Add some type-alias-impl-trait regression tests

[rust.git] / src / librustc_ast_lowering / lib.rs

diff --git a/src/librustc_ast_lowering/lib.rs b/src/librustc_ast_lowering/lib.rs
index 58b8e8a089ad31137380c1584b39b01c875b3174..284ede3b4fa1a119d92a81f3794da7c370aa7f2a 100644 (file)
--- a/src/librustc_ast_lowering/lib.rs
+++ b/src/librustc_ast_lowering/lib.rs
@@ -37,12 +37,10 @@
 use rustc::dep_graph::DepGraph;
 use rustc::hir::map::definitions::{DefKey, DefPathData, Definitions};
 use rustc::hir::map::Map;
-use rustc::lint::builtin;
 use rustc::{bug, span_bug};
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sync::Lrc;
-use rustc_error_codes::*;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Namespace, PartialRes, PerNS, Res};
@@ -51,7 +49,7 @@
 use rustc_hir::{ConstArg, GenericArg, ParamName};
 use rustc_index::vec::IndexVec;
 use rustc_session::config::nightly_options;
-use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
+use rustc_session::lint::{builtin, BuiltinLintDiagnostics, LintBuffer};
 use rustc_session::node_id::NodeMap;
 use rustc_session::Session;
 use rustc_span::hygiene::ExpnId;
@@ -1251,10 +1249,16 @@ fn lower_ty_direct(&mut self, t: &Ty, mut itctx: ImplTraitContext<'_, 'hir>) ->
                     let bounds =
                         this.arena.alloc_from_iter(bounds.iter().filter_map(
                             |bound| match *bound {
-                                GenericBound::Trait(ref ty, TraitBoundModifier::None) => {
+                                GenericBound::Trait(ref ty, TraitBoundModifier::None)
+                                | GenericBound::Trait(ref ty, TraitBoundModifier::MaybeConst) => {
                                     Some(this.lower_poly_trait_ref(ty, itctx.reborrow()))
                                 }
-                                GenericBound::Trait(_, TraitBoundModifier::Maybe) => None,
+                                // `?const ?Bound` will cause an error during AST validation
+                                // anyways, so treat it like `?Bound` as compilation proceeds.
+                                GenericBound::Trait(_, TraitBoundModifier::Maybe)
+                                | GenericBound::Trait(_, TraitBoundModifier::MaybeConstMaybe) => {
+                                    None
+                                }
                                 GenericBound::Outlives(ref lifetime) => {
                                     if lifetime_bound.is_none() {
                                         lifetime_bound = Some(this.lower_lifetime(lifetime));
@@ -2121,12 +2125,14 @@ fn lower_generic_param(
 
                 (hir::ParamName::Plain(param.ident), kind)
             }
-            GenericParamKind::Const { ref ty } => (
-                hir::ParamName::Plain(param.ident),
-                hir::GenericParamKind::Const {
-                    ty: self.lower_ty(&ty, ImplTraitContext::disallowed()),
-                },
-            ),
+            GenericParamKind::Const { ref ty } => {
+                let ty = self
+                    .with_anonymous_lifetime_mode(AnonymousLifetimeMode::ReportError, |this| {
+                        this.lower_ty(&ty, ImplTraitContext::disallowed())
+                    });
+
+                (hir::ParamName::Plain(param.ident), hir::GenericParamKind::Const { ty })
+            }
         };
 
         hir::GenericParam {
@@ -2157,10 +2163,6 @@ fn lower_poly_trait_ref(
         p: &PolyTraitRef,
         mut itctx: ImplTraitContext<'_, 'hir>,
     ) -> hir::PolyTraitRef<'hir> {
-        if p.trait_ref.constness.is_some() {
-            self.diagnostic().span_err(p.span, "`?const` on trait bounds is not yet implemented");
-        }
-
         let bound_generic_params = self.lower_generic_params(
             &p.bound_generic_params,
             &NodeMap::default(),
@@ -2299,7 +2301,13 @@ fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
     fn lower_trait_bound_modifier(&mut self, f: TraitBoundModifier) -> hir::TraitBoundModifier {
         match f {
             TraitBoundModifier::None => hir::TraitBoundModifier::None,
-            TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe,
+            TraitBoundModifier::MaybeConst => hir::TraitBoundModifier::MaybeConst,
+
+            // `MaybeConstMaybe` will cause an error during AST validation, but we need to pick a
+            // placeholder for compilation to proceed.
+            TraitBoundModifier::MaybeConstMaybe | TraitBoundModifier::Maybe => {
+                hir::TraitBoundModifier::Maybe
+            }
         }
     }