self.eq_array_length(ll, rl)
},
(ExprKind::Ret(l), ExprKind::Ret(r)) => both(l, r, |l, r| self.eq_expr(l, r)),
(ExprKind::Path(l), ExprKind::Path(r)) => self.eq_qpath(l, r),
(&ExprKind::Struct(l_path, lf, ref lo), &ExprKind::Struct(r_path, rf, ref ro)) => {
self.eq_qpath(l_path, r_path)
&& both(lo, ro, |l, r| self.eq_expr(l, r))
&& over(lf, rf, |l, r| self.eq_expr_field(l, r))
},
(&ExprKind::Tup(l_tup), &ExprKind::Tup(r_tup)) => self.eq_exprs(l_tup, r_tup),
(&ExprKind::Unary(l_op, le), &ExprKind::Unary(r_op, re)) => l_op == r_op && self.eq_expr(le, re),
(&ExprKind::Array(l), &ExprKind::Array(r)) => self.eq_exprs(l, r),
(&ExprKind::DropTemps(le), &ExprKind::DropTemps(re)) => self.eq_expr(le, re),
(&ExprKind::OffsetOf(l_container, l_fields), &ExprKind::OffsetOf(r_container, r_fields)) => {
self.eq_ty(l_container, r_container) && over(l_fields, r_fields, |l, r| l.name == r.name)
},
_ => false,
};
(is_eq && (!self.should_ignore(left) || !self.should_ignore(right)))
|| self.inner.expr_fallback.as_mut().map_or(false, |f| f(left, right))
}
fn eq_exprs(&mut self, left: &[Expr<'_>], right: &[Expr<'_>]) -> bool {
over(left, right, |l, r| self.eq_expr(l, r))
}
fn eq_expr_field(&mut self, left: &ExprField<'_>, right: &ExprField<'_>) -> bool {
left.ident.name == right.ident.name && self.eq_expr(left.expr, right.expr)
}
fn eq_guard(&mut self, left: &Guard<'_>, right: &Guard<'_>) -> bool {
match (left, right) {
(Guard::If(l), Guard::If(r)) => self.eq_expr(l, r),
(Guard::IfLet(l), Guard::IfLet(r)) => {
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)
},
_ => false,
}
}
fn eq_generic_arg(&mut self, left: &GenericArg<'_>, right: &GenericArg<'_>) -> bool {
match (left, right) {
(GenericArg::Const(l), GenericArg::Const(r)) => self.eq_body(l.value.body, r.value.body),
(GenericArg::Lifetime(l_lt), GenericArg::Lifetime(r_lt)) => Self::eq_lifetime(l_lt, r_lt),
(GenericArg::Type(l_ty), GenericArg::Type(r_ty)) => self.eq_ty(l_ty, r_ty),
(GenericArg::Infer(l_inf), GenericArg::Infer(r_inf)) => self.eq_ty(&l_inf.to_ty(), &r_inf.to_ty()),
_ => false,
}
}
fn eq_lifetime(left: &Lifetime, right: &Lifetime) -> bool {
left.res == right.res
}
fn eq_pat_field(&mut self, left: &PatField<'_>, right: &PatField<'_>) -> bool {
let (PatField { ident: li, pat: lp, .. }, PatField { ident: ri, pat: rp, .. }) = (&left, &right);
li.name == ri.name && self.eq_pat(lp, rp)
}
/// Checks whether two patterns are the same.
