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diff --git a/crates/ra_hir/src/ty/infer/expr.rs b/crates/ra_hir/src/ty/infer/expr.rs
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1//! Type inference for expressions.
2
3use std::iter::{repeat, repeat_with};
4use std::sync::Arc;
5
6use hir_def::{
7 builtin_type::Signedness,
8 generics::GenericParams,
9 path::{GenericArg, GenericArgs},
10 resolver::resolver_for_expr,
11};
12use hir_expand::name;
13
14use crate::{
15 db::HirDatabase,
16 expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
17 ty::{
18 autoderef, method_resolution, op, CallableDef, InferTy, IntTy, Mutability, Namespace,
19 Obligation, ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor, TypeWalk,
20 Uncertain,
21 },
22 Adt, Name,
23};
24
25use super::{BindingMode, Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch};
26
27impl<'a, D: HirDatabase> InferenceContext<'a, D> {
28 pub(super) fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
29 let ty = self.infer_expr_inner(tgt_expr, expected);
30 let could_unify = self.unify(&ty, &expected.ty);
31 if !could_unify {
32 self.result.type_mismatches.insert(
33 tgt_expr,
34 TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() },
35 );
36 }
37 let ty = self.resolve_ty_as_possible(&mut vec![], ty);
38 ty
39 }
40
41 /// Infer type of expression with possibly implicit coerce to the expected type.
42 /// Return the type after possible coercion.
43 fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
44 let ty = self.infer_expr_inner(expr, &expected);
45 let ty = if !self.coerce(&ty, &expected.ty) {
46 self.result
47 .type_mismatches
48 .insert(expr, TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() });
49 // Return actual type when type mismatch.
50 // This is needed for diagnostic when return type mismatch.
51 ty
52 } else if expected.ty == Ty::Unknown {
53 ty
54 } else {
55 expected.ty.clone()
56 };
57
58 self.resolve_ty_as_possible(&mut vec![], ty)
59 }
60
61 fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
62 let body = Arc::clone(&self.body); // avoid borrow checker problem
63 let ty = match &body[tgt_expr] {
64 Expr::Missing => Ty::Unknown,
65 Expr::If { condition, then_branch, else_branch } => {
66 // if let is desugared to match, so this is always simple if
67 self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
68
69 let then_ty = self.infer_expr_inner(*then_branch, &expected);
70 let else_ty = match else_branch {
71 Some(else_branch) => self.infer_expr_inner(*else_branch, &expected),
72 None => Ty::unit(),
73 };
74
75 self.coerce_merge_branch(&then_ty, &else_ty)
76 }
77 Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected),
78 Expr::TryBlock { body } => {
79 let _inner = self.infer_expr(*body, expected);
80 // FIXME should be std::result::Result<{inner}, _>
81 Ty::Unknown
82 }
83 Expr::Loop { body } => {
84 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
85 // FIXME handle break with value
86 Ty::simple(TypeCtor::Never)
87 }
88 Expr::While { condition, body } => {
89 // while let is desugared to a match loop, so this is always simple while
90 self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
91 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
92 Ty::unit()
93 }
94 Expr::For { iterable, body, pat } => {
95 let iterable_ty = self.infer_expr(*iterable, &Expectation::none());
96
97 let pat_ty = match self.resolve_into_iter_item() {
98 Some(into_iter_item_alias) => {
99 let pat_ty = self.new_type_var();
100 let projection = ProjectionPredicate {
101 ty: pat_ty.clone(),
102 projection_ty: ProjectionTy {
103 associated_ty: into_iter_item_alias,
104 parameters: Substs::single(iterable_ty),
105 },
106 };
107 self.obligations.push(Obligation::Projection(projection));
108 self.resolve_ty_as_possible(&mut vec![], pat_ty)
109 }
110 None => Ty::Unknown,
111 };
112
113 self.infer_pat(*pat, &pat_ty, BindingMode::default());
114 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
115 Ty::unit()
116 }
117 Expr::Lambda { body, args, arg_types } => {
118 assert_eq!(args.len(), arg_types.len());
119
120 let mut sig_tys = Vec::new();
121
122 for (arg_pat, arg_type) in args.iter().zip(arg_types.iter()) {
123 let expected = if let Some(type_ref) = arg_type {
124 self.make_ty(type_ref)
125 } else {
126 Ty::Unknown
127 };
128 let arg_ty = self.infer_pat(*arg_pat, &expected, BindingMode::default());
129 sig_tys.push(arg_ty);
130 }
131
132 // add return type
133 let ret_ty = self.new_type_var();
134 sig_tys.push(ret_ty.clone());
135 let sig_ty = Ty::apply(
136 TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 },
137 Substs(sig_tys.into()),
138 );
139 let closure_ty =
140 Ty::apply_one(TypeCtor::Closure { def: self.owner, expr: tgt_expr }, sig_ty);
141
142 // Eagerly try to relate the closure type with the expected
143 // type, otherwise we often won't have enough information to
144 // infer the body.
