1#![allow(clippy::float_cmp)]
6
7use crate::source::{SpanRangeExt, walk_span_to_context};
8use crate::{clip, is_direct_expn_of, sext, unsext};
9
10use rustc_abi::Size;
11use rustc_apfloat::Float;
12use rustc_apfloat::ieee::{Half, Quad};
13use rustc_ast::ast::{self, LitFloatType, LitKind};
14use rustc_hir::def::{DefKind, Res};
15use rustc_hir::{
16 BinOpKind, Block, ConstBlock, Expr, ExprKind, HirId, Item, ItemKind, Node, PatExpr, PatExprKind, QPath, UnOp,
17};
18use rustc_lexer::tokenize;
19use rustc_lint::LateContext;
20use rustc_middle::mir::ConstValue;
21use rustc_middle::mir::interpret::{Scalar, alloc_range};
22use rustc_middle::ty::{self, FloatTy, IntTy, ScalarInt, Ty, TyCtxt, TypeckResults, UintTy};
23use rustc_middle::{bug, mir, span_bug};
24use rustc_span::def_id::DefId;
25use rustc_span::symbol::Ident;
26use rustc_span::{SyntaxContext, sym};
27use std::cell::Cell;
28use std::cmp::Ordering;
29use std::hash::{Hash, Hasher};
30use std::iter;
31
32#[derive(Debug, Clone)]
34pub enum Constant<'tcx> {
35 Adt(mir::Const<'tcx>),
36 Str(String),
38 Binary(Vec<u8>),
40 Char(char),
42 Int(u128),
44 F16(u16),
47 F32(f32),
49 F64(f64),
51 F128(u128),
54 Bool(bool),
56 Vec(Vec<Constant<'tcx>>),
58 Repeat(Box<Constant<'tcx>>, u64),
60 Tuple(Vec<Constant<'tcx>>),
62 RawPtr(u128),
64 Ref(Box<Constant<'tcx>>),
66 Err,
68}
69
70trait IntTypeBounds: Sized {
71 type Output: PartialOrd;
72
73 fn min_max(self) -> Option<(Self::Output, Self::Output)>;
74 fn bits(self) -> Self::Output;
75 fn ensure_fits(self, val: Self::Output) -> Option<Self::Output> {
76 let (min, max) = self.min_max()?;
77 (min <= val && val <= max).then_some(val)
78 }
79}
80impl IntTypeBounds for UintTy {
81 type Output = u128;
82 fn min_max(self) -> Option<(Self::Output, Self::Output)> {
83 Some(match self {
84 UintTy::U8 => (u8::MIN.into(), u8::MAX.into()),
85 UintTy::U16 => (u16::MIN.into(), u16::MAX.into()),
86 UintTy::U32 => (u32::MIN.into(), u32::MAX.into()),
87 UintTy::U64 => (u64::MIN.into(), u64::MAX.into()),
88 UintTy::U128 => (u128::MIN, u128::MAX),
89 UintTy::Usize => (usize::MIN.try_into().ok()?, usize::MAX.try_into().ok()?),
90 })
91 }
92 fn bits(self) -> Self::Output {
93 match self {
94 UintTy::U8 => 8,
95 UintTy::U16 => 16,
96 UintTy::U32 => 32,
97 UintTy::U64 => 64,
98 UintTy::U128 => 128,
99 UintTy::Usize => usize::BITS.into(),
100 }
101 }
102}
103impl IntTypeBounds for IntTy {
104 type Output = i128;
105 fn min_max(self) -> Option<(Self::Output, Self::Output)> {
106 Some(match self {
107 IntTy::I8 => (i8::MIN.into(), i8::MAX.into()),
108 IntTy::I16 => (i16::MIN.into(), i16::MAX.into()),
109 IntTy::I32 => (i32::MIN.into(), i32::MAX.into()),
110 IntTy::I64 => (i64::MIN.into(), i64::MAX.into()),
111 IntTy::I128 => (i128::MIN, i128::MAX),
112 IntTy::Isize => (isize::MIN.try_into().ok()?, isize::MAX.try_into().ok()?),
113 })
114 }
115 fn bits(self) -> Self::Output {
116 match self {
117 IntTy::I8 => 8,
118 IntTy::I16 => 16,
119 IntTy::I32 => 32,
120 IntTy::I64 => 64,
121 IntTy::I128 => 128,
122 IntTy::Isize => isize::BITS.into(),
123 }
124 }
125}
126
127impl PartialEq for Constant<'_> {
128 fn eq(&self, other: &Self) -> bool {
129 match (self, other) {
130 (Self::Str(ls), Self::Str(rs)) => ls == rs,
131 (Self::Binary(l), Self::Binary(r)) => l == r,
132 (&Self::Char(l), &Self::Char(r)) => l == r,
133 (&Self::Int(l), &Self::Int(r)) => l == r,
134 (&Self::F64(l), &Self::F64(r)) => {
135 l.to_bits() == r.to_bits()
139 },
140 (&Self::F32(l), &Self::F32(r)) => {
141 f64::from(l).to_bits() == f64::from(r).to_bits()
145 },
146 (&Self::Bool(l), &Self::Bool(r)) => l == r,
147 (&Self::Vec(ref l), &Self::Vec(ref r)) | (&Self::Tuple(ref l), &Self::Tuple(ref r)) => l == r,
148 (Self::Repeat(lv, ls), Self::Repeat(rv, rs)) => ls == rs && lv == rv,