fn eq_pat(&mut self, left: &Pat<'_>, right: &Pat<'_>) -> bool {
match (&left.kind, &right.kind) {
(&PatKind::Box(l), &PatKind::Box(r)) => self.eq_pat(l, r),
(&PatKind::Struct(ref lp, la, ..), &PatKind::Struct(ref rp, ra, ..)) => {
self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat_field(l, r))
},
(&PatKind::TupleStruct(ref lp, la, ls), &PatKind::TupleStruct(ref rp, ra, rs)) => {
self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat(l, r)) && ls == rs
},
(&PatKind::Binding(lb, li, _, ref lp), &PatKind::Binding(rb, ri, _, ref rp)) => {
let eq = lb == rb && both(lp, rp, |l, r| self.eq_pat(l, r));
if eq {
self.locals.insert(li, ri);
}
eq
},
(PatKind::Path(l), PatKind::Path(r)) => self.eq_qpath(l, r),
(&PatKind::Lit(l), &PatKind::Lit(r)) => self.eq_expr(l, r),
(&PatKind::Tuple(l, ls), &PatKind::Tuple(r, rs)) => ls == rs && over(l, r, |l, r| self.eq_pat(l, r)),
(&PatKind::Range(ref ls, ref le, li), &PatKind::Range(ref rs, ref re, ri)) => {
both(ls, rs, |a, b| self.eq_expr(a, b)) && both(le, re, |a, b| self.eq_expr(a, b)) && (li == ri)
},
(&PatKind::Ref(le, ref lm), &PatKind::Ref(re, ref rm)) => lm == rm && self.eq_pat(le, re),
(&PatKind::Slice(ls, ref li, le), &PatKind::Slice(rs, ref ri, re)) => {
over(ls, rs, |l, r| self.eq_pat(l, r))
&& over(le, re, |l, r| self.eq_pat(l, r))
&& both(li, ri, |l, r| self.eq_pat(l, r))
},
(&PatKind::Wild, &PatKind::Wild) => true,
_ => false,
}
}
#[expect(clippy::similar_names)]
fn eq_qpath(&mut self, left: &QPath<'_>, right: &QPath<'_>) -> bool {
match (left, right) {
(&QPath::Resolved(ref lty, lpath), &QPath::Resolved(ref rty, rpath)) => {
both(lty, rty, |l, r| self.eq_ty(l, r)) && self.eq_path(lpath, rpath)
},
(&QPath::TypeRelative(lty, lseg), &QPath::TypeRelative(rty, rseg)) => {
self.eq_ty(lty, rty) && self.eq_path_segment(lseg, rseg)
},
(&QPath::LangItem(llang_item, ..), &QPath::LangItem(rlang_item, ..)) => llang_item == rlang_item,
_ => false,
}
}
pub fn eq_path(&mut self, left: &Path<'_>, right: &Path<'_>) -> bool {
match (left.res, right.res) {
(Res::Local(l), Res::Local(r)) => l == r || self.locals.get(&l) == Some(&r),
(Res::Local(_), _) | (_, Res::Local(_)) => false,
_ => over(left.segments, right.segments, |l, r| self.eq_path_segment(l, r)),
}
}
fn eq_path_parameters(&mut self, left: &GenericArgs<'_>, right: &GenericArgs<'_>) -> bool {
if left.parenthesized == right.parenthesized {
over(left.args, right.args, |l, r| self.eq_generic_arg(l, r)) // FIXME(flip1995): may not work
&& over(left.bindings, right.bindings, |l, r| self.eq_type_binding(l, r))
} else {
false
}
}
pub fn eq_path_segments(&mut self, left: &[PathSegment<'_>], right: &[PathSegment<'_>]) -> bool {
left.len() == right.len() && left.iter().zip(right).all(|(l, r)| self.eq_path_segment(l, r))
}
pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
// The == of idents doesn't work with different contexts,
// we have to be explicit about hygiene
left.ident.name == right.ident.name && both(&left.args, &right.args, |l, r| self.eq_path_parameters(l, r))
}
pub fn eq_ty(&mut self, left: &Ty<'_>, right: &Ty<'_>) -> bool {
match (&left.kind, &right.kind) {
(&TyKind::Slice(l_vec), &TyKind::Slice(r_vec)) => self.eq_ty(l_vec, r_vec),
(&TyKind::Array(lt, ll), &TyKind::Array(rt, rl)) => self.eq_ty(lt, rt) && self.eq_array_length(ll, rl),
(TyKind::Ptr(l_mut), TyKind::Ptr(r_mut)) => l_mut.mutbl == r_mut.mutbl && self.eq_ty(l_mut.ty, r_mut.ty),
(TyKind::Ref(_, l_rmut), TyKind::Ref(_, r_rmut)) => {
l_rmut.mutbl == r_rmut.mutbl && self.eq_ty(l_rmut.ty, r_rmut.ty)
},
(TyKind::Path(l), TyKind::Path(r)) => self.eq_qpath(l, r),
(&TyKind::Tup(l), &TyKind::Tup(r)) => over(l, r, |l, r| self.eq_ty(l, r)),
(&TyKind::Infer, &TyKind::Infer) => true,
_ => false,
}
}
fn eq_type_binding(&mut self, left: &TypeBinding<'_>, right: &TypeBinding<'_>) -> bool {
left.ident.name == right.ident.name && self.eq_ty(left.ty(), right.ty())
}
fn check_ctxt(&mut self, left: SyntaxContext, right: SyntaxContext) -> bool {
if self.left_ctxt == left && self.right_ctxt == right {
return true;
} else if self.left_ctxt == left || self.right_ctxt == right {
// Only one context has changed. This can only happen if the two nodes are written differently.