145 self.coerce(&closure_ty, &expected.ty);
146
147 self.infer_expr(*body, &Expectation::has_type(ret_ty));
148 closure_ty
149 }
150 Expr::Call { callee, args } => {
151 let callee_ty = self.infer_expr(*callee, &Expectation::none());
152 let (param_tys, ret_ty) = match callee_ty.callable_sig(self.db) {
153 Some(sig) => (sig.params().to_vec(), sig.ret().clone()),
154 None => {
155 // Not callable
156 // FIXME: report an error
157 (Vec::new(), Ty::Unknown)
158 }
159 };
160 self.register_obligations_for_call(&callee_ty);
161 self.check_call_arguments(args, &param_tys);
162 let ret_ty = self.normalize_associated_types_in(ret_ty);
163 ret_ty
164 }
165 Expr::MethodCall { receiver, args, method_name, generic_args } => self
166 .infer_method_call(tgt_expr, *receiver, &args, &method_name, generic_args.as_ref()),
167 Expr::Match { expr, arms } => {
168 let input_ty = self.infer_expr(*expr, &Expectation::none());
169
170 let mut result_ty = self.new_maybe_never_type_var();
171
172 for arm in arms {
173 for &pat in &arm.pats {
174 let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default());
175 }
176 if let Some(guard_expr) = arm.guard {
177 self.infer_expr(
178 guard_expr,
179 &Expectation::has_type(Ty::simple(TypeCtor::Bool)),
180 );
181 }
182
183 let arm_ty = self.infer_expr_inner(arm.expr, &expected);
184 result_ty = self.coerce_merge_branch(&result_ty, &arm_ty);
185 }
186
187 result_ty
188 }
189 Expr::Path(p) => {
190 // FIXME this could be more efficient...
191 let resolver = resolver_for_expr(self.db, self.owner.into(), tgt_expr);
192 self.infer_path(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown)
193 }
194 Expr::Continue => Ty::simple(TypeCtor::Never),
195 Expr::Break { expr } => {
196 if let Some(expr) = expr {
197 // FIXME handle break with value
198 self.infer_expr(*expr, &Expectation::none());
199 }
200 Ty::simple(TypeCtor::Never)
201 }
202 Expr::Return { expr } => {
203 if let Some(expr) = expr {
204 self.infer_expr(*expr, &Expectation::has_type(self.return_ty.clone()));
205 }
206 Ty::simple(TypeCtor::Never)
207 }
208 Expr::RecordLit { path, fields, spread } => {
209 let (ty, def_id) = self.resolve_variant(path.as_ref());
210 if let Some(variant) = def_id {
211 self.write_variant_resolution(tgt_expr.into(), variant);
212 }
213
214 self.unify(&ty, &expected.ty);
215
216 let substs = ty.substs().unwrap_or_else(Substs::empty);
217 let field_types =
218 def_id.map(|it| self.db.field_types(it.into())).unwrap_or_default();
219 for (field_idx, field) in fields.iter().enumerate() {
220 let field_def = def_id.and_then(|it| match it.field(self.db, &field.name) {
221 Some(field) => Some(field),
222 None => {
223 self.push_diagnostic(InferenceDiagnostic::NoSuchField {
224 expr: tgt_expr,
225 field: field_idx,
226 });
227 None
228 }
229 });
230 if let Some(field_def) = field_def {
231 self.result.record_field_resolutions.insert(field.expr, field_def);
232 }
233 let field_ty = field_def
234 .map_or(Ty::Unknown, |it| field_types[it.id].clone())
235 .subst(&substs);
236 self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty));
237 }
238 if let Some(expr) = spread {
239 self.infer_expr(*expr, &Expectation::has_type(ty.clone()));
240 }
241 ty
242 }
243 Expr::Field { expr, name } => {
244 let receiver_ty = self.infer_expr(*expr, &Expectation::none());
245 let canonicalized = self.canonicalizer().canonicalize_ty(receiver_ty);
246 let ty = autoderef::autoderef(
247 self.db,
