Fix annotations not applying properly to packages.

minecraft/minecraft-test/src/main/java/net/fabricmc/minecraft/test/server_only/TestMixinGuiHelper.java

@@ -1,5 +1,8 @@
 package net.fabricmc.minecraft.test.server_only;
 
+import org.quiltmc.loader.api.minecraft.DedicatedServerOnly;
+
+@DedicatedServerOnly
 public class TestMixinGuiHelper {
 
 	public static void help() {

minecraft/minecraft-test/src/main/java/net/fabricmc/minecraft/test/server_only/package-info.java

@@ -1,3 +1,4 @@
-// @org.quiltmc.loader.api.minecraft.DedicatedServerOnly
+//@org.quiltmc.loader.api.minecraft.DedicatedServerOnly
+//@org.quiltmc.loader.api.Requires({"trinkets", "quilt_loader", "minecraft", "buildcraft"})
 // Uncomment the above line to test out package based stripping.
 package net.fabricmc.minecraft.test.server_only;

src/main/java/org/quiltmc/loader/api/Requires.java

@@ -25,7 +25,7 @@
 
 /** Applied to declare that the annotated element requires specific mods to exist.
  * <p>
- * When applied to mod code this will result in quilt-loader removing that element when running without the specified mods.
+ * When applied to mod code this will result in quilt-loader removing that element when running without all of the specified mods.
  * <p>
  * When the annotated element is removed, bytecode associated with the element will not be removed. For example, if a
  * field is removed, its initializer code will not, and will cause an error on execution.

src/main/java/org/quiltmc/loader/impl/launch/common/QuiltLauncher.java

@@ -23,6 +23,7 @@
 import java.net.URL;
 import java.nio.file.Path;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.jar.Manifest;
 
@@ -40,6 +41,7 @@ public interface QuiltLauncher {
 	void setAllowedPrefixes(Path path, String... prefixes);
 	void setTransformCache(URL insideTransformCache);
 	void setHiddenClasses(Set<String> classes);
+	void setHiddenClasses(Map<String, String> classes);
 	void hideParentUrl(URL hidden);
 	void hideParentPath(Path obf);
 	void validateGameClassLoader(Object gameInstance);

src/main/java/org/quiltmc/loader/impl/launch/knot/Knot.java

@@ -313,6 +313,11 @@ public void setHiddenClasses(Set<String> hiddenClasses) {
 		classLoader.getDelegate().setHiddenClasses(hiddenClasses);
 	}
 
+	@Override
+	public void setHiddenClasses(Map<String, String> hiddenClasses) {
+		classLoader.getDelegate().setHiddenClasses(hiddenClasses);
+	}
+
 	@Override
 	public void hideParentUrl(URL parent) {
 		classLoader.getDelegate().hideParentUrl(parent);

src/main/java/org/quiltmc/loader/impl/launch/knot/KnotClassDelegate.java

@@ -52,6 +52,8 @@
 import java.security.CodeSource;
 import java.security.cert.Certificate;
 import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
@@ -97,7 +99,7 @@ public Optional<ModContainer> getQuiltMod() {
 	private IMixinTransformer mixinTransformer;
 	private boolean transformInitialized = false;
 	private boolean transformFinishedLoading = false;
-	private Set<String> hiddenClasses = Collections.emptySet();
+	private Map<String, String> hiddenClasses = Collections.emptyMap();
 	private String transformCacheUrl;
 	private final Map<String, String[]> allowedPrefixes = new ConcurrentHashMap<>();
 	private final Set<String> parentSourcedClasses = Collections.newSetFromMap(new ConcurrentHashMap<>());
@@ -106,8 +108,8 @@ public Optional<ModContainer> getQuiltMod() {
 	 * in this loader. */
 	private final Set<String> parentHiddenUrls = Collections.newSetFromMap(new ConcurrentHashMap<>());
 
-	/** Map of package to whether we can load it in this environment. */
-	private final Map<String, Boolean> packageSideCache = new ConcurrentHashMap<>();
+	/** Map of package to the reason why it cannot be loaded. If the package can be loaded then the value is the empty string. */
+	private final Map<String, String> packageLoadDenyCache = new ConcurrentHashMap<>();
 
 	KnotClassDelegate(boolean isDevelopment, EnvType envType, KnotClassLoaderInterface itf, GameProvider provider) {
 		this.isDevelopment = isDevelopment;
@@ -238,6 +240,25 @@ Class<?> tryLoadClass(String name, boolean allowFromParent) throws ClassNotFound
 			}
 		}
 
