bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Suggestion for call on immutable binding of mutable type

Browse source 
When calling a method requiring a mutable self borrow on an inmutable
to a mutable borrow of the type, suggest making the binding mutable.

Fix #83241.
This commit is contained in:
Esteban Küber 2021-03-17 18:45:49 -07:00 • committed by Esteban Kuber
parent 757a65bfdf
commit e4368de7b1
6 changed files with 188 additions and 34 deletions
Download patch file Download diff file Expand all files Collapse all files

60
compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs
View file

@ -5,7 +5,10 @@ use rustc_middle::mir::{Mutability, Place, PlaceRef, ProjectionElem};
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::{
hir::place::PlaceBase,
mir::{self, ClearCrossCrate, Local, LocalDecl, LocalInfo, LocalKind, Location},
mir::{
self, BindingForm, ClearCrossCrate, ImplicitSelfKind, Local, LocalDecl, LocalInfo,
LocalKind, Location,
},
};
use rustc_span::source_map::DesugaringKind;
use rustc_span::symbol::{kw, Symbol};
@ -241,13 +244,56 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
.map(|l| mut_borrow_of_mutable_ref(l, self.local_names[local]))
.unwrap_or(false) =>
{
let decl = &self.body.local_decls[local];
err.span_label(span, format!("cannot {ACT}", ACT = act));
err.span_suggestion(
span,
"try removing `&mut` here",
String::new(),
Applicability::MaybeIncorrect,
);
if let Some(mir::Statement {
source_info,
kind:
mir::StatementKind::Assign(box (
_,
mir::Rvalue::Ref(
_,
mir::BorrowKind::Mut { allow_two_phase_borrow: false },
_,
),
)),
..
}) = &self.body[location.block].statements.get(location.statement_index)
{
match decl.local_info {
Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
mir::VarBindingForm {
binding_mode: ty::BindingMode::BindByValue(Mutability::Not),
opt_ty_info: Some(sp),
opt_match_place: _,
pat_span: _,
},
)))) => {
err.span_note(sp, "the binding is already a mutable borrow");
}
_ => {
err.span_note(
decl.source_info.span,
"the binding is already a mutable borrow",
);
}
}
err.span_help(source_info.span, "try removing `&mut` here");
} else if decl.mutability == Mutability::Not
&& !matches!(
decl.local_info,
Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(
ImplicitSelfKind::MutRef
))))
)
{
err.span_suggestion_verbose(
decl.source_info.span.shrink_to_lo(),
"consider making the binding mutable",
"mut ".to_string(),
Applicability::MachineApplicable,
);
}
}
// We want to suggest users use `let mut` for local (user