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New upstream version 1.61.0+dfsg1
[rustc.git] / compiler / rustc_typeck / src / check / op.rs
CommitLineData
c34b1796
AL		 1//! Code related to processing overloaded binary and unary operators.
2
7cac9316 3use super::method::MethodCallee;
17df50a5 4use super::{has_expected_num_generic_args, FnCtxt};
29967ef6 5use rustc_ast as ast;
ee023bcb 6use rustc_errors::{self, struct_span_err, Applicability, Diagnostic};
dfeec247 7use rustc_hir as hir;
74b04a01 8use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
ba9703b0
XL		 9use rustc_middle::ty::adjustment::{
10 Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability,
11};
f035d41b 12use rustc_middle::ty::fold::TypeFolder;
ba9703b0 13use rustc_middle::ty::TyKind::{Adt, Array, Char, FnDef, Never, Ref, Str, Tuple, Uint};
f035d41b
XL		 14use rustc_middle::ty::{
15 self, suggest_constraining_type_param, Ty, TyCtxt, TypeFoldable, TypeVisitor,
16};
29967ef6 17use rustc_span::source_map::Spanned;
3dfed10e 18use rustc_span::symbol::{sym, Ident};
dfeec247 19use rustc_span::Span;
ba9703b0 20use rustc_trait_selection::infer::InferCtxtExt;
c295e0f8 21use rustc_trait_selection::traits::{FulfillmentError, TraitEngine, TraitEngineExt};
60c5eb7d 22
29967ef6
XL		 23use std::ops::ControlFlow;
24
dc9dc135 25impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
9fa01778 26 /// Checks a `a <op>= b`
dc9dc135
XL		 27 pub fn check_binop_assign(
28 &self,
dfeec247 29 expr: &'tcx hir::Expr<'tcx>,
dc9dc135 30 op: hir::BinOp,
dfeec247
XL		 31 lhs: &'tcx hir::Expr<'tcx>,
32 rhs: &'tcx hir::Expr<'tcx>,
dc9dc135 33 ) -> Ty<'tcx> {
abe05a73 34 let (lhs_ty, rhs_ty, return_ty) =
dfeec247 35 self.check_overloaded_binop(expr, lhs, rhs, op, IsAssign::Yes);
a7813a04 36
dfeec247
XL		 37 let ty =
38 if !lhs_ty.is_ty_var() && !rhs_ty.is_ty_var() && is_builtin_binop(lhs_ty, rhs_ty, op) {
ee023bcb 39 self.enforce_builtin_binop_types(lhs.span, lhs_ty, rhs.span, rhs_ty, op);
dfeec247
XL		 40 self.tcx.mk_unit()
41 } else {
42 return_ty
43 };
44
3c0e092e 45 self.check_lhs_assignable(lhs, "E0067", op.span);
c34b1796 46
9e0c209e 47 ty
c34b1796 48 }
c34b1796 49
9fa01778 50 /// Checks a potentially overloaded binary operator.
dc9dc135
XL		 51 pub fn check_binop(
52 &self,
dfeec247 53 expr: &'tcx hir::Expr<'tcx>,
dc9dc135 54 op: hir::BinOp,
dfeec247
XL		 55 lhs_expr: &'tcx hir::Expr<'tcx>,
56 rhs_expr: &'tcx hir::Expr<'tcx>,
dc9dc135 57 ) -> Ty<'tcx> {
a7813a04
XL		 58 let tcx = self.tcx;
59
dfeec247
XL		 60 debug!(
61 "check_binop(expr.hir_id={}, expr={:?}, op={:?}, lhs_expr={:?}, rhs_expr={:?})",
62 expr.hir_id, expr, op, lhs_expr, rhs_expr
63 );
a7813a04 64
a7813a04
XL		 65 match BinOpCategory::from(op) {
66 BinOpCategory::Shortcircuit => {
67 // && and || are a simple case.
f035d41b 68 self.check_expr_coercable_to_type(lhs_expr, tcx.types.bool, None);
476ff2be 69 let lhs_diverges = self.diverges.get();
f035d41b 70 self.check_expr_coercable_to_type(rhs_expr, tcx.types.bool, None);
476ff2be
SL		 71
72 // Depending on the LHS' value, the RHS can never execute.
73 self.diverges.set(lhs_diverges);
74
abe05a73 75 tcx.types.bool
c34b1796 76 }
a7813a04
XL		 77 _ => {
78 // Otherwise, we always treat operators as if they are
79 // overloaded. This is the way to be most flexible w/r/t
80 // types that get inferred.
abe05a73 81 let (lhs_ty, rhs_ty, return_ty) =
dfeec247 82 self.check_overloaded_binop(expr, lhs_expr, rhs_expr, op, IsAssign::No);
a7813a04
XL		 83
84 // Supply type inference hints if relevant. Probably these
85 // hints should be enforced during select as part of the
86 // `consider_unification_despite_ambiguity` routine, but this
87 // more convenient for now.
88 //
89 // The basic idea is to help type inference by taking
90 // advantage of things we know about how the impls for
91 // scalar types are arranged. This is important in a
92 // scenario like `1_u32 << 2`, because it lets us quickly
93 // deduce that the result type should be `u32`, even
94 // though we don't know yet what type 2 has and hence
95 // can't pin this down to a specific impl.
dfeec247
XL		 96 if !lhs_ty.is_ty_var()
97 && !rhs_ty.is_ty_var()
98 && is_builtin_binop(lhs_ty, rhs_ty, op)
a7813a04 99 {
74b04a01 100 let builtin_return_ty = self.enforce_builtin_binop_types(
ee023bcb 101 lhs_expr.span,
74b04a01 102 lhs_ty,
ee023bcb 103 rhs_expr.span,
74b04a01
XL		 104 rhs_ty,
105 op,
106 );
a7813a04
XL		 107 self.demand_suptype(expr.span, builtin_return_ty, return_ty);
108 }
c34b1796 109
9e0c209e 110 return_ty
a7813a04 111 }
c34b1796
AL		 112 }
113 }
c34b1796 114
dc9dc135
XL		 115 fn enforce_builtin_binop_types(
116 &self,
ee023bcb 117 lhs_span: Span,
dc9dc135 118 lhs_ty: Ty<'tcx>,
ee023bcb 119 rhs_span: Span,
dc9dc135
XL		 120 rhs_ty: Ty<'tcx>,
121 op: hir::BinOp,
122 ) -> Ty<'tcx> {
a7813a04
XL		 123 debug_assert!(is_builtin_binop(lhs_ty, rhs_ty, op));
124
74b04a01
XL		 125 // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work.
