1 //! Code related to processing overloaded binary and unary operators.
3 use super::method::MethodCallee;
4 use super::{has_expected_num_generic_args, FnCtxt};
6 use rustc_errors::{self, struct_span_err, Applicability, Diagnostic};
8 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
9 use rustc_middle::ty::adjustment::{
10 Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability,
12 use rustc_middle::ty::fold::TypeFolder;
13 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeVisitor};
14 use rustc_span::source_map::Spanned;
15 use rustc_span::symbol::{sym, Ident};
17 use rustc_trait_selection::infer::InferCtxtExt;
18 use rustc_trait_selection::traits::error_reporting::suggestions::InferCtxtExt as _;
19 use rustc_trait_selection::traits::{FulfillmentError, TraitEngine, TraitEngineExt};
20 use rustc_type_ir::sty::TyKind::*;
22 use std::ops::ControlFlow;
24 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
25 /// Checks a `a <op>= b`
26 pub fn check_binop_assign(
28 expr: &'tcx hir::Expr<'tcx>,
30 lhs: &'tcx hir::Expr<'tcx>,
31 rhs: &'tcx hir::Expr<'tcx>,
33 let (lhs_ty, rhs_ty, return_ty) =
34 self.check_overloaded_binop(expr, lhs, rhs, op, IsAssign::Yes);
37 if !lhs_ty.is_ty_var() && !rhs_ty.is_ty_var() && is_builtin_binop(lhs_ty, rhs_ty, op) {
38 self.enforce_builtin_binop_types(lhs.span, lhs_ty, rhs.span, rhs_ty, op);
44 self.check_lhs_assignable(lhs, "E0067", op.span, |err| {
45 if let Some(lhs_deref_ty) = self.deref_once_mutably_for_diagnostic(lhs_ty) {
51 Op::Binary(op, IsAssign::Yes),
55 // Suppress this error, since we already emitted
56 // a deref suggestion in check_overloaded_binop
65 /// Checks a potentially overloaded binary operator.
68 expr: &'tcx hir::Expr<'tcx>,
70 lhs_expr: &'tcx hir::Expr<'tcx>,
71 rhs_expr: &'tcx hir::Expr<'tcx>,
76 "check_binop(expr.hir_id={}, expr={:?}, op={:?}, lhs_expr={:?}, rhs_expr={:?})",
77 expr.hir_id, expr, op, lhs_expr, rhs_expr
80 match BinOpCategory::from(op) {
81 BinOpCategory::Shortcircuit => {
82 // && and || are a simple case.
83 self.check_expr_coercable_to_type(lhs_expr, tcx.types.bool, None);
84 let lhs_diverges = self.diverges.get();
85 self.check_expr_coercable_to_type(rhs_expr, tcx.types.bool, None);
87 // Depending on the LHS' value, the RHS can never execute.
88 self.diverges.set(lhs_diverges);
93 // Otherwise, we always treat operators as if they are
94 // overloaded. This is the way to be most flexible w/r/t
95 // types that get inferred.
96 let (lhs_ty, rhs_ty, return_ty) =
97 self.check_overloaded_binop(expr, lhs_expr, rhs_expr, op, IsAssign::No);
99 // Supply type inference hints if relevant. Probably these
100 // hints should be enforced during select as part of the
101 // `consider_unification_despite_ambiguity` routine, but this
102 // more convenient for now.
104 // The basic idea is to help type inference by taking
105 // advantage of things we know about how the impls for
106 // scalar types are arranged. This is important in a
107 // scenario like `1_u32 << 2`, because it lets us quickly
108 // deduce that the result type should be `u32`, even
109 // though we don't know yet what type 2 has and hence
110 // can't pin this down to a specific impl.
111 if !lhs_ty.is_ty_var()
112 && !rhs_ty.is_ty_var()
113 && is_builtin_binop(lhs_ty, rhs_ty, op)
115 let builtin_return_ty = self.enforce_builtin_binop_types(
122 self.demand_suptype(expr.span, builtin_return_ty, return_ty);
130 fn enforce_builtin_binop_types(
138 debug_assert!(is_builtin_binop(lhs_ty, rhs_ty, op));
140 // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work.