248 &self.resolver.clone(),
249 canonicalized.value.clone(),
250 )
251 .find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) {
252 Ty::Apply(a_ty) => match a_ty.ctor {
253 TypeCtor::Tuple { .. } => name
254 .as_tuple_index()
255 .and_then(|idx| a_ty.parameters.0.get(idx).cloned()),
256 TypeCtor::Adt(Adt::Struct(s)) => s.field(self.db, name).map(|field| {
257 self.write_field_resolution(tgt_expr, field);
258 self.db.field_types(s.id.into())[field.id]
259 .clone()
260 .subst(&a_ty.parameters)
261 }),
262 _ => None,
263 },
264 _ => None,
265 })
266 .unwrap_or(Ty::Unknown);
267 let ty = self.insert_type_vars(ty);
268 self.normalize_associated_types_in(ty)
269 }
270 Expr::Await { expr } => {
271 let inner_ty = self.infer_expr(*expr, &Expectation::none());
272 let ty = match self.resolve_future_future_output() {
273 Some(future_future_output_alias) => {
274 let ty = self.new_type_var();
275 let projection = ProjectionPredicate {
276 ty: ty.clone(),
277 projection_ty: ProjectionTy {
278 associated_ty: future_future_output_alias,
279 parameters: Substs::single(inner_ty),
280 },
281 };
282 self.obligations.push(Obligation::Projection(projection));
283 self.resolve_ty_as_possible(&mut vec![], ty)
284 }
285 None => Ty::Unknown,
286 };
287 ty
288 }
289 Expr::Try { expr } => {
290 let inner_ty = self.infer_expr(*expr, &Expectation::none());
291 let ty = match self.resolve_ops_try_ok() {
292 Some(ops_try_ok_alias) => {
293 let ty = self.new_type_var();
294 let projection = ProjectionPredicate {
295 ty: ty.clone(),
296 projection_ty: ProjectionTy {
297 associated_ty: ops_try_ok_alias,
298 parameters: Substs::single(inner_ty),
299 },
300 };
301 self.obligations.push(Obligation::Projection(projection));
302 self.resolve_ty_as_possible(&mut vec![], ty)
303 }
304 None => Ty::Unknown,
305 };
306 ty
307 }
308 Expr::Cast { expr, type_ref } => {
309 let _inner_ty = self.infer_expr(*expr, &Expectation::none());
310 let cast_ty = self.make_ty(type_ref);
311 // FIXME check the cast...
312 cast_ty
313 }
314 Expr::Ref { expr, mutability } => {
315 let expectation =
316 if let Some((exp_inner, exp_mutability)) = &expected.ty.as_reference() {
317 if *exp_mutability == Mutability::Mut && *mutability == Mutability::Shared {
318 // FIXME: throw type error - expected mut reference but found shared ref,
319 // which cannot be coerced
320 }
321 Expectation::has_type(Ty::clone(exp_inner))
322 } else {
323 Expectation::none()
324 };
325 // FIXME reference coercions etc.
326 let inner_ty = self.infer_expr(*expr, &expectation);
327 Ty::apply_one(TypeCtor::Ref(*mutability), inner_ty)
328 }
329 Expr::Box { expr } => {
330 let inner_ty = self.infer_expr(*expr, &Expectation::none());
331 if let Some(box_) = self.resolve_boxed_box() {
332 Ty::apply_one(TypeCtor::Adt(box_), inner_ty)
333 } else {
334 Ty::Unknown
335 }
336 }
337 Expr::UnaryOp { expr, op } => {
338 let inner_ty = self.infer_expr(*expr, &Expectation::none());
339 match op {
340 UnaryOp::Deref => {
341 let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty);
342 if let Some(derefed_ty) =
343 autoderef::deref(self.db, &self.resolver, &canonicalized.value)
344 {
345 canonicalized.decanonicalize_ty(derefed_ty.value)
346 } else {
347 Ty::Unknown
348 }
349 }
350 UnaryOp::Neg => {
351 match &inner_ty {
352 Ty::Apply(a_ty) => match a_ty.ctor {
353 TypeCtor::Int(Uncertain::Unknown)
354 | TypeCtor::Int(Uncertain::Known(IntTy {
355 signedness: Signedness::Signed,
356 ..
