Track whether a type contains an element archetype in the recursive properties.

Being able to efficiently query for a local archetype is important in SIL.

Author: rjmccall

include/swift/AST/Types.h

@@ -168,7 +168,10 @@ class RecursiveTypeProperties {
     /// This type contains a parameterized existential type \c any P<T>.
     HasParameterizedExistential = 0x2000,
 
-    Last_Property = HasParameterizedExistential
+    /// This type contains an ElementArchetype.
+    HasElementArchetype = 0x4000,
+
+    Last_Property = HasElementArchetype
   };
   enum { BitWidth = countBitsUsed(Property::Last_Property) };
 
@@ -212,9 +215,19 @@ class RecursiveTypeProperties {
   bool hasDependentMember() const { return Bits & HasDependentMember; }
 
   /// Does a type with these properties structurally contain an
-  /// archetype?
+  /// opened existential archetype?
   bool hasOpenedExistential() const { return Bits & HasOpenedExistential; }
 
+  /// Does a type with these properties structurally contain an
+  /// opened element archetype?
+  bool hasElementArchetype() const { return Bits & HasElementArchetype; }
+
+  /// Does a type with these properties structurally contain a local
+  /// archetype?
+  bool hasLocalArchetype() const {
+    return hasOpenedExistential() || hasElementArchetype();
+  }
+
   /// Does a type with these properties structurally contain a
   /// reference to DynamicSelf?
   bool hasDynamicSelf() const { return Bits & HasDynamicSelf; }
@@ -629,6 +642,16 @@ class alignas(1 << TypeAlignInBits) TypeBase
     return getRecursiveProperties().hasOpenedExistential();
   }
 
+  /// Determine whether the type involves an opened element archetype.
+  bool hasElementArchetype() const {
+    return getRecursiveProperties().hasElementArchetype();
+  }
+
+  /// Determine whether the type involves a local archetype.
+  bool hasLocalArchetype() const {
+    return getRecursiveProperties().hasLocalArchetype();
+  }
+
   bool hasParameterPack() const {
     return getRecursiveProperties().hasParameterPack();
   }

lib/AST/Type.cpp

@@ -4024,7 +4024,8 @@ ElementArchetypeType::ElementArchetypeType(
     ArrayRef<ProtocolDecl *> ConformsTo, Type Superclass,
     LayoutConstraint Layout)
     : LocalArchetypeType(TypeKind::ElementArchetype, Ctx,
-                         RecursiveTypeProperties::HasArchetype,
+                         RecursiveTypeProperties::HasArchetype |
+                         RecursiveTypeProperties::HasElementArchetype,
                          InterfaceType,
                          ConformsTo, Superclass, Layout, GenericEnv) {
 }