+		int pkgDelimiterPos = name.lastIndexOf('.');
+		String pkgString = pkgDelimiterPos > 0 ? name.substring(0, pkgDelimiterPos) : null;
+
+		if (pkgString != null) {
+			final boolean allowFromParentFinal = allowFromParent;
+			String denyReason = packageLoadDenyCache.computeIfAbsent(pkgString, pkgName -> {
+				return computePackageDenyLoadReason(pkgName, allowFromParentFinal);
+			});
+
+			if (denyReason != null && !denyReason.isEmpty()) {
+				throw new RuntimeException("Cannot load package " + pkgString + " " + denyReason);
+			}
+		}
+
+		String hideReason = hiddenClasses.get(name);
+		if (hideReason != null) {
+			throw new RuntimeException("Cannot load " + name + " " + hideReason);
+		}
+
 		byte[] input = getPostMixinClassByteArray(url, name);
 		if (input == null) return null;
 
@@ -247,8 +268,6 @@ Class<?> tryLoadClass(String name, boolean allowFromParent) throws ClassNotFound
 
 		KnotClassDelegate.Metadata metadata = getMetadata(name, url);
 
-		int pkgDelimiterPos = name.lastIndexOf('.');
-
 		final String modId;
 
 		if (metadata.codeSource == null) {
@@ -268,19 +287,8 @@ Class<?> tryLoadClass(String name, boolean allowFromParent) throws ClassNotFound
 			return c;
 		}
 
-		if (pkgDelimiterPos > 0) {
+		if (pkgString != null) {
 			// TODO: package definition stub
-			String pkgString = name.substring(0, pkgDelimiterPos);
-
-			final boolean allowFromParentFinal = allowFromParent;
-			Boolean permitted = packageSideCache.computeIfAbsent(pkgString, pkgName -> {
-				return computeCanLoadPackage(pkgName, allowFromParentFinal);
-			});
-
-			if (permitted != null && !permitted) {
-				throw new RuntimeException("Cannot load package " + pkgString + " in environment type " + envType);
-			}
-
 			Package pkg = itf.getPackage(pkgString);
 
 			if (pkg == null) {
@@ -310,28 +318,15 @@ Class<?> tryLoadClass(String name, boolean allowFromParent) throws ClassNotFound
 		return c;
 	}
 
+
 	private boolean shouldRerouteToParent(String name) {
 		return name.startsWith("org.slf4j.") || name.startsWith("org.apache.logging.log4j.");
 	}
 
-	boolean computeCanLoadPackage(String pkgName, boolean allowFromParent) {
+	private String computePackageDenyLoadReason(String pkgName, boolean allowFromParent) {
 		String fileName = pkgName + ".package-info";
-		try {
-			byte[] bytes = getRawClassByteArray(fileName, allowFromParent);
-			if (bytes == null) {
-				// No package-info class file
-				return true;
-			}
-
-			ClassReader reader = new ClassReader(bytes);
-
-			PackageStrippingData strippingData = new PackageStrippingData(QuiltLoaderImpl.ASM_VERSION, envType, modCodeSourceMap);
-			reader.accept(strippingData, ClassReader.SKIP_CODE | ClassReader.SKIP_FRAMES);
-
-			return !strippingData.stripEntirePackage();
-		} catch (IOException e) {
-			throw new RuntimeException("Unable to load " + fileName, e);
-		}
+		String hideReason = hiddenClasses.get(fileName);
+		return hideReason != null ? hideReason : "";
 	}
 
 	Metadata getMetadata(String name, URL resourceURL) {
@@ -508,10 +503,6 @@ public byte[] getRawClassByteArray(String name, boolean allowFromParent) throws
 	}
 
 	public byte[] getRawClassByteArray(URL url, String name) throws IOException {
-		if (hiddenClasses.contains(name)) {
-			return null;
-		}
-
 		try (InputStream inputStream = (url != null ? url.openStream() : null)) {
 			if (inputStream == null) {
 				return null;
@@ -533,6 +524,14 @@ void setTransformCache(URL insideTransformCache) {
 	}
 
 	void setHiddenClasses(Set<String> hiddenClasses) {
+		Map<String, String> map = new HashMap<>();
+		for (String cl : hiddenClasses) {
+			map.put(cl, "unknown reason");
+		}
+		setHiddenClasses(map);
+	}
+
+	void setHiddenClasses(Map<String, String> hiddenClasses) {
 		this.hiddenClasses = hiddenClasses;
 	}
 

