1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
12 use super::check_argument_types;
13 use super::check_expr;
14 use super::check_method_argument_types;
16 use super::DeferredCallResolution;
18 use super::Expectation;
19 use super::expected_types_for_fn_args;
22 use super::structurally_resolved_type;
23 use super::TupleArgumentsFlag;
24 use super::UnresolvedTypeAction;
25 use super::write_call;
28 use middle::cstore::LOCAL_CRATE;
29 use middle::def_id::DefId;
31 use middle::ty::{self, LvaluePreference, Ty};
32 use syntax::codemap::Span;
33 use syntax::parse::token;
38 /// Check that it is legal to call methods of the trait corresponding
39 /// to `trait_id` (this only cares about the trait, not the specific
40 /// method that is called)
41 pub fn check_legal_trait_for_method_call(ccx: &CrateCtxt, span: Span, trait_id: DefId) {
43 let did = Some(trait_id);
44 let li = &tcx.lang_items;
46 if did == li.drop_trait() {
47 span_err!(tcx.sess, span, E0040, "explicit use of destructor method");
48 } else if !tcx.sess.features.borrow().unboxed_closures {
49 // the #[feature(unboxed_closures)] feature isn't
50 // activated so we need to enforce the closure
53 let method = if did == li.fn_trait() {
55 } else if did == li.fn_mut_trait() {
57 } else if did == li.fn_once_trait() {
60 return // not a closure method, everything is OK.
63 span_err!(tcx.sess, span, E0174,
64 "explicit use of unboxed closure method `{}` is experimental",
66 fileline_help!(tcx.sess, span,
67 "add `#![feature(unboxed_closures)]` to the crate attributes to enable");
71 pub fn check_call<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
72 call_expr: &'tcx hir::Expr,
73 callee_expr: &'tcx hir::Expr,
74 arg_exprs: &'tcx [P<hir::Expr>],
75 expected: Expectation<'tcx>)
77 check_expr(fcx, callee_expr);
78 let original_callee_ty = fcx.expr_ty(callee_expr);
79 let (callee_ty, _, result) =
84 UnresolvedTypeAction::Error,
85 LvaluePreference::NoPreference,
87 try_overloaded_call_step(fcx, call_expr, callee_expr, adj_ty, idx)
92 // this will report an error since original_callee_ty is not a fn
93 confirm_builtin_call(fcx, call_expr, original_callee_ty, arg_exprs, expected);
96 Some(CallStep::Builtin) => {
97 confirm_builtin_call(fcx, call_expr, callee_ty, arg_exprs, expected);
100 Some(CallStep::DeferredClosure(fn_sig)) => {
101 confirm_deferred_closure_call(fcx, call_expr, arg_exprs, expected, fn_sig);
104 Some(CallStep::Overloaded(method_callee)) => {
105 confirm_overloaded_call(fcx, call_expr, callee_expr,
106 arg_exprs, expected, method_callee);
111 enum CallStep<'tcx> {
113 DeferredClosure(ty::FnSig<'tcx>),
114 Overloaded(ty::MethodCallee<'tcx>)
117 fn try_overloaded_call_step<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
118 call_expr: &'tcx hir::Expr,
119 callee_expr: &'tcx hir::Expr,
120 adjusted_ty: Ty<'tcx>,
122 -> Option<CallStep<'tcx>>
124 debug!("try_overloaded_call_step(call_expr={:?}, adjusted_ty={:?}, autoderefs={})",
129 // If the callee is a bare function or a closure, then we're all set.
130 match structurally_resolved_type(fcx, callee_expr.span, adjusted_ty).sty {
131 ty::TyBareFn(..) => {
132 fcx.write_autoderef_adjustment(callee_expr.id, autoderefs);
133 return Some(CallStep::Builtin);
136 ty::TyClosure(def_id, ref substs) => {
137 assert_eq!(def_id.krate, LOCAL_CRATE);
139 // Check whether this is a call to a closure where we
140 // haven't yet decided on whether the closure is fn vs
141 // fnmut vs fnonce. If so, we have to defer further processing.
