SILCloner: allow builtin conformances

When cloning SIL, it's OK for conformances to Copyable or Escapable to
be carried-over as a builtin conformance, rather than an abstract
conformance.

This is a workaround for a bug introduced in
`6cd5468cceacc1d600c7dafdd4debc6740d1dfd6`.

resolves rdar://125460667

Author: kavon

include/swift/AST/Type.h

@@ -126,6 +126,17 @@ class MakeAbstractConformanceForGenericType {
                                     ProtocolDecl *conformedProtocol) const;
 };
 
+/// Functor class suitable for use as a \c LookupConformanceFn that provides
+/// only abstract conformances, or builtin conformances for invertible protocols
+/// for generic types. Asserts that the replacement
+/// type is an opaque generic type.
+class MakeAbstractOrBuiltinConformanceForGenericType {
+public:
+  ProtocolConformanceRef operator()(CanType dependentType,
+                                    Type conformingReplacementType,
+                                    ProtocolDecl *conformedProtocol) const;
+};
+
 /// Functor class suitable for use as a \c LookupConformanceFn that fetches
 /// conformances from a generic signature.
 class LookUpConformanceInSignature {

include/swift/SIL/SILCloner.h

@@ -196,7 +196,7 @@ class SILCloner : protected SILInstructionVisitor<ImplClass> {
         // If we found a type containing a local archetype, substitute
         // open existentials throughout the substitution map.
         Subs = Subs.subst(QueryTypeSubstitutionMapOrIdentity{LocalArchetypeSubs},
-                          MakeAbstractConformanceForGenericType());
+                          MakeAbstractOrBuiltinConformanceForGenericType());
       }
     }
 
@@ -219,7 +219,7 @@ class SILCloner : protected SILInstructionVisitor<ImplClass> {
     return Ty.subst(
       Builder.getModule(),
       QueryTypeSubstitutionMapOrIdentity{LocalArchetypeSubs},
-      MakeAbstractConformanceForGenericType(),
+      MakeAbstractOrBuiltinConformanceForGenericType(),
       CanGenericSignature());
   }
   SILType getOpType(SILType Ty) {
@@ -239,7 +239,7 @@ class SILCloner : protected SILInstructionVisitor<ImplClass> {
 
     return ty.subst(
       QueryTypeSubstitutionMapOrIdentity{LocalArchetypeSubs},
-      MakeAbstractConformanceForGenericType()
+      MakeAbstractOrBuiltinConformanceForGenericType()
     )->getCanonicalType();
   }
 
@@ -352,7 +352,7 @@ class SILCloner : protected SILInstructionVisitor<ImplClass> {
         conformance.subst(ty,
                           QueryTypeSubstitutionMapOrIdentity{
                                                         LocalArchetypeSubs},
-                          MakeAbstractConformanceForGenericType());
+                          MakeAbstractOrBuiltinConformanceForGenericType());
     }
 
     return asImpl().remapConformance(getASTTypeInClonedContext(ty),

lib/AST/TypeSubstitution.cpp

@@ -230,6 +230,29 @@ operator()(CanType dependentType, Type conformingReplacementType,
   return Subs.lookupConformance(dependentType, conformedProtocol);
 }
 
+ProtocolConformanceRef MakeAbstractOrBuiltinConformanceForGenericType::
+operator()(CanType dependentType, Type conformingReplacementType,
+           ProtocolDecl *conformedProtocol) const {
+  MakeAbstractConformanceForGenericType useAbstract;
+  if (conformingReplacementType->is<PackType>()) {
+    return useAbstract(dependentType,
+                       conformingReplacementType,
+                       conformedProtocol);
+  }
+
+  // Workaround for rdar://125460667
+  if (conformedProtocol->getInvertibleProtocolKind()) {
+    auto &ctx = conformedProtocol->getASTContext();
+    return ProtocolConformanceRef(
+        ctx.getBuiltinConformance(conformingReplacementType, conformedProtocol,
+                                  BuiltinConformanceKind::Synthesized));
+  }
+
+  return useAbstract(dependentType,
+                     conformingReplacementType,
+                     conformedProtocol);
+}
+
 ProtocolConformanceRef MakeAbstractConformanceForGenericType::
 operator()(CanType dependentType, Type conformingReplacementType,
            ProtocolDecl *conformedProtocol) const {