gccrs: Add dropck_eyepatch feature gate for may_dangle

Add a new feature gate for may_dangle generic param outer attributes.

gcc/rust/ChangeLog:

	* checks/errors/rust-feature-gate.cc: Visit and gate may_dangle
	attributes.
	* checks/errors/rust-feature-gate.h: Update visit function prototype
	and add a new member function to check on a set of attributes whether
	one is may_dangle.
	* checks/errors/rust-feature.cc (Feature::create): Add new
	dropck_eyepatch feature.
	* checks/errors/rust-feature.h: Likewise.
	* util/rust-attribute-values.h: Add new may_dangle attribute value.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

5 files changed, 48 insertions, 3 deletions

diff --git a/gcc/rust/checks/errors/rust-feature-gate.cc b/gcc/rust/checks/errors/rust-feature-gate.cc
index 69348cb..16c5ece 100644
--- a/gcc/rust/checks/errors/rust-feature-gate.cc
+++ b/gcc/rust/checks/errors/rust-feature-gate.cc
@@ -18,6 +18,7 @@
 
 #include "rust-feature-gate.h"
 #include "rust-abi.h"
+#include "rust-attribute-values.h"
 #include "rust-ast-visitor.h"
 #include "rust-feature.h"
 
@@ -124,6 +125,19 @@ FeatureGate::check_rustc_attri (const std::vector<AST::Attribute> &attributes)
 }
 
 void
+FeatureGate::check_may_dangle_attribute (
+  const std::vector<AST::Attribute> &attributes)
+{
+  for (const AST::Attribute &attr : attributes)
+    {
+      if (attr.get_path ().as_string () == Values::Attributes::MAY_DANGLE)
+	gate (Feature::Name::DROPCK_EYEPATCH, attr.get_locus (),
+	      "`may_dangle` has unstable semantics and may be removed in the "
+	      "future");
+    }
+}
+
+void
 FeatureGate::visit (AST::MacroRulesDefinition &rules_def)
 {
   check_rustc_attri (rules_def.get_outer_attrs ());
@@ -153,6 +167,8 @@ FeatureGate::visit (AST::TraitImpl &impl)
   if (impl.is_exclam ())
     gate (Feature::Name::NEGATIVE_IMPLS, impl.get_locus (),
 	  "negative_impls are not yet implemented");
+
+  AST::DefaultASTVisitor::visit (impl);
 };
 
 void
@@ -164,4 +180,25 @@ FeatureGate::visit (AST::BoxExpr &expr)
   AST::DefaultASTVisitor::visit (expr);
 }
 