126 // (See https://github.com/rust-lang/rust/issues/57447.)
127 let (lhs_ty, rhs_ty) = (deref_ty_if_possible(lhs_ty), deref_ty_if_possible(rhs_ty));
128
a7813a04
XL		 129 let tcx = self.tcx;
130 match BinOpCategory::from(op) {
131 BinOpCategory::Shortcircuit => {
ee023bcb
FG		 132 self.demand_suptype(lhs_span, tcx.types.bool, lhs_ty);
133 self.demand_suptype(rhs_span, tcx.types.bool, rhs_ty);
f9f354fc 134 tcx.types.bool
a7813a04 135 }
c34b1796 136
a7813a04
XL		 137 BinOpCategory::Shift => {
138 // result type is same as LHS always
139 lhs_ty
140 }
c34b1796 141
dfeec247 142 BinOpCategory::Math | BinOpCategory::Bitwise => {
a7813a04 143 // both LHS and RHS and result will have the same type
ee023bcb 144 self.demand_suptype(rhs_span, lhs_ty, rhs_ty);
a7813a04
XL		 145 lhs_ty
146 }
c34b1796 147
a7813a04
XL		 148 BinOpCategory::Comparison => {
149 // both LHS and RHS and result will have the same type
ee023bcb 150 self.demand_suptype(rhs_span, lhs_ty, rhs_ty);
f9f354fc 151 tcx.types.bool
a7813a04 152 }
c34b1796
AL		 153 }
154 }
c34b1796 155
dc9dc135
XL		 156 fn check_overloaded_binop(
157 &self,
dfeec247
XL		 158 expr: &'tcx hir::Expr<'tcx>,
159 lhs_expr: &'tcx hir::Expr<'tcx>,
160 rhs_expr: &'tcx hir::Expr<'tcx>,
dc9dc135
XL		 161 op: hir::BinOp,
162 is_assign: IsAssign,
163 ) -> (Ty<'tcx>, Ty<'tcx>, Ty<'tcx>) {
dfeec247
XL		 164 debug!(
165 "check_overloaded_binop(expr.hir_id={}, op={:?}, is_assign={:?})",
166 expr.hir_id, op, is_assign
167 );
a7813a04 168
74d20737
XL		 169 let lhs_ty = match is_assign {
170 IsAssign::No => {
171 // Find a suitable supertype of the LHS expression's type, by coercing to
172 // a type variable, to pass as the `Self` to the trait, avoiding invariant
173 // trait matching creating lifetime constraints that are too strict.
0731742a 174 // e.g., adding `&'a T` and `&'b T`, given `&'x T: Add<&'x T>`, will result
74d20737 175 // in `&'a T <: &'x T` and `&'b T <: &'x T`, instead of `'a = 'b = 'x`.
f035d41b 176 let lhs_ty = self.check_expr(lhs_expr);
dc9dc135
XL		 177 let fresh_var = self.next_ty_var(TypeVariableOrigin {
178 kind: TypeVariableOriginKind::MiscVariable,
179 span: lhs_expr.span,
180 });
f035d41b 181 self.demand_coerce(lhs_expr, lhs_ty, fresh_var, Some(rhs_expr), AllowTwoPhase::No)
74d20737
XL		 182 }
183 IsAssign::Yes => {
184 // rust-lang/rust#52126: We have to use strict
185 // equivalence on the LHS of an assign-op like `+=`;
186 // overwritten or mutably-borrowed places cannot be
187 // coerced to a supertype.
f035d41b 188 self.check_expr(lhs_expr)
74d20737 189 }
abe05a73 190 };
e74abb32 191 let lhs_ty = self.resolve_vars_with_obligations(lhs_ty);
abe05a73 192
0731742a 193 // N.B., as we have not yet type-checked the RHS, we don't have the
a7813a04
XL		 194 // type at hand. Make a variable to represent it. The whole reason
195 // for this indirection is so that, below, we can check the expr
196 // using this variable as the expected type, which sometimes lets
197 // us do better coercions than we would be able to do otherwise,
198 // particularly for things like `String + &String`.
dc9dc135
XL		 199 let rhs_ty_var = self.next_ty_var(TypeVariableOrigin {
200 kind: TypeVariableOriginKind::MiscVariable,
201 span: rhs_expr.span,
202 });
a7813a04 203
ee023bcb
FG		 204 let result = self.lookup_op_method(
205 lhs_ty,
206 Some(rhs_ty_var),
207 Some(rhs_expr),
208 Op::Binary(op, is_assign),
209 );
8bb4bdeb
XL		 210
211 // see `NB` above
f035d41b 212 let rhs_ty = self.check_expr_coercable_to_type(rhs_expr, rhs_ty_var, Some(lhs_expr));
e74abb32 213 let rhs_ty = self.resolve_vars_with_obligations(rhs_ty);
8bb4bdeb 214
7cac9316
XL		 215 let return_ty = match result {
216 Ok(method) => {
217 let by_ref_binop = !op.node.is_by_value();
218 if is_assign == IsAssign::Yes || by_ref_binop {
1b1a35ee 219 if let ty::Ref(region, _, mutbl) = method.sig.inputs()[0].kind() {
94b46f34 220 let mutbl = match mutbl {
dfeec247
XL		 221 hir::Mutability::Not => AutoBorrowMutability::Not,
222 hir::Mutability::Mut => AutoBorrowMutability::Mut {
0531ce1d
XL		 223 // Allow two-phase borrows for binops in initial deployment
224 // since they desugar to methods
83c7162d 225 allow_two_phase_borrow: AllowTwoPhase::Yes,
dfeec247 226 },
2c00a5a8 227 };
7cac9316 228 let autoref = Adjustment {
5099ac24 229 kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)),
dfeec247 230 target: method.sig.inputs()[0],
7cac9316
XL		 231 };
232 self.apply_adjustments(lhs_expr, vec![autoref]);
233 }
234 }
235 if by_ref_binop {
1b1a35ee 236 if let ty::Ref(region, _, mutbl) = method.sig.inputs()[1].kind() {
94b46f34 237 let mutbl = match mutbl {
dfeec247
XL		 238 hir::Mutability::Not => AutoBorrowMutability::Not,
239 hir::Mutability::Mut => AutoBorrowMutability::Mut {
0531ce1d
XL		 240 // Allow two-phase borrows for binops in initial deployment
241 // since they desugar to methods
83c7162d 242 allow_two_phase_borrow: AllowTwoPhase::Yes,
dfeec247 243 },
2c00a5a8 244 };
7cac9316 245 let autoref = Adjustment {
5099ac24 246 kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)),
dfeec247 247 target: method.sig.inputs()[1],
7cac9316
XL		 248 };
249 // HACK(eddyb) Bypass checks due to reborrows being in
250 // some cases applied on the RHS, on top of which we need
251 // to autoref, which is not allowed by apply_adjustments.