141 // (See https://github.com/rust-lang/rust/issues/57447.)
142 let (lhs_ty, rhs_ty) = (deref_ty_if_possible(lhs_ty), deref_ty_if_possible(rhs_ty));
145 match BinOpCategory::from(op) {
146 BinOpCategory::Shortcircuit => {
147 self.demand_suptype(lhs_span, tcx.types.bool, lhs_ty);
148 self.demand_suptype(rhs_span, tcx.types.bool, rhs_ty);
152 BinOpCategory::Shift => {
153 // result type is same as LHS always
157 BinOpCategory::Math | BinOpCategory::Bitwise => {
158 // both LHS and RHS and result will have the same type
159 self.demand_suptype(rhs_span, lhs_ty, rhs_ty);
163 BinOpCategory::Comparison => {
164 // both LHS and RHS and result will have the same type
165 self.demand_suptype(rhs_span, lhs_ty, rhs_ty);
171 fn check_overloaded_binop(
173 expr: &'tcx hir::Expr<'tcx>,
174 lhs_expr: &'tcx hir::Expr<'tcx>,
175 rhs_expr: &'tcx hir::Expr<'tcx>,
178 ) -> (Ty<'tcx>, Ty<'tcx>, Ty<'tcx>) {
180 "check_overloaded_binop(expr.hir_id={}, op={:?}, is_assign={:?})",
181 expr.hir_id, op, is_assign
184 let lhs_ty = match is_assign {
186 // Find a suitable supertype of the LHS expression's type, by coercing to
187 // a type variable, to pass as the `Self` to the trait, avoiding invariant
188 // trait matching creating lifetime constraints that are too strict.
189 // e.g., adding `&'a T` and `&'b T`, given `&'x T: Add<&'x T>`, will result
190 // in `&'a T <: &'x T` and `&'b T <: &'x T`, instead of `'a = 'b = 'x`.
191 let lhs_ty = self.check_expr(lhs_expr);
192 let fresh_var = self.next_ty_var(TypeVariableOrigin {
193 kind: TypeVariableOriginKind::MiscVariable,
196 self.demand_coerce(lhs_expr, lhs_ty, fresh_var, Some(rhs_expr), AllowTwoPhase::No)
199 // rust-lang/rust#52126: We have to use strict
200 // equivalence on the LHS of an assign-op like `+=`;
201 // overwritten or mutably-borrowed places cannot be
202 // coerced to a supertype.
203 self.check_expr(lhs_expr)
206 let lhs_ty = self.resolve_vars_with_obligations(lhs_ty);
208 // N.B., as we have not yet type-checked the RHS, we don't have the
209 // type at hand. Make a variable to represent it. The whole reason
210 // for this indirection is so that, below, we can check the expr
211 // using this variable as the expected type, which sometimes lets
212 // us do better coercions than we would be able to do otherwise,
213 // particularly for things like `String + &String`.