return false;
} else if left != SyntaxContext::root() {
let mut left_data = left.outer_expn_data();
let mut right_data = right.outer_expn_data();
loop {
use TokenKind::{BlockComment, LineComment, Whitespace};
if left_data.macro_def_id != right_data.macro_def_id
|| (matches!(left_data.kind, ExpnKind::Macro(MacroKind::Bang, name) if name == sym::cfg)
&& !eq_span_tokens(self.inner.cx, left_data.call_site, right_data.call_site, |t| {
!matches!(t, Whitespace | LineComment { .. } | BlockComment { .. })
}))
{
// Either a different chain of macro calls, or different arguments to the `cfg` macro.
return false;
}
let left_ctxt = left_data.call_site.ctxt();
let right_ctxt = right_data.call_site.ctxt();
if left_ctxt == SyntaxContext::root() && right_ctxt == SyntaxContext::root() {
break;
}
if left_ctxt == SyntaxContext::root() || right_ctxt == SyntaxContext::root() {
// Different lengths for the expansion stack. This can only happen if nodes are written differently,
// or shouldn't be compared to start with.
return false;
}
left_data = left_ctxt.outer_expn_data();
right_data = right_ctxt.outer_expn_data();
}
}
self.left_ctxt = left;
self.right_ctxt = right;
true
}
}
/// Some simple reductions like `{ return }` => `return`
fn reduce_exprkind<'hir>(cx: &LateContext<'_>, kind: &'hir ExprKind<'hir>) -> &'hir ExprKind<'hir> {
if let ExprKind::Block(block, _) = kind {
match (block.stmts, block.expr) {
// From an `if let` expression without an `else` block. The arm for the implicit wild pattern is an empty
// block with an empty span.
([], None) if block.span.is_empty() => &ExprKind::Tup(&[]),
// `{}` => `()`
([], None) => match snippet_opt(cx, block.span) {
// Don't reduce if there are any tokens contained in the braces
Some(snip)
if tokenize(&snip)
.map(|t| t.kind)
.filter(|t| {
!matches!(
t,
TokenKind::LineComment { .. } | TokenKind::BlockComment { .. } | TokenKind::Whitespace
)
})
.ne([TokenKind::OpenBrace, TokenKind::CloseBrace].iter().copied()) =>
{
kind
},
_ => &ExprKind::Tup(&[]),
},
([], Some(expr)) => match expr.kind {
// `{ return .. }` => `return ..`
ExprKind::Ret(..) => &expr.kind,
_ => kind,
},
([stmt], None) => match stmt.kind {
StmtKind::Expr(expr) | StmtKind::Semi(expr) => match expr.kind {
// `{ return ..; }` => `return ..`
ExprKind::Ret(..) => &expr.kind,
_ => kind,
},
_ => kind,
},
_ => kind,
}
} else {
kind
}
}
fn swap_binop<'a>(
binop: BinOpKind,
lhs: &'a Expr<'a>,
rhs: &'a Expr<'a>,
) -> Option<(BinOpKind, &'a Expr<'a>, &'a Expr<'a>)> {
match binop {
BinOpKind::Add | BinOpKind::Eq | BinOpKind::Ne | BinOpKind::BitAnd | BinOpKind::BitXor | BinOpKind::BitOr => {
Some((binop, rhs, lhs))
},
BinOpKind::Lt => Some((BinOpKind::Gt, rhs, lhs)),
BinOpKind::Le => Some((BinOpKind::Ge, rhs, lhs)),
BinOpKind::Ge => Some((BinOpKind::Le, rhs, lhs)),
BinOpKind::Gt => Some((BinOpKind::Lt, rhs, lhs)),
BinOpKind::Mul // Not always commutative, e.g. with matrices. See issue #5698
| BinOpKind::Shl
| BinOpKind::Shr
| BinOpKind::Rem
| BinOpKind::Sub
| BinOpKind::Div
| BinOpKind::And
| BinOpKind::Or => None,
}
}
/// Checks if the two `Option`s are both `None` or some equal values as per
/// `eq_fn`.