252 // self.apply_adjustments(rhs_expr, vec![autoref]);
3dfed10e 253 self.typeck_results
3b2f2976
XL		 254 .borrow_mut()
255 .adjustments_mut()
256 .entry(rhs_expr.hir_id)
b7449926 257 .or_default()
3b2f2976 258 .push(autoref);
7cac9316
XL		 259 }
260 }
3b2f2976 261 self.write_method_call(expr.hir_id, method);
7cac9316
XL		 262
263 method.sig.output()
264 }
f035d41b 265 // error types are considered "builtin"
c295e0f8
XL		 266 Err(_) if lhs_ty.references_error() || rhs_ty.references_error() => self.tcx.ty_error(),
267 Err(errors) => {
f035d41b 268 let source_map = self.tcx.sess.source_map();
c295e0f8 269 let (mut err, missing_trait, use_output) = match is_assign {
f035d41b
XL		 270 IsAssign::Yes => {
271 let mut err = struct_span_err!(
272 self.tcx.sess,
273 expr.span,
274 E0368,
275 "binary assignment operation `{}=` cannot be applied to type `{}`",
276 op.node.as_str(),
277 lhs_ty,
278 );
279 err.span_label(
280 lhs_expr.span,
281 format!("cannot use `{}=` on type `{}`", op.node.as_str(), lhs_ty),
282 );
283 let missing_trait = match op.node {
284 hir::BinOpKind::Add => Some("std::ops::AddAssign"),
285 hir::BinOpKind::Sub => Some("std::ops::SubAssign"),
286 hir::BinOpKind::Mul => Some("std::ops::MulAssign"),
287 hir::BinOpKind::Div => Some("std::ops::DivAssign"),
288 hir::BinOpKind::Rem => Some("std::ops::RemAssign"),
289 hir::BinOpKind::BitAnd => Some("std::ops::BitAndAssign"),
290 hir::BinOpKind::BitXor => Some("std::ops::BitXorAssign"),
291 hir::BinOpKind::BitOr => Some("std::ops::BitOrAssign"),
292 hir::BinOpKind::Shl => Some("std::ops::ShlAssign"),
293 hir::BinOpKind::Shr => Some("std::ops::ShrAssign"),
294 _ => None,
295 };
c295e0f8
XL		 296 self.note_unmet_impls_on_type(&mut err, errors);
297 (err, missing_trait, false)
f035d41b
XL		 298 }
299 IsAssign::No => {
300 let (message, missing_trait, use_output) = match op.node {
301 hir::BinOpKind::Add => (
ee023bcb 302 format!("cannot add `{rhs_ty}` to `{lhs_ty}`"),
f035d41b
XL		 303 Some("std::ops::Add"),
304 true,
305 ),
306 hir::BinOpKind::Sub => (
ee023bcb 307 format!("cannot subtract `{rhs_ty}` from `{lhs_ty}`"),
f035d41b
XL		 308 Some("std::ops::Sub"),
309 true,
310 ),
311 hir::BinOpKind::Mul => (
ee023bcb 312 format!("cannot multiply `{lhs_ty}` by `{rhs_ty}`"),
f035d41b
XL		 313 Some("std::ops::Mul"),
314 true,
315 ),
316 hir::BinOpKind::Div => (
ee023bcb 317 format!("cannot divide `{lhs_ty}` by `{rhs_ty}`"),
f035d41b
XL		 318 Some("std::ops::Div"),
319 true,
320 ),
321 hir::BinOpKind::Rem => (
ee023bcb 322 format!("cannot mod `{lhs_ty}` by `{rhs_ty}`"),
f035d41b
XL		 323 Some("std::ops::Rem"),
324 true,
325 ),
326 hir::BinOpKind::BitAnd => (
ee023bcb 327 format!("no implementation for `{lhs_ty} & {rhs_ty}`"),
f035d41b
XL		 328 Some("std::ops::BitAnd"),
329 true,
330 ),
331 hir::BinOpKind::BitXor => (
ee023bcb 332 format!("no implementation for `{lhs_ty} ^ {rhs_ty}`"),
f035d41b
XL		 333 Some("std::ops::BitXor"),
334 true,
335 ),
336 hir::BinOpKind::BitOr => (
ee023bcb 337 format!("no implementation for `{lhs_ty} | {rhs_ty}`"),
f035d41b
XL		 338 Some("std::ops::BitOr"),
339 true,
340 ),
341 hir::BinOpKind::Shl => (
ee023bcb 342 format!("no implementation for `{lhs_ty} << {rhs_ty}`"),
f035d41b
XL		 343 Some("std::ops::Shl"),
344 true,
345 ),
346 hir::BinOpKind::Shr => (
ee023bcb 347 format!("no implementation for `{lhs_ty} >> {rhs_ty}`"),
f035d41b
XL		 348 Some("std::ops::Shr"),
349 true,
350 ),
351 hir::BinOpKind::Eq | hir::BinOpKind::Ne => (
352 format!(
353 "binary operation `{}` cannot be applied to type `{}`",
354 op.node.as_str(),
355 lhs_ty
356 ),
357 Some("std::cmp::PartialEq"),
358 false,
359 ),
360 hir::BinOpKind::Lt
361 | hir::BinOpKind::Le
362 | hir::BinOpKind::Gt
363 | hir::BinOpKind::Ge => (
364 format!(
365 "binary operation `{}` cannot be applied to type `{}`",
366 op.node.as_str(),
367 lhs_ty
368 ),
369 Some("std::cmp::PartialOrd"),
370 false,
371 ),
372 _ => (
373 format!(
374 "binary operation `{}` cannot be applied to type `{}`",
375 op.node.as_str(),
376 lhs_ty
377 ),
378 None,
379 false,
380 ),
381 };
382 let mut err =
383 struct_span_err!(self.tcx.sess, op.span, E0369, "{}", message.as_str());
f035d41b 384 if !lhs_expr.span.eq(&rhs_expr.span) {
