mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Highlight conflicting param-env candidates

Browse Source
This commit is contained in:
Michael Goulet 2022-07-02 01:30:07 +00:00
parent 9b21131278
commit 08135254dc
8 changed files with 114 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
compiler/rustc_middle/src/traits/mod.rs
View File

@ -546,9 +546,17 @@ pub enum SelectionError<'tcx> {
ErrorReporting,
/// Multiple applicable `impl`s where found. The `DefId`s correspond to
/// all the `impl`s' Items.
Ambiguous(Vec<DefId>),
Ambiguous(Vec<AmbiguousSelection>),
}
#[derive(Copy, Clone, Debug)]
pub enum AmbiguousSelection {
Impl(DefId),
ParamEnv(Span),
}
TrivialTypeTraversalAndLiftImpls! { AmbiguousSelection, }
/// When performing resolution, it is typically the case that there
/// can be one of three outcomes:
///

41
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
View File

@ -23,7 +23,7 @@
use rustc_hir::Item;
use rustc_hir::Node;
use rustc_infer::infer::error_reporting::same_type_modulo_infer;
use rustc_infer::traits::TraitEngine;
use rustc_infer::traits::{AmbiguousSelection, TraitEngine};
use rustc_middle::thir::abstract_const::NotConstEvaluatable;
use rustc_middle::traits::select::OverflowError;
use rustc_middle::ty::error::ExpectedFound;
@ -1404,7 +1404,7 @@ fn suggest_unsized_bound_if_applicable(
fn annotate_source_of_ambiguity(
&self,
err: &mut Diagnostic,
impls: &[DefId],
impls: &[AmbiguousSelection],
predicate: ty::Predicate<'tcx>,
);
@ -2020,6 +2020,14 @@ fn maybe_report_ambiguity(
);
match selcx.select_from_obligation(&obligation) {
Err(SelectionError::Ambiguous(impls)) if impls.len() > 1 => {
if self.is_tainted_by_errors() && subst.is_none() {
// If `subst.is_none()`, then this is probably two param-env
// candidates or impl candidates that are equal modulo lifetimes.
// Therefore, if we've already emitted an error, just skip this
// one, since it's not particularly actionable.
err.cancel();
return;
}
self.annotate_source_of_ambiguity(&mut err, &impls, predicate);
}
_ => {
@ -2170,24 +2178,35 @@ fn maybe_report_ambiguity(
fn annotate_source_of_ambiguity(
&self,
err: &mut Diagnostic,
impls: &[DefId],
impls: &[AmbiguousSelection],
predicate: ty::Predicate<'tcx>,
) {
let mut spans = vec![];
let mut crates = vec![];
let mut post = vec![];
for def_id in impls {
match self.tcx.span_of_impl(*def_id) {
Ok(span) => spans.push(span),
Err(name) => {
crates.push(name);
if let Some(header) = to_pretty_impl_header(self.tcx, *def_id) {
post.push(header);
let mut or_where_clause = false;
for ambig in impls {
match ambig {
AmbiguousSelection::Impl(def_id) => match self.tcx.span_of_impl(*def_id) {
Ok(span) => spans.push(span),
Err(name) => {
crates.push(name);
if let Some(header) = to_pretty_impl_header(self.tcx, *def_id) {
post.push(header);
}
}
},
AmbiguousSelection::ParamEnv(span) => {
or_where_clause = true;
spans.push(*span);
}
}
}
let msg = format!("multiple `impl`s satisfying `{}` found", predicate);
let msg = format!(
"multiple `impl`s{} satisfying `{}` found",
if or_where_clause { " or `where` clauses" } else { "" },
predicate
);
let mut crate_names: Vec<_> = crates.iter().map(|n| format!("`{}`", n)).collect();
crate_names.sort();
crate_names.dedup();

