diff options
Diffstat (limited to 'compiler/rustc_ast_lowering/src/lib.rs')
| -rw-r--r-- | compiler/rustc_ast_lowering/src/lib.rs | 108 |
1 files changed, 60 insertions, 48 deletions
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs index d53280751fc..0b2969a49ba 100644 --- a/compiler/rustc_ast_lowering/src/lib.rs +++ b/compiler/rustc_ast_lowering/src/lib.rs @@ -2052,6 +2052,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { } } + /// Used when lowering a type argument that turned out to actually be a const argument. + /// + /// Only use for that purpose since otherwise it will create a duplicate def. #[instrument(level = "debug", skip(self))] fn lower_const_path_to_const_arg( &mut self, @@ -2060,51 +2063,58 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { ty_id: NodeId, span: Span, ) -> &'hir hir::ConstArg<'hir> { - let ct_kind = match res { - Res::Def(DefKind::ConstParam, _) => { - let qpath = self.lower_qpath( - ty_id, - &None, - path, - ParamMode::Optional, - AllowReturnTypeNotation::No, - ImplTraitContext::Disallowed(ImplTraitPosition::Path), - None, - ); - hir::ConstArgKind::Path(qpath) - } - _ => { - // Construct an AnonConst where the expr is the "ty"'s path. + let tcx = self.tcx; - let parent_def_id = self.current_def_id_parent; - let node_id = self.next_node_id(); - let span = self.lower_span(span); - - // Add a definition for the in-band const def. - let def_id = - self.create_def(parent_def_id, node_id, kw::Empty, DefKind::AnonConst, span); - let hir_id = self.lower_node_id(node_id); + // FIXME(min_generic_const_args): we only allow one-segment const paths for now + let ct_kind = if path.is_potential_trivial_const_arg() + && (tcx.features().min_generic_const_args() + || matches!(res, Res::Def(DefKind::ConstParam, _))) + { + let qpath = self.lower_qpath( + ty_id, + &None, + path, + ParamMode::Optional, + AllowReturnTypeNotation::No, + // FIXME(min_generic_const_args): update for `fn foo() -> Bar<FOO<impl Trait>>` support + ImplTraitContext::Disallowed(ImplTraitPosition::Path), + None, + ); + hir::ConstArgKind::Path(qpath) + } else { + // Construct an AnonConst where the expr is the "ty"'s path. + + let parent_def_id = self.current_def_id_parent; + let node_id = self.next_node_id(); + let span = self.lower_span(span); + + // Add a definition for the in-band const def. + // We're lowering a const argument that was originally thought to be a type argument, + // so the def collector didn't create the def ahead of time. That's why we have to do + // it here. + let def_id = + self.create_def(parent_def_id, node_id, kw::Empty, DefKind::AnonConst, span); + let hir_id = self.lower_node_id(node_id); + + let path_expr = Expr { + id: ty_id, + kind: ExprKind::Path(None, path.clone()), + span, + attrs: AttrVec::new(), + tokens: None, + }; - let path_expr = Expr { - id: ty_id, - kind: ExprKind::Path(None, path.clone()), + let ct = self.with_new_scopes(span, |this| { + self.arena.alloc(hir::AnonConst { + def_id, + hir_id, + body: this.with_def_id_parent(def_id, |this| { + this.lower_const_body(path_expr.span, Some(&path_expr)) + }), span, - attrs: AttrVec::new(), - tokens: None, - }; - - let ct = self.with_new_scopes(span, |this| { - self.arena.alloc(hir::AnonConst { - def_id, - hir_id, - body: this.with_def_id_parent(def_id, |this| { - this.lower_const_body(path_expr.span, Some(&path_expr)) - }), - span, - }) - }); - hir::ConstArgKind::Anon(ct) - } + }) + }); + hir::ConstArgKind::Anon(ct) }; self.arena.alloc(hir::ConstArg { @@ -2122,6 +2132,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { #[instrument(level = "debug", skip(self))] fn lower_anon_const_to_const_arg_direct(&mut self, anon: &AnonConst) -> hir::ConstArg<'hir> { + let tcx = self.tcx; // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments // currently have to be wrapped in curly brackets, so it's necessary to special-case. let expr = if let ExprKind::Block(block, _) = &anon.value.kind @@ -2135,18 +2146,19 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { }; let maybe_res = self.resolver.get_partial_res(expr.id).and_then(|partial_res| partial_res.full_res()); - debug!("res={:?}", maybe_res); - // FIXME(min_generic_const_args): for now we only lower params to ConstArgKind::Path - if let Some(res) = maybe_res - && let Res::Def(DefKind::ConstParam, _) = res - && let ExprKind::Path(qself, path) = &expr.kind + // FIXME(min_generic_const_args): we only allow one-segment const paths for now + if let ExprKind::Path(None, path) = &expr.kind + && path.is_potential_trivial_const_arg() + && (tcx.features().min_generic_const_args() + || matches!(maybe_res, Some(Res::Def(DefKind::ConstParam, _)))) { let qpath = self.lower_qpath( expr.id, - qself, + &None, path, ParamMode::Optional, AllowReturnTypeNotation::No, + // FIXME(min_generic_const_args): update for `fn foo() -> Bar<FOO<impl Trait>>` support ImplTraitContext::Disallowed(ImplTraitPosition::Path), None, ); |