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Rollup merge of rust-lang#67131 - Centril:item-merge, r=petrochenkov
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Merge `TraitItem` & `ImplItem into `AssocItem`

In this PR we:

- Merge `{Trait,Impl}Item{Kind?}` into `AssocItem{Kind?}` as discussed in rust-lang#65041 (comment).

   - This is done by using the cover grammar of both forms.

   - In particular, it requires that we syntactically allow (under `#[cfg(FALSE)]`):

      - `default`ness on `trait` items,

      - `impl` items without a body / definition (`const`, `type`, and `fn`),

      - and associated `type`s in `impl`s with bounds, e.g., `type Foo: Ord;`.

   - The syntactic restrictions are replaced by semantic ones in `ast_validation`.

- Move syntactic restrictions around C-variadic parameters from the parser into `ast_validation`:

    - `fn`s in all contexts now syntactically allow `...`,

    - `...` can occur anywhere in the list syntactically (`fn foo(..., x: usize) {}`),

    - and `...` can be the sole parameter (`fn foo(...) {}`.

r? @petrochenkov
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@Centril
Centril authored Dec 20, 2019
2 parents ba1a488 + 054458b commit ec82174
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Showing 65 changed files with 1,279 additions and 849 deletions.
83 changes: 36 additions & 47 deletions src/librustc/hir/lowering.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -477,11 +477,11 @@ impl<'a> LoweringContext<'a> {
});
}

fn visit_trait_item(&mut self, item: &'tcx TraitItem) {
fn visit_trait_item(&mut self, item: &'tcx AssocItem) {
self.lctx.allocate_hir_id_counter(item.id);

match item.kind {
TraitItemKind::Method(_, None) => {
AssocItemKind::Fn(_, None) => {
// Ignore patterns in trait methods without bodies
self.with_hir_id_owner(None, |this| {
visit::walk_trait_item(this, item)
Expand All @@ -493,7 +493,7 @@ impl<'a> LoweringContext<'a> {
}
}

fn visit_impl_item(&mut self, item: &'tcx ImplItem) {
fn visit_impl_item(&mut self, item: &'tcx AssocItem) {
self.lctx.allocate_hir_id_counter(item.id);
self.with_hir_id_owner(Some(item.id), |this| {
visit::walk_impl_item(this, item);
Expand Down Expand Up @@ -1211,7 +1211,7 @@ impl<'a> LoweringContext<'a> {
let ct = self.with_new_scopes(|this| {
hir::AnonConst {
hir_id: this.lower_node_id(node_id),
body: this.lower_const_body(&path_expr),
body: this.lower_const_body(path_expr.span, Some(&path_expr)),
}
});
return GenericArg::Const(ConstArg {
Expand Down Expand Up @@ -1253,6 +1253,14 @@ impl<'a> LoweringContext<'a> {
ty
}

fn ty(&mut self, span: Span, kind: hir::TyKind) -> hir::Ty {
hir::Ty { hir_id: self.next_id(), kind, span }
}

fn ty_tup(&mut self, span: Span, tys: HirVec<hir::Ty>) -> hir::Ty {
self.ty(span, hir::TyKind::Tup(tys))
}

fn lower_ty_direct(&mut self, t: &Ty, mut itctx: ImplTraitContext<'_>) -> hir::Ty {
let kind = match t.kind {
TyKind::Infer => hir::TyKind::Infer,
Expand Down Expand Up @@ -1418,7 +1426,13 @@ impl<'a> LoweringContext<'a> {
}
}
TyKind::Mac(_) => bug!("`TyKind::Mac` should have been expanded by now"),
TyKind::CVarArgs => bug!("`TyKind::CVarArgs` should have been handled elsewhere"),
TyKind::CVarArgs => {
self.sess.delay_span_bug(
t.span,
"`TyKind::CVarArgs` should have been handled elsewhere",
);
hir::TyKind::Err
}
};