43
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View File

@ -6,9 +6,11 @@
//!
//! [rustc dev guide]:https://rustc-dev-guide.rust-lang.org/traits/resolution.html#candidate-assembly
use hir::LangItem;
use rustc_data_structures::fx::FxHashMap;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_infer::traits::TraitEngine;
use rustc_infer::traits::util::elaborate_predicates_with_span;
use rustc_infer::traits::{AmbiguousSelection, TraitEngine};
use rustc_infer::traits::{Obligation, SelectionError, TraitObligation};
use rustc_lint_defs::builtin::DEREF_INTO_DYN_SUPERTRAIT;
use rustc_middle::ty::print::with_no_trimmed_paths;
@ -199,11 +201,48 @@ fn candidate_from_obligation_no_cache<'o>(
// and report ambiguity.
if i > 1 {
debug!("multiple matches, ambig");
// Collect a list of (probable) spans that point to a param-env candidate
let tcx = self.infcx.tcx;
let owner = stack.obligation.cause.body_id.owner.to_def_id();
let predicates = tcx.predicates_of(owner).instantiate_identity(tcx);
let param_env_spans: FxHashMap<_, _> = elaborate_predicates_with_span(
tcx,
std::iter::zip(predicates.predicates, predicates.spans),
)
.filter_map(|obligation| {
let kind = obligation.predicate.kind();
if let ty::PredicateKind::Trait(trait_pred) = kind.skip_binder() {
if trait_pred.trait_ref
== ty::TraitRef::identity(tcx, trait_pred.def_id())
.skip_binder()
{
// HACK: Remap the `Self: Trait` predicate that every trait has to a more useful span
Some((
kind.rebind(trait_pred),
tcx.def_span(trait_pred.def_id()),
))
} else {
Some((kind.rebind(trait_pred), obligation.cause.span))
}
} else {
None
}
})
.collect();
return Err(Ambiguous(
candidates
.into_iter()
.filter_map(|c| match c.candidate {
SelectionCandidate::ImplCandidate(def_id) => Some(def_id),
SelectionCandidate::ImplCandidate(def_id) => {
Some(AmbiguousSelection::Impl(def_id))
}
SelectionCandidate::ParamCandidate(predicate) => {
Some(AmbiguousSelection::ParamEnv(
*param_env_spans.get(&predicate)?,
))
}
_ => None,
})
.collect(),

8
src/test/ui/issues/issue-21974.stderr
View File

@ -4,7 +4,13 @@ error[E0283]: type annotations needed: cannot satisfy `&'a T: Foo`
LL | where &'a T : Foo,
| ^^^
|
= note: cannot satisfy `&'a T: Foo`
note: multiple `impl`s or `where` clauses satisfying `&'a T: Foo` found
--> $DIR/issue-21974.rs:11:19
|
LL | where &'a T : Foo,
| ^^^
LL | &'b T : Foo
| ^^^
error: aborting due to previous error

6
src/test/ui/issues/issue-24424.stderr
View File

@ -4,7 +4,11 @@ error[E0283]: type annotations needed: cannot satisfy `T0: Trait0<'l0>`
LL | impl <'l0, 'l1, T0> Trait1<'l0, T0> for bool where T0 : Trait0<'l0>, T0 : Trait0<'l1> {}
| ^^^^^^^^^^^
|
= note: cannot satisfy `T0: Trait0<'l0>`
note: multiple `impl`s or `where` clauses satisfying `T0: Trait0<'l0>` found
--> $DIR/issue-24424.rs:4:57
|
LL | impl <'l0, 'l1, T0> Trait1<'l0, T0> for bool where T0 : Trait0<'l0>, T0 : Trait0<'l1> {}
| ^^^^^^^^^^^ ^^^^^^^^^^^
error: aborting due to previous error

8
src/test/ui/lifetimes/issue-34979.stderr
View File

@ -4,7 +4,13 @@ error[E0283]: type annotations needed: cannot satisfy `&'a (): Foo`
LL | &'a (): Foo,
| ^^^
|
= note: cannot satisfy `&'a (): Foo`
note: multiple `impl`s or `where` clauses satisfying `&'a (): Foo` found
--> $DIR/issue-34979.rs:6:13
|
LL | &'a (): Foo,
| ^^^
LL | &'static (): Foo;
| ^^^
error: aborting due to previous error

9
src/test/ui/traits/issue-85735.stderr
View File

@ -4,7 +4,14 @@ error[E0283]: type annotations needed: cannot satisfy `T: FnMut<(&'a (),)>`
LL | T: FnMut(&'a ()),
| ^^^^^^^^^^^^^
|
= note: cannot satisfy `T: FnMut<(&'a (),)>`
note: multiple `impl`s or `where` clauses satisfying `T: FnMut<(&'a (),)>` found
--> $DIR/issue-85735.rs:7:8
|
LL | T: FnMut(&'a ()),
| ^^^^^^^^^^^^^
LL |
LL | T: FnMut(&'b ()),
| ^^^^^^^^^^^^^
error: aborting due to previous error

8
src/test/ui/type/type-check/issue-40294.stderr
View File

@ -4,7 +4,13 @@ error[E0283]: type annotations needed: cannot satisfy `&'a T: Foo`
LL | where &'a T : Foo,
| ^^^
|
= note: cannot satisfy `&'a T: Foo`
note: multiple `impl`s or `where` clauses satisfying `&'a T: Foo` found
--> $DIR/issue-40294.rs:6:19
|
LL | where &'a T : Foo,
| ^^^
LL | &'b T : Foo
| ^^^
error: aborting due to previous error