149 (Self::Ref(lb), Self::Ref(rb)) => *lb == *rb,
150 _ => false,
152 }
153 }
154}
155
156impl Hash for Constant<'_> {
157 fn hash<H>(&self, state: &mut H)
158 where
159 H: Hasher,
160 {
161 std::mem::discriminant(self).hash(state);
162 match *self {
163 Self::Adt(ref elem) => {
164 elem.hash(state);
165 },
166 Self::Str(ref s) => {
167 s.hash(state);
168 },
169 Self::Binary(ref b) => {
170 b.hash(state);
171 },
172 Self::Char(c) => {
173 c.hash(state);
174 },
175 Self::Int(i) => {
176 i.hash(state);
177 },
178 Self::F16(f) => {
179 f.hash(state);
181 },
182 Self::F32(f) => {
183 f64::from(f).to_bits().hash(state);
184 },
185 Self::F64(f) => {
186 f.to_bits().hash(state);
187 },
188 Self::F128(f) => {
189 f.hash(state);
190 },
191 Self::Bool(b) => {
192 b.hash(state);
193 },
194 Self::Vec(ref v) | Self::Tuple(ref v) => {
195 v.hash(state);
196 },
197 Self::Repeat(ref c, l) => {
198 c.hash(state);
199 l.hash(state);
200 },
201 Self::RawPtr(u) => {
202 u.hash(state);
203 },
204 Self::Ref(ref r) => {
205 r.hash(state);
206 },
207 Self::Err => {},
208 }
209 }
210}
211
212impl Constant<'_> {
213 pub fn partial_cmp(tcx: TyCtxt<'_>, cmp_type: Ty<'_>, left: &Self, right: &Self) -> Option<Ordering> {
214 match (left, right) {
215 (Self::Str(ls), Self::Str(rs)) => Some(ls.cmp(rs)),
216 (Self::Char(l), Self::Char(r)) => Some(l.cmp(r)),
217 (&Self::Int(l), &Self::Int(r)) => match *cmp_type.kind() {
218 ty::Int(int_ty) => Some(sext(tcx, l, int_ty).cmp(&sext(tcx, r, int_ty))),
219 ty::Uint(_) => Some(l.cmp(&r)),
220 _ => bug!("Not an int type"),
221 },
222 (&Self::F64(l), &Self::F64(r)) => l.partial_cmp(&r),
223 (&Self::F32(l), &Self::F32(r)) => l.partial_cmp(&r),
224 (Self::Bool(l), Self::Bool(r)) => Some(l.cmp(r)),
225 (Self::Tuple(l), Self::Tuple(r)) if l.len() == r.len() => match *cmp_type.kind() {
226 ty::Tuple(tys) if tys.len() == l.len() => l
227 .iter()
228 .zip(r)
229 .zip(tys)
230 .map(|((li, ri), cmp_type)| Self::partial_cmp(tcx, cmp_type, li, ri))
231 .find(|r| r.is_none_or(|o| o != Ordering::Equal))
232 .unwrap_or_else(|| Some(l.len().cmp(&r.len()))),
233 _ => None,
234 },
235 (Self::Vec(l), Self::Vec(r)) => {
236 let cmp_type = cmp_type.builtin_index()?;
237 iter::zip(l, r)
238 .map(|(li, ri)| Self::partial_cmp(tcx, cmp_type, li, ri))
239 .find(|r| r.is_none_or(|o| o != Ordering::Equal))
240 .unwrap_or_else(|| Some(l.len().cmp(&r.len())))
241 },
242 (Self::Repeat(lv, ls), Self::Repeat(rv, rs)) => {
243 match Self::partial_cmp(
244 tcx,
245 match *cmp_type.kind() {
246 ty::Array(ty, _) => ty,
247 _ => return None,
248 },
249 lv,
250 rv,
251 ) {
252 Some(Ordering::Equal) => Some(ls.cmp(rs)),
253 x => x,
254 }
255 },
256 (Self::Ref(lb), Self::Ref(rb)) => Self::partial_cmp(
257 tcx,
258 match *cmp_type.kind() {
259 ty::Ref(_, ty, _) => ty,
260 _ => return None,
261 },
262 lb,
263 rb,
264 ),
265 _ => None,
267 }
268 }
269
270 pub fn int_value(&self, tcx: TyCtxt<'_>, val_type: Ty<'_>) -> Option<FullInt> {
272 if let Constant::Int(const_int) = *self {
273 match *val_type.kind() {
274 ty::Int(ity) => Some(FullInt::S(sext(tcx, const_int, ity))),
275 ty::Uint(_) => Some(FullInt::U(const_int)),
276 _ => None,
277 }
278 } else {
279 None
280 }
281 }
282
283 #[must_use]
284 pub fn peel_refs(mut self) -> Self {
285 while let Constant::Ref(r) = self {
286 self = *r;
287 }
288 self
289 }
290
291 fn parse_f16(s: &str) -> Self {
292 let f: Half = s.parse().unwrap();
293 Self::F16(f.to_bits().try_into().unwrap())
294 }
295
296 fn parse_f128(s: &str) -> Self {
297 let f: Quad = s.parse().unwrap();
298 Self::F128(f.to_bits())
299 }
300}
301
302pub fn lit_to_mir_constant<'tcx>(lit: &LitKind, ty: Option<Ty<'tcx>>) -> Constant<'tcx> {
304 match *lit {
305 LitKind::Str(ref is, _) => Constant::Str(is.to_string()),
