use rustc_hir::def_id::DefId;
use rustc_hir::{self as hir, HirId, LangItem};
use rustc_infer::infer::TyCtxtInferExt;
+use rustc_infer::traits::{ImplSource, Obligation, ObligationCause};
use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor};
use rustc_middle::mir::*;
use rustc_middle::ty::cast::CastTy;
use rustc_middle::ty::{
self, adjustment::PointerCast, Instance, InstanceDef, Ty, TyCtxt, TypeAndMut,
};
+use rustc_middle::ty::{Binder, TraitPredicate, TraitRef};
use rustc_span::{sym, Span, Symbol};
use rustc_trait_selection::traits::error_reporting::InferCtxtExt;
-use rustc_trait_selection::traits::{self, TraitEngine};
+use rustc_trait_selection::traits::{self, SelectionContext, TraitEngine};
use std::mem;
use std::ops::Deref;
}
};
- // Resolve a trait method call to its concrete implementation, which may be in a
- // `const` trait impl.
- if self.tcx.features().const_trait_impl {
+ // Attempting to call a trait method?
+ if let Some(trait_id) = tcx.trait_of_item(callee) {
+ if !self.tcx.features().const_trait_impl {
+ self.check_op(ops::FnCallNonConst(callee));
+ return;
+ }
+
+ let trait_ref = TraitRef::from_method(tcx, trait_id, substs);
+ let obligation = Obligation::new(
+ ObligationCause::dummy(),
+ param_env,
+ Binder::bind(TraitPredicate {
+ trait_ref: TraitRef::from_method(tcx, trait_id, substs),
+ }),
+ );
+
+ let implsrc = tcx.infer_ctxt().enter(|infcx| {
+ let mut selcx = SelectionContext::new(&infcx);
+ selcx.select(&obligation).unwrap()
+ });
+
+ // If the method is provided via a where-clause that does not use the `?const`
+ // opt-out, the call is allowed.
+ if let Some(ImplSource::Param(_, hir::Constness::Const)) = implsrc {
+ debug!(
+ "const_trait_impl: provided {:?} via where-clause in {:?}",
+ trait_ref, param_env
+ );
+ return;
+ }
+
+ // Resolve a trait method call to its concrete implementation, which may be in a
+ // `const` trait impl.
let instance = Instance::resolve(tcx, param_env, callee, substs);
debug!("Resolving ({:?}) -> {:?}", callee, instance);
if let Ok(Some(func)) = instance {