Rollup merge of #96271 - compiler-errors:suggest-question-mark, r=estebank

suggest `?` when method is missing on `Result<T, _>` but found on `T`

The wording needs help, I think.

Fixes #95729
This commit is contained in:
Matthias Krüger 2022-06-01 17:11:04 +02:00 committed by GitHub
commit 7d4cf710e2
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4 changed files with 368 additions and 52 deletions

View File

@ -978,45 +978,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
label_span_not_found(&mut err);
}
if let SelfSource::MethodCall(expr) = source
&& let Some((fields, substs)) = self.get_field_candidates(span, actual)
{
let call_expr =
self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id));
for candidate_field in fields.iter() {
if let Some(field_path) = self.check_for_nested_field_satisfying(
span,
&|_, field_ty| {
self.lookup_probe(
span,
item_name,
field_ty,
call_expr,
ProbeScope::AllTraits,
)
.is_ok()
},
candidate_field,
substs,
vec![],
self.tcx.parent_module(expr.hir_id).to_def_id(),
) {
let field_path_str = field_path
.iter()
.map(|id| id.name.to_ident_string())
.collect::<Vec<String>>()
.join(".");
debug!("field_path_str: {:?}", field_path_str);
self.check_for_field_method(&mut err, source, span, actual, item_name);
err.span_suggestion_verbose(
item_name.span.shrink_to_lo(),
"one of the expressions' fields has a method of the same name",
format!("{field_path_str}."),
Applicability::MaybeIncorrect,
);
}
}
}
self.check_for_unwrap_self(&mut err, source, span, actual, item_name);
bound_spans.sort();
bound_spans.dedup();
@ -1343,6 +1307,145 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
false
}
fn check_for_field_method(
&self,
err: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>,
source: SelfSource<'tcx>,
span: Span,
actual: Ty<'tcx>,
item_name: Ident,
) {
if let SelfSource::MethodCall(expr) = source
&& let Some((fields, substs)) = self.get_field_candidates(span, actual)
{
let call_expr = self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id));
for candidate_field in fields.iter() {
if let Some(field_path) = self.check_for_nested_field_satisfying(
span,
&|_, field_ty| {
self.lookup_probe(
span,
item_name,
field_ty,
call_expr,
ProbeScope::AllTraits,
)
.is_ok()
},
candidate_field,
substs,
vec![],
self.tcx.parent_module(expr.hir_id).to_def_id(),
) {
let field_path_str = field_path
.iter()
.map(|id| id.name.to_ident_string())
.collect::<Vec<String>>()
.join(".");
debug!("field_path_str: {:?}", field_path_str);
err.span_suggestion_verbose(
item_name.span.shrink_to_lo(),
"one of the expressions' fields has a method of the same name",
format!("{field_path_str}."),
Applicability::MaybeIncorrect,
);
}
}
}
}
fn check_for_unwrap_self(
&self,
err: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>,
source: SelfSource<'tcx>,
span: Span,
actual: Ty<'tcx>,
item_name: Ident,
) {
let tcx = self.tcx;
let SelfSource::MethodCall(expr) = source else { return; };
let call_expr = tcx.hir().expect_expr(tcx.hir().get_parent_node(expr.hir_id));
let ty::Adt(kind, substs) = actual.kind() else { return; };
if !kind.is_enum() {
return;
}
let matching_variants: Vec<_> = kind
.variants()
.iter()
.flat_map(|variant| {
let [field] = &variant.fields[..] else { return None; };
let field_ty = field.ty(tcx, substs);
// Skip `_`, since that'll just lead to ambiguity.
if self.resolve_vars_if_possible(field_ty).is_ty_var() {
return None;
}
self.lookup_probe(span, item_name, field_ty, call_expr, ProbeScope::AllTraits)
.ok()
.map(|pick| (variant, field, pick))
})
.collect();
let ret_ty_matches = |diagnostic_item| {
if let Some(ret_ty) = self
.ret_coercion
.as_ref()
.map(|c| self.resolve_vars_if_possible(c.borrow().expected_ty()))
&& let ty::Adt(kind, _) = ret_ty.kind()
&& tcx.get_diagnostic_item(diagnostic_item) == Some(kind.did())
{
true
} else {
false
}
};
match &matching_variants[..] {
[(_, field, pick)] => {
let self_ty = field.ty(tcx, substs);
err.span_note(
tcx.def_span(pick.item.def_id),
&format!("the method `{item_name}` exists on the type `{self_ty}`"),
);
let (article, kind, variant, question) =
if Some(kind.did()) == tcx.get_diagnostic_item(sym::Result) {
("a", "Result", "Err", ret_ty_matches(sym::Result))
} else if Some(kind.did()) == tcx.get_diagnostic_item(sym::Option) {
("an", "Option", "None", ret_ty_matches(sym::Option))
} else {
return;
};
if question {
err.span_suggestion_verbose(
expr.span.shrink_to_hi(),
format!(
"use the `?` operator to extract the `{self_ty}` value, propagating \
{article} `{kind}::{variant}` value to the caller"
),
"?".to_owned(),
Applicability::MachineApplicable,
);
} else {
err.span_suggestion_verbose(
expr.span.shrink_to_hi(),
format!(
"consider using `{kind}::expect` to unwrap the `{self_ty}` value, \
panicking if the value is {article} `{kind}::{variant}`"
),
".expect(\"REASON\")".to_owned(),
Applicability::HasPlaceholders,
);
}
}
// FIXME(compiler-errors): Support suggestions for other matching enum variants
_ => {}
}
}
pub(crate) fn note_unmet_impls_on_type(
&self,
err: &mut Diagnostic,
@ -1662,13 +1765,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
(self.tcx.mk_mut_ref(self.tcx.lifetimes.re_erased, rcvr_ty), "&mut "),
(self.tcx.mk_imm_ref(self.tcx.lifetimes.re_erased, rcvr_ty), "&"),
] {
match self.lookup_probe(
span,
item_name,
*rcvr_ty,
rcvr,
crate::check::method::probe::ProbeScope::AllTraits,
) {
match self.lookup_probe(span, item_name, *rcvr_ty, rcvr, ProbeScope::AllTraits) {
Ok(pick) => {
// If the method is defined for the receiver we have, it likely wasn't `use`d.
// We point at the method, but we just skip the rest of the check for arbitrary
@ -1700,13 +1797,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
(self.tcx.mk_diagnostic_item(*rcvr_ty, sym::Arc), "Arc::new"),
(self.tcx.mk_diagnostic_item(*rcvr_ty, sym::Rc), "Rc::new"),
] {
if let Some(new_rcvr_t) = *rcvr_ty && let Ok(pick) = self.lookup_probe(
span,
item_name,
new_rcvr_t,
rcvr,
crate::check::method::probe::ProbeScope::AllTraits,
) {
if let Some(new_rcvr_t) = *rcvr_ty
&& let Ok(pick) = self.lookup_probe(
span,
item_name,
new_rcvr_t,
rcvr,
ProbeScope::AllTraits,
)
{
debug!("try_alt_rcvr: pick candidate {:?}", pick);
let did = Some(pick.item.container.id());
// We don't want to suggest a container type when the missing

