Informative error message for platforms that do not support federated

core/src/main/java/org/lflang/federated/generator/FedGenerator.java

@@ -1,6 +1,7 @@
 package org.lflang.federated.generator;
 
 import static org.lflang.generator.docker.DockerGenerator.dockerGeneratorFactory;
+import static org.lflang.target.property.type.PlatformType.Platform.supportsFederated;
 
 import com.google.inject.Injector;
 import java.io.IOException;
@@ -63,6 +64,7 @@
 import org.lflang.target.property.DockerProperty.DockerOptions;
 import org.lflang.target.property.KeepaliveProperty;
 import org.lflang.target.property.NoCompileProperty;
+import org.lflang.target.property.PlatformProperty;
 import org.lflang.target.property.type.CoordinationModeType.CoordinationMode;
 import org.lflang.util.Averager;
 import org.lflang.util.FileUtil;
@@ -121,7 +123,7 @@ public FedGenerator(LFGeneratorContext context) {
    * @return False if no errors have occurred, true otherwise.
    */
   public boolean doGenerate(Resource resource, LFGeneratorContext context) throws IOException {
-    if (!federatedExecutionIsSupported(resource)) return true;
+    if (!federatedExecutionIsSupported(resource, context)) return true;
     cleanIfNeeded(context);
 
     // In a federated execution, we need keepalive to be true,
@@ -300,7 +302,7 @@ private void cleanIfNeeded(LFGeneratorContext context) {
   }
 
   /** Return whether federated execution is supported for {@code resource}. */
-  private boolean federatedExecutionIsSupported(Resource resource) {
+  private boolean federatedExecutionIsSupported(Resource resource, LFGeneratorContext context) {
     TargetDecl targetDecl = GeneratorUtils.findTargetDecl(resource);
     var target = Target.fromDecl(targetDecl);
     var targetOK =
@@ -316,6 +318,17 @@ private boolean federatedExecutionIsSupported(Resource resource) {
           .error("Federated LF programs with a C target are currently not supported on Windows.");
       targetOK = false;
     }
+    if (target.equals(Target.C) || target.equals(Target.CCPP)) {
+      // Currently, only the C runtime has a platform abstraction.
+      var platform = context.getTargetConfig().get(PlatformProperty.INSTANCE).platform();
+      if (!supportsFederated(platform)) {
+        messageReporter
+            .at(targetDecl)
+            .error(
+                "Federations are not supported by the " + platform.getcMakeName() + " platform.");
+        targetOK = false;
+      }
+    }
 
     return targetOK;
   }

core/src/main/java/org/lflang/target/property/PlatformProperty.java

@@ -166,7 +166,6 @@ private void validateFlexPRET(TargetConfig config, MessageReporter reporter) {
   private void validateZephyr(TargetConfig config, MessageReporter reporter) {
     var platform = config.get(PlatformProperty.INSTANCE);
     var singleThreaded = config.get(SingleThreadedProperty.INSTANCE);
-
     if (singleThreaded) {
       if (platform.userThreads().value() > 0) {
         reporter

core/src/main/java/org/lflang/target/property/type/PlatformType.java

@@ -12,27 +12,23 @@ protected Class<Platform> enumClass() {
 
   public enum Platform {
     AUTO,
-    ARDUINO, // FIXME: not multithreaded
-    NRF52("nRF52", false),
-    RP2040("Rp2040", true),
-    LINUX("Linux", true),
-    MAC("Darwin", true),
-    ZEPHYR("Zephyr", true),
-    FLEXPRET("FlexPRET", true),
-    WINDOWS("Windows", true);
+    ARDUINO,
+    NRF52("nRF52"),
+    RP2040("Rp2040"),
+    LINUX("Linux"),
+    MAC("Darwin"),
+    ZEPHYR("Zephyr"),
+    FLEXPRET("FlexPRET"),
+    WINDOWS("Windows");
 
     final String cMakeName;
 
-    private final boolean multiThreaded;
-
     Platform() {
       this.cMakeName = this.toString();
-      this.multiThreaded = true;
     }
 
-    Platform(String cMakeName, boolean isMultiThreaded) {
+    Platform(String cMakeName) {
       this.cMakeName = cMakeName;
-      this.multiThreaded = isMultiThreaded;
     }
 
     /** Return the name in lower case. */
@@ -46,12 +42,16 @@ public String getcMakeName() {
       return this.cMakeName;
     }
 
-    public boolean isMultiThreaded() {
-      return this.multiThreaded;
-    }
-
     public Platform getDefault() {
       return Platform.AUTO;
     }
+
+    /** Return {@code true} if the given platform supports federated. */
+    public static boolean supportsFederated(Platform platform) {
+      return switch (platform) {
+        case AUTO, LINUX, MAC -> true;
+        default -> false;
+      };
+    }
   }
 }