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Mar 23, 2019
Merged

convert field/method confusion help to suggestions #59297

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83 changes: 50 additions & 33 deletions src/librustc_typeck/check/method/suggest.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -332,44 +332,61 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
// If the method name is the name of a field with a function or closure type,
// give a helping note that it has to be called as `(x.f)(...)`.
if let SelfSource::MethodCall(expr) = source {
for (ty, _) in self.autoderef(span, rcvr_ty) {
if let ty::Adt(def, substs) = ty.sty {
if !def.is_enum() {
let field_receiver = self
.autoderef(span, rcvr_ty)
.find_map(|(ty, _)| match ty.sty {
ty::Adt(def, substs) if !def.is_enum() => {
let variant = &def.non_enum_variant();
if let Some(index) = self.tcx.find_field_index(item_name, variant) {
self.tcx.find_field_index(item_name, variant).map(|index| {
let field = &variant.fields[index];
let snippet = tcx.sess.source_map().span_to_snippet(expr.span);
let expr_string = match snippet {
Ok(expr_string) => expr_string,
_ => "s".into(), // Default to a generic placeholder for the
// expression when we can't generate a
// string snippet.
};

let field_ty = field.ty(tcx, substs);
let scope = self.tcx.hir().get_module_parent_by_hir_id(
self.body_id);
if field.vis.is_accessible_from(scope, self.tcx) {
if self.is_fn_ty(&field_ty, span) {
err.help(&format!("use `({0}.{1})(...)` if you \
meant to call the function \
stored in the `{1}` field",
expr_string,
item_name));
} else {
err.help(&format!("did you mean to write `{0}.{1}` \
instead of `{0}.{1}(...)`?",
expr_string,
item_name));
}
err.span_label(span, "field, not a method");
} else {
err.span_label(span, "private field, not a method");
}
break;
}
(field, field_ty)
})
}
_ => None,
});

if let Some((field, field_ty)) = field_receiver {
let scope = self.tcx.hir().get_module_parent_by_hir_id(self.body_id);
let is_accessible = field.vis.is_accessible_from(scope, self.tcx);

if is_accessible {
if self.is_fn_ty(&field_ty, span) {
let expr_span = expr.span.to(item_name.span);
err.multipart_suggestion(
&format!(
"to call the function stored in `{}`, \
surround the field access with parentheses",
item_name,
),
vec![
(expr_span.shrink_to_lo(), '('.to_string()),
(expr_span.shrink_to_hi(), ')'.to_string()),
],
Applicability::MachineApplicable,
);
} else {
let call_expr = self.tcx.hir().expect_expr_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(expr.hir_id),
);

let span = call_expr.span.trim_start(item_name.span).unwrap();

err.span_suggestion(
span,
"remove the arguments",
String::new(),
Applicability::MaybeIncorrect,
);
}
}

let field_kind = if is_accessible {
"field"
} else {
"private field"
};
err.span_label(item_name.span, format!("{}, not a method", field_kind));
}
} else {
err.span_label(span, format!("{} not found in `{}`", item_kind, ty_str));
Expand Down
4 changes: 3 additions & 1 deletion src/test/ui/confuse-field-and-method/issue-18343.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,10 @@ LL | struct Obj<F> where F: FnMut() -> u32 {
...
LL | o.closure();
| ^^^^^^^ field, not a method
help: to call the function stored in `closure`, surround the field access with parentheses
|
= help: use `(o.closure)(...)` if you meant to call the function stored in the `closure` field
LL | (o.closure)();
| ^ ^

error: aborting due to previous error

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48 changes: 33 additions & 15 deletions src/test/ui/confuse-field-and-method/issue-2392.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,10 @@ LL | struct Obj<F> where F: FnOnce() -> u32 {
...
LL | o_closure.closure();
| ^^^^^^^ field, not a method
help: to call the function stored in `closure`, surround the field access with parentheses
|
= help: use `(o_closure.closure)(...)` if you meant to call the function stored in the `closure` field
LL | (o_closure.closure)();
| ^ ^

error[E0599]: no method named `not_closure` found for type `Obj<[closure@$DIR/issue-2392.rs:39:36: 39:41]>` in the current scope
--> $DIR/issue-2392.rs:42:15
Expand All @@ -16,9 +18,9 @@ LL | struct Obj<F> where F: FnOnce() -> u32 {
| -------------------------------------- method `not_closure` not found for this
...
LL | o_closure.not_closure();
| ^^^^^^^^^^^ field, not a method
|
= help: did you mean to write `o_closure.not_closure` instead of `o_closure.not_closure(...)`?
| ^^^^^^^^^^^-- help: remove the arguments
| |
| field, not a method

error[E0599]: no method named `closure` found for type `Obj<fn() -> u32 {func}>` in the current scope
--> $DIR/issue-2392.rs:46:12
Expand All @@ -28,8 +30,10 @@ LL | struct Obj<F> where F: FnOnce() -> u32 {
...
LL | o_func.closure();
| ^^^^^^^ field, not a method
help: to call the function stored in `closure`, surround the field access with parentheses
|
= help: use `(o_func.closure)(...)` if you meant to call the function stored in the `closure` field
LL | (o_func.closure)();
| ^ ^

error[E0599]: no method named `boxed_closure` found for type `BoxedObj` in the current scope
--> $DIR/issue-2392.rs:49:14
Expand All @@ -39,8 +43,10 @@ LL | struct BoxedObj {
...
LL | boxed_fn.boxed_closure();
| ^^^^^^^^^^^^^ field, not a method
help: to call the function stored in `boxed_closure`, surround the field access with parentheses
|
= help: use `(boxed_fn.boxed_closure)(...)` if you meant to call the function stored in the `boxed_closure` field
LL | (boxed_fn.boxed_closure)();
| ^ ^

error[E0599]: no method named `boxed_closure` found for type `BoxedObj` in the current scope
--> $DIR/issue-2392.rs:52:19
Expand All @@ -50,8 +56,10 @@ LL | struct BoxedObj {
...
LL | boxed_closure.boxed_closure();
| ^^^^^^^^^^^^^ field, not a method
help: to call the function stored in `boxed_closure`, surround the field access with parentheses
|
= help: use `(boxed_closure.boxed_closure)(...)` if you meant to call the function stored in the `boxed_closure` field
LL | (boxed_closure.boxed_closure)();
| ^ ^

error[E0599]: no method named `closure` found for type `Obj<fn() -> u32 {func}>` in the current scope
--> $DIR/issue-2392.rs:57:12
Expand All @@ -61,8 +69,10 @@ LL | struct Obj<F> where F: FnOnce() -> u32 {
...
LL | w.wrap.closure();
| ^^^^^^^ field, not a method
help: to call the function stored in `closure`, surround the field access with parentheses
|
= help: use `(w.wrap.closure)(...)` if you meant to call the function stored in the `closure` field
LL | (w.wrap.closure)();
| ^ ^

error[E0599]: no method named `not_closure` found for type `Obj<fn() -> u32 {func}>` in the current scope
--> $DIR/issue-2392.rs:59:12
Expand All @@ -71,9 +81,9 @@ LL | struct Obj<F> where F: FnOnce() -> u32 {
| -------------------------------------- method `not_closure` not found for this
...
LL | w.wrap.not_closure();
| ^^^^^^^^^^^ field, not a method
|
= help: did you mean to write `w.wrap.not_closure` instead of `w.wrap.not_closure(...)`?
| ^^^^^^^^^^^-- help: remove the arguments
| |
| field, not a method