hir::Ty {
Expand Down Expand Up @@ -2084,32 +2098,19 @@ impl<'a> LoweringContext<'a> {
.iter()
.map(|ty| this.lower_ty_direct(ty, ImplTraitContext::disallowed()))
.collect();
let mk_tup = |this: &mut Self, tys, span| {
hir::Ty { kind: hir::TyKind::Tup(tys), hir_id: this.next_id(), span }
let output_ty = match output {
FunctionRetTy::Ty(ty) => this.lower_ty(&ty, ImplTraitContext::disallowed()),
FunctionRetTy::Default(_) => P(this.ty_tup(span, hir::HirVec::new())),
};
let args = hir_vec![GenericArg::Type(this.ty_tup(span, inputs))];
let binding = hir::TypeBinding {
hir_id: this.next_id(),
ident: Ident::with_dummy_span(FN_OUTPUT_NAME),
span: output_ty.span,
kind: hir::TypeBindingKind::Equality { ty: output_ty },
};
(
hir::GenericArgs {
args: hir_vec![GenericArg::Type(mk_tup(this, inputs, span))],
bindings: hir_vec![
hir::TypeBinding {
hir_id: this.next_id(),
ident: Ident::with_dummy_span(FN_OUTPUT_NAME),
kind: hir::TypeBindingKind::Equality {
ty: output
.as_ref()
.map(|ty| this.lower_ty(
&ty,
ImplTraitContext::disallowed()
))
.unwrap_or_else(||
P(mk_tup(this, hir::HirVec::new(), span))
),
},
span: output.as_ref().map_or(span, |ty| ty.span),
}
],
parenthesized: true,
},
hir::GenericArgs { args, bindings: hir_vec![binding], parenthesized: true },
false,
)
}
Expand Down Expand Up @@ -2474,17 +2475,13 @@ impl<'a> LoweringContext<'a> {
})
);

// Create the `Foo<...>` refernece itself. Note that the `type
// Create the `Foo<...>` reference itself. Note that the `type
// Foo = impl Trait` is, internally, created as a child of the
// async fn, so the *type parameters* are inherited. It's
// only the lifetime parameters that we must supply.
let opaque_ty_ref = hir::TyKind::Def(hir::ItemId { id: opaque_ty_id }, generic_args.into());

hir::FunctionRetTy::Return(P(hir::Ty {
kind: opaque_ty_ref,
span: opaque_ty_span,
hir_id: self.next_id(),
}))
let opaque_ty = self.ty(opaque_ty_span, opaque_ty_ref);
hir::FunctionRetTy::Return(P(opaque_ty))
}

/// Transforms `-> T` into `Future<Output = T>`
Expand All @@ -2496,16 +2493,8 @@ impl<'a> LoweringContext<'a> {
) -> hir::GenericBound {
// Compute the `T` in `Future<Output = T>` from the return type.
let output_ty = match output {
FunctionRetTy::Ty(ty) => {
self.lower_ty(ty, ImplTraitContext::OpaqueTy(Some(fn_def_id)))
}
FunctionRetTy::Default(ret_ty_span) => {
P(hir::Ty {
hir_id: self.next_id(),
kind: hir::TyKind::Tup(hir_vec![]),
span: *ret_ty_span,
})
}
FunctionRetTy::Ty(ty) => self.lower_ty(ty, ImplTraitContext::OpaqueTy(Some(fn_def_id))),
FunctionRetTy::Default(ret_ty_span) => P(self.ty_tup(*ret_ty_span, hir_vec![])),
};

// "<Output = T>"
Expand Down Expand Up @@ -3017,7 +3006,7 @@ impl<'a> LoweringContext<'a> {
self.with_new_scopes(|this| {
hir::AnonConst {
hir_id: this.lower_node_id(c.id),
body: this.lower_const_body(&c.value),
body: this.lower_const_body(c.value.span, Some(&c.value)),
}
})
}
Expand Down
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