+void
+FeatureGate::visit (AST::LifetimeParam &lifetime_param)
+{
+  check_may_dangle_attribute (lifetime_param.get_outer_attrs ());
+  AST::DefaultASTVisitor::visit (lifetime_param);
+}
+
+void
+FeatureGate::visit (AST::ConstGenericParam &const_param)
+{
+  check_may_dangle_attribute (const_param.get_outer_attrs ());
+  AST::DefaultASTVisitor::visit (const_param);
+}
+
+void
+FeatureGate::visit (AST::TypeParam &param)
+{
+  check_may_dangle_attribute (param.get_outer_attrs ());
+  AST::DefaultASTVisitor::visit (param);
+}
+
 } // namespace Rust
diff --git a/gcc/rust/checks/errors/rust-feature-gate.h b/gcc/rust/checks/errors/rust-feature-gate.h
index bef7cf1..5ead1103 100644
--- a/gcc/rust/checks/errors/rust-feature-gate.h
+++ b/gcc/rust/checks/errors/rust-feature-gate.h
@@ -40,8 +40,8 @@ public:
   void visit (AST::AttrInputMetaItemContainer &input) override {}
   void visit (AST::IdentifierExpr &ident_expr) override {}
   void visit (AST::Lifetime &lifetime) override {}
-  void visit (AST::LifetimeParam &lifetime_param) override {}
-  void visit (AST::ConstGenericParam &const_param) override {}
+  void visit (AST::LifetimeParam &lifetime_param) override;
+  void visit (AST::ConstGenericParam &const_param) override;
   void visit (AST::PathInExpression &path) override {}
   void visit (AST::TypePathSegment &segment) override {}
   void visit (AST::TypePathSegmentGeneric &segment) override {}
@@ -104,7 +104,7 @@ public:
   void visit (AST::MatchExpr &expr) override {}
   void visit (AST::AwaitExpr &expr) override {}
   void visit (AST::AsyncBlockExpr &expr) override {}
-  void visit (AST::TypeParam &param) override {}
+  void visit (AST::TypeParam &param) override;
   void visit (AST::LifetimeWhereClauseItem &item) override {}
   void visit (AST::TypeBoundWhereClauseItem &item) override {}
   void visit (AST::Module &module) override {}
@@ -188,6 +188,8 @@ public:
 private:
   void gate (Feature::Name name, location_t loc, const std::string &error_msg);
   void check_rustc_attri (const std::vector<AST::Attribute> &attributes);
+  void
+  check_may_dangle_attribute (const std::vector<AST::Attribute> &attributes);
   std::set<Feature::Name> valid_features;
 };
 } // namespace Rust
diff --git a/gcc/rust/checks/errors/rust-feature.cc b/gcc/rust/checks/errors/rust-feature.cc
index f993bbb..b9a648e 100644
--- a/gcc/rust/checks/errors/rust-feature.cc
+++ b/gcc/rust/checks/errors/rust-feature.cc
@@ -48,6 +48,9 @@ Feature::create (Feature::Name name)
     case Feature::Name::BOX_SYNTAX:
       return Feature (Feature::Name::BOX_SYNTAX, Feature::State::ACTIVE,
 		      "box_syntax", "1.0.0", 49733, tl::nullopt, "");
+    case Feature::Name::DROPCK_EYEPATCH:
+      return Feature (Feature::Name::DROPCK_EYEPATCH, Feature::State::ACTIVE,
+		      "dropck_eyepatch", "1.10.0", 34761, tl::nullopt, "");
     default:
       rust_unreachable ();
     }
@@ -66,6 +69,7 @@ const std::map<std::string, Feature::Name> Feature::name_hash_map = {
   {"lang_items", Feature::Name::LANG_ITEMS},
   {"no_core", Feature::Name::NO_CORE},
   {"box_syntax", Feature::Name::BOX_SYNTAX},
+  {"dropck_eyepatch", Feature::Name::DROPCK_EYEPATCH},
 }; // namespace Rust
 
 tl::optional<Feature::Name>
diff --git a/gcc/rust/checks/errors/rust-feature.h b/gcc/rust/checks/errors/rust-feature.h
index 736d97e..0fb63b5 100644
--- a/gcc/rust/checks/errors/rust-feature.h
+++ b/gcc/rust/checks/errors/rust-feature.h
@@ -47,6 +47,7 @@ public:
     LANG_ITEMS,
     NO_CORE,
     BOX_SYNTAX,
+    DROPCK_EYEPATCH,
   };
 
   const std::string &as_string () { return m_name_str; }
diff --git a/gcc/rust/util/rust-attribute-values.h b/gcc/rust/util/rust-attribute-values.h
index fec73b1..9041701 100644
--- a/gcc/rust/util/rust-attribute-values.h
+++ b/gcc/rust/util/rust-attribute-values.h
@@ -55,6 +55,7 @@ public:
   static constexpr auto &UNSTABLE = "unstable";
   static constexpr auto &RUSTC_CONST_STABLE = "rustc_const_stable";
   static constexpr auto &RUSTC_CONST_UNSTABLE = "rustc_const_unstable";
+  static constexpr auto &MAY_DANGLE = "may_dangle";
 };
 } // namespace Values
 } // namespace Rust