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Rollup merge of #88578 - notriddle:notriddle/suggest-add-reference-to-for-loop-iter, r=nagisa

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fix(rustc): suggest `items` be borrowed in `for i in items[x..]`

Fixes #87994
This commit is contained in:
Manish Goregaokar 2021-09-10 08:23:18 -07:00 committed by GitHub
commit 257f5adf0e
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 105 additions and 6 deletions
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17
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
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@ -23,7 +23,7 @@ use rustc_middle::ty::{
use rustc_middle::ty::{TypeAndMut, TypeckResults};
use rustc_span::def_id::LOCAL_CRATE;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP};
use rustc_span::{BytePos, DesugaringKind, ExpnKind, ForLoopLoc, MultiSpan, Span, DUMMY_SP};
use rustc_target::spec::abi;
use std::fmt;
@ -680,7 +680,13 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
points_at_arg: bool,
has_custom_message: bool,
) -> bool {
if !points_at_arg {
let span = obligation.cause.span;
let points_at_for_iter = matches!(
span.ctxt().outer_expn_data().kind,
ExpnKind::Desugaring(DesugaringKind::ForLoop(ForLoopLoc::IntoIter))
);
if !points_at_arg && !points_at_for_iter {
return false;
}
@ -695,7 +701,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
never_suggest_borrow.push(self.tcx.get_diagnostic_item(sym::send_trait).unwrap());
let span = obligation.cause.span;
let param_env = obligation.param_env;
let trait_ref = trait_ref.skip_binder();
@ -754,7 +759,11 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
);
// This if is to prevent a special edge-case
if !span.from_expansion() {
if matches!(
span.ctxt().outer_expn_data().kind,
ExpnKind::Root
| ExpnKind::Desugaring(DesugaringKind::ForLoop(ForLoopLoc::IntoIter))
) {
// We don't want a borrowing suggestion on the fields in structs,
// ```
// struct Foo {

7
src/test/ui/issues/issue-20605.stderr
View File

@ -2,9 +2,12 @@ error[E0277]: the size for values of type `dyn Iterator<Item = &'a mut u8>` cann
--> $DIR/issue-20605.rs:2:17
|
LL | for item in *things { *item = 0 }
| ^^^^^^^ doesn't have a size known at compile-time
| ^^^^^^^
| |
| expected an implementor of trait `IntoIterator`
| help: consider mutably borrowing here: `&mut *things`
|
= help: the trait `Sized` is not implemented for `dyn Iterator<Item = &'a mut u8>`
= note: the trait bound `dyn Iterator<Item = &'a mut u8>: IntoIterator` is not satisfied
= note: required because of the requirements on the impl of `IntoIterator` for `dyn Iterator<Item = &'a mut u8>`
note: required by `into_iter`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL

16
src/test/ui/suggestions/slice-issue-87994.rs Normal file
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@ -0,0 +1,16 @@
fn main() {
let v = vec![1i32, 2, 3];
for _ in v[1..] {
//~^ ERROR [i32]` is not an iterator [E0277]
//~^^ ERROR known at compilation time
}
struct K {
n: i32,
}
let mut v2 = vec![K { n: 1 }, K { n: 1 }, K { n: 1 }];
for i2 in v2[1..] {
//~^ ERROR [K]` is not an iterator [E0277]
//~^^ ERROR known at compilation time
i2.n = 2;
}
}

71
src/test/ui/suggestions/slice-issue-87994.stderr Normal file
View File

@ -0,0 +1,71 @@
error[E0277]: the size for values of type `[i32]` cannot be known at compilation time
--> $DIR/slice-issue-87994.rs:3:12
|
LL | for _ in v[1..] {
| ^^^^^^
| |
| expected an implementor of trait `IntoIterator`
| help: consider borrowing here: `&v[1..]`
|
= note: the trait bound `[i32]: IntoIterator` is not satisfied
= note: required because of the requirements on the impl of `IntoIterator` for `[i32]`
note: required by `into_iter`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0277]: `[i32]` is not an iterator
--> $DIR/slice-issue-87994.rs:3:12
|
LL | for _ in v[1..] {
| ^^^^^^
| |
| expected an implementor of trait `IntoIterator`
| help: consider borrowing here: `&v[1..]`
|
= note: the trait bound `[i32]: IntoIterator` is not satisfied
= note: required because of the requirements on the impl of `IntoIterator` for `[i32]`
note: required by `into_iter`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0277]: the size for values of type `[K]` cannot be known at compilation time
--> $DIR/slice-issue-87994.rs:11:13
|
LL | for i2 in v2[1..] {
| ^^^^^^^
| |
| expected an implementor of trait `IntoIterator`
| help: consider borrowing here: `&v2[1..]`
|
= note: the trait bound `[K]: IntoIterator` is not satisfied
= note: required because of the requirements on the impl of `IntoIterator` for `[K]`
note: required by `into_iter`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0277]: `[K]` is not an iterator
--> $DIR/slice-issue-87994.rs:11:13
|
LL | for i2 in v2[1..] {
| ^^^^^^^
| |
| expected an implementor of trait `IntoIterator`
| help: consider borrowing here: `&v2[1..]`
|
= note: the trait bound `[K]: IntoIterator` is not satisfied
= note: required because of the requirements on the impl of `IntoIterator` for `[K]`
note: required by `into_iter`
--> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
|
LL | fn into_iter(self) -> Self::IntoIter;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0277`.