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Rollup merge of #117893 - sjwang05:issue-52544-take-1, r=wesleywiser

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Suggest dereferencing the LHS for binops such as `&T == T`

Fixes #52544
This commit is contained in:
Matthias Krüger 2023-11-14 21:50:39 +01:00 committed by GitHub
commit 52f3a6fdb2
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 71 additions and 19 deletions
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60
compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
View File

@ -2326,14 +2326,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
));
}
let needs_parens = match expr.kind {
// parenthesize if needed (Issue #46756)
hir::ExprKind::Cast(_, _) | hir::ExprKind::Binary(_, _, _) => true,
// parenthesize borrows of range literals (Issue #54505)
_ if is_range_literal(expr) => true,
_ => false,
};
if let Some((sugg, msg)) = self.can_use_as_ref(expr) {
return Some((
sugg,
@ -2361,18 +2353,48 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
}
let sugg = mutability.ref_prefix_str();
let (sugg, verbose) = if needs_parens {
(
vec![
(sp.shrink_to_lo(), format!("{prefix}{sugg}(")),
(sp.shrink_to_hi(), ")".to_string()),
],
false,
)
} else {
(vec![(sp.shrink_to_lo(), format!("{prefix}{sugg}"))], true)
let make_sugg = |expr: &Expr<'_>, span: Span, sugg: &str| {
let needs_parens = match expr.kind {
// parenthesize if needed (Issue #46756)
hir::ExprKind::Cast(_, _) | hir::ExprKind::Binary(_, _, _) => true,
// parenthesize borrows of range literals (Issue #54505)
_ if is_range_literal(expr) => true,
_ => false,
};
if needs_parens {
(
vec![
(span.shrink_to_lo(), format!("{prefix}{sugg}(")),
(span.shrink_to_hi(), ")".to_string()),
],
false,
)
} else {
(vec![(span.shrink_to_lo(), format!("{prefix}{sugg}"))], true)
}
};
// Suggest dereferencing the lhs for expressions such as `&T == T`
if let Some(hir::Node::Expr(hir::Expr {
kind: hir::ExprKind::Binary(_, lhs, ..),
..
})) = self.tcx.hir().find_parent(expr.hir_id)
&& let &ty::Ref(..) = self.check_expr(lhs).kind()
{
let (sugg, verbose) = make_sugg(lhs, lhs.span, "*");
return Some((
sugg,
"consider dereferencing the borrow".to_string(),
Applicability::MachineApplicable,
verbose,
false,
));
}
let sugg = mutability.ref_prefix_str();
let (sugg, verbose) = make_sugg(expr, sp, sugg);
return Some((
sugg,
format!("consider {}borrowing here", mutability.mutably_str()),

8
tests/ui/binop/binary-op-suggest-deref.fixed Normal file
View File

@ -0,0 +1,8 @@
// Issue #52544
// run-rustfix
fn main() {
let i: &i64 = &1;
if *i < 0 {}
//~^ ERROR mismatched types [E0308]
}

8
tests/ui/binop/binary-op-suggest-deref.rs Normal file
View File

@ -0,0 +1,8 @@
// Issue #52544
// run-rustfix
fn main() {
let i: &i64 = &1;
if i < 0 {}
//~^ ERROR mismatched types [E0308]
}

14
tests/ui/binop/binary-op-suggest-deref.stderr Normal file
View File

@ -0,0 +1,14 @@
error[E0308]: mismatched types
--> $DIR/binary-op-suggest-deref.rs:6:12
|
LL | if i < 0 {}
| ^ expected `&i64`, found integer
|
help: consider dereferencing the borrow
|
LL | if *i < 0 {}
| +
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.