306 LitKind::Byte(b) => Constant::Int(u128::from(b)),
307 LitKind::ByteStr(ref s, _) | LitKind::CStr(ref s, _) => {
308 Constant::Binary(s.as_byte_str().to_vec())
309 }
310 LitKind::Char(c) => Constant::Char(c),
311 LitKind::Int(n, _) => Constant::Int(n.get()),
312 LitKind::Float(ref is, LitFloatType::Suffixed(fty)) => match fty {
313 ast::FloatTy::F16 => Constant::parse_f16(is.as_str()),
315 ast::FloatTy::F32 => Constant::F32(is.as_str().parse().unwrap()),
316 ast::FloatTy::F64 => Constant::F64(is.as_str().parse().unwrap()),
317 ast::FloatTy::F128 => Constant::parse_f128(is.as_str()),
318 },
319 LitKind::Float(ref is, LitFloatType::Unsuffixed) => match ty.expect("type of float is known").kind() {
320 ty::Float(FloatTy::F16) => Constant::parse_f16(is.as_str()),
321 ty::Float(FloatTy::F32) => Constant::F32(is.as_str().parse().unwrap()),
322 ty::Float(FloatTy::F64) => Constant::F64(is.as_str().parse().unwrap()),
323 ty::Float(FloatTy::F128) => Constant::parse_f128(is.as_str()),
324 _ => bug!(),
325 },
326 LitKind::Bool(b) => Constant::Bool(b),
327 LitKind::Err(_) => Constant::Err,
328 }
329}
330
331#[derive(Clone, Copy)]
333pub enum ConstantSource {
334 Local,
336 Constant,
338 CoreConstant,
340}
341impl ConstantSource {
342 pub fn is_local(self) -> bool {
343 matches!(self, Self::Local)
344 }
345}
346
347#[derive(Copy, Clone, Debug, Eq)]
348pub enum FullInt {
349 S(i128),
350 U(u128),
351}
352
353impl PartialEq for FullInt {
354 fn eq(&self, other: &Self) -> bool {
355 self.cmp(other) == Ordering::Equal
356 }
357}
358
359impl PartialOrd for FullInt {
360 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
361 Some(self.cmp(other))
362 }
363}
364
365impl Ord for FullInt {
366 fn cmp(&self, other: &Self) -> Ordering {
367 use FullInt::{S, U};
368
369 fn cmp_s_u(s: i128, u: u128) -> Ordering {
370 u128::try_from(s).map_or(Ordering::Less, |x| x.cmp(&u))
371 }
372
373 match (*self, *other) {
374 (S(s), S(o)) => s.cmp(&o),
375 (U(s), U(o)) => s.cmp(&o),
376 (S(s), U(o)) => cmp_s_u(s, o),
377 (U(s), S(o)) => cmp_s_u(o, s).reverse(),
378 }
379 }
380}
381
382pub struct ConstEvalCtxt<'tcx> {
388 tcx: TyCtxt<'tcx>,
389 typing_env: ty::TypingEnv<'tcx>,
390 typeck: &'tcx TypeckResults<'tcx>,
391 source: Cell<ConstantSource>,
392}
393
394impl<'tcx> ConstEvalCtxt<'tcx> {
395 pub fn new(cx: &LateContext<'tcx>) -> Self {
398 Self {
399 tcx: cx.tcx,
400 typing_env: cx.typing_env(),
401 typeck: cx.typeck_results(),
402 source: Cell::new(ConstantSource::Local),
403 }
404 }
405
406 pub fn with_env(tcx: TyCtxt<'tcx>, typing_env: ty::TypingEnv<'tcx>, typeck: &'tcx TypeckResults<'tcx>) -> Self {
408 Self {
409 tcx,
410 typing_env,
411 typeck,
412 source: Cell::new(ConstantSource::Local),
413 }
414 }
415
416 pub fn eval_with_source(&self, e: &Expr<'_>) -> Option<(Constant<'tcx>, ConstantSource)> {
419 self.source.set(ConstantSource::Local);
420 self.expr(e).map(|c| (c, self.source.get()))
421 }
422
423 pub fn eval(&self, e: &Expr<'_>) -> Option<Constant<'tcx>> {
425 self.expr(e)
426 }
427
428 pub fn eval_simple(&self, e: &Expr<'_>) -> Option<Constant<'tcx>> {
430 match self.eval_with_source(e) {
431 Some((x, ConstantSource::Local)) => Some(x),
432 _ => None,
433 }
434 }
435
436 pub fn eval_full_int(&self, e: &Expr<'_>) -> Option<FullInt> {
438 match self.eval_with_source(e) {
439 Some((x, ConstantSource::Local)) => x.int_value(self.tcx, self.typeck.expr_ty(e)),
440 _ => None,
441 }
442 }
443
444 pub fn eval_pat_expr(&self, pat_expr: &PatExpr<'_>) -> Option<Constant<'tcx>> {
445 match &pat_expr.kind {
446 PatExprKind::Lit { lit, negated } => {
447 let ty = self.typeck.node_type_opt(pat_expr.hir_id);
448 let val = lit_to_mir_constant(&lit.node, ty);
449 if *negated {
450 self.constant_negate(&val, ty?)