pub fn both<X>(l: &Option<X>, r: &Option<X>, mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
l.as_ref()
.map_or_else(|| r.is_none(), |x| r.as_ref().map_or(false, |y| eq_fn(x, y)))
}
/// Checks if two slices are equal as per `eq_fn`.
pub fn over<X>(left: &[X], right: &[X], mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
left.len() == right.len() && left.iter().zip(right).all(|(x, y)| eq_fn(x, y))
}
/// Counts how many elements of the slices are equal as per `eq_fn`.
pub fn count_eq<X: Sized>(
left: &mut dyn Iterator<Item = X>,
right: &mut dyn Iterator<Item = X>,
mut eq_fn: impl FnMut(&X, &X) -> bool,
) -> usize {
left.zip(right).take_while(|(l, r)| eq_fn(l, r)).count()
}
/// Checks if two expressions evaluate to the same value, and don't contain any side effects.
pub fn eq_expr_value(cx: &LateContext<'_>, left: &Expr<'_>, right: &Expr<'_>) -> bool {
SpanlessEq::new(cx).deny_side_effects().eq_expr(left, right)
}
/// Type used to hash an ast element. This is different from the `Hash` trait
/// on ast types as this
/// trait would consider IDs and spans.
///
/// All expressions kind are hashed, but some might have a weaker hash.
pub struct SpanlessHash<'a, 'tcx> {
/// Context used to evaluate constant expressions.
cx: &'a LateContext<'tcx>,
maybe_typeck_results: Option<&'tcx TypeckResults<'tcx>>,
s: FxHasher,
}
impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
pub fn new(cx: &'a LateContext<'tcx>) -> Self {
Self {
cx,
maybe_typeck_results: cx.maybe_typeck_results(),
s: FxHasher::default(),
}
}
pub fn finish(self) -> u64 {
self.s.finish()
}
pub fn hash_block(&mut self, b: &Block<'_>) {
for s in b.stmts {
self.hash_stmt(s);
}
if let Some(e) = b.expr {
self.hash_expr(e);
}
std::mem::discriminant(&b.rules).hash(&mut self.s);
}
#[expect(clippy::too_many_lines)]
pub fn hash_expr(&mut self, e: &Expr<'_>) {
let simple_const = self
.maybe_typeck_results
.and_then(|typeck_results| constant_simple(self.cx, typeck_results, e));
// const hashing may result in the same hash as some unrelated node, so add a sort of
// discriminant depending on which path we're choosing next
simple_const.hash(&mut self.s);
if simple_const.is_some() {
return;
}
std::mem::discriminant(&e.kind).hash(&mut self.s);
match e.kind {
ExprKind::AddrOf(kind, m, e) => {
std::mem::discriminant(&kind).hash(&mut self.s);
m.hash(&mut self.s);
self.hash_expr(e);
},
ExprKind::Continue(i) => {
if let Some(i) = i.label {
self.hash_name(i.ident.name);
}
},
ExprKind::Assign(l, r, _) => {
self.hash_expr(l);
self.hash_expr(r);
},
ExprKind::AssignOp(ref o, l, r) => {
std::mem::discriminant(&o.node).hash(&mut self.s);
self.hash_expr(l);
self.hash_expr(r);
},
ExprKind::Block(b, _) => {
self.hash_block(b);
},
ExprKind::Binary(op, l, r) => {
std::mem::discriminant(&op.node).hash(&mut self.s);
self.hash_expr(l);
self.hash_expr(r);
},
ExprKind::Break(i, ref j) => {
if let Some(i) = i.label {
self.hash_name(i.ident.name);
}
if let Some(j) = *j {
self.hash_expr(j);
}
},
ExprKind::DropTemps(e) | ExprKind::Yield(e, _) => {
self.hash_expr(e);
},
ExprKind::Call(fun, args) => {
self.hash_expr(fun);
self.hash_exprs(args);
},
ExprKind::Cast(e, ty) | ExprKind::Type(e, ty) => {
self.hash_expr(e);
self.hash_ty(ty);
},
ExprKind::Closure(&Closure {
capture_clause, body, ..