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@ -0,0 +1,59 @@
// compile-flags: --edition=2021
// run-rustfix
#![allow(unused)]
struct Foo;
impl Foo {
fn get(&self) -> u8 {
42
}
}
fn test_result_in_result() -> Result<(), ()> {
let res: Result<_, ()> = Ok(Foo);
res?.get();
//~^ ERROR no method named `get` found for enum `Result` in the current scope
//~| HELP use the `?` operator
Ok(())
}
async fn async_test_result_in_result() -> Result<(), ()> {
let res: Result<_, ()> = Ok(Foo);
res?.get();
//~^ ERROR no method named `get` found for enum `Result` in the current scope
//~| HELP use the `?` operator
Ok(())
}
fn test_result_in_unit_return() {
let res: Result<_, ()> = Ok(Foo);
res.expect("REASON").get();
//~^ ERROR no method named `get` found for enum `Result` in the current scope
//~| HELP consider using `Result::expect` to unwrap the `Foo` value, panicking if the value is a `Result::Err`
}
async fn async_test_result_in_unit_return() {
let res: Result<_, ()> = Ok(Foo);
res.expect("REASON").get();
//~^ ERROR no method named `get` found for enum `Result` in the current scope
//~| HELP consider using `Result::expect` to unwrap the `Foo` value, panicking if the value is a `Result::Err`
}
fn test_option_in_option() -> Option<()> {
let res: Option<_> = Some(Foo);
res?.get();
//~^ ERROR no method named `get` found for enum `Option` in the current scope
//~| HELP use the `?` operator
Some(())
}
fn test_option_in_unit_return() {
let res: Option<_> = Some(Foo);
res.expect("REASON").get();
//~^ ERROR no method named `get` found for enum `Option` in the current scope
//~| HELP consider using `Option::expect` to unwrap the `Foo` value, panicking if the value is an `Option::None`
}
fn main() {}