451 } else {
452 Some(val)
453 }
454 },
455 PatExprKind::ConstBlock(ConstBlock { body, .. }) => self.expr(self.tcx.hir_body(*body).value),
456 PatExprKind::Path(qpath) => self.qpath(qpath, pat_expr.hir_id),
457 }
458 }
459
460 fn qpath(&self, qpath: &QPath<'_>, hir_id: HirId) -> Option<Constant<'tcx>> {
461 let is_core_crate = if let Some(def_id) = self.typeck.qpath_res(qpath, hir_id).opt_def_id() {
462 self.tcx.crate_name(def_id.krate) == sym::core
463 } else {
464 false
465 };
466 self.fetch_path_and_apply(qpath, hir_id, self.typeck.node_type(hir_id), |self_, result| {
467 let result = mir_to_const(self_.tcx, result)?;
468 self_.source.set(
470 if is_core_crate && !matches!(self_.source.get(), ConstantSource::Constant) {
471 ConstantSource::CoreConstant
472 } else {
473 ConstantSource::Constant
474 },
475 );
476 Some(result)
477 })
478 }
479
480 fn expr(&self, e: &Expr<'_>) -> Option<Constant<'tcx>> {
482 match e.kind {
483 ExprKind::ConstBlock(ConstBlock { body, .. }) => self.expr(self.tcx.hir_body(body).value),
484 ExprKind::DropTemps(e) => self.expr(e),
485 ExprKind::Path(ref qpath) => self.qpath(qpath, e.hir_id),
486 ExprKind::Block(block, _) => self.block(block),
487 ExprKind::Lit(lit) => {
488 if is_direct_expn_of(e.span, sym::cfg).is_some() {
489 None
490 } else {
491 Some(lit_to_mir_constant(&lit.node, self.typeck.expr_ty_opt(e)))
492 }
493 },
494 ExprKind::Array(vec) => self.multi(vec).map(Constant::Vec),
495 ExprKind::Tup(tup) => self.multi(tup).map(Constant::Tuple),
496 ExprKind::Repeat(value, _) => {
497 let n = match self.typeck.expr_ty(e).kind() {
498 ty::Array(_, n) => n.try_to_target_usize(self.tcx)?,
499 _ => span_bug!(e.span, "typeck error"),
500 };
501 self.expr(value).map(|v| Constant::Repeat(Box::new(v), n))
502 },
503 ExprKind::Unary(op, operand) => self.expr(operand).and_then(|o| match op {
504 UnOp::Not => self.constant_not(&o, self.typeck.expr_ty(e)),
505 UnOp::Neg => self.constant_negate(&o, self.typeck.expr_ty(e)),
506 UnOp::Deref => Some(if let Constant::Ref(r) = o { *r } else { o }),
507 }),
508 ExprKind::If(cond, then, ref otherwise) => self.ifthenelse(cond, then, *otherwise),
509 ExprKind::Binary(op, left, right) => self.binop(op.node, left, right),
510 ExprKind::Call(callee, []) => {
511 if let ExprKind::Path(qpath) = &callee.kind
513 && let Some(did) = self.typeck.qpath_res(qpath, callee.hir_id).opt_def_id()
514 {
515 match self.tcx.get_diagnostic_name(did) {
516 Some(sym::i8_legacy_fn_max_value) => Some(Constant::Int(i8::MAX as u128)),
517 Some(sym::i16_legacy_fn_max_value) => Some(Constant::Int(i16::MAX as u128)),
518 Some(sym::i32_legacy_fn_max_value) => Some(Constant::Int(i32::MAX as u128)),
519 Some(sym::i64_legacy_fn_max_value) => Some(Constant::Int(i64::MAX as u128)),
520 Some(sym::i128_legacy_fn_max_value) => Some(Constant::Int(i128::MAX as u128)),
521 _ => None,
522 }
523 } else {
524 None
525 }
526 },
527 ExprKind::Index(arr, index, _) => self.index(arr, index),
528 ExprKind::AddrOf(_, _, inner) => self.expr(inner).map(|r| Constant::Ref(Box::new(r))),
529 ExprKind::Field(local_expr, ref field) => {
530 let result = self.expr(local_expr);