357 }))
358 | TypeCtor::Float(..) => inner_ty,
359 _ => Ty::Unknown,
360 },
361 Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => {
362 inner_ty
363 }
364 // FIXME: resolve ops::Neg trait
365 _ => Ty::Unknown,
366 }
367 }
368 UnaryOp::Not => {
369 match &inner_ty {
370 Ty::Apply(a_ty) => match a_ty.ctor {
371 TypeCtor::Bool | TypeCtor::Int(_) => inner_ty,
372 _ => Ty::Unknown,
373 },
374 Ty::Infer(InferTy::IntVar(..)) => inner_ty,
375 // FIXME: resolve ops::Not trait for inner_ty
376 _ => Ty::Unknown,
377 }
378 }
379 }
380 }
381 Expr::BinaryOp { lhs, rhs, op } => match op {
382 Some(op) => {
383 let lhs_expectation = match op {
384 BinaryOp::LogicOp(..) => Expectation::has_type(Ty::simple(TypeCtor::Bool)),
385 _ => Expectation::none(),
386 };
387 let lhs_ty = self.infer_expr(*lhs, &lhs_expectation);
388 // FIXME: find implementation of trait corresponding to operation
389 // symbol and resolve associated `Output` type
390 let rhs_expectation = op::binary_op_rhs_expectation(*op, lhs_ty);
391 let rhs_ty = self.infer_expr(*rhs, &Expectation::has_type(rhs_expectation));
392
393 // FIXME: similar as above, return ty is often associated trait type
394 op::binary_op_return_ty(*op, rhs_ty)
395 }
396 _ => Ty::Unknown,
397 },
398 Expr::Index { base, index } => {
399 let _base_ty = self.infer_expr(*base, &Expectation::none());
400 let _index_ty = self.infer_expr(*index, &Expectation::none());
401 // FIXME: use `std::ops::Index::Output` to figure out the real return type
402 Ty::Unknown
403 }
404 Expr::Tuple { exprs } => {
405 let mut tys = match &expected.ty {
406 ty_app!(TypeCtor::Tuple { .. }, st) => st
407 .iter()
408 .cloned()
409 .chain(repeat_with(|| self.new_type_var()))
410 .take(exprs.len())
411 .collect::<Vec<_>>(),
412 _ => (0..exprs.len()).map(|_| self.new_type_var()).collect(),
413 };
414
415 for (expr, ty) in exprs.iter().zip(tys.iter_mut()) {
416 self.infer_expr_coerce(*expr, &Expectation::has_type(ty.clone()));
417 }
418
419 Ty::apply(TypeCtor::Tuple { cardinality: tys.len() as u16 }, Substs(tys.into()))
420 }
421 Expr::Array(array) => {
422 let elem_ty = match &expected.ty {
423 ty_app!(TypeCtor::Array, st) | ty_app!(TypeCtor::Slice, st) => {
424 st.as_single().clone()
425 }
426 _ => self.new_type_var(),
427 };
428
429 match array {
430 Array::ElementList(items) => {
431 for expr in items.iter() {
432 self.infer_expr_coerce(*expr, &Expectation::has_type(elem_ty.clone()));
433 }
434 }
435 Array::Repeat { initializer, repeat } => {
436 self.infer_expr_coerce(
437 *initializer,
438 &Expectation::has_type(elem_ty.clone()),
439 );
440 self.infer_expr(
441 *repeat,
442 &Expectation::has_type(Ty::simple(TypeCtor::Int(Uncertain::Known(
443 IntTy::usize(),
444 )))),
445 );
446 }
447 }
448
449 Ty::apply_one(TypeCtor::Array, elem_ty)
450 }
451 Expr::Literal(lit) => match lit {
452 Literal::Bool(..) => Ty::simple(TypeCtor::Bool),
453 Literal::String(..) => {
454 Ty::apply_one(TypeCtor::Ref(Mutability::Shared), Ty::simple(TypeCtor::Str))
455 }
456 Literal::ByteString(..) => {
457 let byte_type = Ty::simple(TypeCtor::Int(Uncertain::Known(IntTy::u8())));
458 let slice_type = Ty::apply_one(TypeCtor::Slice, byte_type);
459 Ty::apply_one(TypeCtor::Ref(Mutability::Shared), slice_type)
460 }
461 Literal::Char(..) => Ty::simple(TypeCtor::Char),
462 Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int((*ty).into())),
463 Literal::Float(_v, ty) => Ty::simple(TypeCtor::Float((*ty).into())),
464 },
465 };
466 // use a new type variable if we got Ty::Unknown here
467 let ty = self.insert_type_vars_shallow(ty);
468 let ty = self.resolve_ty_as_possible(&mut vec![], ty);
469 self.write_expr_ty(tgt_expr, ty.clone());
470 ty
471 }
472
473 fn infer_block(
