diff options
Diffstat (limited to 'compiler/rustc_typeck/src/check/op.rs')
| -rw-r--r-- | compiler/rustc_typeck/src/check/op.rs | 1076 |
1 files changed, 1076 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/check/op.rs b/compiler/rustc_typeck/src/check/op.rs new file mode 100644 index 000000000..920b3e688 --- /dev/null +++ b/compiler/rustc_typeck/src/check/op.rs @@ -0,0 +1,1076 @@ +//! Code related to processing overloaded binary and unary operators. + +use super::method::MethodCallee; +use super::{has_expected_num_generic_args, FnCtxt}; +use crate::check::Expectation; +use rustc_ast as ast; +use rustc_errors::{self, struct_span_err, Applicability, Diagnostic}; +use rustc_hir as hir; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_infer::traits::ObligationCauseCode; +use rustc_middle::ty::adjustment::{ + Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, +}; +use rustc_middle::ty::{ + self, Ty, TyCtxt, TypeFolder, TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitor, +}; +use rustc_span::source_map::Spanned; +use rustc_span::symbol::{sym, Ident}; +use rustc_span::Span; +use rustc_trait_selection::infer::InferCtxtExt; +use rustc_trait_selection::traits::error_reporting::suggestions::InferCtxtExt as _; +use rustc_trait_selection::traits::{FulfillmentError, TraitEngine, TraitEngineExt}; +use rustc_type_ir::sty::TyKind::*; + +use std::ops::ControlFlow; + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + /// Checks a `a <op>= b` + pub fn check_binop_assign( + &self, + expr: &'tcx hir::Expr<'tcx>, + op: hir::BinOp, + lhs: &'tcx hir::Expr<'tcx>, + rhs: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let (lhs_ty, rhs_ty, return_ty) = + self.check_overloaded_binop(expr, lhs, rhs, op, IsAssign::Yes, expected); + + let ty = + if !lhs_ty.is_ty_var() && !rhs_ty.is_ty_var() && is_builtin_binop(lhs_ty, rhs_ty, op) { + self.enforce_builtin_binop_types(lhs.span, lhs_ty, rhs.span, rhs_ty, op); + self.tcx.mk_unit() + } else { + return_ty + }; + + self.check_lhs_assignable(lhs, "E0067", op.span, |err| { + if let Some(lhs_deref_ty) = self.deref_once_mutably_for_diagnostic(lhs_ty) { + if self + .lookup_op_method( + lhs_deref_ty, + Some(rhs_ty), + Some(rhs), + Op::Binary(op, IsAssign::Yes), + expected, + ) + .is_ok() + { + // Suppress this error, since we already emitted + // a deref suggestion in check_overloaded_binop + err.delay_as_bug(); + } + } + }); + + ty + } + + /// Checks a potentially overloaded binary operator. + pub fn check_binop( + &self, + expr: &'tcx hir::Expr<'tcx>, + op: hir::BinOp, + lhs_expr: &'tcx hir::Expr<'tcx>, + rhs_expr: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let tcx = self.tcx; + + debug!( + "check_binop(expr.hir_id={}, expr={:?}, op={:?}, lhs_expr={:?}, rhs_expr={:?})", + expr.hir_id, expr, op, lhs_expr, rhs_expr + ); + + match BinOpCategory::from(op) { + BinOpCategory::Shortcircuit => { + // && and || are a simple case. + self.check_expr_coercable_to_type(lhs_expr, tcx.types.bool, None); + let lhs_diverges = self.diverges.get(); + self.check_expr_coercable_to_type(rhs_expr, tcx.types.bool, None); + + // Depending on the LHS' value, the RHS can never execute. + self.diverges.set(lhs_diverges); + + tcx.types.bool + } + _ => { + // Otherwise, we always treat operators as if they are + // overloaded. This is the way to be most flexible w/r/t + // types that get inferred. + let (lhs_ty, rhs_ty, return_ty) = self.check_overloaded_binop( + expr, + lhs_expr, + rhs_expr, + op, + IsAssign::No, + expected, + ); + + // Supply type inference hints if relevant. Probably these + // hints should be enforced during select as part of the + // `consider_unification_despite_ambiguity` routine, but this + // more convenient for now. + // + // The basic idea is to help type inference by taking + // advantage of things we know about how the impls for + // scalar types are arranged. This is important