531 if let Some(Constant::Adt(constant)) = &self.expr(local_expr)
532 && let ty::Adt(adt_def, _) = constant.ty().kind()
533 && adt_def.is_struct()
534 && let Some(desired_field) = field_of_struct(*adt_def, self.tcx, *constant, field)
535 {
536 mir_to_const(self.tcx, desired_field)
537 } else {
538 result
539 }
540 },
541 _ => None,
542 }
543 }
544
545 pub fn eval_is_empty(&self, e: &Expr<'_>) -> Option<bool> {
549 match e.kind {
550 ExprKind::ConstBlock(ConstBlock { body, .. }) => self.eval_is_empty(self.tcx.hir_body(body).value),
551 ExprKind::DropTemps(e) => self.eval_is_empty(e),
552 ExprKind::Path(ref qpath) => {
553 if !self
554 .typeck
555 .qpath_res(qpath, e.hir_id)
556 .opt_def_id()
557 .is_some_and(DefId::is_local)
558 {
559 return None;
560 }
561 self.fetch_path_and_apply(qpath, e.hir_id, self.typeck.expr_ty(e), |self_, result| {
562 mir_is_empty(self_.tcx, result)
563 })
564 },
565 ExprKind::Lit(lit) => {
566 if is_direct_expn_of(e.span, sym::cfg).is_some() {
567 None
568 } else {
569 match &lit.node {
570 LitKind::Str(is, _) => Some(is.is_empty()),
571 LitKind::ByteStr(s, _) | LitKind::CStr(s, _) => {
572 Some(s.as_byte_str().is_empty())
573 }
574 _ => None,
575 }
576 }
577 },
578 ExprKind::Array(vec) => self.multi(vec).map(|v| v.is_empty()),
579 ExprKind::Repeat(..) => {
580 if let ty::Array(_, n) = self.typeck.expr_ty(e).kind() {
581 Some(n.try_to_target_usize(self.tcx)? == 0)
582 } else {
583 span_bug!(e.span, "typeck error");
584 }
585 },
586 _ => None,
587 }
588 }
589
590 #[expect(clippy::cast_possible_wrap)]
591 fn constant_not(&self, o: &Constant<'tcx>, ty: Ty<'_>) -> Option<Constant<'tcx>> {
592 use self::Constant::{Bool, Int};
593 match *o {
594 Bool(b) => Some(Bool(!b)),
595 Int(value) => {
596 let value = !value;
597 match *ty.kind() {
598 ty::Int(ity) => Some(Int(unsext(self.tcx, value as i128, ity))),
599 ty::Uint(ity) => Some(Int(clip(self.tcx, value, ity))),
600 _ => None,
601 }
602 },
603 _ => None,
604 }
605 }
606
607 fn constant_negate(&self, o: &Constant<'tcx>, ty: Ty<'_>) -> Option<Constant<'tcx>> {
608 use self::Constant::{F32, F64, Int};
609 match *o {
610 Int(value) => {
611 let ty::Int(ity) = *ty.kind() else { return None };
612 let (min, _) = ity.min_max()?;
613 let value = sext(self.tcx, value, ity);
615
616 if value == min {
618 return None;
619 }
620
621 let value = value.checked_neg()?;
622 Some(Int(unsext(self.tcx, value, ity)))
624 },
625 F32(f) => Some(F32(-f)),
626 F64(f) => Some(F64(-f)),
627 _ => None,
628 }
629 }
630
631 fn multi(&self, vec: &[Expr<'_>]) -> Option<Vec<Constant<'tcx>>> {
634 vec.iter().map(|elem| self.expr(elem)).collect::<Option<_>>()
635 }
636
637 fn fetch_path_and_apply<T, F>(&self, qpath: &QPath<'_>, id: HirId, ty: Ty<'tcx>, f: F) -> Option<T>
639 where
640 F: FnOnce(&Self, mir::Const<'tcx>) -> Option<T>,
641 {
642 let res = self.typeck.qpath_res(qpath, id);
643 match res {
644 Res::Def(DefKind::Const | DefKind::AssocConst, def_id) => {
645 if let Some(node) = self.tcx.hir_get_if_local(def_id)
648 && let Node::Item(Item {
649 kind: ItemKind::Const(.., body_id),
650 ..
651 }) = node
652 && let Node::Expr(Expr {
653 kind: ExprKind::Lit(_),
654 span,
655 ..
