PaperMC/paper-server/patches/sources/net/minecraft/server/commands/SetSpawnCommand.java.patch

--- a/net/minecraft/server/commands/SetSpawnCommand.java
+++ b/net/minecraft/server/commands/SetSpawnCommand.java
@@ -66,24 +_,34 @@
     private static int setSpawn(CommandSourceStack source, Collection<ServerPlayer> targets, BlockPos pos, float angle) {
         ResourceKey<Level> resourceKey = source.getLevel().dimension();
 
+        final Collection<ServerPlayer> actualTargets = new java.util.ArrayList<>(); // Paper - Add PlayerSetSpawnEvent
         for (ServerPlayer serverPlayer : targets) {
-            serverPlayer.setRespawnPosition(resourceKey, pos, angle, true, false);
-        }
+            // Paper start - Add PlayerSetSpawnEvent
+            if (serverPlayer.setRespawnPosition(resourceKey, pos, angle, true, false, com.destroystokyo.paper.event.player.PlayerSetSpawnEvent.Cause.COMMAND)) {
+                actualTargets.add(serverPlayer);
+            }
+            // Paper end - Add PlayerSetSpawnEvent
+        }
+        // Paper start - Add PlayerSetSpawnEvent
+        if (actualTargets.isEmpty()) {
+            return 0;
+        }
+        // Paper end - Add PlayerSetSpawnEvent
 
         String string = resourceKey.location().toString();
-        if (targets.size() == 1) {
+        if (actualTargets.size() == 1) { // Paper - Add PlayerSetSpawnEvent
             source.sendSuccess(
                 () -> Component.translatable(
-                    "commands.spawnpoint.success.single", pos.getX(), pos.getY(), pos.getZ(), angle, string, targets.iterator().next().getDisplayName()
+                    "commands.spawnpoint.success.single", pos.getX(), pos.getY(), pos.getZ(), angle, string, actualTargets.iterator().next().getDisplayName() // Paper - Add PlayerSetSpawnEvent
                 ),
                 true
             );
         } else {
             source.sendSuccess(
-                () -> Component.translatable("commands.spawnpoint.success.multiple", pos.getX(), pos.getY(), pos.getZ(), angle, string, targets.size()), true
+                () -> Component.translatable("commands.spawnpoint.success.multiple", pos.getX(), pos.getY(), pos.getZ(), angle, string, actualTargets.size()), true // Paper - Add PlayerSetSpawnEvent
             );
         }
 
-        return targets.size();
+        return actualTargets.size(); // Paper - Add PlayerSetSpawnEvent
     }
 }