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fix: split classpath from module path to prevent Forge split-package error

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- Build two separate classpaths: modulePath (libraries only) and classpath (libraries + version jar)
- Intercept manifest -p to use modulePath (no version jar) preventing _1._20._1 vs minecraft module conflict
- Intercept manifest -cp to skip (our explicit -cp already added)
- Fix --version to use getVersionId() instead of instance.getName()
This commit is contained in:
SashegDev
2026-07-13 14:24:25 +00:00
parent 546652f44c
commit 1efd283234
1 changed files with 44 additions and 36 deletions
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launcher/launcher/src/main/java/sashegdev/zernmc/launcher/minecraft/launch/LaunchCommandBuilder.java
+36 -28
View File
@@ -63,44 +63,50 @@ public class LaunchCommandBuilder {
// always use ModLauncher as main class (version.json might have
// BootstrapLauncher which breaks with Java module system)
if ("forge".equals(loaderType) || "neoforge".equals(loaderType)) {
// BootstrapLauncher creates the module layer ModLauncher needs
// for ServiceLoader discovery.
// Build classpath from manifest (shorter, ordered).
// Only JARs explicitly listed in version.json go on the classpath.
// Do NOT append JARs from recursive scan — tool JARs like
// ForgeAutoRenamingTool that contain shaded ASM packages cause
// split-package conflicts with the Java module system when
// --add-modules=ALL-MODULE-PATH resolves them as automatic modules.
// Build TWO classpaths for Forge/NeoForge:
// 1. modulePath: libraries only (for -p module path) — version jar excluded
// to prevent split-package conflict with Forge's "minecraft" module
// 2. classpath: libraries + version jar (for -cp classpath) — version jar
// included so PreparableReloadListener and other MC classes are loadable
String modulePath;
String classpath;
if (manifest != null) {
classpath = buildClasspathFromManifest(manifest);
modulePath = buildClasspathFromManifest(manifest, false);
classpath = buildClasspathFromManifest(manifest, true);
} else {
modulePath = "";
classpath = "";
}
if (classpath == null || classpath.isEmpty()) {
classpath = buildVanillaClasspath();
} else {
// Safety net: remove JARs from classpath that are already
// on the module path (from manifest JVM args) to prevent
// Java module system split-package conflicts.
classpath = filterClasspathAgainstModulePath(classpath, manifest.getJvmArguments());
if (modulePath == null || modulePath.isEmpty()) {
modulePath = buildVanillaClasspath();
}
if (classpath == null || classpath.isEmpty()) {
classpath = modulePath;
}
command.add("-cp");
String cpFile = writeClasspathFile(classpath);
String mpFile = writeClasspathFile(modulePath);
command.add(cpFile);
// Add JVM arguments from version.json manifest
// Includes -DignoreList, -p (module path), --add-modules, --add-opens,
// and -DlibraryDirectory — all required for BootstrapLauncher to
// resolve cpw.mods.securejarhandler as a module.
// Forge manifest JVM args also contain "-cp ${classpath}" — we resolve
// it here so the manifest's -cp takes precedence (avoids duplicate -cp
// issues and ensures the manifest controls the final classpath).
// Add JVM arguments from version.json manifest.
// Intercept -p / --module-path to use mpFile (no version jar)
// and -cp / --classpath to skip (we already added our own -cp).
if (manifest != null) {
Map<String, String> vars = buildVariableMap(options);
vars.put("classpath", cpFile);
for (String arg : manifest.getJvmArguments()) {
command.add(resolveVariable(arg, vars));
List<String> jvmArgs = manifest.getJvmArguments();
for (int i = 0; i < jvmArgs.size(); i++) {
String raw = jvmArgs.get(i);
if (("-p".equals(raw) || "--module-path".equals(raw)) && i + 1 < jvmArgs.size()) {
command.add(raw);
i++;
command.add(mpFile);
} else if (("-cp".equals(raw) || "--classpath".equals(raw)) && i + 1 < jvmArgs.size()) {
i++;
} else {
command.add(resolveVariable(raw, vars));
}
}
}
@@ -125,7 +131,7 @@ public class LaunchCommandBuilder {
command.addAll(getVanillaGameArguments(options));
}
} else if (manifest != null) {
String classpath = buildClasspathFromManifest(manifest);
String classpath = buildClasspathFromManifest(manifest, true);
// Fallback if classpath is empty
if (classpath.isEmpty() || classpath.equals(instance.getPath().resolve("versions").resolve(getVersionId()).resolve(getVersionId() + ".jar").toAbsolutePath().toString())) {
@@ -417,7 +423,7 @@ public class LaunchCommandBuilder {
List<String> args = new ArrayList<>();
args.add("--version");
args.add(instance.getName());
args.add(getVersionId());
args.add("--gameDir");
args.add(instance.getPath().toAbsolutePath().toString());
args.add("--assetsDir");
@@ -491,7 +497,7 @@ public class LaunchCommandBuilder {
return result;
}
private String buildClasspathFromManifest(VersionManifest manifest) throws Exception {
private String buildClasspathFromManifest(VersionManifest manifest, boolean includeVersionJar) throws Exception {
List<String> paths = new ArrayList<>();
Path librariesDir = instance.getPath().resolve("libraries");
@@ -549,6 +555,7 @@ public class LaunchCommandBuilder {
System.out.println(ZAnsi.cyan(" Paths dir: " + instance.getPath().resolve("versions")));
}
if (includeVersionJar) {
Path versionJar = findVersionJar();
if (versionJar != null) {
if (isValidJar(versionJar)) {
@@ -559,6 +566,7 @@ public class LaunchCommandBuilder {
Files.delete(versionJar);
}
}
}
String separator = System.getProperty("os.name").toLowerCase().contains("win") ? ";" : ":";
return String.join(separator, paths);