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Use suggestion for assoc fn called like method
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When encountering an unexisting method for a given trait where an
associated function has the same name, suggest using the appropriate
syntax, instead of using `help` text.

When only one candidate is found, do not call it "candidate #1", just
call it "the candidate".
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@estebank
estebank committed May 27, 2018
1 parent dcb4056 commit 447d894
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Showing 4 changed files with 51 additions and 24 deletions.
52 changes: 38 additions & 14 deletions src/librustc_typeck/check/method/suggest.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -119,11 +119,16 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
}
};

let note_str = format!("candidate #{} is defined in an impl{} \
for the type `{}`",
idx + 1,
insertion,
impl_ty);
let note_str = if sources.len() > 1 {
format!("candidate #{} is defined in an impl{} for the type `{}`",
idx + 1,
insertion,
impl_ty)
} else {
format!("the candidate is defined in an impl{} for the type `{}`",
insertion,
impl_ty)
};
if let Some(note_span) = note_span {
// We have a span pointing to the method. Show note with snippet.
err.span_note(self.tcx.sess.codemap().def_span(note_span), &note_str);
Expand All @@ -137,11 +142,18 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
.unwrap();
let item_span = self.tcx.sess.codemap()
.def_span(self.tcx.def_span(item.def_id));
span_note!(err,
item_span,
"candidate #{} is defined in the trait `{}`",
idx + 1,
self.tcx.item_path_str(trait_did));
if sources.len() > 1 {
span_note!(err,
item_span,
"candidate #{} is defined in the trait `{}`",
idx + 1,
self.tcx.item_path_str(trait_did));
} else {
span_note!(err,
item_span,
"the candidate is defined in the trait `{}`",
self.tcx.item_path_str(trait_did));
}
err.help(&format!("to disambiguate the method call, write `{}::{}({}{})` \
instead",
self.tcx.item_path_str(trait_did),
Expand Down Expand Up @@ -368,7 +380,14 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
if !static_sources.is_empty() {
err.note("found the following associated functions; to be used as methods, \
functions must have a `self` parameter");
err.help(&format!("try with `{}::{}`", self.ty_to_string(actual), item_name));
if let Some(expr) = rcvr_expr {
err.span_suggestion(expr.span.to(span),
"use associated function syntax intead",
format!("{}::{}", self.ty_to_string(actual), item_name));
} else {
err.help(&format!("try with `{}::{}`",
self.ty_to_string(actual), item_name));
}

report_candidates(&mut err, static_sources);
}
Expand Down Expand Up @@ -468,9 +487,14 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
} else {
let limit = if candidates.len() == 5 { 5 } else { 4 };
for (i, trait_did) in candidates.iter().take(limit).enumerate() {
msg.push_str(&format!("\ncandidate #{}: `use {};`",
i + 1,
self.tcx.item_path_str(*trait_did)));
if candidates.len() > 1 {
msg.push_str(&format!("\ncandidate #{}: `use {};`",
i + 1,
self.tcx.item_path_str(*trait_did)));
} else {
msg.push_str(&format!("\n`use {};`",
self.tcx.item_path_str(*trait_did)));
}
}
if candidates.len() > limit {
msg.push_str(&format!("\nand {} others", candidates.len() - limit));
Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/hygiene/no_implicit_prelude.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ LL | ().clone() //~ ERROR no method named `clone` found
|
= help: items from traits can only be used if the trait is in scope
= note: the following trait is implemented but not in scope, perhaps add a `use` for it:
candidate #1: `use std::clone::Clone;`
`use std::clone::Clone;`

error: aborting due to 3 previous errors

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/hygiene/trait_items.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ LL | pub macro m() { ().f() } //~ ERROR no method named `f` found for type `
|
= help: items from traits can only be used if the trait is in scope
= note: the following trait is implemented but not in scope, perhaps add a `use` for it:
candidate #1: `use foo::T;`
`use foo::T;`

error: aborting due to previous error

Expand Down
19 changes: 11 additions & 8 deletions src/test/ui/span/issue-7575.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,11 @@ error[E0599]: no method named `f9` found for type `usize` in the current scope
--> $DIR/issue-7575.rs:74:18
|
LL | u.f8(42) + u.f9(342) + m.fff(42)
| ^^
| --^^
| |
| help: use associated function syntax intead: `usize::f9`
|
= note: found the following associated functions; to be used as methods, functions must have a `self` parameter
= help: try with `usize::f9`
note: candidate #1 is defined in the trait `CtxtFn`
--> $DIR/issue-7575.rs:16:5
|
Expand Down Expand Up @@ -37,11 +38,12 @@ LL | struct Myisize(isize);
| ---------------------- method `fff` not found for this
...
LL | u.f8(42) + u.f9(342) + m.fff(42)
| ^^^
| --^^^
| |
| help: use associated function syntax intead: `Myisize::fff`
|
= note: found the following associated functions; to be used as methods, functions must have a `self` parameter
= help: try with `Myisize::fff`
note: candidate #1 is defined in an impl for the type `Myisize`
note: the candidate is defined in an impl for the type `Myisize`
--> $DIR/issue-7575.rs:51:5
|
LL | fn fff(i: isize) -> isize {
Expand All @@ -51,11 +53,12 @@ error[E0599]: no method named `is_str` found for type `T` in the current scope
--> $DIR/issue-7575.rs:82:7
|
LL | t.is_str()
| ^^^^^^
| --^^^^^^
| |
| help: use associated function syntax intead: `T::is_str`
|
= note: found the following associated functions; to be used as methods, functions must have a `self` parameter
= help: try with `T::is_str`
note: candidate #1 is defined in the trait `ManyImplTrait`
note: the candidate is defined in the trait `ManyImplTrait`
--> $DIR/issue-7575.rs:57:5
|
LL | fn is_str() -> bool {
Expand Down

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