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

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Tweak borrowing suggestion in `for` loop
This commit is contained in:
Yuki Okushi 2021-07-31 04:09:30 +09:00 committed by GitHub
commit 5e2655d27f
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 76 additions and 44 deletions
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69
compiler/rustc_mir/src/borrow_check/diagnostics/move_errors.rs
View File

@ -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,
);
}

3
src/test/ui/suggestions/for-i-in-vec.fixed
View File

@ -3,12 +3,15 @@
struct Foo {
v: Vec<u32>,
h: std::collections::HashMap<i32, i32>,
}
impl Foo {
fn bar(&self) {
for _ in &self.v { //~ ERROR cannot move out of `self.v` which is behind a shared reference
}
for _ in &self.h { //~ ERROR cannot move out of `self.h` which is behind a shared reference
}
}
}

3
src/test/ui/suggestions/for-i-in-vec.rs
View File

@ -3,12 +3,15 @@
struct Foo {
v: Vec<u32>,
h: std::collections::HashMap<i32, i32>,
}
impl Foo {
fn bar(&self) {
for _ in self.v { //~ ERROR cannot move out of `self.v` which is behind a shared reference
}
for _ in self.h { //~ ERROR cannot move out of `self.h` which is behind a shared reference
}
}
}

25
src/test/ui/suggestions/for-i-in-vec.stderr
View File

@ -1,12 +1,25 @@
error[E0507]: cannot move out of `self.v` which is behind a shared reference
--> $DIR/for-i-in-vec.rs:10:18
--> $DIR/for-i-in-vec.rs:11:18
|
LL | for _ in self.v {
| ^^^^^^
| |
| move occurs because `self.v` has type `Vec<u32>`, which does not implement the `Copy` trait
| help: consider iterating over a slice of the `Vec<_>`'s content: `&self.v`
| ^^^^^^ move occurs because `self.v` has type `Vec<u32>`, which does not implement the `Copy` trait
|
help: consider iterating over a slice of the `Vec<u32>`'s content
|
LL | for _ in &self.v {
| ^
error: aborting due to previous error
error[E0507]: cannot move out of `self.h` which is behind a shared reference
--> $DIR/for-i-in-vec.rs:13:18
|
LL | for _ in self.h {
| ^^^^^^ move occurs because `self.h` has type `HashMap<i32, i32>`, which does not implement the `Copy` trait
|
help: consider iterating over a slice of the `HashMap<i32, i32>`'s content
|
LL | for _ in &self.h {
| ^
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0507`.

20
src/test/ui/suggestions/option-content-move.stderr
View File

@ -2,19 +2,23 @@ error[E0507]: cannot move out of `selection.1` which is behind a shared referenc
--> $DIR/option-content-move.rs:11:20
|
LL | if selection.1.unwrap().contains(selection.0) {
| ^^^^^^^^^^^
| |
| move occurs because `selection.1` has type `Option<String>`, which does not implement the `Copy` trait
| help: consider borrowing the `Option`'s content: `selection.1.as_ref()`
| ^^^^^^^^^^^ move occurs because `selection.1` has type `Option<String>`, which does not implement the `Copy` trait
|
help: consider borrowing the `Option`'s content
|
LL | if selection.1.as_ref().unwrap().contains(selection.0) {
| ^^^^^^^^^
error[E0507]: cannot move out of `selection.1` which is behind a shared reference
--> $DIR/option-content-move.rs:29:20
|
LL | if selection.1.unwrap().contains(selection.0) {
| ^^^^^^^^^^^
| |
| move occurs because `selection.1` has type `Result<String, String>`, which does not implement the `Copy` trait
| help: consider borrowing the `Result`'s content: `selection.1.as_ref()`
| ^^^^^^^^^^^ move occurs because `selection.1` has type `Result<String, String>`, which does not implement the `Copy` trait
|
help: consider borrowing the `Result`'s content
|
LL | if selection.1.as_ref().unwrap().contains(selection.0) {
| ^^^^^^^^^
error: aborting due to 2 previous errors