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Rollup merge of #127596 - tesuji:help-unwrap-or, r=compiler-errors

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More suggestion for converting `Option<&Vec<T>>` to `Option<&[T]>`

Please review commit-by-commit.
This commit is contained in:
Matthias Krüger 2024-07-12 03:43:35 +02:00 committed by GitHub
commit 83d1a1b252
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3 changed files with 61 additions and 15 deletions
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52
compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
View File

@ -466,21 +466,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
borrow_removal_span,
});
return true;
} else if let Some((deref_ty, _)) =
self.autoderef(expr.span, found_ty_inner).silence_errors().nth(1)
&& self.can_eq(self.param_env, deref_ty, peeled)
&& error_tys_equate_as_ref
{
let sugg = prefix_wrap(".as_deref()");
err.subdiagnostic(errors::SuggestConvertViaMethod {
span: expr.span.shrink_to_hi(),
sugg,
expected,
found,
borrow_removal_span,
});
return true;
} else if let ty::Adt(adt, _) = found_ty_inner.peel_refs().kind()
} else if let ty::Ref(_, peeled_found_ty, _) = found_ty_inner.kind()
&& let ty::Adt(adt, _) = peeled_found_ty.peel_refs().kind()
&& self.tcx.is_lang_item(adt.did(), LangItem::String)
&& peeled.is_str()
// `Result::map`, conversely, does not take ref of the error type.
@ -496,12 +483,47 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
Applicability::MachineApplicable,
);
return true;
} else {
if !error_tys_equate_as_ref {
return false;
}
let mut steps = self.autoderef(expr.span, found_ty_inner).silence_errors();
if let Some((deref_ty, _)) = steps.nth(1)
&& self.can_eq(self.param_env, deref_ty, peeled)
{
let sugg = prefix_wrap(".as_deref()");
err.subdiagnostic(errors::SuggestConvertViaMethod {
span: expr.span.shrink_to_hi(),
sugg,
expected,
found,
borrow_removal_span,
});
return true;
}
for (deref_ty, n_step) in steps {
if self.can_eq(self.param_env, deref_ty, peeled) {
let explicit_deref = "*".repeat(n_step);
let sugg = prefix_wrap(&format!(".map(|v| &{explicit_deref}v)"));
err.subdiagnostic(errors::SuggestConvertViaMethod {
span: expr.span.shrink_to_hi(),
sugg,
expected,
found,
borrow_removal_span,
});
return true;
}
}
}
}
false
}
/// If `ty` is `Option<T>`, returns `T, T, None`.
/// If `ty` is `Result<T, E>`, returns `T, T, Some(E, E)`.
/// Otherwise, returns `None`.
fn deconstruct_option_or_result(
&self,
found_ty: Ty<'tcx>,

6
tests/ui/mismatched_types/transforming-option-ref-issue-127545.rs Normal file
View File

@ -0,0 +1,6 @@
// Regression test for <https://github.com/rust-lang/rust/issues/127545>.
#![crate_type = "lib"]
pub fn foo(arg: Option<&Vec<i32>>) -> Option<&[i32]> {
arg //~ ERROR 5:5: 5:8: mismatched types [E0308]
}

18
tests/ui/mismatched_types/transforming-option-ref-issue-127545.stderr Normal file
View File

@ -0,0 +1,18 @@
error[E0308]: mismatched types
--> $DIR/transforming-option-ref-issue-127545.rs:5:5
|
LL | pub fn foo(arg: Option<&Vec<i32>>) -> Option<&[i32]> {
| -------------- expected `Option<&[i32]>` because of return type
LL | arg
| ^^^ expected `Option<&[i32]>`, found `Option<&Vec<i32>>`
|
= note: expected enum `Option<&[i32]>`
found enum `Option<&Vec<i32>>`
help: try using `.map(|v| &**v)` to convert `Option<&Vec<i32>>` to `Option<&[i32]>`
|
LL | arg.map(|v| &**v)
| ++++++++++++++
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0308`.