656 }) = self.tcx.hir_node(body_id.hir_id)
657 && is_direct_expn_of(*span, sym::cfg).is_some()
658 {
659 return None;
660 }
661
662 let args = self.typeck.node_args(id);
663 let result = self
664 .tcx
665 .const_eval_resolve(self.typing_env, mir::UnevaluatedConst::new(def_id, args), qpath.span())
666 .ok()
667 .map(|val| mir::Const::from_value(val, ty))?;
668 f(self, result)
669 },
670 _ => None,
671 }
672 }
673
674 fn index(&self, lhs: &'_ Expr<'_>, index: &'_ Expr<'_>) -> Option<Constant<'tcx>> {
675 let lhs = self.expr(lhs);
676 let index = self.expr(index);
677
678 match (lhs, index) {
679 (Some(Constant::Vec(vec)), Some(Constant::Int(index))) => match vec.get(index as usize) {
680 Some(Constant::F16(x)) => Some(Constant::F16(*x)),
681 Some(Constant::F32(x)) => Some(Constant::F32(*x)),
682 Some(Constant::F64(x)) => Some(Constant::F64(*x)),
683 Some(Constant::F128(x)) => Some(Constant::F128(*x)),
684 _ => None,
685 },
686 (Some(Constant::Vec(vec)), _) => {
687 if !vec.is_empty() && vec.iter().all(|x| *x == vec[0]) {
688 match vec.first() {
689 Some(Constant::F16(x)) => Some(Constant::F16(*x)),
690 Some(Constant::F32(x)) => Some(Constant::F32(*x)),
691 Some(Constant::F64(x)) => Some(Constant::F64(*x)),
692 Some(Constant::F128(x)) => Some(Constant::F128(*x)),
693 _ => None,
694 }
695 } else {
696 None
697 }
698 },
699 _ => None,
700 }
701 }
702
703 fn block(&self, block: &Block<'_>) -> Option<Constant<'tcx>> {
705 if block.stmts.is_empty()
706 && let Some(expr) = block.expr
707 {
708 let span = block.span.data();
710 if span.ctxt == SyntaxContext::root() {
711 if let Some(expr_span) = walk_span_to_context(expr.span, span.ctxt)
712 && let expr_lo = expr_span.lo()
713 && expr_lo >= span.lo
714 && let Some(src) = (span.lo..expr_lo).get_source_range(&self.tcx)
715 && let Some(src) = src.as_str()
716 {
717 use rustc_lexer::TokenKind::{BlockComment, LineComment, OpenBrace, Semi, Whitespace};
718 if !tokenize(src)
719 .map(|t| t.kind)
720 .filter(|t| !matches!(t, Whitespace | LineComment { .. } | BlockComment { .. } | Semi))
721 .eq([OpenBrace])
722 {
723 self.source.set(ConstantSource::Constant);
724 }
725 } else {
726 self.source.set(ConstantSource::Constant);
728 }
729 }
730
731 self.expr(expr)
732 } else {
733 None
734 }
735 }
736
737 fn ifthenelse(&self, cond: &Expr<'_>, then: &Expr<'_>, otherwise: Option<&Expr<'_>>) -> Option<Constant<'tcx>> {
738 if let Some(Constant::Bool(b)) = self.expr(cond) {
739 if b {
740 self.expr(then)
741 } else {
742 otherwise.as_ref().and_then(|expr| self.expr(expr))
743 }
744 } else {
745 None
746 }
747 }
748
749 fn binop(&self, op: BinOpKind, left: &Expr<'_>, right: &Expr<'_>) -> Option<Constant<'tcx>> {
750 let l = self.expr(left)?;
751 let r = self.expr(right);
752 match (l, r) {
753 (Constant::Int(l), Some(Constant::Int(r))) => match *self.typeck.expr_ty_opt(left)?.kind() {
754 ty::Int(ity) => {
755 let (ty_min_value, _) = ity.min_max()?;
756 let bits = ity.bits();
757 let l = sext(self.tcx, l, ity);
758 let r = sext(self.tcx, r, ity);
759
760 if let BinOpKind::Div | BinOpKind::Rem = op
763 && l == ty_min_value
764 && r == -1
765 {
766 return None;
767 }
768
769 let zext = |n: i128| Constant::Int(unsext(self.tcx, n, ity));
770 match op {
771 BinOpKind::Add => l.checked_add(r).and_then(|n| ity.ensure_fits(n)).map(zext),
774 BinOpKind::Sub => l.checked_sub(r).and_then(|n| ity.ensure_fits(n)).map(zext),
775 BinOpKind::Mul => l.checked_mul(r).and_then(|n| ity.ensure_fits(n)).map(zext),
776 BinOpKind::Div if r != 0 => l.checked_div(r).map(zext),
777 BinOpKind::Rem if r != 0 => l.checked_rem(r).map(zext),
778 BinOpKind::Shr if r < bits && !r.is_negative() => l.checked_shr(r.try_into().ok()?).map(zext),
781 BinOpKind::Shl if r < bits && !r.is_negative() => l.checked_shl(r.try_into().ok()?).map(zext),
