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suppress duplicate -- or near duplicate -- type test errors

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This commit is contained in:
Niko Matsakis 2018-10-18 09:00:11 -04:00
parent bfb1d959c3
commit e20fa70bb3
2 changed files with 27 additions and 5 deletions
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2
src/librustc/infer/region_constraints/mod.rs
View file

@ -149,7 +149,7 @@ pub struct Verify<'tcx> {
pub bound: VerifyBound<'tcx>,
}
#[derive(Copy, Clone, PartialEq, Eq)]
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
pub enum GenericKind<'tcx> {
Param(ty::ParamTy),
Projection(ty::ProjectionTy<'tcx>),

30
src/librustc_mir/borrow_check/nll/region_infer/mod.rs
View file

@ -25,7 +25,7 @@ use rustc::mir::{
use rustc::ty::{self, RegionVid, Ty, TyCtxt, TypeFoldable};
use rustc::util::common;
use rustc_data_structures::bit_set::BitSet;
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::graph::scc::Sccs;
use rustc_data_structures::indexed_vec::IndexVec;
use rustc_errors::{Diagnostic, DiagnosticBuilder};
@ -580,6 +580,11 @@ impl<'tcx> RegionInferenceContext<'tcx> {
) {
let tcx = infcx.tcx;
// Sometimes we register equivalent type-tests that would
// result in basically the exact same error being reported to
// the user. Avoid that.
let mut deduplicate_errors = FxHashSet::default();
for type_test in &self.type_tests {
debug!("check_type_test: {:?}", type_test);
@ -605,11 +610,29 @@ impl<'tcx> RegionInferenceContext<'tcx> {
}
}
// Oh the humanity. Obviously we will do better than this error eventually.
// Type-test failed. Report the error.
// Try to convert the lower-bound region into something named we can print for the user.
let lower_bound_region = self.to_error_region(type_test.lower_bound);
// Skip duplicate-ish errors.
let type_test_span = type_test.locations.span(mir);
let erased_generic_kind = tcx.erase_regions(&type_test.generic_kind);
if !deduplicate_errors.insert((erased_generic_kind, lower_bound_region, type_test.locations)) {
continue;
} else {
debug!(
"check_type_test: reporting error for erased_generic_kind={:?}, \
lower_bound_region={:?}, \
type_test.locations={:?}",
erased_generic_kind,
lower_bound_region,
type_test.locations,
);
}
if let Some(lower_bound_region) = lower_bound_region {
let region_scope_tree = &tcx.region_scope_tree(mir_def_id);
let type_test_span = type_test.locations.span(mir);
infcx
.construct_generic_bound_failure(
region_scope_tree,
@ -629,7 +652,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
// to report it; we could probably handle it by
// iterating over the universal regions and reporting
// an error that multiple bounds are required.
let type_test_span = type_test.locations.span(mir);
tcx.sess
.struct_span_err(
type_test_span,