src/main/java/org/quiltmc/loader/impl/transformer/AbstractStripData.java

@@ -0,0 +1,110 @@
+package org.quiltmc.loader.impl.transformer;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+import org.objectweb.asm.ClassVisitor;
+import org.quiltmc.loader.api.Requires;
+import org.quiltmc.loader.impl.util.QuiltLoaderInternal;
+import org.quiltmc.loader.impl.util.QuiltLoaderInternalType;
+
+import net.fabricmc.api.EnvType;
+
+/** Contains string processing for both {@link PackageStrippingData} and {@link ClassStrippingData} */
+@QuiltLoaderInternal(QuiltLoaderInternalType.NEW_INTERNAL)
+public abstract class AbstractStripData extends ClassVisitor {
+
+	protected final EnvType envType;
+	protected final Set<String> mods;
+
+	protected final List<String> denyLoadReasons = new ArrayList<>();
+
+	protected AbstractStripData(int api, EnvType envType, Set<String> mods) {
+		this(api, null, envType, mods);
+	}
+
+	protected AbstractStripData(int api, ClassVisitor classVisitor, EnvType envType, Set<String> mods) {
+		super(api, classVisitor);
+		this.envType = envType;
+		this.mods = mods;
+	}
+
+	/** @return What this represents - generally "package" or "class". */
+	protected abstract String type();
+
+	public List<String> getDenyLoadReasons() {
+		return Collections.unmodifiableList(denyLoadReasons);
+	}
+
+	public String summarizeDenyLoadReasons() {
+		if (denyLoadReasons.isEmpty()) {
+			return "";
+		}
+		StringBuilder sb = new StringBuilder();
+		if (denyLoadReasons.size() == 1) {
+			sb.append("because ");
+			sb.append(denyLoadReasons.get(0));
+		} else {
+			sb.append("because:");
+			for (String reason : denyLoadReasons) {
+				sb.append("\n- ");
+				sb.append(reason);
+			}
+		}
+		return sb.toString();
+	}
+
+	/** Appends a client-only deny reason to {@link #denyLoadReasons}. */
+	protected void denyClientOnlyLoad() {
+		denyLoadReasons.add("the " + type() + " is annotated with @ClientOnly but we're on the dedicated server");
+	}
+
+	/** Appends a dedicated server only deny reason to {@link #denyLoadReasons}. */
+	protected void denyDediServerOnlyLoad() {
+		denyLoadReasons.add("the " + type() + " is annotated with @DedicatedServerOnly but we're on the client");
+	}
+
+	/** Checks to see if all mods given are in {@link #mods}, and appends a deny reason to {@link #denyLoadReasons} if
+	 * any are missing. Assumes the annotation is {@link Requires} in the error message */
+	protected void checkHasAllMods(List<String> requiredMods) {
+		List<String> missingMods = new ArrayList<>();
+		for (String mod : requiredMods) {
+			if (!mods.contains(mod)) {
+				missingMods.add(mod);
+			}
+		}
+
+		checkHasAllMods(requiredMods, missingMods);
+	}
+
+	/** Checks to see if the missing mods list is empty, and appends a deny reason to {@link #denyLoadReasons} if it is
+	 * not. Assumes the annotation is {@link Requires} in the error message */
+	protected void checkHasAllMods(List<String> requiredMods, List<String> missingMods) {
+		if (!missingMods.isEmpty()) {
+			StringBuilder all = new StringBuilder();
+			if (requiredMods.size() > 1) {
+				all.append("{");
+			}
+
+			for (String mod : requiredMods) {
+				if (all.length() > 1) {
+					all.append(", ");
+				}
+				all.append("\"");
+				all.append(mod);
+				all.append("\"");
+			}
+
+			if (requiredMods.size() > 1) {
+				all.append("}");
+			}
+
+			denyLoadReasons.add(
+				"the " + type() + " is annotated with @Requires(" + all + ") but the mods " + missingMods
+					+ " are not loaded!"
+			);
+		}
+	}
+}

src/main/java/org/quiltmc/loader/impl/transformer/ChasmInvoker.java

@@ -213,7 +213,7 @@ public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IO
 				case REMOVED: {
 					QuiltMetadata qm = this_value_is_actually_nullable(result.getMetadata().get(QuiltMetadata.class));
 					if (qm != null) {
-						cache.hideClass(LoaderUtil.getClassNameFromTransformCache(qm.name));
+						cache.hideClass(LoaderUtil.getClassNameFromTransformCache(qm.name), "it was removed by a chasm transformer");
 					} else {
 						throw new UnsupportedOperationException("Cannot remove unknown class");
 					}