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Provide more suggestions on invalid equality where bounds #120751

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Feb 13, 2024
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Provide more suggestions on invalid equality where bounds #120751

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0c1b273
Provide more suggestions on invalid equality where bounds
estebank Feb 7, 2024
535c643
Do not leave stray commas after applying suggestion
estebank Feb 8, 2024
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117 changes: 56 additions & 61 deletions compiler/rustc_ast_passes/src/ast_validation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1593,6 +1593,58 @@ fn deny_equality_constraints(
}
}
}

let mut suggest =
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|poly: &PolyTraitRef, potential_assoc: &PathSegment, predicate: &WhereEqPredicate| {
if let [trait_segment] = &poly.trait_ref.path.segments[..] {
let assoc = pprust::path_to_string(&ast::Path::from_ident(potential_assoc.ident));
let ty = pprust::ty_to_string(&predicate.rhs_ty);
let (args, span) = match &trait_segment.args {
Some(args) => match args.deref() {
ast::GenericArgs::AngleBracketed(args) => {
let Some(arg) = args.args.last() else {
return;
};
(format!(", {assoc} = {ty}"), arg.span().shrink_to_hi())
}
_ => return,
},
None => (format!("<{assoc} = {ty}>"), trait_segment.span().shrink_to_hi()),
};
let removal_span = if generics.where_clause.predicates.len() == 1 {
// We're removing th eonly where bound left, remove the whole thing.
generics.where_clause.span
} else {
let mut span = predicate.span;
let mut prev: Option<Span> = None;
let mut preds = generics.where_clause.predicates.iter().peekable();
// Find the predicate that shouldn't have been in the where bound list.
while let Some(pred) = preds.next() {
if let WherePredicate::EqPredicate(pred) = pred
&& pred.span == predicate.span
{
if let Some(next) = preds.peek() {
// This is the first predicate, remove the trailing comma as well.
span = span.with_hi(next.span().lo());
} else if let Some(prev) = prev {
// Remove the previous comma as well.
span = span.with_lo(prev.hi());
}
}
prev = Some(pred.span());
}
span
};
err.assoc2 = Some(errors::AssociatedSuggestion2 {
span,
args,
predicate: removal_span,
trait_segment: trait_segment.ident,
potential_assoc: potential_assoc.ident,
});
}
};

if let TyKind::Path(None, full_path) = &predicate.lhs_ty.kind {
// Given `A: Foo, Foo::Bar = RhsTy`, suggest `A: Foo<Bar = RhsTy>`.
for bounds in generics.params.iter().map(|p| &p.bounds).chain(
Expand All @@ -1608,37 +1660,9 @@ fn deny_equality_constraints(
.map(|segment| segment.ident.name)
.zip(poly.trait_ref.path.segments.iter().map(|segment| segment.ident.name))
.all(|(a, b)| a == b)
&& let Some(potential_assoc) = full_path.segments.iter().last()
{
let potential_assoc = full_path.segments.iter().last().unwrap();
// println!("asd");
if let [trait_segment] = &poly.trait_ref.path.segments[..] {
let assoc = pprust::path_to_string(&ast::Path::from_ident(
potential_assoc.ident,
));
let ty = pprust::ty_to_string(&predicate.rhs_ty);
let (args, span) = match &trait_segment.args {
Some(args) => match args.deref() {
ast::GenericArgs::AngleBracketed(args) => {
let Some(arg) = args.args.last() else {
continue;
};
(format!(", {assoc} = {ty}"), arg.span().shrink_to_hi())
}
_ => continue,
},
None => (
format!("<{assoc} = {ty}>"),
trait_segment.span().shrink_to_hi(),
),
};
err.assoc2 = Some(errors::AssociatedSuggestion2 {
span,
args,
predicate: predicate.span,
trait_segment: trait_segment.ident,
potential_assoc: potential_assoc.ident,
});
}
suggest(poly, potential_assoc, predicate);
}
}
}
Expand All @@ -1658,37 +1682,8 @@ fn deny_equality_constraints(
) {
if ident == potential_param.ident {
for bound in bounds {
if let ast::GenericBound::Trait(trait_ref, TraitBoundModifiers::NONE) =
bound
{
if let [trait_segment] = &trait_ref.trait_ref.path.segments[..] {
let assoc = pprust::path_to_string(&ast::Path::from_ident(
potential_assoc.ident,
));
let ty = pprust::ty_to_string(&predicate.rhs_ty);
let (args, span) = match &trait_segment.args {
Some(args) => match args.deref() {
ast::GenericArgs::AngleBracketed(args) => {
let Some(arg) = args.args.last() else {
continue;
};
(format!(", {assoc} = {ty}"), arg.span().shrink_to_hi())
}
_ => continue,
},
None => (
format!("<{assoc} = {ty}>"),
trait_segment.span().shrink_to_hi(),
),
};
err.assoc2 = Some(errors::AssociatedSuggestion2 {
span,
args,
predicate: predicate.span,
trait_segment: trait_segment.ident,
potential_assoc: potential_assoc.ident,
});
}
if let ast::GenericBound::Trait(poly, TraitBoundModifiers::NONE) = bound {
suggest(poly, potential_assoc, predicate);
}
}
}
Expand Down
39 changes: 25 additions & 14 deletions tests/ui/generic-associated-types/equality-bound.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,10 +17,7 @@ use std::iter::FromIterator;
struct X {}

