Don't add empty TimeZoneSupport in OS other than Windows

Author: Zeavee

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/TimeZoneSubstitutions.java

@@ -100,10 +100,8 @@ private static String getSystemTimeZoneID(String javaHome) {
             if (ImageSingletons.contains(TimeZoneSupport.class)) {
                 byte[] content = ImageSingletons.lookup(TimeZoneSupport.class).getTzMappingsContent();
                 contentLen = content.length;
-                if (contentLen != 0) {
-                    refContent = PrimitiveArrayView.createForReading(content);
-                    tzMappingsPtr = refContent.addressOfArrayElement(0);
-                }
+                refContent = PrimitiveArrayView.createForReading(content);
+                tzMappingsPtr = refContent.addressOfArrayElement(0);
             }
             CCharPointer tzId = LibCHelper.SVM_FindJavaTZmd(tzMappingsPtr, contentLen);
             String result = CTypeConversion.toJavaString(tzId);
@@ -187,11 +185,6 @@ private static byte[] cleanCR(byte[] buffer) {
     public void afterRegistration(AfterRegistrationAccess access) {
 
         if (OS.getCurrent() != OS.WINDOWS) {
-            if (ImageLayerBuildingSupport.buildingImageLayer()) {
-                // GR-75591: The ImageSingletons.contains plugin records this application-layer
-                // singleton even when the platform-specific payload is unused.
-                ImageSingletons.add(TimeZoneSupport.class, new TimeZoneSupport(new byte[0]));
-            }
             return;
         }
 

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/imagelayer/ImageSingletonDataImpl.java

@@ -31,6 +31,7 @@
 import com.oracle.svm.core.graal.code.CGlobalDataInfo;
 import com.oracle.svm.core.imagelayer.AccessImageSingletonFactory;
 import com.oracle.svm.hosted.c.CGlobalDataFeature;
+import com.oracle.svm.shared.BuildPhaseProvider;
 import com.oracle.svm.shared.singletons.LayeredImageSingletonSupport;
 import com.oracle.svm.shared.util.VMError;
 
@@ -100,7 +101,13 @@ void setApplicationLayerConstant() {
 
     @Override
     public final boolean isApplicationLayerConstant() {
-        return applicationLayerConstant;
+        VMError.guarantee(BuildPhaseProvider.isAnalysisStarted(), "The singleton can still be added until the analysis starts.");
+        /*
+         * Application layer singletons are optional, so even if they are looked up in a shared
+         * layer, they might still not be present in the final image. In that case, the lookup
+         * throws at runtime and the singleton cannot be folded.
+         */
+        return applicationLayerConstant && ImageSingletons.contains(slotData.key);
     }
 }