HACK add option to launch without a main jar

api/logic/minecraft/LaunchProfile.cpp

@@ -162,12 +162,20 @@ const LibraryPtr LaunchProfile::getMainJar() const
     return m_mainJar;
 }
 
-void LaunchProfile::applyMainJar(LibraryPtr jar)
+void LaunchProfile::applyMainJar(LibraryPtr jar, bool removeMainJar)
 {
-    if(jar)
+    if(removeMainJar)
+    {
+        m_mainJar.reset();
+    }
+    else if(jar)
     {
         m_mainJar = jar;
     }
+    else
+    {
+        // mainJar was not specified, NOOP
+    }
 }
 
 void LaunchProfile::applyProblemSeverity(ProblemSeverity severity)

api/logic/minecraft/LaunchProfile.h

@@ -20,7 +20,7 @@ public: /* application of profile variables from patches */
     void applyJarMods(const QList<LibraryPtr> &jarMods);
     void applyMods(const QList<LibraryPtr> &jarMods);
     void applyLibrary(LibraryPtr library);
-    void applyMainJar(LibraryPtr jar);
+    void applyMainJar(LibraryPtr jar, bool removeMainJar);
     void applyProblemSeverity(ProblemSeverity severity);
     /// clear the profile
     void clear();

api/logic/minecraft/OneSixVersionFormat.cpp

@@ -187,8 +187,16 @@ VersionFilePtr OneSixVersionFormat::versionFileFromJson(const QJsonDocument &doc
     // if we have mainJar, just use it
     if(root.contains("mainJar"))
     {
-        QJsonObject libObj = requireObject(root, "mainJar");
-        out->mainJar = libraryFromJson(libObj, filename);
+        auto val = root.value("mainJar");
+        if(val.isNull())
+        {
+            out->removeMainJar = true;
+        }
+        else
+        {
+            QJsonObject libObj = requireObject(root, "mainJar");
+            out->mainJar = libraryFromJson(libObj, filename);
+        }
     }
     // else reconstruct it from downloads and id ... if that's available
     else if(!out->minecraftVersion.isEmpty())
@@ -276,6 +284,10 @@ QJsonDocument OneSixVersionFormat::versionFileToJson(const VersionFilePtr &patch
     {
         root.insert("mainJar", libraryToJson(patch->mainJar.get()));
     }
+    else if(patch->removeMainJar)
+    {
+        root.insert("mainJar", QJsonValue());
+    }
     writeString(root, "appletClass", patch->appletClass);
     writeStringList(root, "+tweakers", patch->addTweakers);
     writeStringList(root, "+traits", patch->traits.toList());

api/logic/minecraft/VersionFile.cpp

@@ -28,7 +28,7 @@ void VersionFile::applyTo(LaunchProfile *profile)
         profile->applyMinecraftAssets(mojangAssetIndex);
     }
 
-    profile->applyMainJar(mainJar);
+    profile->applyMainJar(mainJar, removeMainJar);
     profile->applyMainClass(mainClass);
     profile->applyAppletClass(appletClass);
     profile->applyMinecraftArguments(minecraftArguments);

api/logic/minecraft/VersionFile.h

@@ -77,6 +77,7 @@ public: /* data */
 
     /// The main jar (Minecraft version library, normally)
     LibraryPtr mainJar;
+    bool removeMainJar = false;
 
     /// MultiMC: list of attached traits of this version file - used to enable features
     QSet<QString> traits;

api/logic/minecraft/update/LibrariesTask.cpp

@@ -45,7 +45,11 @@ void LibrariesTask::executeTask()
     QList<LibraryPtr> libArtifactPool;
     libArtifactPool.append(profile->getLibraries());
     libArtifactPool.append(profile->getNativeLibraries());
-    libArtifactPool.append(profile->getMainJar());
+    auto mainJar = profile->getMainJar();
+    if(mainJar)
+    {
+        libArtifactPool.append(mainJar);
+    }
     processArtifactPool(libArtifactPool, failedLocalLibraries, inst->getLocalLibraryPath());
 
     QStringList failedLocalJarMods;