}) => {
std::mem::discriminant(&capture_clause).hash(&mut self.s);
// closures inherit TypeckResults
self.hash_expr(self.cx.tcx.hir().body(body).value);
},
ExprKind::Field(e, ref f) => {
self.hash_expr(e);
self.hash_name(f.name);
},
ExprKind::Index(a, i) => {
self.hash_expr(a);
self.hash_expr(i);
},
ExprKind::InlineAsm(asm) => {
for piece in asm.template {
match piece {
InlineAsmTemplatePiece::String(s) => s.hash(&mut self.s),
InlineAsmTemplatePiece::Placeholder {
operand_idx,
modifier,
span: _,
} => {
operand_idx.hash(&mut self.s);
modifier.hash(&mut self.s);
},
}
}
asm.options.hash(&mut self.s);
for (op, _op_sp) in asm.operands {
match op {
InlineAsmOperand::In { reg, expr } => {
reg.hash(&mut self.s);
self.hash_expr(expr);
},
InlineAsmOperand::Out { reg, late, expr } => {
reg.hash(&mut self.s);
late.hash(&mut self.s);
if let Some(expr) = expr {
self.hash_expr(expr);
}
},
InlineAsmOperand::InOut { reg, late, expr } => {
reg.hash(&mut self.s);
late.hash(&mut self.s);
self.hash_expr(expr);
},
InlineAsmOperand::SplitInOut {
reg,
late,
in_expr,
out_expr,
} => {
reg.hash(&mut self.s);
late.hash(&mut self.s);
self.hash_expr(in_expr);
if let Some(out_expr) = out_expr {
self.hash_expr(out_expr);
}
},
InlineAsmOperand::Const { anon_const } | InlineAsmOperand::SymFn { anon_const } => {
self.hash_body(anon_const.body);
},
InlineAsmOperand::SymStatic { path, def_id: _ } => self.hash_qpath(path),
}
}
},
ExprKind::OffsetOf(container, fields) => {
self.hash_ty(container);
for field in fields {
self.hash_name(field.name);
}
},
ExprKind::Let(Let { pat, init, ty, .. }) => {
self.hash_expr(init);
if let Some(ty) = ty {
self.hash_ty(ty);
}
self.hash_pat(pat);
},
ExprKind::Err(_) => {},
ExprKind::Lit(l) => {
l.node.hash(&mut self.s);
},
ExprKind::Loop(b, ref i, ..) => {
self.hash_block(b);
if let Some(i) = *i {
self.hash_name(i.ident.name);
}
},
ExprKind::If(cond, then, ref else_opt) => {
self.hash_expr(cond);
self.hash_expr(then);
if let Some(e) = *else_opt {
self.hash_expr(e);
}
},
ExprKind::Match(e, arms, ref s) => {
self.hash_expr(e);
for arm in arms {
self.hash_pat(arm.pat);
if let Some(ref e) = arm.guard {
self.hash_guard(e);
}
self.hash_expr(arm.body);
}
s.hash(&mut self.s);
},
ExprKind::MethodCall(path, receiver, args, ref _fn_span) => {
self.hash_name(path.ident.name);
self.hash_expr(receiver);
self.hash_exprs(args);
},
ExprKind::ConstBlock(ref l_id) => {
self.hash_body(l_id.body);
},
ExprKind::Repeat(e, len) => {
self.hash_expr(e);
self.hash_array_length(len);
},
ExprKind::Ret(ref e) => {
if let Some(e) = *e {
self.hash_expr(e);
}
},
ExprKind::Path(ref qpath) => {
self.hash_qpath(qpath);
},
ExprKind::Struct(path, fields, ref expr) => {
self.hash_qpath(path);
for f in fields {
self.hash_name(f.ident.name);
self.hash_expr(f.expr);
}
if let Some(e) = *expr {
self.hash_expr(e);
}
},
ExprKind::Tup(tup) => {
self.hash_exprs(tup);
},
ExprKind::Array(v) => {
self.hash_exprs(v);
},
ExprKind::Unary(lop, le) => {
std::mem::discriminant(&lop).hash(&mut self.s);
self.hash_expr(le);
},
}
}
pub fn hash_exprs(&mut self, e: &[Expr<'_>]) {
for e in e {
self.hash_expr(e);
}
}
pub fn hash_name(&mut self, n: Symbol) {
n.hash(&mut self.s);