c295e0f8 385 self.add_type_neq_err_label(
f035d41b
XL		 386 &mut err,
387 lhs_expr.span,
b7449926 388 lhs_ty,
f035d41b 389 rhs_ty,
ee023bcb 390 rhs_expr,
f035d41b
XL		 391 op,
392 is_assign,
b7449926 393 );
c295e0f8 394 self.add_type_neq_err_label(
f035d41b
XL		 395 &mut err,
396 rhs_expr.span,
397 rhs_ty,
398 lhs_ty,
ee023bcb 399 lhs_expr,
f035d41b
XL		 400 op,
401 is_assign,
b7449926 402 );
32a655c1 403 }
c295e0f8
XL		 404 self.note_unmet_impls_on_type(&mut err, errors);
405 (err, missing_trait, use_output)
f035d41b
XL		 406 }
407 };
1b1a35ee 408 if let Ref(_, rty, _) = lhs_ty.kind() {
5099ac24 409 if self.infcx.type_is_copy_modulo_regions(self.param_env, *rty, lhs_expr.span)
ee023bcb
FG		 410 && self
411 .lookup_op_method(
412 *rty,
413 Some(rhs_ty),
414 Some(rhs_expr),
415 Op::Binary(op, is_assign),
416 )
417 .is_ok()
3c0e092e 418 {
f035d41b
XL		 419 if let Ok(lstring) = source_map.span_to_snippet(lhs_expr.span) {
420 let msg = &format!(
421 "`{}{}` can be used on `{}`, you can dereference `{}`",
422 op.node.as_str(),
423 match is_assign {
424 IsAssign::Yes => "=",
425 IsAssign::No => "",
426 },
427 rty.peel_refs(),
428 lstring,
dfeec247 429 );
f035d41b
XL		 430 err.span_suggestion_verbose(
431 lhs_expr.span.shrink_to_lo(),
432 msg,
433 "*".to_string(),
434 rustc_errors::Applicability::MachineApplicable,
435 );
f035d41b
XL		 436 }
437 }
438 }
439 if let Some(missing_trait) = missing_trait {
5099ac24 440 let mut visitor = TypeParamVisitor(vec![]);
f035d41b
XL		 441 visitor.visit_ty(lhs_ty);
442
443 if op.node == hir::BinOpKind::Add
444 && self.check_str_addition(
445 lhs_expr, rhs_expr, lhs_ty, rhs_ty, &mut err, is_assign, op,
446 )
447 {
448 // This has nothing here because it means we did string
449 // concatenation (e.g., "Hello " + "World!"). This means
450 // we don't want the note in the else clause to be emitted
5099ac24 451 } else if let [ty] = &visitor.0[..] {
1b1a35ee 452 if let ty::Param(p) = *ty.kind() {
f035d41b
XL		 453 // Check if the method would be found if the type param wasn't
454 // involved. If so, it means that adding a trait bound to the param is
455 // enough. Otherwise we do not give the suggestion.
c295e0f8 456 let mut eraser = TypeParamEraser(self, expr.span);
f035d41b
XL		 457 let needs_bound = self
458 .lookup_op_method(
459 eraser.fold_ty(lhs_ty),
ee023bcb
FG		 460 Some(eraser.fold_ty(rhs_ty)),
461 Some(rhs_expr),
f035d41b
XL		 462 Op::Binary(op, is_assign),
463 )
464 .is_ok();
465 if needs_bound {
466 suggest_constraining_param(
467 self.tcx,
468 self.body_id,
48663c56 469 &mut err,
5099ac24 470 *ty,
48663c56 471 rhs_ty,
f035d41b
XL		 472 missing_trait,
473 p,
474 use_output,
48663c56 475 );
f035d41b
XL		 476 } else if *ty != lhs_ty {
477 // When we know that a missing bound is responsible, we don't show
478 // this note as it is redundant.
479 err.note(&format!(
ee023bcb 480 "the trait `{missing_trait}` is not implemented for `{lhs_ty}`"
f035d41b 481 ));
532ac7d7 482 }
f035d41b 483 } else {
1b1a35ee 484 bug!("type param visitor stored a non type param: {:?}", ty.kind());
a7813a04 485 }
b039eaaf
SL		 486 }
487 }
f035d41b
XL		 488 err.emit();
489 self.tcx.ty_error()
c34b1796 490 }
a7813a04 491 };
c34b1796 492
abe05a73 493 (lhs_ty, rhs_ty, return_ty)
a7813a04 494 }
c34b1796 495
48663c56 496 /// If one of the types is an uncalled function and calling it would yield the other type,
ba9703b0 497 /// suggest calling the function. Returns `true` if suggestion would apply (even if not given).
48663c56
XL		 498 fn add_type_neq_err_label(
499 &self,
ee023bcb 500 err: &mut Diagnostic,
48663c56
XL		 501 span: Span,
502 ty: Ty<'tcx>,
503 other_ty: Ty<'tcx>,
ee023bcb 504 other_expr: &'tcx hir::Expr<'tcx>,
48663c56
XL		 505 op: hir::BinOp,
506 is_assign: IsAssign,
3c0e092e 507 ) -> bool /* did we suggest to call a function because of missing parentheses? */ {
48663c56 508 err.span_label(span, ty.to_string());
1b1a35ee 509 if let FnDef(def_id, _) = *ty.kind() {
3dfed10e 510 if !self.tcx.has_typeck_results(def_id) {
48663c56
XL		 511 return false;
512 }
fc512014
XL		 513 // FIXME: Instead of exiting early when encountering bound vars in
514 // the function signature, consider keeping the binder here and
515 // propagating it downwards.
