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Use hir::Map to prevent false positives

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This commit is contained in:
Hirochika Matsumoto 2022-08-28 15:59:06 +09:00
parent bafa89bc46
commit 722d136766
3 changed files with 58 additions and 40 deletions
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80
compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
View file

@ -524,8 +524,8 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
if self.not_enough_args_provided() {
self.suggest_adding_args(err);
} else if self.too_many_args_provided() {
self.suggest_moving_args_from_assoc_fn_to_trait(err);
self.suggest_removing_args_or_generics(err);
self.suggest_moving_args(err);
} else {
unreachable!();
}
@ -661,34 +661,62 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
/// ```compile_fail
/// Into::into::<Option<_>>(42) // suggests considering `Into::<Option<_>>::into(42)`
/// ```
fn suggest_moving_args(&self, err: &mut Diagnostic) {
if let Some(trait_) = self.tcx.trait_of_item(self.def_id) {
// HACK(hkmatsumoto): Ugly way to tell "<trait>::<assoc fn>()" from "x.<assoc fn>()";
// we don't care the latter (for now).
if self.path_segment.res == Some(hir::def::Res::Err) {
return;
fn suggest_moving_args_from_assoc_fn_to_trait(&self, err: &mut Diagnostic) {
let trait_ = match self.tcx.trait_of_item(self.def_id) {
Some(def_id) => def_id,
None => return,
};
// Skip suggestion when the associated function is itself generic, it is unclear
// how to split the provided parameters between those to suggest to the trait and
// those to remain on the associated type.
let num_assoc_fn_expected_args =
self.num_expected_type_or_const_args() + self.num_expected_lifetime_args();
if num_assoc_fn_expected_args > 0 {
return;
}
let num_assoc_fn_excess_args =
self.num_excess_type_or_const_args() + self.num_excess_lifetime_args();
let trait_generics = self.tcx.generics_of(trait_);
let num_trait_generics_except_self =
trait_generics.count() - if trait_generics.has_self { 1 } else { 0 };
if let Some(hir_id) = self.path_segment.hir_id
&& let Some(parent_node) = self.tcx.hir().find_parent_node(hir_id)
&& let Some(parent_node) = self.tcx.hir().find(parent_node)
&& let hir::Node::Expr(expr) = parent_node {
match expr.kind {
hir::ExprKind::Path(ref qpath) => {
self.suggest_moving_args_from_assoc_fn_to_trait_for_qualified_path(
err,
trait_,
qpath,
num_assoc_fn_excess_args,
num_trait_generics_except_self
)
},
// TODO(hkmatsumoto): Emit similar suggestion for "x.<assoc fn>()"
hir::ExprKind::MethodCall(..) => return,
_ => return,
}
}
}
// Say, if the assoc fn takes `A`, `B` and `C` as generic arguments while expecting 1
// argument, and its trait expects 2 arguments. It is hard to "split" them right as
// there are too many cases to handle: `A` `B` | `C`, `A` `B` | `C`, `A` `C` | `B`, ...
let num_assoc_fn_expected_args =
self.num_expected_type_or_const_args() + self.num_expected_lifetime_args();
if num_assoc_fn_expected_args > 0 {
return;
}
fn suggest_moving_args_from_assoc_fn_to_trait_for_qualified_path(
&self,
err: &mut Diagnostic,
trait_: DefId,
qpath: &'tcx hir::QPath<'tcx>,
num_assoc_fn_excess_args: usize,
num_trait_generics_except_self: usize,
) {
if let hir::QPath::Resolved(_, path) = qpath
&& let Some(trait_path_segment) = path.segments.get(0) {
let num_generic_args_supplied_to_trait = trait_path_segment.args().num_generic_params();
let num_assoc_fn_excess_args =
self.num_excess_type_or_const_args() + self.num_excess_lifetime_args();
let trait_generics = self.tcx.generics_of(trait_);
let num_trait_generics_except_self =
trait_generics.count() - if trait_generics.has_self { 1 } else { 0 };
// FIXME(hkmatsumoto): RHS of this condition ideally should be
// `num_trait_generics_except_self` - "# of generic args already provided to trait"
// but unable to get that information with `self.def_id`.
if num_assoc_fn_excess_args == num_trait_generics_except_self {
if num_assoc_fn_excess_args == num_trait_generics_except_self - num_generic_args_supplied_to_trait {
if let Some(span) = self.gen_args.span_ext()
&& let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
let msg = format!(

2
src/test/ui/suggestions/issue-89064.rs
View file

@ -24,9 +24,7 @@ fn main() {
//~| HELP remove these generics
//~| HELP consider moving these generic arguments
// bad suggestion
let _ = A::<S>::foo::<S>();
//~^ ERROR
//~| HELP remove these generics
//~| HELP consider moving this generic argument
}

16
src/test/ui/suggestions/issue-89064.stderr
View file

@ -43,26 +43,18 @@ LL + let _ = B::<S, S>::bar();
|
error[E0107]: this associated function takes 0 generic arguments but 1 generic argument was supplied
--> $DIR/issue-89064.rs:28:21
--> $DIR/issue-89064.rs:27:21
|
LL | let _ = A::<S>::foo::<S>();
| ^^^ expected 0 generic arguments
| ^^^----- help: remove these generics
| |
| expected 0 generic arguments
|
note: associated function defined here, with 0 generic parameters
--> $DIR/issue-89064.rs:4:8
|
LL | fn foo() {}
| ^^^
help: remove these generics
|
LL - let _ = A::<S>::foo::<S>();
LL + let _ = A::<S>::foo();
|
help: consider moving this generic argument to the `A` trait, which takes up to 1 argument
|
LL - let _ = A::<S>::foo::<S>();
LL + let _ = A::<S>::<S>::foo();
|
error: aborting due to 3 previous errors