142 if fcx.infcx().closure_kind(def_id).is_none() {
144 fcx.infcx().closure_type(def_id, substs);
146 fcx.infcx().replace_late_bound_regions_with_fresh_var(call_expr.span,
149 fcx.record_deferred_call_resolution(def_id, Box::new(CallResolution {
150 call_expr: call_expr,
151 callee_expr: callee_expr,
152 adjusted_ty: adjusted_ty,
153 autoderefs: autoderefs,
154 fn_sig: fn_sig.clone(),
155 closure_def_id: def_id
157 return Some(CallStep::DeferredClosure(fn_sig));
161 // Hack: we know that there are traits implementing Fn for &F
162 // where F:Fn and so forth. In the particular case of types
163 // like `x: &mut FnMut()`, if there is a call `x()`, we would
164 // normally translate to `FnMut::call_mut(&mut x, ())`, but
165 // that winds up requiring `mut x: &mut FnMut()`. A little
166 // over the top. The simplest fix by far is to just ignore
167 // this case and deref again, so we wind up with
168 // `FnMut::call_mut(&mut *x, ())`.
169 ty::TyRef(..) if autoderefs == 0 => {
176 try_overloaded_call_traits(fcx, call_expr, callee_expr, adjusted_ty, autoderefs)
177 .map(|method_callee| CallStep::Overloaded(method_callee))
180 fn try_overloaded_call_traits<'a,'tcx>(fcx: &FnCtxt<'a, 'tcx>,
181 call_expr: &hir::Expr,
182 callee_expr: &hir::Expr,
183 adjusted_ty: Ty<'tcx>,
185 -> Option<ty::MethodCallee<'tcx>>
187 // Try the options that are least restrictive on the caller first.
188 for &(opt_trait_def_id, method_name) in &[
189 (fcx.tcx().lang_items.fn_trait(), token::intern("call")),
190 (fcx.tcx().lang_items.fn_mut_trait(), token::intern("call_mut")),
191 (fcx.tcx().lang_items.fn_once_trait(), token::intern("call_once")),
193 let trait_def_id = match opt_trait_def_id {
194 Some(def_id) => def_id,
198 match method::lookup_in_trait_adjusted(fcx,
208 Some(method_callee) => {
209 return Some(method_callee);
217 fn confirm_builtin_call<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
218 call_expr: &hir::Expr,
220 arg_exprs: &'tcx [P<hir::Expr>],
221 expected: Expectation<'tcx>)
225 let fn_sig = match callee_ty.sty {
226 ty::TyBareFn(_, &ty::BareFnTy {ref sig, ..}) => {
230 fcx.type_error_message(call_expr.span, |actual| {
231 format!("expected function, found `{}`", actual)
234 if let hir::ExprCall(ref expr, _) = call_expr.node {
236 if let Some(pr) = tcx.def_map.borrow().get(&expr.id) {
238 if let Some(span) = tcx.map.span_if_local(pr.def_id()) {
239 tcx.sess.span_note(span, "defined here")
245 // This is the "default" function signature, used in case of error.
246 // In that case, we check each argument against "error" in order to
247 // set up all the node type bindings.
248 error_fn_sig = ty::Binder(ty::FnSig {
249 inputs: err_args(fcx.tcx(), arg_exprs.len()),
250 output: ty::FnConverging(fcx.tcx().types.err),
258 // Replace any late-bound regions that appear in the function
259 // signature with region variables. We also have to
260 // renormalize the associated types at this point, since they
261 // previously appeared within a `Binder<>` and hence would not
262 // have been normalized before.
264 fcx.infcx().replace_late_bound_regions_with_fresh_var(call_expr.span,
268 fcx.normalize_associated_types_in(call_expr.span, &fn_sig);
270 // Call the generic checker.