impl FromIterator<bool> for X {
fn from_iter<T>(_: T) -> Self
where
T: IntoIterator,
IntoIterator::Item = A,
fn from_iter<T>(_: T) -> Self where T: IntoIterator, IntoIterator::Item = A,
//~^ ERROR equality constraints are not yet supported in `where` clauses
//~| ERROR cannot find type `A` in this scope
{
Expand All @@ -31,10 +28,7 @@ impl FromIterator<bool> for X {
struct Y {}

impl FromIterator<bool> for Y {
fn from_iter<T>(_: T) -> Self
where
T: IntoIterator,
T::Item = A,
fn from_iter<T>(_: T) -> Self where T: IntoIterator, T::Item = A,
//~^ ERROR equality constraints are not yet supported in `where` clauses
//~| ERROR cannot find type `A` in this scope
{
Expand All @@ -45,9 +39,7 @@ impl FromIterator<bool> for Y {
struct Z {}

impl FromIterator<bool> for Z {
fn from_iter<T: IntoIterator>(_: T) -> Self
where
IntoIterator::Item = A,
fn from_iter<T: IntoIterator>(_: T) -> Self where IntoIterator::Item = A,
//~^ ERROR equality constraints are not yet supported in `where` clauses
//~| ERROR cannot find type `A` in this scope
{
Expand All @@ -58,14 +50,33 @@ impl FromIterator<bool> for Z {
struct K {}

impl FromIterator<bool> for K {
fn from_iter<T: IntoIterator>(_: T) -> Self
where
T::Item = A,
fn from_iter<T: IntoIterator>(_: T) -> Self where T::Item = A,
//~^ ERROR equality constraints are not yet supported in `where` clauses
//~| ERROR cannot find type `A` in this scope
{
todo!()
}
}

struct L {}

impl FromIterator<bool> for L {
fn from_iter<T>(_: T) -> Self where IntoIterator::Item = A, T: IntoIterator,
//~^ ERROR equality constraints are not yet supported in `where` clauses
//~| ERROR cannot find type `A` in this scope
{
todo!()
}
}

struct M {}

impl FromIterator<bool> for M {
fn from_iter<T>(_: T) -> Self where T::Item = A, T: IntoIterator,
//~^ ERROR equality constraints are not yet supported in `where` clauses
//~| ERROR cannot find type `A` in this scope
{
todo!()
}
}
fn main() {}