in a + // scenario like `1_u32 << 2`, because it lets us quickly + // deduce that the result type should be `u32`, even + // though we don't know yet what type 2 has and hence + // can't pin this down to a specific impl. + if !lhs_ty.is_ty_var() + && !rhs_ty.is_ty_var() + && is_builtin_binop(lhs_ty, rhs_ty, op) + { + let builtin_return_ty = self.enforce_builtin_binop_types( + lhs_expr.span, + lhs_ty, + rhs_expr.span, + rhs_ty, + op, + ); + self.demand_suptype(expr.span, builtin_return_ty, return_ty); + } + + return_ty + } + } + } + + fn enforce_builtin_binop_types( + &self, + lhs_span: Span, + lhs_ty: Ty<'tcx>, + rhs_span: Span, + rhs_ty: Ty<'tcx>, + op: hir::BinOp, + ) -> Ty<'tcx> { + debug_assert!(is_builtin_binop(lhs_ty, rhs_ty, op)); + + // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work. + // (See https://github.com/rust-lang/rust/issues/57447.) + let (lhs_ty, rhs_ty) = (deref_ty_if_possible(lhs_ty), deref_ty_if_possible(rhs_ty)); + + let tcx = self.tcx; + match BinOpCategory::from(op) { + BinOpCategory::Shortcircuit => { + self.demand_suptype(lhs_span, tcx.types.bool, lhs_ty); + self.demand_suptype(rhs_span, tcx.types.bool, rhs_ty); + tcx.types.bool + } + + BinOpCategory::Shift => { + // result type is same as LHS always + lhs_ty + } + + BinOpCategory::Math | BinOpCategory::Bitwise => { + // both LHS and RHS and result will have the same type + self.demand_suptype(rhs_span, lhs_ty, rhs_ty); + lhs_ty + } + + BinOpCategory::Comparison => { + // both LHS and RHS and result will have the same type + self.demand_suptype(rhs_span, lhs_ty, rhs_ty); + tcx.types.bool + } + } + } + + fn check_overloaded_binop( + &self, + expr: &'tcx hir::Expr<'tcx>, + lhs_expr: &'tcx hir::Expr<'tcx>, + rhs_expr: &'tcx hir::Expr<'tcx>, + op: hir::BinOp, + is_assign: IsAssign, + expected: Expectation<'tcx>, + ) -> (Ty<'tcx>, Ty<'tcx>, Ty<'tcx>) { + debug!( + "check_overloaded_binop(expr.hir_id={}, op={:?}, is_assign={:?})", + expr.hir_id, op, is_assign + ); + + let lhs_ty = match is_assign { + IsAssign::No => { + // Find a suitable supertype of the LHS expression's type, by coercing to + // a type variable, to pass as the `Self` to the trait, avoiding invariant + // trait matching creating lifetime constraints that are too strict. + // e.g., adding `&'a T` and `&'b T`, given `&'x T: Add<&'x T>`, will result + // in `&'a T <: &'x T` and `&'b T <: &'x T`, instead of `'a = 'b = 'x`. + let lhs_ty = self.check_expr(lhs_expr); + let fresh_var = self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::MiscVariable, + span: lhs_expr.span, + }); + self.demand_coerce(lhs_expr, lhs_ty, fresh_var, Some(rhs_expr), AllowTwoPhase::No) + } + IsAssign::Yes => { + // rust-lang/rust#52126: We have to use strict + // equivalence on the LHS of an assign-op like `+=`; + // overwritten or mutably-borrowed places cannot be + // coerced to a supertype. + self.check_expr(lhs_expr) + } + }; + let lhs_ty = self.resolve_vars_with_obligations(lhs_ty); + + // N.B., as we have not yet type-checked the RHS, we don't have the + // type at hand. Make a variable to represent it. The whole reason + // for this indirection is so that, below, we can check the expr + // using this variable as the expected type, which sometimes lets + // us do better coercions than we would be able to do otherwise, + // particularly for things like `String + &String`. + let rhs_ty_var = self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::MiscVariable, + span: rhs_expr.span, + }); + + let result = self.lookup_op_method( + lhs_ty, + Some(rhs_ty_var), + Some(rhs_expr), + Op::Binary(op, is_assign), + expected, + ); + + // see `NB` above + let rhs_ty = self.check_expr_coercable_to_type(rhs_expr, rhs_ty_var, Some(lhs_expr)); + let rhs_ty = self.resolve_vars_with_obligations(rhs_ty); + + let return_ty = match result { + Ok(method) => { + let by_ref_binop = !op.node.is_by_value(); + if