Allow genEclipseRuns to be executed without the Eclipse plugin

The point of requiring the Eclipse plugin for `genEclipseRuns` was to get the accurate compiler output directory and project name as defined by the Eclipse project. However, the absense of the task itself can cause issues in various buildscript setups.

Since it is generally difficult to configure these attributes for an Eclipse project, the task will now run without the Eclipse plugin and use best-guess defaults for these values. However, a warning will be emitted to the problems reporter if any Eclipse run config generation task is run without the Eclipse plugin being loaded.

Author: Jonathing

src/main/java/net/minecraftforge/gradle/internal/ForgeGradleProblems.java

@@ -215,6 +215,19 @@ void reportUnmergedSourceSets() {
             .solution("Do not use the 'eclipse' plugin if you (or no one in your team) is using Eclipse.")
             .solution(HELP_MESSAGE));
     }
+
+    void reportMissingEclipsePlugin(String taskName) {
+        report("eclipse-missing-for-run-generation", "Eclipse plugin is not loaded", spec -> spec
+            .details("""
+                The Eclipse plugin is not loaded into this build, yet it was tasked with creating Eclipse run configurations.
+                This may cause incorrect values to be used for the Eclipse project's output directory and project name.
+                It is highly recommended to use the 'eclipse' plugin with your project if you plan on regularly using Eclipse."""
+            )
+            .severity(Severity.WARNING)
+            .solution("Use the 'eclipse' plugin in your build.")
+            .solution("Run the '%s' task directly from Eclipse.".formatted(taskName))
+            .solution(HELP_MESSAGE));
+    }
     //endregion
 
     //region Access Transformers

src/main/java/net/minecraftforge/gradle/internal/MinecraftExtensionImpl.java

@@ -155,7 +155,7 @@ private void finish(Settings settings) {
     }
 
     static abstract class ForProjectImpl extends MinecraftExtensionImpl implements ForProject {
-        private @Nullable TaskProvider<Task> genEclipseRuns;
+        private final TaskProvider<Task> genEclipseRuns;
         final DirectoryProperty eclipseOutputDir = getObjects().directoryProperty().convention(getProjectLayout().getProjectDirectory().dir("bin"));
 
         // Slime Launcher
@@ -230,17 +230,16 @@ public ForProjectImpl(ForgeGradlePlugin plugin) {
                 );
             }
 
-            getProject().getPluginManager().withPlugin("eclipse", appliedEclipsePlugin -> {
-                var eclipse = getProject().getExtensions().getByType(EclipseModel.class);
-
-                this.genEclipseRuns = getProject().getTasks().register("genEclipseRuns", task -> {
-                    task.setGroup("IDE");
-                    task.setDescription("Generates the run configuration launch files for Eclipse.");
-                });
-                eclipse.synchronizationTasks(genEclipseRuns);
-
-                this.eclipseOutputDir.fileProvider(getProviders().provider(() -> eclipse.getClasspath().getDefaultOutputDir()));
+            genEclipseRuns = getProject().getTasks().register("genEclipseRuns", task -> {
+                task.setGroup("IDE");
+                task.setDescription("Generates the run configuration launch files for Eclipse.");
             });
+            getProject().getPluginManager().withPlugin("eclipse", appliedPlugin ->
+                getProject().getExtensions().configure(EclipseModel.class, eclipse -> {
+                    eclipse.synchronizationTasks(genEclipseRuns);
+                    eclipseOutputDir.fileProvider(getProviders().provider(() -> eclipse.getClasspath().getDefaultOutputDir()));
+                })
+            );
 
             // Finish when the project is evaluated
             getProject().afterEvaluate(this::finish);
@@ -324,15 +323,16 @@ private void finish(Project project) {
                     sourceSet.getJava().getDestinationDirectory().set(unifiedDir);
                 }
 
-                project.getPluginManager().withPlugin("eclipse", eclipsePlugin -> {
-                    var eclipse = project.getExtensions().getByType(EclipseModel.class);
-                    eclipse.synchronizationTasks(syncMavenizer);
+                project.getPluginManager().withPlugin("eclipse", appliedPlugin ->
+                    project.getExtensions().configure(EclipseModel.class, eclipse -> eclipse.synchronizationTasks(syncMavenizer))
+                );
+            });
 
-                    if (mergeSourceSets)
-                        eclipse.getClasspath().setDefaultOutputDir(sourceSetsDir.getAsFile().get());
-                    else
-                        problems.reportUnmergedSourceSets();
-                });
+            project.getPluginManager().withPlugin("eclipse", eclipsePlugin -> {
+                if (mergeSourceSets)
+                    project.getExtensions().configure(EclipseModel.class, eclipse -> eclipse.getClasspath().setDefaultOutputDir(sourceSetsDir.getAsFile().get()));
+                else
+                    problems.reportUnmergedSourceSets();
             });
 
             for (var minecraftDependency : this.minecraftDependencies) {

src/main/java/net/minecraftforge/gradle/internal/SlimeLauncherEclipseConfiguration.java

@@ -108,6 +108,9 @@ public SlimeLauncherEclipseConfiguration() {
 
     @TaskAction
     protected void exec() {
+        if (!this.getEclipseProjectName().isPresent())
+            problems.reportMissingEclipsePlugin(this.getName());
+
         List<String> args;
         List<String> jvmArgs;
         MapProperty<String, String> environment;