}
pub fn hash_qpath(&mut self, p: &QPath<'_>) {
match *p {
QPath::Resolved(_, path) => {
self.hash_path(path);
},
QPath::TypeRelative(_, path) => {
self.hash_name(path.ident.name);
},
QPath::LangItem(lang_item, ..) => {
std::mem::discriminant(&lang_item).hash(&mut self.s);
},
}
// self.maybe_typeck_results.unwrap().qpath_res(p, id).hash(&mut self.s);
}
pub fn hash_pat(&mut self, pat: &Pat<'_>) {
std::mem::discriminant(&pat.kind).hash(&mut self.s);
match pat.kind {
PatKind::Binding(BindingAnnotation(by_ref, mutability), _, _, pat) => {
std::mem::discriminant(&by_ref).hash(&mut self.s);
std::mem::discriminant(&mutability).hash(&mut self.s);
if let Some(pat) = pat {
self.hash_pat(pat);
}
},
PatKind::Box(pat) => self.hash_pat(pat),
PatKind::Lit(expr) => self.hash_expr(expr),
PatKind::Or(pats) => {
for pat in pats {
self.hash_pat(pat);
}
},
PatKind::Path(ref qpath) => self.hash_qpath(qpath),
PatKind::Range(s, e, i) => {
if let Some(s) = s {
self.hash_expr(s);
}
if let Some(e) = e {
self.hash_expr(e);
}
std::mem::discriminant(&i).hash(&mut self.s);
},
PatKind::Ref(pat, mu) => {
self.hash_pat(pat);
std::mem::discriminant(&mu).hash(&mut self.s);
},
PatKind::Slice(l, m, r) => {
for pat in l {
self.hash_pat(pat);
}
if let Some(pat) = m {
self.hash_pat(pat);
}
for pat in r {
self.hash_pat(pat);
}
},
PatKind::Struct(ref qpath, fields, e) => {
self.hash_qpath(qpath);
for f in fields {
self.hash_name(f.ident.name);
self.hash_pat(f.pat);
}
e.hash(&mut self.s);
},
PatKind::Tuple(pats, e) => {
for pat in pats {
self.hash_pat(pat);
}
e.hash(&mut self.s);
},
PatKind::TupleStruct(ref qpath, pats, e) => {
self.hash_qpath(qpath);
for pat in pats {
self.hash_pat(pat);
}
e.hash(&mut self.s);
},
PatKind::Wild => {},
}
}
pub fn hash_path(&mut self, path: &Path<'_>) {
match path.res {
// constant hash since equality is dependant on inter-expression context
// e.g. The expressions `if let Some(x) = foo() {}` and `if let Some(y) = foo() {}` are considered equal
// even though the binding names are different and they have different `HirId`s.
Res::Local(_) => 1_usize.hash(&mut self.s),
_ => {
for seg in path.segments {
self.hash_name(seg.ident.name);
self.hash_generic_args(seg.args().args);
}
},
}
}
pub fn hash_stmt(&mut self, b: &Stmt<'_>) {
std::mem::discriminant(&b.kind).hash(&mut self.s);
match &b.kind {
StmtKind::Local(local) => {
self.hash_pat(local.pat);
if let Some(init) = local.init {
self.hash_expr(init);
}
if let Some(els) = local.els {
self.hash_block(els);
}
},
StmtKind::Item(..) => {},
StmtKind::Expr(expr) | StmtKind::Semi(expr) => {
self.hash_expr(expr);
},
}
}
pub fn hash_guard(&mut self, g: &Guard<'_>) {
match g {
Guard::If(expr) | Guard::IfLet(Let { init: expr, .. }) => {
self.hash_expr(expr);
},
}
}
pub fn hash_lifetime(&mut self, lifetime: &Lifetime) {
lifetime.ident.name.hash(&mut self.s);
std::mem::discriminant(&lifetime.res).hash(&mut self.s);
if let LifetimeName::Param(param_id) = lifetime.res {
param_id.hash(&mut self.s);
}
}
pub fn hash_ty(&mut self, ty: &Ty<'_>) {
std::mem::discriminant(&ty.kind).hash(&mut self.s);
self.hash_tykind(&ty.kind);
}
pub fn hash_tykind(&mut self, ty: &TyKind<'_>) {