214 let rhs_ty_var = self.next_ty_var(TypeVariableOrigin {
215 kind: TypeVariableOriginKind::MiscVariable,
219 let result = self.lookup_op_method(
223 Op::Binary(op, is_assign),
227 let rhs_ty = self.check_expr_coercable_to_type(rhs_expr, rhs_ty_var, Some(lhs_expr));
228 let rhs_ty = self.resolve_vars_with_obligations(rhs_ty);
230 let return_ty = match result {
232 let by_ref_binop = !op.node.is_by_value();
233 if is_assign == IsAssign::Yes || by_ref_binop {
234 if let ty::Ref(region, _, mutbl) = method.sig.inputs()[0].kind() {
235 let mutbl = match mutbl {
236 hir::Mutability::Not => AutoBorrowMutability::Not,
237 hir::Mutability::Mut => AutoBorrowMutability::Mut {
238 // Allow two-phase borrows for binops in initial deployment
239 // since they desugar to methods
240 allow_two_phase_borrow: AllowTwoPhase::Yes,
243 let autoref = Adjustment {
244 kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)),
245 target: method.sig.inputs()[0],
247 self.apply_adjustments(lhs_expr, vec![autoref]);
251 if let ty::Ref(region, _, mutbl) = method.sig.inputs()[1].kind() {
252 let mutbl = match mutbl {
253 hir::Mutability::Not => AutoBorrowMutability::Not,
254 hir::Mutability::Mut => AutoBorrowMutability::Mut {
255 // Allow two-phase borrows for binops in initial deployment
256 // since they desugar to methods
257 allow_two_phase_borrow: AllowTwoPhase::Yes,
260 let autoref = Adjustment {
261 kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)),
262 target: method.sig.inputs()[1],
264 // HACK(eddyb) Bypass checks due to reborrows being in
265 // some cases applied on the RHS, on top of which we need
266 // to autoref, which is not allowed by apply_adjustments.
267 // self.apply_adjustments(rhs_expr, vec![autoref]);
271 .entry(rhs_expr.hir_id)
276 self.write_method_call(expr.hir_id, method);
280 // error types are considered "builtin"
281 Err(_) if lhs_ty.references_error() || rhs_ty.references_error() => self.tcx.ty_error(),
283 let source_map = self.tcx.sess.source_map();
284 let (mut err, missing_trait, _use_output) = match is_assign {
286 let mut err = struct_span_err!(
290 "binary assignment operation `{}=` cannot be applied to type `{}`",
296 format!("cannot use `{}=` on type `{}`", op.node.as_str(), lhs_ty),
298 let missing_trait = match op.node {
299 hir::BinOpKind::Add => Some("std::ops::AddAssign"),
300 hir::BinOpKind::Sub => Some("std::ops::SubAssign"),
301 hir::BinOpKind::Mul => Some("std::ops::MulAssign"),
302 hir::BinOpKind::Div => Some("std::ops::DivAssign"),
303 hir::BinOpKind::Rem => Some("std::ops::RemAssign"),
304 hir::BinOpKind::BitAnd => Some("std::ops::BitAndAssign"),
305 hir::BinOpKind::BitXor => Some("std::ops::BitXorAssign"),
306 hir::BinOpKind::BitOr => Some("std::ops::BitOrAssign"),
307 hir::BinOpKind::Shl => Some("std::ops::ShlAssign"),
308 hir::BinOpKind::Shr => Some("std::ops::ShrAssign"),
311 self.note_unmet_impls_on_type(&mut err, errors);
312 (err, missing_trait, false)
315 let (message, missing_trait, use_output) = match op.node {
316 hir::BinOpKind::Add => (
317 format!("cannot add `{rhs_ty}` to `{lhs_ty}`"),
318 Some("std::ops::Add"),
321 hir::BinOpKind::Sub => (
322 format!("cannot subtract `{rhs_ty}` from `{lhs_ty}`"),
323 Some("std::ops::Sub"),
326 hir::BinOpKind::Mul => (
327 format!("cannot multiply `{lhs_ty}` by `{rhs_ty}`"),
328 Some("std::ops::Mul"),
331 hir::BinOpKind::Div => (
332 format!("cannot divide `{lhs_ty}` by `{rhs_ty}`"),
333 Some("std::ops::Div"),
336 hir::BinOpKind::Rem => (
337 format!("cannot mod `{lhs_ty}` by `{rhs_ty}`"),
338 Some("std::ops::Rem"),
341 hir::BinOpKind::BitAnd => (