is_assign == IsAssign::Yes || by_ref_binop { + if let ty::Ref(region, _, mutbl) = method.sig.inputs()[0].kind() { + let mutbl = match mutbl { + hir::Mutability::Not => AutoBorrowMutability::Not, + hir::Mutability::Mut => AutoBorrowMutability::Mut { + // Allow two-phase borrows for binops in initial deployment + // since they desugar to methods + allow_two_phase_borrow: AllowTwoPhase::Yes, + }, + }; + let autoref = Adjustment { + kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)), + target: method.sig.inputs()[0], + }; + self.apply_adjustments(lhs_expr, vec![autoref]); + } + } + if by_ref_binop { + if let ty::Ref(region, _, mutbl) = method.sig.inputs()[1].kind() { + let mutbl = match mutbl { + hir::Mutability::Not => AutoBorrowMutability::Not, + hir::Mutability::Mut => AutoBorrowMutability::Mut { + // Allow two-phase borrows for binops in initial deployment + // since they desugar to methods + allow_two_phase_borrow: AllowTwoPhase::Yes, + }, + }; + let autoref = Adjustment { + kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)), + target: method.sig.inputs()[1], + }; + // HACK(eddyb) Bypass checks due to reborrows being in + // some cases applied on the RHS, on top of which we need + // to autoref, which is not allowed by apply_adjustments. + // self.apply_adjustments(rhs_expr, vec![autoref]); + self.typeck_results + .borrow_mut() + .adjustments_mut() + .entry(rhs_expr.hir_id) + .or_default() + .push(autoref); + } + } + self.write_method_call(expr.hir_id, method); + + method.sig.output() + } + // error types are considered "builtin" + Err(_) if lhs_ty.references_error() || rhs_ty.references_error() => self.tcx.ty_error(), + Err(errors) => { + let source_map = self.tcx.sess.source_map(); + let (mut err, missing_trait, use_output) = match is_assign { + IsAssign::Yes => { + let mut err = struct_span_err!( + self.tcx.sess, + expr.span, + E0368, + "binary assignment operation `{}=` cannot be applied to type `{}`", + op.node.as_str(), + lhs_ty, + ); + err.span_label( + lhs_expr.span, + format!("cannot use `{}=` on type `{}`", op.node.as_str(), lhs_ty), + ); + let missing_trait = match op.node { + hir::BinOpKind::Add => Some("std::ops::AddAssign"), + hir::BinOpKind::Sub => Some("std::ops::SubAssign"), + hir::BinOpKind::Mul => Some("std::ops::MulAssign"), + hir::BinOpKind::Div => Some("std::ops::DivAssign"), + hir::BinOpKind::Rem => Some("std::ops::RemAssign"), + hir::BinOpKind::BitAnd => Some("std::ops::BitAndAssign"), + hir::BinOpKind::BitXor => Some("std::ops::BitXorAssign"), + hir::BinOpKind::BitOr => Some("std::ops::BitOrAssign"), + hir::BinOpKind::Shl => Some("std::ops::ShlAssign"), + hir::BinOpKind::Shr => Some("std::ops::ShrAssign"), + _ => None, + }; + self.note_unmet_impls_on_type(&mut err, errors); + (err, missing_trait, false) + } + IsAssign::No => { + let (message, missing_trait, use_output) = match op.node { + hir::BinOpKind::Add => ( + format!("cannot add `{rhs_ty}` to `{lhs_ty}`"), + Some("std::ops::Add"), + true, + ), + hir::BinOpKind::Sub => ( + format!("cannot subtract `{rhs_ty}` from `{lhs_ty}`"), + Some("std::ops::Sub"), + true, + ), + hir::BinOpKind::Mul => ( + format!("cannot multiply `{lhs_ty}` by `{rhs_ty}`"), + Some("std::ops::Mul"), + true, + ), + hir::BinOpKind::Div => ( + format!("cannot divide `{lhs_ty}` by `{rhs_ty}`"), + Some("std::ops::Div"), + true, + ), + hir::BinOpKind::Rem => ( + format!("cannot mod `{lhs_ty}` by `{rhs_ty}`"), + Some("std::ops::Rem"), + true, + ), + hir::BinOpKind::BitAnd => ( + format!("no implementation for `{lhs_ty} & {rhs_ty}`"), + Some("std::ops::BitAnd"), + true, + ), + hir::BinOpKind::BitXor => ( + format!("no implementation for `{lhs_ty} ^ {rhs_ty}`"), + Some("std::ops::BitXor"), + true, + ), + hir::BinOpKind::BitOr => ( + format!("no implementation for `{lhs_ty} | {rhs_ty}`"), + Some("std::ops::BitOr"), + true, + ), + hir::BinOpKind::Shl => ( + format!("no implementation for `{lhs_ty} << {rhs_ty}`"), + Some("std::ops::Shl"), + true, + ), + hir::BinOpKind::Shr => ( + format!("no implementation for `{lhs_ty} >> {rhs_ty}`"), + Some("std::ops::Shr"), + true, + ), + hir::BinOpKind::Eq | hir::BinOpKind::Ne => ( + format!( + "binary operation `{}` cannot be applied to type `{}`", + op.node.as_str(), + lhs_ty + ), + Some("std::cmp::PartialEq"), + false, + ), + hir::BinOpKind::Lt + | hir::BinOpKind::Le + | hir::BinOpKind::Gt + | hir::BinOpKind::Ge => ( + format!( + "binary operation `{}` cannot be applied to type `{}`", + op.node.as_str(), + lhs_ty + ), + Some("std::cmp::PartialOrd"), + false, + ), + _ => ( + format!( + "binary operation `{}` cannot be applied to type `{}`", + op.node.as_str(), + lhs_ty + ), + None, + false, + ), + }; + let mut err = struct_span_err!(self.tcx.sess, op.span, E0369, "{message}"); + if !lhs_expr.span.eq(&rhs_expr.span) { + self.add_type_neq_err_label( + &mut err, + lhs_expr.span, + lhs_ty, + rhs_ty, + rhs_expr, + op, + is_assign, + expected, + ); + self.add_type_neq_err_label( + &mut err, + rhs_expr.span, + rhs_ty, + lhs_ty, + lhs_expr, + op, + is_assign, + expected, + ); + } + self.note_unmet_impls_on_type(&mut err, errors); + (err, missing_trait, use_output) + } + }; + + let mut suggest_deref_binop = |lhs_deref_ty: Ty<'tcx>| { + if self + .lookup_op_method( + lhs_deref_ty, + Some(rhs_ty), + Some(rhs_expr), + Op::Binary(op, is_assign), + expected, + ) + .is_ok() + { + if let Ok(lstring) = source_map.span_to_snippet(lhs_expr.span) { + let msg = &format!( + "`{}{}` can be used on `{}`, you can dereference `{}`", + op.node.as_str(), + match is_assign { + IsAssign::Yes => "=", + IsAssign::No => "", + }, + lhs_deref_ty.peel_refs(), + lstring, + ); + err.span_suggestion_verbose( + lhs_expr.span.shrink_to_lo(), + msg, + "*", + rustc_errors::Applicability::MachineApplicable, + ); + } + } + }; + + // We should suggest `a + b` => `*a + b` if `a` is copy, and suggest + // `a += b` => `*a += b` if a is a mut ref. + if is_assign == IsAssign::Yes + && let Some(lhs_deref_ty) = self.deref_once_mutably_for_diagnostic(lhs_ty) { + suggest_deref_binop(lhs_deref_ty); + } else if is_assign == IsAssign::No + && let Ref(_, lhs_deref_ty, _) = lhs_ty.kind() { + if self.type_is_copy_modulo_regions(self.param_env, *lhs_deref_ty, lhs_expr.span) { + suggest_deref_binop(*lhs_deref_ty); + } + } + if let Some(missing_trait) = missing_trait { + let mut visitor = TypeParamVisitor(vec![]); + visitor.visit_ty(lhs_ty); + + if op.node == hir::BinOpKind::Add + && self.check_str_addition( + lhs_expr, rhs_expr, lhs_ty, rhs_ty, &mut err, is_assign, op, + ) + { + // This has nothing here because it means we did string + // concatenation (e.g., "Hello " + "World!"). This means + // we don't want the note in the else clause to be emitted + } else if let [ty] = &visitor.0[..] { + // Look for a TraitPredicate in the Fulfillment errors, + // and use it to generate a suggestion. + // + // Note that lookup_op_method must be called again but + // with a specific rhs_ty instead of a placeholder so + // the resulting predicate generates a more specific + // suggestion for the user. + let errors = self + .lookup_op_method( + lhs_ty, + Some(rhs_ty), + Some(rhs_expr), + Op::Binary(op, is_assign), + expected, + ) + .unwrap_err(); + if !errors.is_empty() { + for error in errors { + if let Some(trait_pred) = + error.obligation.predicate.to_opt_poly_trait_pred() + { + let proj_pred = match error.obligation.cause.code() { + ObligationCauseCode::BinOp { + output_pred: Some(output_pred), + .. + } if use_output => { + output_pred.to_opt_poly_projection_pred() + } + _ => None, + }; + + self.suggest_restricting_param_bound( + &mut err, + trait_pred, + proj_pred, + self.body_id, + ); + } + } + } else if *ty != lhs_ty { + // When we know that a missing bound is responsible, we don't show + // this note as it is redundant. + err.note(&format!