error[E0599]: no method named `closure` found for type `Obj<std::boxed::Box<(dyn std::boxed::FnBox<(), Output=u32> + 'static)>>` in the current scope
--> $DIR/issue-2392.rs:62:24
Expand All @@ -83,8 +93,10 @@ LL | struct Obj<F> where F: FnOnce() -> u32 {
...
LL | check_expression().closure();
| ^^^^^^^ field, not a method
help: to call the function stored in `closure`, surround the field access with parentheses
|
= help: use `(check_expression().closure)(...)` if you meant to call the function stored in the `closure` field
LL | (check_expression().closure)();
| ^ ^

error[E0599]: no method named `f1` found for type `FuncContainer` in the current scope
--> $DIR/issue-2392.rs:68:31
Expand All @@ -94,8 +106,10 @@ LL | struct FuncContainer {
...
LL | (*self.container).f1(1);
| ^^ field, not a method
help: to call the function stored in `f1`, surround the field access with parentheses
|
= help: use `((*self.container).f1)(...)` if you meant to call the function stored in the `f1` field
LL | ((*self.container).f1)(1);
| ^ ^

error[E0599]: no method named `f2` found for type `FuncContainer` in the current scope
--> $DIR/issue-2392.rs:69:31
Expand All @@ -105,8 +119,10 @@ LL | struct FuncContainer {
...
LL | (*self.container).f2(1);
| ^^ field, not a method
help: to call the function stored in `f2`, surround the field access with parentheses
|
= help: use `((*self.container).f2)(...)` if you meant to call the function stored in the `f2` field
LL | ((*self.container).f2)(1);
| ^ ^

error[E0599]: no method named `f3` found for type `FuncContainer` in the current scope
--> $DIR/issue-2392.rs:70:31
Expand All @@ -116,8 +132,10 @@ LL | struct FuncContainer {
...
LL | (*self.container).f3(1);
| ^^ field, not a method
help: to call the function stored in `f3`, surround the field access with parentheses
|
= help: use `((*self.container).f3)(...)` if you meant to call the function stored in the `f3` field
LL | ((*self.container).f3)(1);
| ^ ^

error: aborting due to 11 previous errors

Expand Down
4 changes: 3 additions & 1 deletion src/test/ui/confuse-field-and-method/issue-32128.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,10 @@ LL | struct Example {
...
LL | demo.example(1);
| ^^^^^^^ field, not a method
help: to call the function stored in `example`, surround the field access with parentheses
|
= help: use `(demo.example)(...)` if you meant to call the function stored in the `example` field
LL | (demo.example)(1);
| ^ ^

error: aborting due to previous error

Expand Down
12 changes: 9 additions & 3 deletions src/test/ui/confuse-field-and-method/issue-33784.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -3,24 +3,30 @@ error[E0599]: no method named `closure` found for type `&Obj<[closure@$DIR/issue
|
LL | p.closure();
| ^^^^^^^ field, not a method
help: to call the function stored in `closure`, surround the field access with parentheses
|
= help: use `(p.closure)(...)` if you meant to call the function stored in the `closure` field
LL | (p.closure)();
| ^ ^

error[E0599]: no method named `fn_ptr` found for type `&&Obj<[closure@$DIR/issue-33784.rs:25:43: 25:48]>` in the current scope
--> $DIR/issue-33784.rs:29:7
|
LL | q.fn_ptr();
| ^^^^^^ field, not a method
help: to call the function stored in `fn_ptr`, surround the field access with parentheses
|
= help: use `(q.fn_ptr)(...)` if you meant to call the function stored in the `fn_ptr` field
LL | (q.fn_ptr)();
| ^ ^

error[E0599]: no method named `c_fn_ptr` found for type `&D` in the current scope
--> $DIR/issue-33784.rs:32:7
|
LL | s.c_fn_ptr();
| ^^^^^^^^ field, not a method
help: to call the function stored in `c_fn_ptr`, surround the field access with parentheses
|
= help: use `(s.c_fn_ptr)(...)` if you meant to call the function stored in the `c_fn_ptr` field
LL | (s.c_fn_ptr)();
| ^ ^

error: aborting due to 3 previous errors

Expand Down