3c0e092e 516 let Some(fn_sig) = self.tcx.fn_sig(def_id).no_bound_vars() else {
fc512014
XL		 517 return false;
518 };
48663c56 519
1b1a35ee 520 let other_ty = if let FnDef(def_id, _) = *other_ty.kind() {
3dfed10e 521 if !self.tcx.has_typeck_results(def_id) {
48663c56
XL		 522 return false;
523 }
ba9703b0
XL		 524 // We're emitting a suggestion, so we can just ignore regions
525 self.tcx.fn_sig(def_id).skip_binder().output()
48663c56
XL		 526 } else {
527 other_ty
528 };
529
dfeec247 530 if self
ee023bcb
FG		 531 .lookup_op_method(
532 fn_sig.output(),
533 Some(other_ty),
534 Some(other_expr),
535 Op::Binary(op, is_assign),
536 )
dfeec247
XL		 537 .is_ok()
538 {
a2a8927a
XL		 539 let (variable_snippet, applicability) = if !fn_sig.inputs().is_empty() {
540 ("( /* arguments */ )".to_string(), Applicability::HasPlaceholders)
541 } else {
542 ("()".to_string(), Applicability::MaybeIncorrect)
543 };
48663c56 544
a2a8927a
XL		 545 err.span_suggestion_verbose(
546 span.shrink_to_hi(),
547 "you might have forgotten to call this function",
548 variable_snippet,
549 applicability,
550 );
48663c56
XL		 551 return true;
552 }
553 }
554 false
555 }
556
557 /// Provide actionable suggestions when trying to add two strings with incorrect types,
558 /// like `&str + &str`, `String + String` and `&str + &String`.
559 ///
560 /// If this function returns `true` it means a note was printed, so we don't need
561 /// to print the normal "implementation of `std::ops::Add` might be missing" note
8faf50e0
XL		 562 fn check_str_addition(
563 &self,
dfeec247
XL		 564 lhs_expr: &'tcx hir::Expr<'tcx>,
565 rhs_expr: &'tcx hir::Expr<'tcx>,
8faf50e0
XL		 566 lhs_ty: Ty<'tcx>,
567 rhs_ty: Ty<'tcx>,
ee023bcb 568 err: &mut Diagnostic,
f035d41b 569 is_assign: IsAssign,
532ac7d7 570 op: hir::BinOp,
8faf50e0 571 ) -> bool {
5099ac24
FG		 572 let str_concat_note = "string concatenation requires an owned `String` on the left";
573 let rm_borrow_msg = "remove the borrow to obtain an owned `String`";
574 let to_owned_msg = "create an owned `String` from a string reference";
48663c56 575
c295e0f8 576 let string_type = self.tcx.get_diagnostic_item(sym::String);
3dfed10e 577 let is_std_string = |ty: Ty<'tcx>| match ty.ty_adt_def() {
ee023bcb 578 Some(ty_def) => Some(ty_def.did()) == string_type,
3dfed10e
XL		 579 None => false,
580 };
48663c56 581
1b1a35ee 582 match (lhs_ty.kind(), rhs_ty.kind()) {
48663c56 583 (&Ref(_, l_ty, _), &Ref(_, r_ty, _)) // &str or &String + &str, &String or &&str
1b1a35ee
XL		 584 if (*l_ty.kind() == Str || is_std_string(l_ty)) && (
585 *r_ty.kind() == Str || is_std_string(r_ty) ||
48663c56
XL		 586 &format!("{:?}", rhs_ty) == "&&str"
587 ) =>
588 {
f035d41b 589 if let IsAssign::No = is_assign { // Do not supply this message if `&str += &str`
5099ac24
FG		 590 err.span_label(op.span, "`+` cannot be used to concatenate two `&str` strings");
591 err.note(str_concat_note);
592 if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind {
593 err.span_suggestion_verbose(
594 lhs_expr.span.until(lhs_inner_expr.span),
595 rm_borrow_msg,
596 "".to_owned(),
597 Applicability::MachineApplicable
598 );
599 } else {
600 err.span_suggestion_verbose(
601 lhs_expr.span.shrink_to_hi(),
602 to_owned_msg,
603 ".to_owned()".to_owned(),
604 Applicability::MachineApplicable
605 );
606 }
8faf50e0 607 }
0531ce1d 608 true
8bb4bdeb 609 }
48663c56 610 (&Ref(_, l_ty, _), &Adt(..)) // Handle `&str` & `&String` + `String`
1b1a35ee 611 if (*l_ty.kind() == Str || is_std_string(l_ty)) && is_std_string(rhs_ty) =>
48663c56
XL		 612 {
613 err.span_label(
614 op.span,
615 "`+` cannot be used to concatenate a `&str` with a `String`",
616 );
5099ac24
FG		 617 match is_assign {
618 IsAssign::No => {
619 let sugg_msg;
620 let lhs_sugg = if let hir::ExprKind::AddrOf(_, _, lhs_inner_expr) = lhs_expr.kind {
621 sugg_msg = "remove the borrow on the left and add one on the right";
622 (lhs_expr.span.until(lhs_inner_expr.span), "".to_owned())
48663c56 623 } else {
5099ac24
FG		 624 sugg_msg = "create an owned `String` on the left and add a borrow on the right";
625 (lhs_expr.span.shrink_to_hi(), ".to_owned()".to_owned())
48663c56 626 };
5099ac24
FG		 627 let suggestions = vec![
628 lhs_sugg,
629 (rhs_expr.span.shrink_to_lo(), "&".to_owned()),
630 ];
631 err.multipart_suggestion_verbose(
632 sugg_msg,
633 suggestions,
0bf4aa26
XL		 634 Applicability::MachineApplicable,
635 );
8faf50e0 636 }
5099ac24
FG		 637 IsAssign::Yes => {
638 err.note(str_concat_note);
0531ce1d 639 }
5099ac24 640 }
0531ce1d
XL		 641 true
642 }
643 _ => false,
8bb4bdeb 644 }
8bb4bdeb
XL		 645 }
646
dc9dc135
XL		 647 pub fn check_user_unop(
648 &self,
dfeec247 649 ex: &'tcx hir::Expr<'tcx>,
dc9dc135
XL		 650 operand_ty: Ty<'tcx>,