474 &mut self,
475 statements: &[Statement],
476 tail: Option<ExprId>,
477 expected: &Expectation,
478 ) -> Ty {
479 let mut diverges = false;
480 for stmt in statements {
481 match stmt {
482 Statement::Let { pat, type_ref, initializer } => {
483 let decl_ty =
484 type_ref.as_ref().map(|tr| self.make_ty(tr)).unwrap_or(Ty::Unknown);
485
486 // Always use the declared type when specified
487 let mut ty = decl_ty.clone();
488
489 if let Some(expr) = initializer {
490 let actual_ty =
491 self.infer_expr_coerce(*expr, &Expectation::has_type(decl_ty.clone()));
492 if decl_ty == Ty::Unknown {
493 ty = actual_ty;
494 }
495 }
496
497 let ty = self.resolve_ty_as_possible(&mut vec![], ty);
498 self.infer_pat(*pat, &ty, BindingMode::default());
499 }
500 Statement::Expr(expr) => {
501 if let ty_app!(TypeCtor::Never) = self.infer_expr(*expr, &Expectation::none()) {
502 diverges = true;
503 }
504 }
505 }
506 }
507
508 let ty = if let Some(expr) = tail {
509 self.infer_expr_coerce(expr, expected)
510 } else {
511 self.coerce(&Ty::unit(), &expected.ty);
512 Ty::unit()
513 };
514 if diverges {
515 Ty::simple(TypeCtor::Never)
516 } else {
517 ty
518 }
519 }
520
521 fn infer_method_call(
522 &mut self,
523 tgt_expr: ExprId,
524 receiver: ExprId,
525 args: &[ExprId],
526 method_name: &Name,
527 generic_args: Option<&GenericArgs>,
528 ) -> Ty {
529 let receiver_ty = self.infer_expr(receiver, &Expectation::none());
530 let canonicalized_receiver = self.canonicalizer().canonicalize_ty(receiver_ty.clone());
531 let resolved = method_resolution::lookup_method(
532 &canonicalized_receiver.value,
533 self.db,
534 method_name,
535 &self.resolver,
536 );
537 let (derefed_receiver_ty, method_ty, def_generics) = match resolved {
538 Some((ty, func)) => {
539 let ty = canonicalized_receiver.decanonicalize_ty(ty);
540 self.write_method_resolution(tgt_expr, func);
541 (
542 ty,
543 self.db.type_for_def(func.into(), Namespace::Values),
544 Some(self.db.generic_params(func.id.into())),
545 )
546 }
547 None => (receiver_ty, Ty::Unknown, None),
548 };
549 let substs = self.substs_for_method_call(def_generics, generic_args, &derefed_receiver_ty);
550 let method_ty = method_ty.apply_substs(substs);
551 let method_ty = self.insert_type_vars(method_ty);
552 self.register_obligations_for_call(&method_ty);
553 let (expected_receiver_ty, param_tys, ret_ty) = match method_ty.callable_sig(self.db) {
554 Some(sig) => {
555 if !sig.params().is_empty() {
556 (sig.params()[0].clone(), sig.params()[1..].to_vec(), sig.ret().clone())
557 } else {
558 (Ty::Unknown, Vec::new(), sig.ret().clone())
559 }
560 }
561 None => (Ty::Unknown, Vec::new(), Ty::Unknown),
562 };
563 // Apply autoref so the below unification works correctly
564 // FIXME: return correct autorefs from lookup_method
565 let actual_receiver_ty = match expected_receiver_ty.as_reference() {
566 Some((_, mutability)) => Ty::apply_one(TypeCtor::Ref(mutability), derefed_receiver_ty),
567 _ => derefed_receiver_ty,
568 };
569 self.unify(&expected_receiver_ty, &actual_receiver_ty);
570
571 self.check_call_arguments(args, &param_tys);
572 let ret_ty = self.normalize_associated_types_in(ret_ty);
573 ret_ty
574 }
575
576 fn check_call_arguments(&mut self, args: &[ExprId], param_tys: &[Ty]) {
577 // Quoting https://github.com/rust-lang/rust/blob/6ef275e6c3cb1384ec78128eceeb4963ff788dca/src/librustc_typeck/check/mod.rs#L3325 --
578 // We do this in a pretty awful way: first we type-check any arguments
579 // that are not closures, then we type-check the closures. This is so
580 // that we have more information about the types of arguments when we
581 // type-check the functions. This isn't really the right way to do this.
