[Serialization] Intro distinct compiler revision string for serialization

include/swift/Basic/Version.h

@@ -167,9 +167,14 @@ StringRef getSwiftRevision();
 /// and \c getCurrentCompilerTag returns the version tuple in string format.
 bool isCurrentCompilerTagged();
 
-/// Retrieves the distribtion tag of the running compiler, if any.
+/// Retrieves the distribution tag of the running compiler, if any.
 StringRef getCurrentCompilerTag();
 
+/// Retrieves the distribution tag of the running compiler for serialization,
+/// if any. This can hold more information than \c getCurrentCompilerTag
+/// depending on the vendor.
+StringRef getCurrentCompilerSerializationTag();
+
 } // end namespace version
 } // end namespace swift
 

lib/Basic/Version.cpp

@@ -297,5 +297,13 @@ StringRef getCurrentCompilerTag() {
 #endif
 }
 
+StringRef getCurrentCompilerSerializationTag() {
+#ifdef SWIFT_COMPILER_VERSION
+  return SWIFT_COMPILER_VERSION;
+#else
+  return StringRef();
+#endif
+}
+
 } // end namespace version
 } // end namespace swift

lib/Serialization/ModuleFileSharedCore.cpp

@@ -370,7 +370,7 @@ static ValidationInfo validateControlBlock(
       if (forcedDebugRevision ||
           (requiresRevisionMatch && version::isCurrentCompilerTagged())) {
         StringRef compilerRevision = forcedDebugRevision ?
-          forcedDebugRevision : version::getCurrentCompilerTag();
+          forcedDebugRevision : version::getCurrentCompilerSerializationTag();
         if (moduleRevision != compilerRevision) {
           result.status = Status::RevisionIncompatible;
 

lib/Serialization/Serialization.cpp

@@ -1011,7 +1011,7 @@ void Serializer::writeHeader(const SerializationOptions &options) {
     static const char* forcedDebugRevision =
       ::getenv("SWIFT_DEBUG_FORCE_SWIFTMODULE_REVISION");
     auto revision = forcedDebugRevision ?
-      forcedDebugRevision : version::getCurrentCompilerTag();
+      forcedDebugRevision : version::getCurrentCompilerSerializationTag();
     Revision.emit(ScratchRecord, revision);
 
     IsOSSA.emit(ScratchRecord, options.IsOSSA);