651 op: hir::UnOp,
652 ) -> Ty<'tcx> {
a7813a04 653 assert!(op.is_by_value());
ee023bcb 654 match self.lookup_op_method(operand_ty, None, None, Op::Unary(op, ex.span)) {
7cac9316 655 Ok(method) => {
3b2f2976 656 self.write_method_call(ex.hir_id, method);
7cac9316
XL		 657 method.sig.output()
658 }
c295e0f8 659 Err(errors) => {
fc512014 660 let actual = self.resolve_vars_if_possible(operand_ty);
7cac9316 661 if !actual.references_error() {
dfeec247
XL		 662 let mut err = struct_span_err!(
663 self.tcx.sess,
664 ex.span,
665 E0600,
666 "cannot apply unary operator `{}` to type `{}`",
667 op.as_str(),
668 actual
669 );
670 err.span_label(
671 ex.span,
f035d41b 672 format!("cannot apply unary operator `{}`", op.as_str()),
dfeec247 673 );
ee023bcb
FG		 674 let missing_trait = match op {
675 hir::UnOp::Deref => unreachable!("check unary op `-` or `!` only"),
676 hir::UnOp::Not => "std::ops::Not",
677 hir::UnOp::Neg => "std::ops::Neg",
678 };
679 let mut visitor = TypeParamVisitor(vec![]);
680 visitor.visit_ty(operand_ty);
681 if let [ty] = &visitor.0[..] && let ty::Param(p) = *operand_ty.kind() {
682 suggest_constraining_param(
683 self.tcx,
684 self.body_id,
685 &mut err,
686 *ty,
687 operand_ty,
688 missing_trait,
689 p,
690 true,
691 );
692 }
c295e0f8
XL		 693
694 let sp = self.tcx.sess.source_map().start_point(ex.span);
695 if let Some(sp) =
696 self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp)
697 {
698 // If the previous expression was a block expression, suggest parentheses
699 // (turning this into a binary subtraction operation instead.)
700 // for example, `{2} - 2` -> `({2}) - 2` (see src\test\ui\parser\expr-as-stmt.rs)
701 self.tcx.sess.parse_sess.expr_parentheses_needed(&mut err, *sp);
702 } else {
703 match actual.kind() {
704 Uint(_) if op == hir::UnOp::Neg => {
705 err.note("unsigned values cannot be negated");
706
707 if let hir::ExprKind::Unary(
708 _,
709 hir::Expr {
710 kind:
711 hir::ExprKind::Lit(Spanned {
712 node: ast::LitKind::Int(1, _),
713 ..
714 }),
715 ..
716 },
717 ) = ex.kind
718 {
719 err.span_suggestion(
720 ex.span,
721 &format!(
ee023bcb 722 "you may have meant the maximum value of `{actual}`",
c295e0f8 723 ),
ee023bcb 724 format!("{actual}::MAX"),
c295e0f8
XL		 725 Applicability::MaybeIncorrect,
726 );
727 }
728 }
729 Str | Never | Char | Tuple(_) | Array(_, _) => {}
730 Ref(_, lty, _) if *lty.kind() == Str => {}
731 _ => {
732 self.note_unmet_impls_on_type(&mut err, errors);
29967ef6 733 }
94b46f34
XL		 734 }
735 }
736 err.emit();
7cac9316 737 }
f035d41b 738 self.tcx.ty_error()
a7813a04 739 }
c34b1796
AL		 740 }
741 }
c34b1796 742
dfeec247
XL		 743 fn lookup_op_method(
744 &self,
745 lhs_ty: Ty<'tcx>,
ee023bcb
FG		 746 other_ty: Option<Ty<'tcx>>,
747 other_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
dfeec247 748 op: Op,
c295e0f8 749 ) -> Result<MethodCallee<'tcx>, Vec<FulfillmentError<'tcx>>> {
ea8adc8c 750 let lang = self.tcx.lang_items();
a7813a04 751
7cac9316
XL		 752 let span = match op {
753 Op::Binary(op, _) => op.span,
dfeec247 754 Op::Unary(_, span) => span,
7cac9316
XL		 755 };
756 let (opname, trait_did) = if let Op::Binary(op, IsAssign::Yes) = op {
a7813a04 757 match op.node {
3dfed10e
XL		 758 hir::BinOpKind::Add => (sym::add_assign, lang.add_assign_trait()),
759 hir::BinOpKind::Sub => (sym::sub_assign, lang.sub_assign_trait()),
760 hir::BinOpKind::Mul => (sym::mul_assign, lang.mul_assign_trait()),
761 hir::BinOpKind::Div => (sym::div_assign, lang.div_assign_trait()),
762 hir::BinOpKind::Rem => (sym::rem_assign, lang.rem_assign_trait()),
763 hir::BinOpKind::BitXor => (sym::bitxor_assign, lang.bitxor_assign_trait()),
764 hir::BinOpKind::BitAnd => (sym::bitand_assign, lang.bitand_assign_trait()),
765 hir::BinOpKind::BitOr => (sym::bitor_assign, lang.bitor_assign_trait()),
766 hir::BinOpKind::Shl => (sym::shl_assign, lang.shl_assign_trait()),
767 hir::BinOpKind::Shr => (sym::shr_assign, lang.shr_assign_trait()),
dfeec247
XL		 768 hir::BinOpKind::Lt
769 | hir::BinOpKind::Le
770 | hir::BinOpKind::Ge
771 | hir::BinOpKind::Gt
772 | hir::BinOpKind::Eq
773 | hir::BinOpKind::Ne
774 | hir::BinOpKind::And
775 | hir::BinOpKind::Or => {
776 span_bug!(span, "impossible assignment operation: {}=", op.node.as_str())
a7813a04 777 }
b039eaaf 778 }
7cac9316 779 } else if let Op::Binary(op, IsAssign::No) = op {
a7813a04 780 match op.node {
3dfed10e
XL		 781 hir::BinOpKind::Add => (sym::add, lang.add_trait()),
782 hir::BinOpKind::Sub => (sym::sub, lang.sub_trait()),
783 hir::BinOpKind::Mul => (sym::mul, lang.mul_trait()),
784 hir::BinOpKind::Div => (sym::div, lang.div_trait()),
785 hir::BinOpKind::Rem => (sym::rem, lang.rem_trait()),
786 hir::BinOpKind::BitXor => (sym::bitxor, lang.bitxor_trait()),
