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Suggest calling the instance method of the same name when method not found #103531

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merged 2 commits into from
Nov 11, 2022
Merged

Suggest calling the instance method of the same name when method not found #103531

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32a2f0d
suggest calling the method of the same name when method not found
chenyukang Oct 25, 2022
2716449
add testcase for suggest self
chenyukang Oct 25, 2022
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24 changes: 12 additions & 12 deletions compiler/rustc_resolve/src/late/diagnostics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -213,26 +213,26 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
let (mod_prefix, mod_str, suggestion) = if path.len() == 1 {
debug!(?self.diagnostic_metadata.current_impl_items);
debug!(?self.diagnostic_metadata.current_function);
let suggestion = if let Some(items) = self.diagnostic_metadata.current_impl_items
let suggestion = if self.current_trait_ref.is_none()
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&& let Some((fn_kind, _)) = self.diagnostic_metadata.current_function
&& self.current_trait_ref.is_none()
&& let Some(FnCtxt::Assoc(_)) = fn_kind.ctxt()
&& let Some(items) = self.diagnostic_metadata.current_impl_items
&& let Some(item) = items.iter().find(|i| {
if let AssocItemKind::Fn(fn_) = &i.kind
&& !fn_.sig.decl.has_self()
&& i.ident.name == item_str.name
if let AssocItemKind::Fn(_) = &i.kind && i.ident.name == item_str.name
{
debug!(?item_str.name);
debug!(?fn_.sig.decl.inputs);
return true
}
false
})
&& let AssocItemKind::Fn(fn_) = &item.kind
{
debug!(?fn_);
let self_sugg = if fn_.sig.decl.has_self() { "self." } else { "Self::" };
Some((
item_span,
item_span.shrink_to_lo(),
"consider using the associated function",
format!("Self::{}", item.ident)
self_sugg.to_string()
))
} else {
None
Expand Down Expand Up @@ -381,11 +381,13 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
}

fn suggest_self_or_self_ref(&mut self, err: &mut Diagnostic, path: &[Segment], span: Span) {
let is_assoc_fn = self.self_type_is_available();
if !self.self_type_is_available() {
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This probably causes a regression in the suggestions for the code:

struct Foo {
    i: i32,
}

impl Foo {
    fn needs_self() {
        this.i
    }
}

Which currently looks like:

error[[E0425]](https://doc.rust-lang.org/stable/error-index.html#E0425): cannot find value `this` in this scope
 --> src/lib.rs:7:9
  |
7 |         this.i
  |         ^^^^ not found in this scope
  |
help: you might have meant to use `self` here instead
  |
7 |         self.i
  |         ~~~~
help: if you meant to use `self`, you are also missing a `self` receiver argument
  |
6 |     fn needs_self(&self) {
  |                   +++++

Can you check that it still works? Also useful to commit a test for it.

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This testcase still works, I didn't change the meaning of suggest_self_or_self_ref, I moved the check from L388 to beginning of this function, removed a variable is_assoc_fn.

I will add this code into tests.

return;
}
let Some(path_last_segment) = path.last() else { return };
let item_str = path_last_segment.ident;
// Emit help message for fake-self from other languages (e.g., `this` in Javascript).
if ["this", "my"].contains(&item_str.as_str()) && is_assoc_fn {
if ["this", "my"].contains(&item_str.as_str()) {
err.span_suggestion_short(
span,
"you might have meant to use `self` here instead",
Expand Down Expand Up @@ -436,7 +438,6 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
let is_enum_variant = &|res| matches!(res, Res::Def(DefKind::Variant, _));
let path_str = Segment::names_to_string(path);
let ident_span = path.last().map_or(span, |ident| ident.ident.span);

let mut candidates = self
.r
.lookup_import_candidates(ident, ns, &self.parent_scope, is_expected)
Expand Down Expand Up @@ -1512,7 +1513,6 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
_ => None,
}
}

// Fields are generally expected in the same contexts as locals.
if filter_fn(Res::Local(ast::DUMMY_NODE_ID)) {
if let Some(node_id) =
Expand Down
28 changes: 28 additions & 0 deletions src/test/ui/resolve/issue-103474.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,28 @@
struct S {}
impl S {
fn first(&self) {}

fn second(&self) {
first()
//~^ ERROR cannot find function `first` in this scope
}

fn third(&self) {
no_method_err()
//~^ ERROR cannot find function `no_method_err` in this scope
}
}

// https://github.com/rust-lang/rust/pull/103531#discussion_r1004728080
struct Foo {
i: i32,
}

impl Foo {
fn needs_self() {
this.i
//~^ ERROR cannot find value `this` in this scope
}
}

fn main() {}
35 changes: 35 additions & 0 deletions src/test/ui/resolve/issue-103474.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
error[E0425]: cannot find value `this` in this scope
--> $DIR/issue-103474.rs:23:9
|
LL | this.i
| ^^^^ not found in this scope
|
help: you might have meant to use `self` here instead
|
LL | self.i
| ~~~~
help: if you meant to use `self`, you are also missing a `self` receiver argument
|
LL | fn needs_self(&self) {
| +++++

error[E0425]: cannot find function `first` in this scope
--> $DIR/issue-103474.rs:6:9
|
LL | first()
| ^^^^^ not found in this scope
|
help: consider using the associated function
|
LL | self.first()
| +++++

error[E0425]: cannot find function `no_method_err` in this scope
--> $DIR/issue-103474.rs:11:9
|
LL | no_method_err()
| ^^^^^^^^^^^^^ not found in this scope

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0425`.
4 changes: 2 additions & 2 deletions src/test/ui/resolve/issue-2356.stderr
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Expand Up @@ -85,7 +85,7 @@ LL | static_method();
help: consider using the associated function
|
LL | Self::static_method();
| ~~~~~~~~~~~~~~~~~~~
| ++++++

error[E0425]: cannot find function `purr` in this scope
--> $DIR/issue-2356.rs:54:9
Expand Down Expand Up @@ -114,7 +114,7 @@ LL | grow_older();
help: consider using the associated function
|
LL | Self::grow_older();
| ~~~~~~~~~~~~~~~~
| ++++++

error[E0425]: cannot find function `shave` in this scope
--> $DIR/issue-2356.rs:74:5
Expand Down
4 changes: 4 additions & 0 deletions src/test/ui/self/class-missing-self.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,10 @@ error[E0425]: cannot find function `sleep` in this scope
LL | sleep();
| ^^^^^ not found in this scope
|
help: consider using the associated function
|
LL | self.sleep();
| +++++
help: consider importing this function
|
LL | use std::thread::sleep;
Expand Down
9 changes: 7 additions & 2 deletions src/test/ui/suggestions/assoc_fn_without_self.stderr
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Expand Up @@ -7,13 +7,18 @@ LL | foo();
help: consider using the associated function
|
LL | Self::foo();
| ~~~~~~~~~
| ++++++

error[E0425]: cannot find function `bar` in this scope
--> $DIR/assoc_fn_without_self.rs:17:9
|
LL | bar();
| ^^^ not found in this scope
|
help: consider using the associated function
|
LL | self.bar();
| +++++

error[E0425]: cannot find function `baz` in this scope
--> $DIR/assoc_fn_without_self.rs:18:9
Expand All @@ -24,7 +29,7 @@ LL | baz(2, 3);
help: consider using the associated function
|
LL | Self::baz(2, 3);
| ~~~~~~~~~
| ++++++

error[E0425]: cannot find function `foo` in this scope
--> $DIR/assoc_fn_without_self.rs:14:13
Expand Down