[Basic][Serialization] Intro and use isCurrentCompilerTagged

include/swift/Basic/Version.h

@@ -184,6 +184,11 @@ std::string getSwiftFullVersion(Version effectiveLanguageVersion =
 /// this Swift was built.
 StringRef getSwiftRevision();
 
+/// Is the running compiler built with a version tag for distribution?
+/// When true, \c Version::getCurrentCompilerVersion returns a valid version
+/// and \c getSwiftRevision returns the version tuple in string format.
+bool isCurrentCompilerTagged();
+
 } // end namespace version
 } // end namespace swift
 

lib/Basic/Version.cpp

@@ -446,5 +446,13 @@ StringRef getSwiftRevision() {
 #endif
 }
 
+bool isCurrentCompilerTagged() {
+#ifdef SWIFT_COMPILER_VERSION
+  return true;
+#else
+  return false;
+#endif
+}
+
 } // end namespace version
 } // end namespace swift

lib/Serialization/ModuleFileSharedCore.cpp

@@ -313,7 +313,7 @@ static ValidationInfo validateControlBlock(
       // env var is set (for testing).
       static const char* forceDebugPreSDKRestriction =
         ::getenv("SWIFT_DEBUG_FORCE_SWIFTMODULE_PER_SDK");
-      if (version::Version::getCurrentCompilerVersion().empty() &&
+      if (!version::isCurrentCompilerTagged() &&
           !forceDebugPreSDKRestriction) {
         break;
       }
@@ -354,7 +354,7 @@ static ValidationInfo validateControlBlock(
         ::getenv("SWIFT_DEBUG_FORCE_SWIFTMODULE_REVISION");
 
       bool isCompilerTagged = forcedDebugRevision ||
-        !version::Version::getCurrentCompilerVersion().empty();
+        version::isCurrentCompilerTagged();
 
       StringRef moduleRevision = blobData;
       if (isCompilerTagged) {