787 hir::BinOpKind::BitAnd => (sym::bitand, lang.bitand_trait()),
788 hir::BinOpKind::BitOr => (sym::bitor, lang.bitor_trait()),
789 hir::BinOpKind::Shl => (sym::shl, lang.shl_trait()),
790 hir::BinOpKind::Shr => (sym::shr, lang.shr_trait()),
791 hir::BinOpKind::Lt => (sym::lt, lang.partial_ord_trait()),
792 hir::BinOpKind::Le => (sym::le, lang.partial_ord_trait()),
793 hir::BinOpKind::Ge => (sym::ge, lang.partial_ord_trait()),
794 hir::BinOpKind::Gt => (sym::gt, lang.partial_ord_trait()),
795 hir::BinOpKind::Eq => (sym::eq, lang.eq_trait()),
796 hir::BinOpKind::Ne => (sym::ne, lang.eq_trait()),
8faf50e0 797 hir::BinOpKind::And | hir::BinOpKind::Or => {
7cac9316 798 span_bug!(span, "&& and || are not overloadable")
a7813a04 799 }
b039eaaf 800 }
6a06907d 801 } else if let Op::Unary(hir::UnOp::Not, _) = op {
3dfed10e 802 (sym::not, lang.not_trait())
6a06907d 803 } else if let Op::Unary(hir::UnOp::Neg, _) = op {
3dfed10e 804 (sym::neg, lang.neg_trait())
7cac9316
XL		 805 } else {
806 bug!("lookup_op_method: op not supported: {:?}", op)
807 };
c34b1796 808
dfeec247
XL		 809 debug!(
810 "lookup_op_method(lhs_ty={:?}, op={:?}, opname={:?}, trait_did={:?})",
811 lhs_ty, op, opname, trait_did
812 );
7cac9316 813
17df50a5
XL		 814 // Catches cases like #83893, where a lang item is declared with the
815 // wrong number of generic arguments. Should have yielded an error
816 // elsewhere by now, but we have to catch it here so that we do not
817 // index `other_tys` out of bounds (if the lang item has too many
818 // generic arguments, `other_tys` is too short).
819 if !has_expected_num_generic_args(
820 self.tcx,
821 trait_did,
822 match op {
823 // Binary ops have a generic right-hand side, unary ops don't
824 Op::Binary(..) => 1,
825 Op::Unary(..) => 0,
826 },
827 ) {
c295e0f8 828 return Err(vec![]);
17df50a5
XL		 829 }
830
c295e0f8 831 let opname = Ident::with_dummy_span(opname);
7cac9316 832 let method = trait_did.and_then(|trait_did| {
ee023bcb 833 self.lookup_op_method_in_trait(span, opname, trait_did, lhs_ty, other_ty, other_ty_expr)
7cac9316 834 });
c34b1796 835
c295e0f8
XL		 836 match (method, trait_did) {
837 (Some(ok), _) => {
cc61c64b 838 let method = self.register_infer_ok_obligations(ok);
e1599b0c 839 self.select_obligations_where_possible(false, |_| {});
7cac9316 840 Ok(method)
a7813a04 841 }
c295e0f8
XL		 842 (None, None) => Err(vec![]),
843 (None, Some(trait_did)) => {
844 let (obligation, _) =
ee023bcb 845 self.obligation_for_op_method(span, trait_did, lhs_ty, other_ty, other_ty_expr);
c295e0f8
XL		 846 let mut fulfill = <dyn TraitEngine<'_>>::new(self.tcx);
847 fulfill.register_predicate_obligation(self, obligation);
3c0e092e 848 Err(fulfill.select_where_possible(&self.infcx))
c295e0f8 849 }
c34b1796
AL		 850 }
851 }
852}
853
854// Binary operator categories. These categories summarize the behavior
ee023bcb 855// with respect to the builtin operations supported.
c34b1796
AL		 856enum BinOpCategory {
857 /// &&, || -- cannot be overridden
858 Shortcircuit,
859
860 /// <<, >> -- when shifting a single integer, rhs can be any
861 /// integer type. For simd, types must match.
862 Shift,
863
864 /// +, -, etc -- takes equal types, produces same type as input,
865 /// applicable to ints/floats/simd
866 Math,
867
868 /// &, |, ^ -- takes equal types, produces same type as input,
869 /// applicable to ints/floats/simd/bool
870 Bitwise,
871
872 /// ==, !=, etc -- takes equal types, produces bools, except for simd,
873 /// which produce the input type
874 Comparison,
875}
876
877impl BinOpCategory {
e9174d1e 878 fn from(op: hir::BinOp) -> BinOpCategory {
c34b1796 879 match op.node {
dfeec247
XL		 880 hir::BinOpKind::Shl | hir::BinOpKind::Shr => BinOpCategory::Shift,
881
882 hir::BinOpKind::Add
883 | hir::BinOpKind::Sub
884 | hir::BinOpKind::Mul
885 | hir::BinOpKind::Div
886 | hir::BinOpKind::Rem => BinOpCategory::Math,
887
888 hir::BinOpKind::BitXor | hir::BinOpKind::BitAnd | hir::BinOpKind::BitOr => {
889 BinOpCategory::Bitwise
890 }
891
892 hir::BinOpKind::Eq
893 | hir::BinOpKind::Ne
894 | hir::BinOpKind::Lt
895 | hir::BinOpKind::Le
896 | hir::BinOpKind::Ge
897 | hir::BinOpKind::Gt => BinOpCategory::Comparison,
898
899 hir::BinOpKind::And | hir::BinOpKind::Or => BinOpCategory::Shortcircuit,
c34b1796
AL		 900 }
901 }
902}
903
b039eaaf 904/// Whether the binary operation is an assignment (`a += b`), or not (`a + b`)
7cac9316 905#[derive(Clone, Copy, Debug, PartialEq)]
b039eaaf
SL		 906enum IsAssign {
907 No,
908 Yes,
909}
910
7cac9316
XL		 911#[derive(Clone, Copy, Debug)]
912enum Op {
913 Binary(hir::BinOp, IsAssign),
914 Unary(hir::UnOp, Span),
915}
916
74b04a01 917/// Dereferences a single level of immutable referencing.
