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Rollup merge of rust-lang#59025 - aoikonomopoulos:issue-57924, r=varkor
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Fix generic argument lookup for Self

Rewrite the SelfCtor early and use the replacement Def when
calculating the path_segs.

Note that this also changes which def is seen by the code that
computes user_self_ty and is_alias_variant_ctor; I don't see a
immediate issue with that, but I'm not 100% clear on the
implications.

Fixes rust-lang#57924

r? @eddyb
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pietroalbini authored Mar 13, 2019
2 parents ba9323f + 311025e commit ae5856f
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Showing 2 changed files with 69 additions and 59 deletions.
119 changes: 60 additions & 59 deletions src/librustc_typeck/check/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -5288,6 +5288,53 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
Some(original_span.with_lo(original_span.hi() - BytePos(1)))
}

// Rewrite `SelfCtor` to `StructCtor`
pub fn rewrite_self_ctor(&self, def: Def, span: Span) -> (Def, DefId, Ty<'tcx>) {
let tcx = self.tcx;
if let Def::SelfCtor(impl_def_id) = def {
let ty = self.impl_self_ty(span, impl_def_id).ty;
let adt_def = ty.ty_adt_def();

match adt_def {
Some(adt_def) if adt_def.has_ctor() => {
let variant = adt_def.non_enum_variant();
let def = Def::StructCtor(variant.did, variant.ctor_kind);
(def, variant.did, tcx.type_of(variant.did))
}
_ => {
let mut err = tcx.sess.struct_span_err(span,
"the `Self` constructor can only be used with tuple or unit structs");
if let Some(adt_def) = adt_def {
match adt_def.adt_kind() {
AdtKind::Enum => {
err.help("did you mean to use one of the enum's variants?");
},
AdtKind::Struct |
AdtKind::Union => {
err.span_suggestion(
span,
"use curly brackets",
String::from("Self { /* fields */ }"),
Applicability::HasPlaceholders,
);
}
}
}
err.emit();

(def, impl_def_id, tcx.types.err)
}
}
} else {
let def_id = def.def_id();

// The things we are substituting into the type should not contain
// escaping late-bound regions, and nor should the base type scheme.
let ty = tcx.type_of(def_id);
(def, def_id, ty)
}
}

// Instantiates the given path, which must refer to an item with the given
// number of type parameters and type.
pub fn instantiate_value_path(&self,
Expand All @@ -5307,6 +5354,18 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {

let tcx = self.tcx;

match def {
Def::Local(nid) | Def::Upvar(nid, ..) => {
let hid = self.tcx.hir().node_to_hir_id(nid);
let ty = self.local_ty(span, hid).decl_ty;
let ty = self.normalize_associated_types_in(span, &ty);
self.write_ty(hir_id, ty);
return (ty, def);
}
_ => {}
}

let (def, def_id, ty) = self.rewrite_self_ctor(def, span);
let path_segs = AstConv::def_ids_for_path_segments(self, segments, self_ty, def);

let mut user_self_ty = None;
Expand Down Expand Up @@ -5368,17 +5427,6 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
user_self_ty = None;
}

match def {
Def::Local(nid) | Def::Upvar(nid, ..) => {
let hid = self.tcx.hir().node_to_hir_id(nid);
let ty = self.local_ty(span, hid).decl_ty;
let ty = self.normalize_associated_types_in(span, &ty);
self.write_ty(hir_id, ty);
return (ty, def);
}
_ => {}
}

// Now we have to compare the types that the user *actually*
// provided against the types that were *expected*. If the user
// did not provide any types, then we want to substitute inference
Expand Down Expand Up @@ -5411,53 +5459,6 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
tcx.generics_of(*def_id).has_self
}).unwrap_or(false);

let mut new_def = def;
let (def_id, ty) = match def {
Def::SelfCtor(impl_def_id) => {
let ty = self.impl_self_ty(span, impl_def_id).ty;
let adt_def = ty.ty_adt_def();

match adt_def {
Some(adt_def) if adt_def.has_ctor() => {
let variant = adt_def.non_enum_variant();
new_def = Def::StructCtor(variant.did, variant.ctor_kind);
(variant.did, tcx.type_of(variant.did))
}
_ => {
let mut err = tcx.sess.struct_span_err(span,
"the `Self` constructor can only be used with tuple or unit structs");
if let Some(adt_def) = adt_def {
match adt_def.adt_kind() {
AdtKind::Enum => {
err.help("did you mean to use one of the enum's variants?");
},
AdtKind::Struct |
AdtKind::Union => {
err.span_suggestion(
span,
"use curly brackets",
String::from("Self { /* fields */ }"),
Applicability::HasPlaceholders,
);
}
}
}
err.emit();

(impl_def_id, tcx.types.err)
}
}
}
_ => {
let def_id = def.def_id();

// The things we are substituting into the type should not contain
// escaping late-bound regions, and nor should the base type scheme.
let ty = tcx.type_of(def_id);
(def_id, ty)
}
};

let substs = AstConv::create_substs_for_generic_args(
tcx,
def_id,
Expand Down Expand Up @@ -5573,7 +5574,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
ty_substituted);
self.write_substs(hir_id, substs);

(ty_substituted, new_def)
(ty_substituted, def)
}

fn check_rustc_args_require_const(&self,
Expand Down
9 changes: 9 additions & 0 deletions src/test/run-pass/issues/issue-57924.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
pub struct Gcm<E>(E);

impl<E> Gcm<E> {
pub fn crash(e: E) -> Self {
Self::<E>(e)
}
}

fn main() {}

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