271 let expected_arg_tys = expected_types_for_fn_args(fcx,
276 check_argument_types(fcx,
279 &expected_arg_tys[..],
282 TupleArgumentsFlag::DontTupleArguments);
284 write_call(fcx, call_expr, fn_sig.output);
287 fn confirm_deferred_closure_call<'a,'tcx>(fcx: &FnCtxt<'a,'tcx>,
288 call_expr: &hir::Expr,
289 arg_exprs: &'tcx [P<hir::Expr>],
290 expected: Expectation<'tcx>,
291 fn_sig: ty::FnSig<'tcx>)
293 // `fn_sig` is the *signature* of the cosure being called. We
294 // don't know the full details yet (`Fn` vs `FnMut` etc), but we
295 // do know the types expected for each argument and the return
298 let expected_arg_tys =
299 expected_types_for_fn_args(fcx,
302 fn_sig.output.clone(),
305 check_argument_types(fcx,
311 TupleArgumentsFlag::TupleArguments);
313 write_call(fcx, call_expr, fn_sig.output);
316 fn confirm_overloaded_call<'a,'tcx>(fcx: &FnCtxt<'a, 'tcx>,
317 call_expr: &hir::Expr,
318 callee_expr: &'tcx hir::Expr,
319 arg_exprs: &'tcx [P<hir::Expr>],
320 expected: Expectation<'tcx>,
321 method_callee: ty::MethodCallee<'tcx>)
324 check_method_argument_types(fcx,
329 TupleArgumentsFlag::TupleArguments,
331 write_call(fcx, call_expr, output_type);
333 write_overloaded_call_method_map(fcx, call_expr, method_callee);
336 fn write_overloaded_call_method_map<'a,'tcx>(fcx: &FnCtxt<'a, 'tcx>,
337 call_expr: &hir::Expr,
338 method_callee: ty::MethodCallee<'tcx>) {
339 let method_call = ty::MethodCall::expr(call_expr.id);
340 fcx.inh.tables.borrow_mut().method_map.insert(method_call, method_callee);
344 struct CallResolution<'tcx> {
345 call_expr: &'tcx hir::Expr,
346 callee_expr: &'tcx hir::Expr,
347 adjusted_ty: Ty<'tcx>,
349 fn_sig: ty::FnSig<'tcx>,
350 closure_def_id: DefId,
353 impl<'tcx> DeferredCallResolution<'tcx> for CallResolution<'tcx> {
354 fn resolve<'a>(&mut self, fcx: &FnCtxt<'a,'tcx>) {
355 debug!("DeferredCallResolution::resolve() {:?}",
358 // we should not be invoked until the closure kind has been
359 // determined by upvar inference
360 assert!(fcx.infcx().closure_kind(self.closure_def_id).is_some());
362 // We may now know enough to figure out fn vs fnmut etc.
363 match try_overloaded_call_traits(fcx, self.call_expr, self.callee_expr,
364 self.adjusted_ty, self.autoderefs) {
365 Some(method_callee) => {
366 // One problem is that when we get here, we are going
367 // to have a newly instantiated function signature
368 // from the call trait. This has to be reconciled with
369 // the older function signature we had before. In
370 // principle we *should* be able to fn_sigs(), but we
371 // can't because of the annoying need for a TypeTrace.
372 // (This always bites me, should find a way to
374 let method_sig = fcx.tcx().no_late_bound_regions(method_callee.ty.fn_sig())
377 debug!("attempt_resolution: method_callee={:?}",
380 for (&method_arg_ty, &self_arg_ty) in
381 method_sig.inputs[1..].iter().zip(&self.fn_sig.inputs)
383 demand::eqtype(fcx, self.call_expr.span, self_arg_ty, method_arg_ty);
386 let nilty = fcx.tcx().mk_nil();
389 method_sig.output.unwrap_or(nilty),
390 self.fn_sig.output.unwrap_or(nilty));
392 write_overloaded_call_method_map(fcx, self.call_expr, method_callee);
395 fcx.tcx().sess.span_bug(
397 "failed to find an overloaded call trait for closure call");