a2a8927a 918fn deref_ty_if_possible<'tcx>(ty: Ty<'tcx>) -> Ty<'tcx> {
1b1a35ee 919 match ty.kind() {
5099ac24 920 ty::Ref(_, ty, hir::Mutability::Not) => *ty,
74b04a01
XL		 921 _ => ty,
922 }
923}
924
9fa01778 925/// Returns `true` if this is a built-in arithmetic operation (e.g., u32
c34b1796
AL		 926/// + u32, i16x4 == i16x4) and false if these types would have to be
927/// overloaded to be legal. There are two reasons that we distinguish
928/// builtin operations from overloaded ones (vs trying to drive
929/// everything uniformly through the trait system and intrinsics or
930/// something like that):
931///
932/// 1. Builtin operations can trivially be evaluated in constants.
933/// 2. For comparison operators applied to SIMD types the result is
9fa01778 934/// not of type `bool`. For example, `i16x4 == i16x4` yields a
c34b1796
AL		 935/// type like `i16x4`. This means that the overloaded trait
936/// `PartialEq` is not applicable.
937///
938/// Reason #2 is the killer. I tried for a while to always use
94b46f34 939/// overloaded logic and just check the types in constants/codegen after
c34b1796 940/// the fact, and it worked fine, except for SIMD types. -nmatsakis
74b04a01
XL		 941fn is_builtin_binop<'tcx>(lhs: Ty<'tcx>, rhs: Ty<'tcx>, op: hir::BinOp) -> bool {
942 // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work.
943 // (See https://github.com/rust-lang/rust/issues/57447.)
944 let (lhs, rhs) = (deref_ty_if_possible(lhs), deref_ty_if_possible(rhs));
945
c34b1796 946 match BinOpCategory::from(op) {
dfeec247 947 BinOpCategory::Shortcircuit => true,
c34b1796
AL		 948
949 BinOpCategory::Shift => {
dfeec247
XL		 950 lhs.references_error()
951 || rhs.references_error()
952 || lhs.is_integral() && rhs.is_integral()
c34b1796
AL		 953 }
954
955 BinOpCategory::Math => {
dfeec247
XL		 956 lhs.references_error()
957 || rhs.references_error()
958 || lhs.is_integral() && rhs.is_integral()
959 || lhs.is_floating_point() && rhs.is_floating_point()
c34b1796
AL		 960 }
961
962 BinOpCategory::Bitwise => {
dfeec247
XL		 963 lhs.references_error()
964 || rhs.references_error()
965 || lhs.is_integral() && rhs.is_integral()
966 || lhs.is_floating_point() && rhs.is_floating_point()
967 || lhs.is_bool() && rhs.is_bool()
c34b1796
AL		 968 }
969
970 BinOpCategory::Comparison => {
dfeec247 971 lhs.references_error() || rhs.references_error() || lhs.is_scalar() && rhs.is_scalar()
c34b1796
AL		 972 }
973 }
974}
74b04a01 975
f9f354fc
XL		 976fn suggest_constraining_param(
977 tcx: TyCtxt<'_>,
978 body_id: hir::HirId,
ee023bcb 979 mut err: &mut Diagnostic,
f9f354fc
XL		 980 lhs_ty: Ty<'_>,
981 rhs_ty: Ty<'_>,
982 missing_trait: &str,
983 p: ty::ParamTy,
984 set_output: bool,
985) {
986 let hir = tcx.hir();
ee023bcb 987 let msg = &format!("`{lhs_ty}` might need a bound for `{missing_trait}`");
f9f354fc
XL		 988 // Try to find the def-id and details for the parameter p. We have only the index,
989 // so we have to find the enclosing function's def-id, then look through its declared
990 // generic parameters to get the declaration.
991 let def_id = hir.body_owner_def_id(hir::BodyId { hir_id: body_id });
992 let generics = tcx.generics_of(def_id);
993 let param_def_id = generics.type_param(&p, tcx).def_id;
994 if let Some(generics) = param_def_id
995 .as_local()
3dfed10e 996 .map(|id| hir.local_def_id_to_hir_id(id))
5099ac24 997 .and_then(|id| hir.find_by_def_id(hir.get_parent_item(id)))
f9f354fc
XL		 998 .as_ref()
999 .and_then(|node| node.generics())
1000 {
ee023bcb 1001 let output = if set_output { format!("<Output = {rhs_ty}>") } else { String::new() };
f9f354fc
XL		 1002 suggest_constraining_type_param(
1003 tcx,
1004 generics,
1005 &mut err,
ee023bcb
FG		 1006 &lhs_ty.to_string(),
1007 &format!("{missing_trait}{output}"),
f9f354fc
XL		 1008 None,
1009 );
1010 } else {
1011 let span = tcx.def_span(param_def_id);
1012 err.span_label(span, msg);
1013 }
1014}
f035d41b 1015
5099ac24 1016struct TypeParamVisitor<'tcx>(Vec<Ty<'tcx>>);
f035d41b
XL		 1017
1018impl<'tcx> TypeVisitor<'tcx> for TypeParamVisitor<'tcx> {
fc512014 1019 fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1b1a35ee 1020 if let ty::Param(_) = ty.kind() {
5099ac24 1021 self.0.push(ty);
f035d41b
XL		 1022 }
1023 ty.super_visit_with(self)
1024 }
1025}
1026
1027struct TypeParamEraser<'a, 'tcx>(&'a FnCtxt<'a, 'tcx>, Span);
1028
a2a8927a 1029impl<'tcx> TypeFolder<'tcx> for TypeParamEraser<'_, 'tcx> {
f035d41b
XL		 1030 fn tcx(&self) -> TyCtxt<'tcx> {
1031 self.0.tcx
1032 }
1033
1034 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
1b1a35ee 1035 match ty.kind() {
f035d41b
XL		 1036 ty::Param(_) => self.0.next_ty_var(TypeVariableOrigin {
1037 kind: TypeVariableOriginKind::MiscVariable,
1038 span: self.1,
1039 }),
1040 _ => ty.super_fold_with(self),
1041 }
1042 }
1043}
backport for Debian buster