342 format!("no implementation for `{lhs_ty} & {rhs_ty}`"),
343 Some("std::ops::BitAnd"),
346 hir::BinOpKind::BitXor => (
347 format!("no implementation for `{lhs_ty} ^ {rhs_ty}`"),
348 Some("std::ops::BitXor"),
351 hir::BinOpKind::BitOr => (
352 format!("no implementation for `{lhs_ty} | {rhs_ty}`"),
353 Some("std::ops::BitOr"),
356 hir::BinOpKind::Shl => (
357 format!("no implementation for `{lhs_ty} << {rhs_ty}`"),
358 Some("std::ops::Shl"),
361 hir::BinOpKind::Shr => (
362 format!("no implementation for `{lhs_ty} >> {rhs_ty}`"),
363 Some("std::ops::Shr"),
366 hir::BinOpKind::Eq | hir::BinOpKind::Ne => (
368 "binary operation `{}` cannot be applied to type `{}`",
372 Some("std::cmp::PartialEq"),
378 | hir::BinOpKind::Ge => (
380 "binary operation `{}` cannot be applied to type `{}`",
384 Some("std::cmp::PartialOrd"),
389 "binary operation `{}` cannot be applied to type `{}`",
398 struct_span_err!(self.tcx.sess, op.span, E0369, "{}", message.as_str());
399 if !lhs_expr.span.eq(&rhs_expr.span) {
400 self.add_type_neq_err_label(
409 self.add_type_neq_err_label(
419 self.note_unmet_impls_on_type(&mut err, errors);
420 (err, missing_trait, use_output)
424 let mut suggest_deref_binop = |lhs_deref_ty: Ty<'tcx>| {
430 Op::Binary(op, is_assign),
434 if let Ok(lstring) = source_map.span_to_snippet(lhs_expr.span) {
436 "`{}{}` can be used on `{}`, you can dereference `{}`",
439 IsAssign::Yes => "=",
442 lhs_deref_ty.peel_refs(),
445 err.span_suggestion_verbose(
446 lhs_expr.span.shrink_to_lo(),
449 rustc_errors::Applicability::MachineApplicable,
455 // We should suggest `a + b` => `*a + b` if `a` is copy, and suggest
456 // `a += b` => `*a += b` if a is a mut ref.
457 if is_assign == IsAssign::Yes
458 && let Some(lhs_deref_ty) = self.deref_once_mutably_for_diagnostic(lhs_ty) {
459 suggest_deref_binop(lhs_deref_ty);
460 } else if is_assign == IsAssign::No
461 && let Ref(_, lhs_deref_ty, _) = lhs_ty.kind() {
462 if self.infcx.type_is_copy_modulo_regions(self.param_env, *lhs_deref_ty, lhs_expr.span) {
463 suggest_deref_binop(*lhs_deref_ty);
466 if let Some(missing_trait) = missing_trait {
467 let mut visitor = TypeParamVisitor(vec![]);
468 visitor.visit_ty(lhs_ty);
470 if op.node == hir::BinOpKind::Add
471 && self.check_str_addition(
472 lhs_expr, rhs_expr, lhs_ty, rhs_ty, &mut err, is_assign, op,
475 // This has nothing here because it means we did string
476 // concatenation (e.g., "Hello " + "World!"). This means
477 // we don't want the note in the else clause to be emitted
478 } else if let [ty] = &visitor.0[..] {
479 // Look for a TraitPredicate in the Fulfillment errors,
480 // and use it to generate a suggestion.
482 // Note that lookup_op_method must be called again but
483 // with a specific rhs_ty instead of a placeholder so
484 // the resulting predicate generates a more specific
485 // suggestion for the user.
491 Op::Binary(op, is_assign),
494 let predicates = errors
496 .filter_map(|error| error.obligation.predicate.to_opt_poly_trait_pred())
497 .collect::<Vec<_>>();
498 if !predicates.is_empty() {
499 for pred in predicates {
500 self.infcx.suggest_restricting_param_bound(
506 } else if *ty != lhs_ty {
507 // When we know that a missing bound is responsible, we don't show
508 // this note as it is redundant.
510 "the trait `{missing_trait}` is not implemented for `{lhs_ty}`"
520 (lhs_ty, rhs_ty, return_ty)
523 /// If one of the types is an uncalled function and calling it would yield the other type,
524 /// suggest calling the function. Returns `true` if suggestion would apply (even if not given).
