Runtime: Add GenericRequirementKind::SameShape and stub out cases

Author: slavapestov

include/swift/ABI/GenericContext.h

@@ -235,6 +235,7 @@ class TargetGenericRequirementDescriptor {
     case GenericRequirementKind::Protocol:
     case GenericRequirementKind::SameConformance:
     case GenericRequirementKind::SameType:
+    case GenericRequirementKind::SameShape:
       return true;
     }
 

include/swift/ABI/MetadataValues.h

@@ -1890,7 +1890,9 @@ enum class GenericRequirementKind : uint8_t {
   /// A "same-conformance" requirement, implied by a same-type or base-class
   /// constraint that binds a parameter with protocol requirements.
   SameConformance = 3,
-  /// A layout constraint.
+  /// A same-shape requirement between generic parameter packs.
+  SameShape = 4,
+  /// A layout requirement.
   Layout = 0x1F,
 };
 

include/swift/Remote/MetadataReader.h

@@ -1244,6 +1244,9 @@ class MetadataReader {
       case GenericRequirementKind::Layout:
         return TypeLookupError(
             "Unexpected layout requirement in runtime generic signature");
+      case GenericRequirementKind::SameShape:
+        return TypeLookupError(
+            "Unexpected same-shape requirement in runtime generic signature");
       }
     }
 
@@ -2771,6 +2774,9 @@ class MetadataReader {
             }
             break;
           }
+
+          case GenericRequirementKind::SameShape:
+            llvm_unreachable("Implement me");
           }
         }
 

stdlib/public/runtime/ProtocolConformance.cpp

@@ -1387,6 +1387,10 @@ llvm::Optional<TypeLookupError> swift::_checkGenericRequirements(
       // FIXME: Implement this check.
       continue;
     }
+
+    case GenericRequirementKind::SameShape: {
+      llvm_unreachable("Implement me");
+    }
     }
 
     // Unknown generic requirement kind.