582 for &check_closures in &[false, true] {
583 let param_iter = param_tys.iter().cloned().chain(repeat(Ty::Unknown));
584 for (&arg, param_ty) in args.iter().zip(param_iter) {
585 let is_closure = match &self.body[arg] {
586 Expr::Lambda { .. } => true,
587 _ => false,
588 };
589
590 if is_closure != check_closures {
591 continue;
592 }
593
594 let param_ty = self.normalize_associated_types_in(param_ty);
595 self.infer_expr_coerce(arg, &Expectation::has_type(param_ty.clone()));
596 }
597 }
598 }
599
600 fn substs_for_method_call(
601 &mut self,
602 def_generics: Option<Arc<GenericParams>>,
603 generic_args: Option<&GenericArgs>,
604 receiver_ty: &Ty,
605 ) -> Substs {
606 let (parent_param_count, param_count) =
607 def_generics.as_ref().map_or((0, 0), |g| (g.count_parent_params(), g.params.len()));
608 let mut substs = Vec::with_capacity(parent_param_count + param_count);
609 // Parent arguments are unknown, except for the receiver type
610 if let Some(parent_generics) = def_generics.and_then(|p| p.parent_params.clone()) {
611 for param in &parent_generics.params {
612 if param.name == name::SELF_TYPE {
613 substs.push(receiver_ty.clone());
614 } else {
615 substs.push(Ty::Unknown);
616 }
617 }
618 }
619 // handle provided type arguments
620 if let Some(generic_args) = generic_args {
621 // if args are provided, it should be all of them, but we can't rely on that
622 for arg in generic_args.args.iter().take(param_count) {
623 match arg {
624 GenericArg::Type(type_ref) => {
625 let ty = self.make_ty(type_ref);
626 substs.push(ty);
627 }
628 }
629 }
630 };
631 let supplied_params = substs.len();
632 for _ in supplied_params..parent_param_count + param_count {
633 substs.push(Ty::Unknown);
634 }
635 assert_eq!(substs.len(), parent_param_count + param_count);
636 Substs(substs.into())
637 }
638
639 fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
640 if let Ty::Apply(a_ty) = callable_ty {
641 if let TypeCtor::FnDef(def) = a_ty.ctor {
642 let generic_predicates = self.db.generic_predicates(def.into());
643 for predicate in generic_predicates.iter() {
644 let predicate = predicate.clone().subst(&a_ty.parameters);
645 if let Some(obligation) = Obligation::from_predicate(predicate) {
646 self.obligations.push(obligation);
647 }
648 }
649 // add obligation for trait implementation, if this is a trait method
650 match def {
651 CallableDef::Function(f) => {
652 if let Some(trait_) = f.parent_trait(self.db) {
653 // construct a TraitDef
654 let substs = a_ty.parameters.prefix(
655 self.db
656 .generic_params(trait_.id.into())
657 .count_params_including_parent(),
658 );
659 self.obligations.push(Obligation::Trait(TraitRef { trait_, substs }));
660 }
661 }
662 CallableDef::Struct(_) | CallableDef::EnumVariant(_) => {}
663 }
664 }
665 }
666 }
667}
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-17 05:01:48 +0100