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Rollup merge of #87559 - estebank:consider-borrowing, r=oli-obk

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Tweak borrowing suggestion in `for` loop
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Yuki Okushi 2021-07-31 04:09:30 +09:00 • committed by GitHub
commit 5e2655d27f
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5 changed files with 76 additions and 44 deletions
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69
compiler/rustc_mir/src/borrow_check/diagnostics/move_errors.rs
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@ -2,7 +2,8 @@ use rustc_errors::{Applicability, DiagnosticBuilder};
use rustc_middle::mir::*;
use rustc_middle::ty;
use rustc_span::source_map::DesugaringKind;
use rustc_span::{sym, Span};
use rustc_span::{sym, Span, DUMMY_SP};
use rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions;
use crate::borrow_check::diagnostics::UseSpans;
use crate::borrow_check::prefixes::PrefixSet;
@ -384,36 +385,44 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
}
}
};
if let Ok(snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(span) {
let def_id = match *move_place.ty(self.body, self.infcx.tcx).ty.kind() {
ty::Adt(self_def, _) => self_def.did,
ty::Foreign(def_id)
| ty::FnDef(def_id, _)
| ty::Closure(def_id, _)
| ty::Generator(def_id, ..)
| ty::Opaque(def_id, _) => def_id,
_ => return err,
let ty = move_place.ty(self.body, self.infcx.tcx).ty;
let def_id = match *ty.kind() {
ty::Adt(self_def, _) => self_def.did,
ty::Foreign(def_id)
| ty::FnDef(def_id, _)
| ty::Closure(def_id, _)
| ty::Generator(def_id, ..)
| ty::Opaque(def_id, _) => def_id,
_ => return err,
};
let is_option = self.infcx.tcx.is_diagnostic_item(sym::option_type, def_id);
let is_result = self.infcx.tcx.is_diagnostic_item(sym::result_type, def_id);
if (is_option || is_result) && use_spans.map_or(true, |v| !v.for_closure()) {
err.span_suggestion_verbose(
span.shrink_to_hi(),
&format!(
"consider borrowing the `{}`'s content",
if is_option { "Option" } else { "Result" }
),
".as_ref()".to_string(),
Applicability::MaybeIncorrect,
);
} else if matches!(span.desugaring_kind(), Some(DesugaringKind::ForLoop(_))) {
let suggest = match self.infcx.tcx.get_diagnostic_item(sym::IntoIterator) {
Some(def_id) => type_known_to_meet_bound_modulo_regions(
&self.infcx,
self.param_env,
self.infcx.tcx.mk_imm_ref(self.infcx.tcx.lifetimes.re_erased, ty),
def_id,
DUMMY_SP,
),
_ => false,
};
let is_option = self.infcx.tcx.is_diagnostic_item(sym::option_type, def_id);
let is_result = self.infcx.tcx.is_diagnostic_item(sym::result_type, def_id);
if (is_option || is_result) && use_spans.map_or(true, |v| !v.for_closure()) {
err.span_suggestion(
span,
&format!(
"consider borrowing the `{}`'s content",
if is_option { "Option" } else { "Result" }
),
format!("{}.as_ref()", snippet),
Applicability::MaybeIncorrect,
);
} else if matches!(span.desugaring_kind(), Some(DesugaringKind::ForLoop(_)))
&& self.infcx.tcx.is_diagnostic_item(sym::vec_type, def_id)
{
// FIXME: suggest for anything that implements `IntoIterator`.
err.span_suggestion(
span,
"consider iterating over a slice of the `Vec<_>`'s content",
format!("&{}", snippet),
if suggest {
err.span_suggestion_verbose(
span.shrink_to_lo(),
&format!("consider iterating over a slice of the `{}`'s content", ty),
"&".to_string(),
Applicability::MaybeIncorrect,
);
}