Remove never-used "version" field from ContextDescriptorFlags.

(cherry picked from commit 223645c)

Author: DougGregor

include/swift/ABI/MetadataValues.h

@@ -1688,13 +1688,11 @@ struct ContextDescriptorFlags {
   constexpr ContextDescriptorFlags(ContextDescriptorKind kind,
                                    bool isGeneric,
                                    bool isUnique,
-                                   uint8_t version,
                                    uint16_t kindSpecificFlags)
     : ContextDescriptorFlags(ContextDescriptorFlags()
                                .withKind(kind)
                                .withGeneric(isGeneric)
                                .withUnique(isUnique)
-                               .withVersion(version)
                                .withKindSpecificFlags(kindSpecificFlags))
   {}
 
@@ -1713,12 +1711,6 @@ struct ContextDescriptorFlags {
     return (Value & 0x40u) != 0;
   }
 
-  /// The format version of the descriptor. Higher version numbers may have
-  /// additional fields that aren't present in older versions.
-  constexpr uint8_t getVersion() const {
-    return (Value >> 8u) & 0xFFu;
-  }
-
   /// The most significant two bytes of the flags word, which can have
   /// kind-specific meaning.
   constexpr uint16_t getKindSpecificFlags() const {
@@ -1740,10 +1732,6 @@ struct ContextDescriptorFlags {
                                   | (isUnique ? 0x40u : 0));
   }
 
-  constexpr ContextDescriptorFlags withVersion(uint8_t version) const {
-    return ContextDescriptorFlags((Value & 0xFFFF00FFu) | (version << 8u));
-  }
-
   constexpr ContextDescriptorFlags
   withKindSpecificFlags(uint16_t flags) const {
     return ContextDescriptorFlags((Value & 0xFFFFu) | (flags << 16u));

lib/IRGen/GenMeta.cpp

@@ -498,7 +498,6 @@ namespace {
         ContextDescriptorFlags(asImpl().getContextKind(),
                                !asImpl().getGenericSignature().isNull(),
                                asImpl().isUniqueDescriptor(),
-                               asImpl().getVersion(),
                                asImpl().getKindSpecificFlags())
           .getIntValue());
     }
@@ -578,10 +577,6 @@ namespace {
       irgen::addGenericPackShapeDescriptors(IGM, B, shapes, packArgs);
     }
 
-    uint8_t getVersion() {
-      return 0;
-    }
-    
     uint16_t getKindSpecificFlags() {
       return 0;
     }

unittests/runtime/MetadataObjectBuilder.h

@@ -34,7 +34,6 @@ inline void addModuleContextDescriptor(AnyObjectBuilder &builder,
   auto contextFlags = ContextDescriptorFlags(ContextDescriptorKind::Module,
                                              /*generic*/ false,
                                              /*unique*/ true,
-                                             /*version*/ 0,
                                              /*kindSpecific*/ 0);
   builder.add32(contextFlags.getIntValue());
 
@@ -55,7 +54,6 @@ inline void addProtocolDescriptor(AnyObjectBuilder &builder,
   auto contextFlags = ContextDescriptorFlags(ContextDescriptorKind::Protocol,
                                              /*generic*/ false,
                                              /*unique*/ true,
-                                             /*version*/ 0,
                                              /*kindSpecific*/ 0);
   builder.add32(contextFlags.getIntValue());
 
@@ -158,4 +156,4 @@ buildGlobalProtocolDescriptor(const ModuleContextDescriptor *module, Fn &&fn) {
 
 } // end namespace swift
 
-#endif
+#endif