( + "the trait `{missing_trait}` is not implemented for `{lhs_ty}`" + )); + } + } + } + err.emit(); + self.tcx.ty_error() + } + }; + + (lhs_ty, rhs_ty, return_ty) + } + + /// If one of the types is an uncalled function and calling it would yield the other type, + /// suggest calling the function. Returns `true` if suggestion would apply (even if not given). + fn add_type_neq_err_label( + &self, + err: &mut Diagnostic, + span: Span, + ty: Ty<'tcx>, + other_ty: Ty<'tcx>, + other_expr: &'tcx hir::Expr<'tcx>, + op: hir::BinOp, + is_assign: IsAssign, + expected: Expectation<'tcx>, + ) -> bool /* did we suggest to call a function because of missing parentheses? */ { + err.span_label(span, ty.to_string()); + if let FnDef(def_id, _) = *ty.kind() { + if !self.tcx.has_typeck_results(def_id) { + return false; + } + // FIXME: Instead of exiting early when encountering bound vars in + // the function signature, consider keeping the binder here and + // propagating it downwards. + let Some(fn_sig) = self.tcx.fn_sig(def_id).no_bound_vars() else { + return false; + }; + + let other_ty = if let FnDef(def_id, _) = *other_ty.kind() { + if !self.tcx.has_typeck_results(def_id) { + return false; + } + // We're emitting a suggestion, so we can just ignore regions + self.tcx.fn_sig(def_id).skip_binder().output() + } else { + other_ty + }; + + if self + .lookup_op_method( + fn_sig.output(), + Some(other_ty), + Some(other_expr), + Op::Binary(op, is_assign), + expected, + ) + .is_ok() + { + let (variable_snippet, applicability) = if !fn_sig.inputs().is_empty() { + ("( /* arguments */ )", Applicability::HasPlaceholders) + } else { + ("()", Applicability::MaybeIncorrect) + }; + + err.span_suggestion_verbose( + span.shrink_to_hi(), + "you might have forgotten to call this function", + variable_snippet, + applicability, + ); + return true; + } + } + false + } + + /// Provide actionable suggestions when trying to add two strings with incorrect types, + /// like `&str + &str`, `String + String` and `&str + &String`. + /// + /// If this function returns `true` it means a note was printed, so we don't need + /// to print the normal "implementation of `std::ops::Add` might be missing" note + fn check_str_addition( + &self, + lhs_expr: &'tcx hir::Expr<'tcx>, + rhs_expr: &'tcx hir::Expr<'tcx>, + lhs_ty: Ty<'tcx>, + rhs_ty: Ty<'tcx>, + err: &mut Diagnostic, + is_assign: IsAssign, + op: hir::BinOp, + ) -> bool { + let str_concat_note = "string concatenation requires an owned `String` on the left"; + let rm_borrow_msg = "remove the borrow to obtain an owned `String`"; + let to_owned_msg = "create an owned `String` from a string reference"; + + let is_std_string = |ty: Ty<'tcx>| { + ty.ty_adt_def() + .map_or(false, |ty_def| self.tcx.is_diagnostic_item(sym::String, ty_def.did())) + }; + + match (lhs_ty.kind(), rhs_ty.kind()) { + (&Ref(_, l_ty, _), &Ref(_, r_ty, _)) // &str or &String + &str, &String or &&str + if (*l_ty.kind() == Str || is_std_string(l_ty)) + && (*r_ty.kind() == Str + || is_std_string(r_ty) + || matches!( + r_ty.kind(), Ref(_, inner_ty, _) if *inner_ty.kind() == Str + )) => + { + if let IsAssign::No = is_assign { // Do not supply this message if `&str += &str` + err.span_label(op.span, "`+` cannot be used to concatenate two `&str` strings"); + err.note(str_concat_note); + if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind { + err.span_suggestion_verbose( + lhs_expr.span.until(lhs_inner_expr.span), + rm_borrow_msg, + "", + Applicability::MachineApplicable + ); + } else { + err.span_suggestion_verbose( + lhs_expr.span.shrink_to_hi(), + to_owned_msg, + ".to_owned()", + Applicability::MachineApplicable + ); + } + } + true + } + (&Ref(_, l_ty, _), &Adt(..)) // Handle `&str` & `&String` + `String` + if (*l_ty.kind() == Str || is_std_string(l_ty)) && is_std_string(rhs_ty) => + { + err.span_label( + op.span, + "`+` cannot be