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Store all generic bounds as where predicates.

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This commit is contained in:
Camille GILLOT 2022-02-07 22:58:30 +01:00
parent 05b29f9a92
commit 94449e6101
30 changed files with 770 additions and 953 deletions
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31
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
View file

@ -2420,25 +2420,14 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
let sized_trait = self.tcx.lang_items().sized_trait();
debug!("maybe_suggest_unsized_generics: generics.params={:?}", generics.params);
debug!("maybe_suggest_unsized_generics: generics.predicates={:?}", generics.predicates);
let param = generics.params.iter().filter(|param| param.span == span).find(|param| {
// Check that none of the explicit trait bounds is `Sized`. Assume that an explicit
// `Sized` bound is there intentionally and we don't need to suggest relaxing it.
param
.bounds
.iter()
.all(|bound| bound.trait_ref().and_then(|tr| tr.trait_def_id()) != sized_trait)
});
let Some(param) = param else {
let Some(param) = generics.params.iter().find(|param| param.span == span) else {
return;
};
let param_def_id = self.tcx.hir().local_def_id(param.hir_id).to_def_id();
let preds = generics.predicates.iter();
let explicitly_sized = preds
.filter_map(|pred| match pred {
hir::WherePredicate::BoundPredicate(bp) => Some(bp),
_ => None,
})
.filter(|bp| bp.is_param_bound(param_def_id))
let param_def_id = self.tcx.hir().local_def_id(param.hir_id);
// Check that none of the explicit trait bounds is `Sized`. Assume that an explicit
// `Sized` bound is there intentionally and we don't need to suggest relaxing it.
let explicitly_sized = generics
.bounds_for_param(param_def_id)
.flat_map(|bp| bp.bounds)
.any(|bound| bound.trait_ref().and_then(|tr| tr.trait_def_id()) == sized_trait);
if explicitly_sized {
@ -2461,9 +2450,11 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
_ => {}
};
// Didn't add an indirection suggestion, so add a general suggestion to relax `Sized`.
let (span, separator) = match param.bounds {
[] => (span.shrink_to_hi(), ":"),
[.., bound] => (bound.span().shrink_to_hi(), " +"),
let (span, separator) = if let Some(s) = generics.bounds_span_for_suggestions(param_def_id)
{
(s, " +")
} else {
(span.shrink_to_hi(), ":")
};
err.span_suggestion_verbose(
span,

21
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -320,7 +320,7 @@ pub trait InferCtxtExt<'tcx> {
fn predicate_constraint(generics: &hir::Generics<'_>, pred: String) -> (Span, String) {
(
generics.tail_span_for_predicate_suggestion(),
format!("{} {}", if !generics.predicates.is_empty() { "," } else { " where" }, pred,),
format!("{} {}", if generics.has_where_clause { "," } else { " where" }, pred,),
)
}
@ -392,21 +392,10 @@ fn suggest_restriction<'tcx>(
let pred = trait_pred.to_predicate(tcx).to_string();
let pred = pred.replace(&impl_trait_str, &type_param_name);
let mut sugg = vec![
// Find the last of the generic parameters contained within the span of
// the generics
match generics
.params
.iter()
.map(|p| p.bounds_span_for_suggestions().unwrap_or(p.span.shrink_to_hi()))
.filter(|&span| generics.span.contains(span) && span.can_be_used_for_suggestions())
.max_by_key(|span| span.hi())
{
// `fn foo(t: impl Trait)`
// ^ suggest `<T: Trait>` here
None => (generics.span, format!("<{}>", type_param)),
// `fn foo<A>(t: impl Trait)`
// ^^^ suggest `<A, T: Trait>` here
Some(span) => (span, format!(", {}", type_param)),
if let Some(span) = generics.span_for_param_suggestion() {
(span, format!(", {}", type_param))
} else {
(generics.span, format!("<{}>", type_param))
},
// `fn foo(t: impl Trait)`
// ^ suggest `where <T as Trait>::A: Bound`