525 fn add_type_neq_err_label(
527 err: &mut Diagnostic,
531 other_expr: &'tcx hir::Expr<'tcx>,
534 ) -> bool /* did we suggest to call a function because of missing parentheses? */ {
535 err.span_label(span, ty.to_string());
536 if let FnDef(def_id, _) = *ty.kind() {
537 if !self.tcx.has_typeck_results(def_id) {
540 // FIXME: Instead of exiting early when encountering bound vars in
541 // the function signature, consider keeping the binder here and
542 // propagating it downwards.
543 let Some(fn_sig) = self.tcx.fn_sig(def_id).no_bound_vars() else {
547 let other_ty = if let FnDef(def_id, _) = *other_ty.kind() {
548 if !self.tcx.has_typeck_results(def_id) {
551 // We're emitting a suggestion, so we can just ignore regions
552 self.tcx.fn_sig(def_id).skip_binder().output()
562 Op::Binary(op, is_assign),
566 let (variable_snippet, applicability) = if !fn_sig.inputs().is_empty() {
567 ("( /* arguments */ )".to_string(), Applicability::HasPlaceholders)
569 ("()".to_string(), Applicability::MaybeIncorrect)
572 err.span_suggestion_verbose(
574 "you might have forgotten to call this function",
584 /// Provide actionable suggestions when trying to add two strings with incorrect types,
585 /// like `&str + &str`, `String + String` and `&str + &String`.
587 /// If this function returns `true` it means a note was printed, so we don't need
588 /// to print the normal "implementation of `std::ops::Add` might be missing" note
589 fn check_str_addition(
591 lhs_expr: &'tcx hir::Expr<'tcx>,
592 rhs_expr: &'tcx hir::Expr<'tcx>,
595 err: &mut Diagnostic,
599 let str_concat_note = "string concatenation requires an owned `String` on the left";
600 let rm_borrow_msg = "remove the borrow to obtain an owned `String`";
601 let to_owned_msg = "create an owned `String` from a string reference";
603 let string_type = self.tcx.get_diagnostic_item(sym::String);
604 let is_std_string = |ty: Ty<'tcx>| match ty.ty_adt_def() {
605 Some(ty_def) => Some(ty_def.did()) == string_type,
609 match (lhs_ty.kind(), rhs_ty.kind()) {
610 (&Ref(_, l_ty, _), &Ref(_, r_ty, _)) // &str or &String + &str, &String or &&str
611 if (*l_ty.kind() == Str || is_std_string(l_ty)) && (
612 *r_ty.kind() == Str || is_std_string(r_ty) ||
613 &format!("{:?}", rhs_ty) == "&&str"
616 if let IsAssign::No = is_assign { // Do not supply this message if `&str += &str`
617 err.span_label(op.span, "`+` cannot be used to concatenate two `&str` strings");
618 err.note(str_concat_note);
619 if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind {
620 err.span_suggestion_verbose(
621 lhs_expr.span.until(lhs_inner_expr.span),
624 Applicability::MachineApplicable
627 err.span_suggestion_verbose(
628 lhs_expr.span.shrink_to_hi(),
630 ".to_owned()".to_owned(),
631 Applicability::MachineApplicable
637 (&Ref(_, l_ty, _), &Adt(..)) // Handle `&str` & `&String` + `String`
638 if (*l_ty.kind() == Str || is_std_string(l_ty)) && is_std_string(rhs_ty) =>
642 "`+` cannot be used to concatenate a `&str` with a `String`",
647 let lhs_sugg = if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind {
648 sugg_msg = "remove the borrow on the left and add one on the right";
