Add missing builtin mappings for never type

Author: philberty

gcc/rust/hir/rust-ast-lower-type.h

@@ -291,6 +291,19 @@ class ASTLoweringType : public ASTLoweringBase
 			       translated);
   }
 
+  void visit (AST::NeverType &type) override
+  {
+    auto crate_num = mappings->get_current_crate ();
+    Analysis::NodeMapping mapping (crate_num, type.get_node_id (),
+				   mappings->get_next_hir_id (crate_num),
+				   mappings->get_next_localdef_id (crate_num));
+
+    translated = new HIR::NeverType (mapping, type.get_locus ());
+
+    mappings->insert_hir_type (mapping.get_crate_num (), mapping.get_hirid (),
+			       translated);
+  }
+
   void visit (AST::TraitObjectTypeOneBound &type) override;
 
   void visit (AST::TraitObjectType &type) override;

gcc/rust/resolve/rust-ast-resolve-type.cc

@@ -197,6 +197,12 @@ ResolveType::visit (AST::InferredType &type)
   ok = true;
 }
 
+void
+ResolveType::visit (AST::NeverType &type)
+{
+  ok = true;
+}
+
 void
 ResolveType::visit (AST::SliceType &type)
 {

gcc/rust/resolve/rust-ast-resolve-type.h

@@ -386,6 +386,8 @@ class ResolveType : public ResolverBase
 
   void visit (AST::InferredType &type) override;
 
+  void visit (AST::NeverType &type) override;
+
   void visit (AST::RawPointerType &type) override;
 
   void visit (AST::TraitObjectTypeOneBound &type) override;

gcc/rust/resolve/rust-ast-resolve.cc

@@ -187,6 +187,7 @@ Resolver::generate_builtins ()
   auto isize = new TyTy::ISizeType (mappings->get_next_hir_id ());
   auto char_tyty = new TyTy::CharType (mappings->get_next_hir_id ());
   auto str = new TyTy::StrType (mappings->get_next_hir_id ());
+  auto never = new TyTy::NeverType (mappings->get_next_hir_id ());
 
   MKBUILTIN_TYPE ("u8", builtins, u8);
   MKBUILTIN_TYPE ("u16", builtins, u16);
@@ -205,6 +206,7 @@ Resolver::generate_builtins ()
   MKBUILTIN_TYPE ("isize", builtins, isize);
   MKBUILTIN_TYPE ("char", builtins, char_tyty);
   MKBUILTIN_TYPE ("str", builtins, str);
+  MKBUILTIN_TYPE ("!", builtins, never);
 
   // unit type ()
   TyTy::TupleType *unit_tyty

gcc/rust/typecheck/rust-hir-type-check-type.h

@@ -145,6 +145,15 @@ class TypeCheckType : public TypeCheckBase
 				      type.get_locus ());
   }
 
+  void visit (HIR::NeverType &type) override
+  {
+    TyTy::BaseType *lookup = nullptr;
+    bool ok = context->lookup_builtin ("!", &lookup);
+    rust_assert (ok);
+
+    translated = lookup->clone ();
+  }
+
   void visit (HIR::TraitObjectType &type) override;
 
 private: