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Add requested comments, restructure some small bits of code. Fix extern
declarations allowing impl Trait.
This commit is contained in:
Christopher Vittal 2017-11-14 16:24:35 -05:00
parent 7e9948f92f
commit 9b4372e3b1
3 changed files with 22 additions and 11 deletions
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21
src/librustc/hir/lowering.rs
View file

@ -1130,11 +1130,19 @@ impl<'a> LoweringContext<'a> {
}).collect()
}
fn lower_fn_decl(&mut self,
decl: &FnDecl,
fn_def_id: Option<DefId>,
impl_trait_return_allow: bool)
-> P<hir::FnDecl> {
// NOTE: The two last paramters here have to do with impl Trait. If fn_def_id is Some,
// then impl Trait arguments are lowered into generic paramters on the given
// fn_def_id, otherwise impl Trait is disallowed. (for now)
//
// Furthermore, if impl_trait_return_allow is true, then impl Trait may be used in
// return positions as well. This guards against trait declarations and their impls
// where impl Trait is disallowed. (again for now)
P(hir::FnDecl {
inputs: decl.inputs.iter()
.map(|arg| if let Some(def_id) = fn_def_id {
@ -1143,9 +1151,9 @@ impl<'a> LoweringContext<'a> {
self.lower_ty(&arg.ty, ImplTraitContext::Disallowed)
}).collect(),
output: match decl.output {
FunctionRetTy::Ty(ref ty) => match (impl_trait_return_allow, fn_def_id) {
(false, _) => hir::Return(self.lower_ty(ty, ImplTraitContext::Disallowed)),
(_, Some(_)) => hir::Return(self.lower_ty(ty, ImplTraitContext::Existential)),
FunctionRetTy::Ty(ref ty) => match fn_def_id {
Some(_) if impl_trait_return_allow =>
hir::Return(self.lower_ty(ty, ImplTraitContext::Existential)),
_ => hir::Return(self.lower_ty(ty, ImplTraitContext::Disallowed)),
},
FunctionRetTy::Default(span) => hir::DefaultReturn(span),
@ -1730,7 +1738,8 @@ impl<'a> LoweringContext<'a> {
this.expr_block(body, ThinVec::new())
});
let impl_trait_return_allow = !this.is_in_trait_impl;
hir::ImplItemKind::Method(this.lower_method_sig(sig, fn_def_id,
hir::ImplItemKind::Method(this.lower_method_sig(sig,
fn_def_id,
impl_trait_return_allow),
body_id)
}
@ -1833,8 +1842,8 @@ impl<'a> LoweringContext<'a> {
attrs: this.lower_attrs(&i.attrs),
node: match i.node {
ForeignItemKind::Fn(ref fdec, ref generics) => {
let fn_def_id = this.resolver.definitions().opt_local_def_id(i.id);
hir::ForeignItemFn(this.lower_fn_decl(fdec, fn_def_id, true),
// Disallow impl Trait in foreign items
hir::ForeignItemFn(this.lower_fn_decl(fdec, None, false),
this.lower_fn_args_to_names(fdec),
this.lower_generics(generics))
}

10
src/librustc_typeck/collect.rs
View file

@ -1763,9 +1763,13 @@ fn extract_universal_impl_trait_info<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
}
let mut visitor = ImplTraitUniversalVisitor { items: Vec::new() };
opt_inputs.map(|inputs| for t in inputs.iter() {
visitor.visit_ty(t);
});
if let Some(inputs) = opt_inputs {
for t in inputs.iter() {
visitor.visit_ty(t);
}
}
visitor.items.into_iter().map(|ty| if let hir::TyImplTraitUniversal(_, ref bounds) = ty.node {
ImplTraitUniversalInfo {
id: ty.id,

2
src/test/compile-fail/impl-trait/where-allowed.rs
View file

@ -144,11 +144,9 @@ impl DummyType {
extern "C" {
fn in_foreign_parameters(_: impl Debug);
//~^ ERROR `impl Trait` not allowed outside of function and inherent method return types
// FIXME currently allowed
fn in_foreign_return() -> impl Debug;
//~^ ERROR `impl Trait` not allowed outside of function and inherent method return types
// FIXME currently allowed
}
// Allowed