649 (lhs_expr.span.until(lhs_inner_expr.span), "".to_owned())
651 sugg_msg = "create an owned `String` on the left and add a borrow on the right";
652 (lhs_expr.span.shrink_to_hi(), ".to_owned()".to_owned())
654 let suggestions = vec![
656 (rhs_expr.span.shrink_to_lo(), "&".to_owned()),
658 err.multipart_suggestion_verbose(
661 Applicability::MachineApplicable,
665 err.note(str_concat_note);
674 pub fn check_user_unop(
676 ex: &'tcx hir::Expr<'tcx>,
677 operand_ty: Ty<'tcx>,
680 assert!(op.is_by_value());
681 match self.lookup_op_method(operand_ty, None, None, Op::Unary(op, ex.span)) {
683 self.write_method_call(ex.hir_id, method);
687 let actual = self.resolve_vars_if_possible(operand_ty);
688 if !actual.references_error() {
689 let mut err = struct_span_err!(
693 "cannot apply unary operator `{}` to type `{}`",
699 format!("cannot apply unary operator `{}`", op.as_str()),
702 let mut visitor = TypeParamVisitor(vec![]);
703 visitor.visit_ty(operand_ty);
704 if let [_] = &visitor.0[..] && let ty::Param(_) = *operand_ty.kind() {
705 let predicates = errors
707 .filter_map(|error| {
708 error.obligation.predicate.to_opt_poly_trait_pred()
710 for pred in predicates {
711 self.infcx.suggest_restricting_param_bound(
719 let sp = self.tcx.sess.source_map().start_point(ex.span);
721 self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp)
723 // If the previous expression was a block expression, suggest parentheses
724 // (turning this into a binary subtraction operation instead.)
725 // for example, `{2} - 2` -> `({2}) - 2` (see src\test\ui\parser\expr-as-stmt.rs)
726 self.tcx.sess.parse_sess.expr_parentheses_needed(&mut err, *sp);
728 match actual.kind() {
729 Uint(_) if op == hir::UnOp::Neg => {
730 err.note("unsigned values cannot be negated");
732 if let hir::ExprKind::Unary(
736 hir::ExprKind::Lit(Spanned {
737 node: ast::LitKind::Int(1, _),
747 "you may have meant the maximum value of `{actual}`",
749 format!("{actual}::MAX"),
750 Applicability::MaybeIncorrect,
754 Str | Never | Char | Tuple(_) | Array(_, _) => {}
755 Ref(_, lty, _) if *lty.kind() == Str => {}
757 self.note_unmet_impls_on_type(&mut err, errors);
771 other_ty: Option<Ty<'tcx>>,
772 other_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
774 ) -> Result<MethodCallee<'tcx>, Vec<FulfillmentError<'tcx>>> {
775 let lang = self.tcx.lang_items();
777 let span = match op {
778 Op::Binary(op, _) => op.span,
779 Op::Unary(_, span) => span,
781 let (opname, trait_did) = if let Op::Binary(op, IsAssign::Yes) = op {
783 hir::BinOpKind::Add => (sym::add_assign, lang.add_assign_trait()),
784 hir::BinOpKind::Sub => (sym::sub_assign, lang.sub_assign_trait()),
785 hir::BinOpKind::Mul => (sym::mul_assign, lang.mul_assign_trait()),
786 hir::BinOpKind::Div => (sym::div_assign, lang.div_assign_trait()),
787 hir::BinOpKind::Rem => (sym::rem_assign, lang.rem_assign_trait()),
788 hir::BinOpKind::BitXor => (sym::bitxor_assign, lang.bitxor_assign_trait()),
789 hir::BinOpKind::BitAnd => (sym::bitand_assign, lang.bitand_assign_trait()),
790 hir::BinOpKind::BitOr => (sym::bitor_assign, lang.bitor_assign_trait()),