used to concatenate a `&str` with a `String`", + ); + match is_assign { + IsAssign::No => { + let sugg_msg; + let lhs_sugg = if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind { + sugg_msg = "remove the borrow on the left and add one on the right"; + (lhs_expr.span.until(lhs_inner_expr.span), "".to_owned()) + } else { + sugg_msg = "create an owned `String` on the left and add a borrow on the right"; + (lhs_expr.span.shrink_to_hi(), ".to_owned()".to_owned()) + }; + let suggestions = vec![ + lhs_sugg, + (rhs_expr.span.shrink_to_lo(), "&".to_owned()), + ]; + err.multipart_suggestion_verbose( + sugg_msg, + suggestions, + Applicability::MachineApplicable, + ); + } + IsAssign::Yes => { + err.note(str_concat_note); + } + } + true + } + _ => false, + } + } + + pub fn check_user_unop( + &self, + ex: &'tcx hir::Expr<'tcx>, + operand_ty: Ty<'tcx>, + op: hir::UnOp, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + assert!(op.is_by_value()); + match self.lookup_op_method(operand_ty, None, None, Op::Unary(op, ex.span), expected) { + Ok(method) => { + self.write_method_call(ex.hir_id, method); + method.sig.output() + } + Err(errors) => { + let actual = self.resolve_vars_if_possible(operand_ty); + if !actual.references_error() { + let mut err = struct_span_err!( + self.tcx.sess, + ex.span, + E0600, + "cannot apply unary operator `{}` to type `{}`", + op.as_str(), + actual + ); + err.span_label( + ex.span, + format!("cannot apply unary operator `{}`", op.as_str()), + ); + + let mut visitor = TypeParamVisitor(vec![]); + visitor.visit_ty(operand_ty); + if let [_] = &visitor.0[..] && let ty::Param(_) = *operand_ty.kind() { + let predicates = errors + .iter() + .filter_map(|error| { + error.obligation.predicate.to_opt_poly_trait_pred() + }); + for pred in predicates { + self.suggest_restricting_param_bound( + &mut err, + pred, + None, + self.body_id, + ); + } + } + + let sp = self.tcx.sess.source_map().start_point(ex.span); + if let Some(sp) = + self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) + { + // If the previous expression was a block expression, suggest parentheses + // (turning this into a binary subtraction operation instead.) + // for example, `{2} - 2` -> `({2}) - 2` (see src\test\ui\parser\expr-as-stmt.rs) + self.tcx.sess.parse_sess.expr_parentheses_needed(&mut err, *sp); + } else { + match actual.kind() { + Uint(_) if op == hir::UnOp::Neg => { + err.note("unsigned values cannot be negated"); + + if let hir::ExprKind::Unary( + _, + hir::Expr { + kind: + hir::ExprKind::Lit(Spanned { + node: ast::LitKind::Int(1, _), + .. + }), + .. + }, + ) = ex.kind + { + err.span_suggestion( + ex.span, + &format!( + "you may have meant the maximum value of `{actual}`", + ), + format!("{actual}::MAX"), + Applicability::MaybeIncorrect, + ); + } + } + Str | Never | Char | Tuple(_) | Array(_, _) => {} + Ref(_, lty, _) if *lty.kind() == Str => {} + _ => { + self.note_unmet_impls_on_type(&mut err, errors); + } + } + } + err.emit(); + } + self.tcx.ty_error() + } + } + } + + fn lookup_op_method( + &self, + lhs_ty: Ty<'tcx>, + other_ty: Option<Ty<'tcx>>, + other_ty_expr: Option<&'tcx hir::Expr<'tcx>>, + op: Op, + expected: Expectation<'tcx>, + ) -> Result<MethodCallee<'tcx>, Vec<FulfillmentError<'tcx>>> { + let lang = self.tcx.lang_items(); + + let span = match op { + Op::Binary(op, _) => op.span, + Op::Unary(_, span) => span, + }; + let (opname, trait_did) = if let Op::Binary(op, IsAssign::Yes) = op { + match op.node { + hir::BinOpKind::Add => (sym::add_assign, lang.add_assign_trait()), + hir::BinOpKind::Sub => (sym::sub_assign, lang.sub_assign_trait()), + hir::BinOpKind::Mul => (sym::mul_assign, lang.mul_assign_trait()), + hir::BinOpKind::Div => (sym::div_assign, lang.div_assign_trait()), + hir::BinOpKind::Rem => (sym::rem_assign, lang.rem_assign_trait()), + hir::BinOpKind::BitXor => (sym::bitxor_assign, lang.bitxor_assign_trait()), + hir::BinOpKind::BitAnd => (sym::bitand_assign, lang.bitand_assign_trait()), + hir::BinOpKind::BitOr => (sym::bitor_assign, lang.bitor_assign_trait()), + hir::BinOpKind::Shl => (sym::shl_assign, lang.shl_assign_trait()), + hir::BinOpKind::Shr => (sym::shr_assign, lang.shr_assign_trait()), + hir::BinOpKind::Lt + | hir::BinOpKind::Le + | hir::BinOpKind::Ge + | hir::BinOpKind::Gt + | hir::BinOpKind::Eq + | hir::BinOpKind::Ne + | hir::BinOpKind::And + | hir::BinOpKind::Or => { + span_bug!