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Mention implementers of unsatisfied trait

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When encountering an unsatisfied trait bound, if there are no other
suggestions, mention all the types that *do* implement that trait:

```
error[E0277]: the trait bound `f32: Foo` is not satisfied
  --> $DIR/impl_wf.rs:22:6
   |
LL | impl Baz<f32> for f32 { }
   |      ^^^^^^^^ the trait `Foo` is not implemented for `f32`
   |
   = help: the following other types implement trait `Foo`:
             Option<T>
             i32
             str
note: required by a bound in `Baz`
  --> $DIR/impl_wf.rs:18:31
   |
LL | trait Baz<U: ?Sized> where U: Foo { }
   |                               ^^^ required by this bound in `Baz`
```

Mention implementers of traits in `ImplObligation`s.

Do not mention other `impl`s for closures, ranges and `?`.
This commit is contained in:
Esteban Kuber
2021-12-13 20:56:40 +00:00
parent 6a9080b25e
commit 3aac307ca6
115 changed files with 690 additions and 183 deletions
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25
compiler/rustc_mir_transform/src/check_packed_ref.rs
View File

@@ -1,10 +1,9 @@
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::def_id::LocalDefId;
use rustc_middle::mir::visit::{PlaceContext, Visitor};
use rustc_middle::mir::*;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{self, TyCtxt};
use rustc_session::lint::builtin::UNALIGNED_REFERENCES;
use rustc_span::symbol::sym;
use crate::util;
use crate::MirLint;
@@ -50,22 +49,6 @@ fn unsafe_derive_on_repr_packed(tcx: TyCtxt<'_>, def_id: LocalDefId) {
});
}
fn builtin_derive_def_id(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
debug!("builtin_derive_def_id({:?})", def_id);
if let Some(impl_def_id) = tcx.impl_of_method(def_id) {
if tcx.has_attr(impl_def_id, sym::automatically_derived) {
debug!("builtin_derive_def_id({:?}) - is {:?}", def_id, impl_def_id);
Some(impl_def_id)
} else {
debug!("builtin_derive_def_id({:?}) - not automatically derived", def_id);
None
}
} else {
debug!("builtin_derive_def_id({:?}) - not a method", def_id);
None
}
}
impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
// Make sure we know where in the MIR we are.
@@ -83,7 +66,11 @@ impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
if context.is_borrow() {
if util::is_disaligned(self.tcx, self.body, self.param_env, *place) {
let def_id = self.body.source.instance.def_id();
if let Some(impl_def_id) = builtin_derive_def_id(self.tcx, def_id) {
if let Some(impl_def_id) = self
.tcx
.impl_of_method(def_id)
.filter(|&def_id| self.tcx.is_builtin_derive(def_id))
{
// If a method is defined in the local crate,
// the impl containing that method should also be.
self.tcx.ensure().unsafe_derive_on_repr_packed(impl_def_id.expect_local());