791 hir::BinOpKind::Shl => (sym::shl_assign, lang.shl_assign_trait()),
792 hir::BinOpKind::Shr => (sym::shr_assign, lang.shr_assign_trait()),
799 | hir::BinOpKind::And
800 | hir::BinOpKind::Or => {
801 span_bug!(span, "impossible assignment operation: {}=", op.node.as_str())
804 } else if let Op::Binary(op, IsAssign::No) = op {
806 hir::BinOpKind::Add => (sym::add, lang.add_trait()),
807 hir::BinOpKind::Sub => (sym::sub, lang.sub_trait()),
808 hir::BinOpKind::Mul => (sym::mul, lang.mul_trait()),
809 hir::BinOpKind::Div => (sym::div, lang.div_trait()),
810 hir::BinOpKind::Rem => (sym::rem, lang.rem_trait()),
811 hir::BinOpKind::BitXor => (sym::bitxor, lang.bitxor_trait()),
812 hir::BinOpKind::BitAnd => (sym::bitand, lang.bitand_trait()),
813 hir::BinOpKind::BitOr => (sym::bitor, lang.bitor_trait()),
814 hir::BinOpKind::Shl => (sym::shl, lang.shl_trait()),
815 hir::BinOpKind::Shr => (sym::shr, lang.shr_trait()),
816 hir::BinOpKind::Lt => (sym::lt, lang.partial_ord_trait()),
817 hir::BinOpKind::Le => (sym::le, lang.partial_ord_trait()),
818 hir::BinOpKind::Ge => (sym::ge, lang.partial_ord_trait()),
819 hir::BinOpKind::Gt => (sym::gt, lang.partial_ord_trait()),
820 hir::BinOpKind::Eq => (sym::eq, lang.eq_trait()),
821 hir::BinOpKind::Ne => (sym::ne, lang.eq_trait()),
822 hir::BinOpKind::And | hir::BinOpKind::Or => {
823 span_bug!(span, "&& and || are not overloadable")
826 } else if let Op::Unary(hir::UnOp::Not, _) = op {
827 (sym::not, lang.not_trait())
828 } else if let Op::Unary(hir::UnOp::Neg, _) = op {
829 (sym::neg, lang.neg_trait())
831 bug!("lookup_op_method: op not supported: {:?}", op)
835 "lookup_op_method(lhs_ty={:?}, op={:?}, opname={:?}, trait_did={:?})",
836 lhs_ty, op, opname, trait_did
839 // Catches cases like #83893, where a lang item is declared with the
840 // wrong number of generic arguments. Should have yielded an error
841 // elsewhere by now, but we have to catch it here so that we do not
842 // index `other_tys` out of bounds (if the lang item has too many
843 // generic arguments, `other_tys` is too short).
844 if !has_expected_num_generic_args(
848 // Binary ops have a generic right-hand side, unary ops don't
856 let opname = Ident::with_dummy_span(opname);
857 let method = trait_did.and_then(|trait_did| {
858 self.lookup_op_method_in_trait(span, opname, trait_did, lhs_ty, other_ty, other_ty_expr)
861 match (method, trait_did) {
863 let method = self.register_infer_ok_obligations(ok);
864 self.select_obligations_where_possible(false, |_| {});
867 (None, None) => Err(vec![]),
868 (None, Some(trait_did)) => {
869 let (obligation, _) =
870 self.obligation_for_op_method(span, trait_did, lhs_ty, other_ty, other_ty_expr);
871 let mut fulfill = <dyn TraitEngine<'_>>::new(self.tcx);
872 fulfill.register_predicate_obligation(self, obligation);
873 Err(fulfill.select_where_possible(&self.infcx))
879 // Binary operator categories. These categories summarize the behavior
880 // with respect to the builtin operations supported.
882 /// &&, || -- cannot be overridden
885 /// <<, >> -- when shifting a single integer, rhs can be any
886 /// integer type. For simd, types must match.