782 BinOpKind::BitXor => Some(zext(l ^ r)),
783 BinOpKind::BitOr => Some(zext(l | r)),
784 BinOpKind::BitAnd => Some(zext(l & r)),
785 BinOpKind::Eq => Some(Constant::Bool(l == r)),
786 BinOpKind::Ne => Some(Constant::Bool(l != r)),
787 BinOpKind::Lt => Some(Constant::Bool(l < r)),
788 BinOpKind::Le => Some(Constant::Bool(l <= r)),
789 BinOpKind::Ge => Some(Constant::Bool(l >= r)),
790 BinOpKind::Gt => Some(Constant::Bool(l > r)),
791 _ => None,
792 }
793 },
794 ty::Uint(ity) => {
795 let bits = ity.bits();
796
797 match op {
798 BinOpKind::Add => l.checked_add(r).and_then(|n| ity.ensure_fits(n)).map(Constant::Int),
799 BinOpKind::Sub => l.checked_sub(r).and_then(|n| ity.ensure_fits(n)).map(Constant::Int),
800 BinOpKind::Mul => l.checked_mul(r).and_then(|n| ity.ensure_fits(n)).map(Constant::Int),
801 BinOpKind::Div => l.checked_div(r).map(Constant::Int),
802 BinOpKind::Rem => l.checked_rem(r).map(Constant::Int),
803 BinOpKind::Shr if r < bits => l.checked_shr(r.try_into().ok()?).map(Constant::Int),
804 BinOpKind::Shl if r < bits => l.checked_shl(r.try_into().ok()?).map(Constant::Int),
805 BinOpKind::BitXor => Some(Constant::Int(l ^ r)),
806 BinOpKind::BitOr => Some(Constant::Int(l | r)),
807 BinOpKind::BitAnd => Some(Constant::Int(l & r)),
808 BinOpKind::Eq => Some(Constant::Bool(l == r)),
809 BinOpKind::Ne => Some(Constant::Bool(l != r)),
810 BinOpKind::Lt => Some(Constant::Bool(l < r)),
811 BinOpKind::Le => Some(Constant::Bool(l <= r)),
812 BinOpKind::Ge => Some(Constant::Bool(l >= r)),
813 BinOpKind::Gt => Some(Constant::Bool(l > r)),
814 _ => None,
815 }
816 },
817 _ => None,
818 },
819 (Constant::F32(l), Some(Constant::F32(r))) => match op {
821 BinOpKind::Add => Some(Constant::F32(l + r)),
822 BinOpKind::Sub => Some(Constant::F32(l - r)),
823 BinOpKind::Mul => Some(Constant::F32(l * r)),
824 BinOpKind::Div => Some(Constant::F32(l / r)),
825 BinOpKind::Rem => Some(Constant::F32(l % r)),
826 BinOpKind::Eq => Some(Constant::Bool(l == r)),
827 BinOpKind::Ne => Some(Constant::Bool(l != r)),
828 BinOpKind::Lt => Some(Constant::Bool(l < r)),
829 BinOpKind::Le => Some(Constant::Bool(l <= r)),
830 BinOpKind::Ge => Some(Constant::Bool(l >= r)),
831 BinOpKind::Gt => Some(Constant::Bool(l > r)),
832 _ => None,
833 },
834 (Constant::F64(l), Some(Constant::F64(r))) => match op {
835 BinOpKind::Add => Some(Constant::F64(l + r)),
836 BinOpKind::Sub => Some(Constant::F64(l - r)),
837 BinOpKind::Mul => Some(Constant::F64(l * r)),
838 BinOpKind::Div => Some(Constant::F64(l / r)),
839 BinOpKind::Rem => Some(Constant::F64(l % r)),
840 BinOpKind::Eq => Some(Constant::Bool(l == r)),
841 BinOpKind::Ne => Some(Constant::Bool(l != r)),
842 BinOpKind::Lt => Some(Constant::Bool(l < r)),
843 BinOpKind::Le => Some(Constant::Bool(l <= r)),
844 BinOpKind::Ge => Some(Constant::Bool(l >= r)),
845 BinOpKind::Gt => Some(Constant::Bool(l > r)),
846 _ => None,
847 },
848 (l, r) => match (op, l, r) {
849 (BinOpKind::And, Constant::Bool(false), _) => Some(Constant::Bool(false)),
850 (BinOpKind::Or, Constant::Bool(true), _) => Some(Constant::Bool(true)),
851 (BinOpKind::And, Constant::Bool(true), Some(r)) | (BinOpKind::Or, Constant::Bool(false), Some(r)) => {
852 Some(r)
853 },
854 (BinOpKind::BitXor, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l ^ r)),
855 (BinOpKind::BitAnd, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l & r)),
856 (BinOpKind::BitOr, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l | r)),
857 _ => None,
858 },
859 }
860 }
861}
862
863pub fn mir_to_const<'tcx>(tcx: TyCtxt<'tcx>, result: mir::Const<'tcx>) -> Option<Constant<'tcx>> {
864 let mir::Const::Val(val, _) = result else {
865 return None;
867 };
868 match (val, result.ty().kind()) {
869 (ConstValue::Scalar(Scalar::Int(int)), _) => match result.ty().kind() {