match ty {
TyKind::Slice(ty) => {
self.hash_ty(ty);
},
&TyKind::Array(ty, len) => {
self.hash_ty(ty);
self.hash_array_length(len);
},
TyKind::Ptr(ref mut_ty) => {
self.hash_ty(mut_ty.ty);
mut_ty.mutbl.hash(&mut self.s);
},
TyKind::Ref(lifetime, ref mut_ty) => {
self.hash_lifetime(lifetime);
self.hash_ty(mut_ty.ty);
mut_ty.mutbl.hash(&mut self.s);
},
TyKind::BareFn(bfn) => {
bfn.unsafety.hash(&mut self.s);
bfn.abi.hash(&mut self.s);
for arg in bfn.decl.inputs {
self.hash_ty(arg);
}
std::mem::discriminant(&bfn.decl.output).hash(&mut self.s);
match bfn.decl.output {
FnRetTy::DefaultReturn(_) => {},
FnRetTy::Return(ty) => {
self.hash_ty(ty);
},
}
bfn.decl.c_variadic.hash(&mut self.s);
},
TyKind::Tup(ty_list) => {
for ty in *ty_list {
self.hash_ty(ty);
}
},
TyKind::Path(ref qpath) => self.hash_qpath(qpath),
TyKind::OpaqueDef(_, arg_list, in_trait) => {
self.hash_generic_args(arg_list);
in_trait.hash(&mut self.s);
},
TyKind::TraitObject(_, lifetime, _) => {
self.hash_lifetime(lifetime);
},
TyKind::Typeof(anon_const) => {
self.hash_body(anon_const.body);
},
TyKind::Err(_) | TyKind::Infer | TyKind::Never => {},
}
}
pub fn hash_array_length(&mut self, length: ArrayLen) {
match length {
ArrayLen::Infer(..) => {},
ArrayLen::Body(anon_const) => self.hash_body(anon_const.body),
}
}
pub fn hash_body(&mut self, body_id: BodyId) {
// swap out TypeckResults when hashing a body
let old_maybe_typeck_results = self.maybe_typeck_results.replace(self.cx.tcx.typeck_body(body_id));
self.hash_expr(self.cx.tcx.hir().body(body_id).value);
self.maybe_typeck_results = old_maybe_typeck_results;
}
fn hash_generic_args(&mut self, arg_list: &[GenericArg<'_>]) {
for arg in arg_list {
match *arg {
GenericArg::Lifetime(l) => self.hash_lifetime(l),
GenericArg::Type(ty) => self.hash_ty(ty),
GenericArg::Const(ref ca) => self.hash_body(ca.value.body),
GenericArg::Infer(ref inf) => self.hash_ty(&inf.to_ty()),
}
}
}
}
pub fn hash_stmt(cx: &LateContext<'_>, s: &Stmt<'_>) -> u64 {
let mut h = SpanlessHash::new(cx);
h.hash_stmt(s);
h.finish()
}
pub fn is_bool(ty: &Ty<'_>) -> bool {
if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
matches!(path.res, Res::PrimTy(PrimTy::Bool))
} else {
false
}
}
pub fn hash_expr(cx: &LateContext<'_>, e: &Expr<'_>) -> u64 {
let mut h = SpanlessHash::new(cx);
h.hash_expr(e);
h.finish()
}
#[expect(clippy::similar_names)]
fn eq_span_tokens(
cx: &LateContext<'_>,
left: impl SpanRange,
right: impl SpanRange,
pred: impl Fn(TokenKind) -> bool,
) -> bool {
fn f(cx: &LateContext<'_>, left: Range<BytePos>, right: Range<BytePos>, pred: impl Fn(TokenKind) -> bool) -> bool {
if let Some(lsrc) = get_source_text(cx, left)
&& let Some(lsrc) = lsrc.as_str()
&& let Some(rsrc) = get_source_text(cx, right)
&& let Some(rsrc) = rsrc.as_str()
{
let pred = |t: &(_, _)| pred(t.0);
let map = |(_, x)| x;
let ltok = tokenize_with_text(lsrc)
.filter(pred)
.map(map);
let rtok = tokenize_with_text(rsrc)
.filter(pred)
.map(map);
ltok.eq(rtok)
} else {
// Unable to access the source. Conservatively assume the blocks aren't equal.
false
}
}
f(cx, left.into_range(), right.into_range(), pred)
}
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