889 /// +, -, etc -- takes equal types, produces same type as input,
890 /// applicable to ints/floats/simd
893 /// &, |, ^ -- takes equal types, produces same type as input,
894 /// applicable to ints/floats/simd/bool
897 /// ==, !=, etc -- takes equal types, produces bools, except for simd,
898 /// which produce the input type
903 fn from(op: hir::BinOp) -> BinOpCategory {
905 hir::BinOpKind::Shl | hir::BinOpKind::Shr => BinOpCategory::Shift,
908 | hir::BinOpKind::Sub
909 | hir::BinOpKind::Mul
910 | hir::BinOpKind::Div
911 | hir::BinOpKind::Rem => BinOpCategory::Math,
913 hir::BinOpKind::BitXor | hir::BinOpKind::BitAnd | hir::BinOpKind::BitOr => {
914 BinOpCategory::Bitwise
922 | hir::BinOpKind::Gt => BinOpCategory::Comparison,
924 hir::BinOpKind::And | hir::BinOpKind::Or => BinOpCategory::Shortcircuit,
929 /// Whether the binary operation is an assignment (`a += b`), or not (`a + b`)
930 #[derive(Clone, Copy, Debug, PartialEq)]
936 #[derive(Clone, Copy, Debug)]
938 Binary(hir::BinOp, IsAssign),
939 Unary(hir::UnOp, Span),
942 /// Dereferences a single level of immutable referencing.
943 fn deref_ty_if_possible<'tcx>(ty: Ty<'tcx>) -> Ty<'tcx> {
945 ty::Ref(_, ty, hir::Mutability::Not) => *ty,
950 /// Returns `true` if this is a built-in arithmetic operation (e.g., u32
951 /// + u32, i16x4 == i16x4) and false if these types would have to be
952 /// overloaded to be legal. There are two reasons that we distinguish
953 /// builtin operations from overloaded ones (vs trying to drive
954 /// everything uniformly through the trait system and intrinsics or
955 /// something like that):
957 /// 1. Builtin operations can trivially be evaluated in constants.
958 /// 2. For comparison operators applied to SIMD types the result is
959 /// not of type `bool`. For example, `i16x4 == i16x4` yields a
960 /// type like `i16x4`. This means that the overloaded trait
961 /// `PartialEq` is not applicable.
963 /// Reason #2 is the killer. I tried for a while to always use
964 /// overloaded logic and just check the types in constants/codegen after
965 /// the fact, and it worked fine, except for SIMD types. -nmatsakis
966 fn is_builtin_binop<'tcx>(lhs: Ty<'tcx>, rhs: Ty<'tcx>, op: hir::BinOp) -> bool {
967 // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work.
968 // (See https://github.com/rust-lang/rust/issues/57447.)
969 let (lhs, rhs) = (deref_ty_if_possible(lhs), deref_ty_if_possible(rhs));
971 match BinOpCategory::from(op) {
972 BinOpCategory::Shortcircuit => true,
974 BinOpCategory::Shift => {
975 lhs.references_error()
976 || rhs.references_error()
977 || lhs.is_integral() && rhs.is_integral()
980 BinOpCategory::Math => {
981 lhs.references_error()
982 || rhs.references_error()
983 || lhs.is_integral() && rhs.is_integral()
984 || lhs.is_floating_point() && rhs.is_floating_point()
987 BinOpCategory::Bitwise => {
988 lhs.references_error()
989 || rhs.references_error()
990 || lhs.is_integral() && rhs.is_integral()
991 || lhs.is_floating_point() && rhs.is_floating_point()
992 || lhs.is_bool() && rhs.is_bool()
995 BinOpCategory::Comparison => {
996 lhs.references_error() || rhs.references_error() || lhs.is_scalar() && rhs.is_scalar()
1001 struct TypeParamVisitor<'tcx>(Vec<Ty<'tcx>>);
1003 impl<'tcx> TypeVisitor<'tcx> for TypeParamVisitor<'tcx> {
1004 fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1005 if let ty::Param(_) = ty.kind() {
1008 ty.super_visit_with(self)
1012 struct TypeParamEraser<'a, 'tcx>(&'a FnCtxt<'a, 'tcx>, Span);
1014 impl<'tcx> TypeFolder<'tcx> for TypeParamEraser<'_, 'tcx> {
1015 fn tcx(&self) -> TyCtxt<'tcx> {
1019 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
1021 ty::Param(_) => self.0.next_ty_var(TypeVariableOrigin {
1022 kind: TypeVariableOriginKind::MiscVariable,
1025 _ => ty.super_fold_with(self),