870 ty::Adt(adt_def, _) if adt_def.is_struct() => Some(Constant::Adt(result)),
871 ty::Bool => Some(Constant::Bool(int == ScalarInt::TRUE)),
872 ty::Uint(_) | ty::Int(_) => Some(Constant::Int(int.to_bits(int.size()))),
873 ty::Float(FloatTy::F16) => Some(Constant::F16(int.into())),
874 ty::Float(FloatTy::F32) => Some(Constant::F32(f32::from_bits(int.into()))),
875 ty::Float(FloatTy::F64) => Some(Constant::F64(f64::from_bits(int.into()))),
876 ty::Float(FloatTy::F128) => Some(Constant::F128(int.into())),
877 ty::RawPtr(_, _) => Some(Constant::RawPtr(int.to_bits(int.size()))),
878 _ => None,
879 },
880 (_, ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Str) => {
881 let data = val.try_get_slice_bytes_for_diagnostics(tcx)?;
882 String::from_utf8(data.to_owned()).ok().map(Constant::Str)
883 },
884 (_, ty::Adt(adt_def, _)) if adt_def.is_struct() => Some(Constant::Adt(result)),
885 (ConstValue::Indirect { alloc_id, offset }, ty::Array(sub_type, len)) => {
886 let alloc = tcx.global_alloc(alloc_id).unwrap_memory().inner();
887 let len = len.try_to_target_usize(tcx)?;
888 let ty::Float(flt) = sub_type.kind() else {
889 return None;
890 };
891 let size = Size::from_bits(flt.bit_width());
892 let mut res = Vec::new();
893 for idx in 0..len {
894 let range = alloc_range(offset + size * idx, size);
895 let val = alloc.read_scalar(&tcx, range, false).ok()?;
896 res.push(match flt {
897 FloatTy::F16 => Constant::F16(val.to_u16().discard_err()?),
898 FloatTy::F32 => Constant::F32(f32::from_bits(val.to_u32().discard_err()?)),
899 FloatTy::F64 => Constant::F64(f64::from_bits(val.to_u64().discard_err()?)),
900 FloatTy::F128 => Constant::F128(val.to_u128().discard_err()?),
901 });
902 }
903 Some(Constant::Vec(res))
904 },
905 _ => None,
906 }
907}
908
909fn mir_is_empty<'tcx>(tcx: TyCtxt<'tcx>, result: mir::Const<'tcx>) -> Option<bool> {
910 let mir::Const::Val(val, _) = result else {
911 return None;
913 };
914 match (val, result.ty().kind()) {
915 (_, ty::Ref(_, inner_ty, _)) => match inner_ty.kind() {
916 ty::Str | ty::Slice(_) => {
917 if let ConstValue::Indirect { alloc_id, offset } = val {
918 let a = tcx.global_alloc(alloc_id).unwrap_memory().inner();
921 let ptr_size = tcx.data_layout.pointer_size();
922 if a.size() < offset + 2 * ptr_size {
923 return None;
925 }
926 let len = a
927 .read_scalar(&tcx, alloc_range(offset + ptr_size, ptr_size), false)
928 .ok()?
929 .to_target_usize(&tcx)
930 .discard_err()?;
931 Some(len == 0)
932 } else {
933 None
934 }
935 },
936 ty::Array(_, len) => Some(len.try_to_target_usize(tcx)? == 0),
937 _ => None,
938 },
939 (ConstValue::Indirect { .. }, ty::Array(_, len)) => Some(len.try_to_target_usize(tcx)? == 0),
940 (ConstValue::ZeroSized, _) => Some(true),
941 _ => None,
942 }
943}
944
945fn field_of_struct<'tcx>(
946 adt_def: ty::AdtDef<'tcx>,
947 tcx: TyCtxt<'tcx>,
948 result: mir::Const<'tcx>,
949 field: &Ident,
950) -> Option<mir::Const<'tcx>> {
951 if let mir::Const::Val(result, ty) = result
952 && let Some(dc) = tcx.try_destructure_mir_constant_for_user_output(result, ty)
953 && let Some(dc_variant) = dc.variant
954 && let Some(variant) = adt_def.variants().get(dc_variant)
955 && let Some(field_idx) = variant.fields.iter().position(|el| el.name == field.name)
956 && let Some(&(val, ty)) = dc.fields.get(field_idx)
957 {
958 Some(mir::Const::Val(val, ty))
959 } else {
960 None
961 }
962}
963
964pub fn integer_const(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<u128> {
966 if let Some(Constant::Int(value)) = ConstEvalCtxt::new(cx).eval_simple(expr) {
967 Some(value)
968 } else {
969 None
970 }
971}
972
973#[inline]
975pub fn is_zero_integer_const(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
976 integer_const(cx, expr) == Some(0)
977}