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@ -0,0 +1,59 @@
// compile-flags: --edition=2021
// run-rustfix
#![allow(unused)]
struct Foo;
impl Foo {
fn get(&self) -> u8 {
42
}
}
fn test_result_in_result() -> Result<(), ()> {
let res: Result<_, ()> = Ok(Foo);
res.get();
//~^ ERROR no method named `get` found for enum `Result` in the current scope
//~| HELP use the `?` operator
Ok(())
}
async fn async_test_result_in_result() -> Result<(), ()> {
let res: Result<_, ()> = Ok(Foo);
res.get();
//~^ ERROR no method named `get` found for enum `Result` in the current scope
//~| HELP use the `?` operator
Ok(())
}
fn test_result_in_unit_return() {
let res: Result<_, ()> = Ok(Foo);
res.get();
//~^ ERROR no method named `get` found for enum `Result` in the current scope
//~| HELP consider using `Result::expect` to unwrap the `Foo` value, panicking if the value is a `Result::Err`
}
async fn async_test_result_in_unit_return() {
let res: Result<_, ()> = Ok(Foo);
res.get();
//~^ ERROR no method named `get` found for enum `Result` in the current scope
//~| HELP consider using `Result::expect` to unwrap the `Foo` value, panicking if the value is a `Result::Err`
}
fn test_option_in_option() -> Option<()> {
let res: Option<_> = Some(Foo);
res.get();
//~^ ERROR no method named `get` found for enum `Option` in the current scope
//~| HELP use the `?` operator
Some(())
}
fn test_option_in_unit_return() {
let res: Option<_> = Some(Foo);
res.get();
//~^ ERROR no method named `get` found for enum `Option` in the current scope
//~| HELP consider using `Option::expect` to unwrap the `Foo` value, panicking if the value is an `Option::None`
}
fn main() {}

View File

@ -0,0 +1,99 @@
error[E0599]: no method named `get` found for enum `Result` in the current scope
--> $DIR/enum-method-probe.rs:24:9
|
LL | res.get();
| ^^^ method not found in `Result<Foo, ()>`
|
note: the method `get` exists on the type `Foo`
--> $DIR/enum-method-probe.rs:9:5
|
LL | fn get(&self) -> u8 {
| ^^^^^^^^^^^^^^^^^^^
help: use the `?` operator to extract the `Foo` value, propagating a `Result::Err` value to the caller
|
LL | res?.get();
| +
error[E0599]: no method named `get` found for enum `Result` in the current scope
--> $DIR/enum-method-probe.rs:39:9
|
LL | res.get();
| ^^^ method not found in `Result<Foo, ()>`
|
note: the method `get` exists on the type `Foo`
--> $DIR/enum-method-probe.rs:9:5
|
LL | fn get(&self) -> u8 {
| ^^^^^^^^^^^^^^^^^^^
help: consider using `Result::expect` to unwrap the `Foo` value, panicking if the value is a `Result::Err`
|
LL | res.expect("REASON").get();
| +++++++++++++++++
error[E0599]: no method named `get` found for enum `Result` in the current scope
--> $DIR/enum-method-probe.rs:16:9
|
LL | res.get();
| ^^^ method not found in `Result<Foo, ()>`
|
note: the method `get` exists on the type `Foo`
--> $DIR/enum-method-probe.rs:9:5
|
LL | fn get(&self) -> u8 {
| ^^^^^^^^^^^^^^^^^^^
help: use the `?` operator to extract the `Foo` value, propagating a `Result::Err` value to the caller
|
LL | res?.get();
| +
error[E0599]: no method named `get` found for enum `Result` in the current scope
--> $DIR/enum-method-probe.rs:32:9
|
LL | res.get();
| ^^^ method not found in `Result<Foo, ()>`
|
note: the method `get` exists on the type `Foo`
--> $DIR/enum-method-probe.rs:9:5
|
LL | fn get(&self) -> u8 {
| ^^^^^^^^^^^^^^^^^^^
help: consider using `Result::expect` to unwrap the `Foo` value, panicking if the value is a `Result::Err`
|
LL | res.expect("REASON").get();
| +++++++++++++++++
error[E0599]: no method named `get` found for enum `Option` in the current scope
--> $DIR/enum-method-probe.rs:46:9
|
LL | res.get();
| ^^^ method not found in `Option<Foo>`
|
note: the method `get` exists on the type `Foo`
--> $DIR/enum-method-probe.rs:9:5
|
LL | fn get(&self) -> u8 {
| ^^^^^^^^^^^^^^^^^^^
help: use the `?` operator to extract the `Foo` value, propagating an `Option::None` value to the caller
|
LL | res?.get();
| +
error[E0599]: no method named `get` found for enum `Option` in the current scope
--> $DIR/enum-method-probe.rs:54:9
|
LL | res.get();
| ^^^ method not found in `Option<Foo>`
|
note: the method `get` exists on the type `Foo`
--> $DIR/enum-method-probe.rs:9:5
|
LL | fn get(&self) -> u8 {
| ^^^^^^^^^^^^^^^^^^^
help: consider using `Option::expect` to unwrap the `Foo` value, panicking if the value is an `Option::None`
|
LL | res.expect("REASON").get();
| +++++++++++++++++
error: aborting due to 6 previous errors
For more information about this error, try `rustc --explain E0599`.