(span, "impossible assignment operation: {}=", op.node.as_str()) + } + } + } else if let Op::Binary(op, IsAssign::No) = op { + match op.node { + hir::BinOpKind::Add => (sym::add, lang.add_trait()), + hir::BinOpKind::Sub => (sym::sub, lang.sub_trait()), + hir::BinOpKind::Mul => (sym::mul, lang.mul_trait()), + hir::BinOpKind::Div => (sym::div, lang.div_trait()), + hir::BinOpKind::Rem => (sym::rem, lang.rem_trait()), + hir::BinOpKind::BitXor => (sym::bitxor, lang.bitxor_trait()), + hir::BinOpKind::BitAnd => (sym::bitand, lang.bitand_trait()), + hir::BinOpKind::BitOr => (sym::bitor, lang.bitor_trait()), + hir::BinOpKind::Shl => (sym::shl, lang.shl_trait()), + hir::BinOpKind::Shr => (sym::shr, lang.shr_trait()), + hir::BinOpKind::Lt => (sym::lt, lang.partial_ord_trait()), + hir::BinOpKind::Le => (sym::le, lang.partial_ord_trait()), + hir::BinOpKind::Ge => (sym::ge, lang.partial_ord_trait()), + hir::BinOpKind::Gt => (sym::gt, lang.partial_ord_trait()), + hir::BinOpKind::Eq => (sym::eq, lang.eq_trait()), + hir::BinOpKind::Ne => (sym::ne, lang.eq_trait()), + hir::BinOpKind::And | hir::BinOpKind::Or => { + span_bug!(span, "&& and || are not overloadable") + } + } + } else if let Op::Unary(hir::UnOp::Not, _) = op { + (sym::not, lang.not_trait()) + } else if let Op::Unary(hir::UnOp::Neg, _) = op { + (sym::neg, lang.neg_trait()) + } else { + bug!("lookup_op_method: op not supported: {:?}", op) + }; + + debug!( + "lookup_op_method(lhs_ty={:?}, op={:?}, opname={:?}, trait_did={:?})", + lhs_ty, op, opname, trait_did + ); + + // Catches cases like #83893, where a lang item is declared with the + // wrong number of generic arguments. Should have yielded an error + // elsewhere by now, but we have to catch it here so that we do not + // index `other_tys` out of bounds (if the lang item has too many + // generic arguments, `other_tys` is too short). + if !has_expected_num_generic_args( + self.tcx, + trait_did, + match op { + // Binary ops have a generic right-hand side, unary ops don't + Op::Binary(..) => 1, + Op::Unary(..) => 0, + }, + ) { + return Err(vec![]); + } + + let opname = Ident::with_dummy_span(opname); + let method = trait_did.and_then(|trait_did| { + self.lookup_op_method_in_trait( + span, + opname, + trait_did, + lhs_ty, + other_ty, + other_ty_expr, + expected, + ) + }); + + match (method, trait_did) { + (Some(ok), _) => { + let method = self.register_infer_ok_obligations(ok); + self.select_obligations_where_possible(false, |_| {}); + Ok(method) + } + (None, None) => Err(vec![]), + (None, Some(trait_did)) => { + let (obligation, _) = self.obligation_for_op_method( + span, + trait_did, + lhs_ty, + other_ty, + other_ty_expr, + expected, + ); + let mut fulfill = <dyn TraitEngine<'_>>::new(self.tcx); + fulfill.register_predicate_obligation(self, obligation); + Err(fulfill.select_where_possible(&self.infcx)) + } + } + } +} + +// Binary operator categories. These categories summarize the behavior +// with respect to the builtin operations supported. +enum BinOpCategory { + /// &&, || -- cannot be overridden + Shortcircuit, + + /// <<, >> -- when shifting a single integer, rhs can be any + /// integer type. For simd, types must match. + Shift, + + /// +, -, etc -- takes equal types, produces same type as input, + /// applicable to ints/floats/simd + Math, + + /// &, |, ^ -- takes equal types, produces same type as input, + /// applicable to ints/floats/simd/bool + Bitwise, + + /// ==, !