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Rollup merge of #82194 - estebank:arbitrary-bounds-suggestion, r=petrochenkov

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In some limited cases, suggest `where` bounds for non-type params

Partially address #81971.
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Dylan DPC 2021-02-18 16:57:36 +01:00 • committed by GitHub
commit f01b339dae
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7 changed files with 74 additions and 4 deletions
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26
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
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@ -17,8 +17,8 @@ use rustc_hir::intravisit::Visitor;
use rustc_hir::lang_items::LangItem;
use rustc_hir::{AsyncGeneratorKind, GeneratorKind, Node};
use rustc_middle::ty::{
self, suggest_constraining_type_param, AdtKind, DefIdTree, Infer, InferTy, ToPredicate, Ty,
TyCtxt, TypeFoldable, WithConstness,
self, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind, DefIdTree,
Infer, InferTy, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness,
};
use rustc_middle::ty::{TypeAndMut, TypeckResults};
use rustc_span::symbol::{kw, sym, Ident, Symbol};
@ -334,7 +334,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
let (param_ty, projection) = match self_ty.kind() {
ty::Param(_) => (true, None),
ty::Projection(projection) => (false, Some(projection)),
_ => return,
_ => (false, None),
};
// FIXME: Add check for trait bound that is already present, particularly `?Sized` so we
@ -453,6 +453,26 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
}
}
hir::Node::Item(hir::Item {
kind:
hir::ItemKind::Struct(_, generics)
| hir::ItemKind::Enum(_, generics)
| hir::ItemKind::Union(_, generics)
| hir::ItemKind::Trait(_, _, generics, ..)
| hir::ItemKind::Impl(hir::Impl { generics, .. })
| hir::ItemKind::Fn(_, generics, _)
| hir::ItemKind::TyAlias(_, generics)
| hir::ItemKind::TraitAlias(generics, _)
| hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. }),
..
}) if !param_ty => {
// Missing generic type parameter bound.
let param_name = self_ty.to_string();
let constraint = trait_ref.print_only_trait_path().to_string();
if suggest_arbitrary_trait_bound(generics, &mut err, &param_name, &constraint) {
return;
}
}
hir::Node::Crate(..) => return,
_ => {}