bjoernager/rust
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pretty: trim paths of unique symbols

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If a symbol name can only be imported from one place for a type, and
as long as it was not glob-imported anywhere in the current crate, we
can trim its printed path and print only the name.

This has wide implications on error messages with types, for example,
shortening `std::vec::Vec` to just `Vec`, as long as there is no other
`Vec` importable anywhere.

This adds a new '-Z trim-diagnostic-paths=false' option to control this
feature.

On the good path, with no diagnosis printed, we should try to avoid
issuing this query, so we need to prevent trimmed_def_paths query on
several cases.

This change also relies on a previous commit that differentiates
between `Debug` and `Display` on various rustc types, where the latter
is trimmed and presented to the user and the former is not.
This commit is contained in:
Dan Aloni 2020-09-02 10:40:56 +03:00
parent 7b2deb5628
commit 07e7823c01
1325 changed files with 4806 additions and 4546 deletions
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34
compiler/rustc_trait_selection/src/traits/select/mod.rs
View file

@ -32,6 +32,7 @@ use rustc_hir::def_id::DefId;
use rustc_middle::dep_graph::{DepKind, DepNodeIndex};
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::ty::fast_reject;
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::relate::TypeRelation;
use rustc_middle::ty::subst::{GenericArgKind, Subst, SubstsRef};
use rustc_middle::ty::{
@ -778,14 +779,16 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
if !candidate_set.ambiguous && candidate_set.vec.is_empty() {
let trait_ref = stack.obligation.predicate.skip_binder().trait_ref;
let self_ty = trait_ref.self_ty();
let cause = IntercrateAmbiguityCause::DownstreamCrate {
trait_desc: trait_ref.print_only_trait_path().to_string(),
self_desc: if self_ty.has_concrete_skeleton() {
Some(self_ty.to_string())
} else {
None
},
};
let cause =
with_no_trimmed_paths(|| IntercrateAmbiguityCause::DownstreamCrate {
trait_desc: trait_ref.print_only_trait_path().to_string(),
self_desc: if self_ty.has_concrete_skeleton() {
Some(self_ty.to_string())
} else {
None
},
});
debug!("evaluate_stack: pushing cause = {:?}", cause);
self.intercrate_ambiguity_causes.as_mut().unwrap().push(cause);
}
@ -1030,12 +1033,15 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
if !candidate_set.ambiguous && no_candidates_apply {
let trait_ref = stack.obligation.predicate.skip_binder().trait_ref;
let self_ty = trait_ref.self_ty();
let trait_desc = trait_ref.print_only_trait_path().to_string();
let self_desc = if self_ty.has_concrete_skeleton() {
Some(self_ty.to_string())
} else {
None
};
let (trait_desc, self_desc) = with_no_trimmed_paths(|| {
let trait_desc = trait_ref.print_only_trait_path().to_string();
let self_desc = if self_ty.has_concrete_skeleton() {
Some(self_ty.to_string())
} else {
None
};
(trait_desc, self_desc)
});
let cause = if let Conflict::Upstream = conflict {
IntercrateAmbiguityCause::UpstreamCrateUpdate { trait_desc, self_desc }
} else {