=, etc -- takes equal types, produces bools, except for simd, + /// which produce the input type + Comparison, +} + +impl BinOpCategory { + fn from(op: hir::BinOp) -> BinOpCategory { + match op.node { + hir::BinOpKind::Shl | hir::BinOpKind::Shr => BinOpCategory::Shift, + + hir::BinOpKind::Add + | hir::BinOpKind::Sub + | hir::BinOpKind::Mul + | hir::BinOpKind::Div + | hir::BinOpKind::Rem => BinOpCategory::Math, + + hir::BinOpKind::BitXor | hir::BinOpKind::BitAnd | hir::BinOpKind::BitOr => { + BinOpCategory::Bitwise + } + + hir::BinOpKind::Eq + | hir::BinOpKind::Ne + | hir::BinOpKind::Lt + | hir::BinOpKind::Le + | hir::BinOpKind::Ge + | hir::BinOpKind::Gt => BinOpCategory::Comparison, + + hir::BinOpKind::And | hir::BinOpKind::Or => BinOpCategory::Shortcircuit, + } + } +} + +/// Whether the binary operation is an assignment (`a += b`), or not (`a + b`) +#[derive(Clone, Copy, Debug, PartialEq)] +enum IsAssign { + No, + Yes, +} + +#[derive(Clone, Copy, Debug)] +enum Op { + Binary(hir::BinOp, IsAssign), + Unary(hir::UnOp, Span), +} + +/// Dereferences a single level of immutable referencing. +fn deref_ty_if_possible<'tcx>(ty: Ty<'tcx>) -> Ty<'tcx> { + match ty.kind() { + ty::Ref(_, ty, hir::Mutability::Not) => *ty, + _ => ty, + } +} + +/// Returns `true` if this is a built-in arithmetic operation (e.g., u32 +/// + u32, i16x4 == i16x4) and false if these types would have to be +/// overloaded to be legal. There are two reasons that we distinguish +/// builtin operations from overloaded ones (vs trying to drive +/// everything uniformly through the trait system and intrinsics or +/// something like that): +/// +/// 1. Builtin operations can trivially be evaluated in constants. +/// 2. For comparison operators applied to SIMD types the result is +/// not of type `bool`. For example, `i16x4 == i16x4` yields a +/// type like `i16x4`. This means that the overloaded trait +/// `PartialEq` is not applicable. +/// +/// Reason #2 is the killer. I tried for a while to always use +/// overloaded logic and just check the types in constants/codegen after +/// the fact, and it worked fine, except for SIMD types. -nmatsakis +fn is_builtin_binop<'tcx>(lhs: Ty<'tcx>, rhs: Ty<'tcx>, op: hir::BinOp) -> bool { + // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work. + // (See https://github.com/rust-lang/rust/issues/57447.) + let (lhs, rhs) = (deref_ty_if_possible(lhs), deref_ty_if_possible(rhs)); + + match BinOpCategory::from(op) { + BinOpCategory::Shortcircuit => true, + + BinOpCategory::Shift => { + lhs.references_error() + || rhs.references_error() + || lhs.is_integral() && rhs.is_integral() + } + + BinOpCategory::Math => { + lhs.references_error() + || rhs.references_error() + || lhs.is_integral() && rhs.is_integral() + || lhs.is_floating_point() && rhs.is_floating_point() + } + + BinOpCategory::Bitwise => { + lhs.references_error() + || rhs.references_error() + || lhs.is_integral() && rhs.is_integral() + || lhs.is_floating_point() && rhs.is_floating_point() + || lhs.is_bool() && rhs.is_bool() + } + + BinOpCategory::Comparison => { + lhs.references_error() || rhs.references_error() || lhs.is_scalar() && rhs.is_scalar() + } + } +} + +struct TypeParamVisitor<'tcx>(Vec<Ty<'tcx>>); + +impl<'tcx> TypeVisitor<'tcx> for TypeParamVisitor<'tcx> { + fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { + if let ty::Param(_) = ty.kind() { + self.0.push(ty); + } + ty.super_visit_with(self) + } +} + +struct TypeParamEraser<'a, 'tcx>(&'a FnCtxt<'a, 'tcx>, Span); + +impl<'tcx> TypeFolder<'tcx> for TypeParamEraser<'_, 'tcx> { + fn tcx(&self) -> TyCtxt<'tcx> { + self.0.tcx + } + + fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { + match ty.kind() { + ty::Param(_) => self.0.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::MiscVariable, + span: self.1, + }), + _ => ty.super_fold_with(self), + } + } +} |