Handle removing mod load options properly

src/main/java/org/quiltmc/loader/api/plugin/QuiltPluginContext.java

@@ -142,7 +142,7 @@ default <V> QuiltPluginTask<V> addGuiRequest() {
 	 * {@link QuiltLoaderPlugin#resolve(QuiltPluginContext, TentativeLoadOption)}, if it is selected.
 	 * 
 	 * @param option */
-	<T extends LoadOption & TentativeLoadOption> void addTentativeOption(T option);
+	<T extends LoadOption & TentativeLoadOption> void addTentativeOption(T option, Class<T> clazz);
 
 	/** Only callable during {@link QuiltLoaderPlugin#handleError(java.util.List)} to identify the given rule as one
 	 * which can be removed for the purposes of error message generation. */

src/main/java/org/quiltmc/loader/api/plugin/solver/Rule.java

@@ -29,11 +29,11 @@ public abstract class Rule {
 	public Rule() {}
 
 	/** @return true if {@link #define(RuleDefiner)} needs to be called again, or false if the added option had no
-	 *         affect on this rule. */
+	 *         effect on this rule. */
 	public abstract boolean onLoadOptionAdded(LoadOption option);
 
 	/** @return true if {@link #define(RuleDefiner)} needs to be called again, or false if the removed option had no
-	 *         affect on this rule. */
+	 *         effect on this rule. */
 	public abstract boolean onLoadOptionRemoved(LoadOption option);
 
 	/** Called whenever a {@link LoadOption} is changed. Not all {@link Rule}s are expected to be able to update to all

src/main/java/org/quiltmc/loader/impl/plugin/BasePluginContext.java

@@ -114,7 +114,7 @@ public void addModLoadOption(ModLoadOption mod, PluginGuiTreeNode guiNode) {
 	}
 
 	@Override
-	public <T extends LoadOption & TentativeLoadOption> void addTentativeOption(T option) {
+	public <T extends LoadOption & TentativeLoadOption> void addTentativeOption(T option, Class<T> clazz) {
 		addTentativeOption0(option);
 	}
 

src/main/java/org/quiltmc/loader/impl/plugin/quilt/MandatoryModIdDefinition.java

@@ -28,6 +28,7 @@
 @QuiltLoaderInternal(QuiltLoaderInternalType.NEW_INTERNAL)
 public final class MandatoryModIdDefinition extends ModIdDefinition {
 	public final ModLoadOption option;
+	private boolean optionGone = false;
 
 	public MandatoryModIdDefinition(ModLoadOption candidate) {
 		this.option = candidate;
@@ -45,7 +46,9 @@ ModLoadOption[] sources() {
 
 	@Override
 	public void define(RuleDefiner definer) {
-		definer.atLeastOneOf(option);
+		if (!optionGone) {
+			definer.atLeastOneOf(option);
+		}
 	}
 
 	@Override
@@ -55,7 +58,7 @@ public boolean onLoadOptionAdded(LoadOption option) {
 
 	@Override
 	public boolean onLoadOptionRemoved(LoadOption option) {
-		return false;
+		return optionGone = option == this.option;
 	}
 
 	@Override
@@ -74,5 +77,8 @@ public void fallbackErrorDescription(StringBuilder errors) {
 		errors.append(getFriendlyName());
 		errors.append(" v");
 		errors.append(option.metadata().version());
+		if (optionGone) {
+			errors.append(" (gone)");
+		}
 	}
 }

src/main/java/org/quiltmc/loader/impl/plugin/quilt/OptionalModIdDefintion.java

@@ -129,6 +129,10 @@ private void recalculateWeights() {
 
 	@Override
 	public void define(RuleDefiner definer) {
+		if (sources.isEmpty()) {
+			return;
+		}
+
 		boolean anyAreAlways = false;
 
 		for (ModLoadOption mod : sources) {

src/main/java/org/quiltmc/loader/impl/plugin/quilt/StandardQuiltPlugin.java

@@ -80,6 +80,7 @@ public class StandardQuiltPlugin extends BuiltinQuiltPlugin {
 
 	private QuiltOverrides overrides;
 	private final Map<String, OptionalModIdDefintion> modDefinitions = new HashMap<>();
+	private final Map<ModLoadOption, List<ModLoadOption>> providedMods = new HashMap<>();
 
 	@Override
 	public void load(QuiltPluginContext context, Map<String, LoaderValue> previousData) {
@@ -327,7 +328,9 @@ public void onLoadOptionAdded(LoadOption option) {
 					PluginGuiTreeNode guiNode = context().manager().getGuiNode(mod)//
 						.addChild(QuiltLoaderText.translate("gui.text.providing", provided.id()));
 					guiNode.mainIcon(guiNode.manager().iconUnknownFile());
-					context().addModLoadOption(new ProvidedModOption(mod, provided), guiNode);
+					ProvidedModOption providedOption = new ProvidedModOption(mod, provided);
+					providedMods.computeIfAbsent(mod, i -> new ArrayList<>(provides.size())).add(providedOption);
+					context().addModLoadOption(providedOption, guiNode);
 				}
 			}
 
@@ -364,7 +367,19 @@ public void onLoadOptionAdded(LoadOption option) {
 					}
 				}
 			}
+
+		}
+	}
+
+	@Override
+	public void onLoadOptionRemoved(LoadOption option) {
+		// remove provided options
+		if (providedMods.containsKey(option)) {
+			for (ModLoadOption modLoadOption : providedMods.get(option)) {
+				context().ruleContext().removeOption(modLoadOption);
+			}
 		}
+		providedMods.remove(option);
 	}
 
 	private static void warn(String msg) {

src/main/java/org/quiltmc/loader/impl/solver/Sat4jWrapper.java

@@ -156,6 +156,9 @@ public void addOption(LoadOption option) {
 		}
 
 		for (Rule rule : rulesToRedefine) {
+			if (LOG) {
+				Log.info(CATEGORY, "Redefining rule " + rule + " because of added load option" + option);
+			}
 			redefine(rule);
 		}
 	}
@@ -197,6 +200,9 @@ public void removeOption(LoadOption option) {
 		}
 
 		for (Rule rule : rulesToRedefine) {
+			if (LOG) {
+				Log.info(CATEGORY, "Redefining rule " + rule + " because of removed load option " + option);
+			}
 			redefine(rule);
 		}
 	}
@@ -235,7 +241,7 @@ public void removeRule(Rule rule) {
 	public void redefine(Rule rule) {
 
 		if (LOG) {
-			Log.info(CATEGORY, "Redefining rule " + rule);
+			Log.info(CATEGORY, "Doing redefine of rule " + rule);
 		}
 
 		validateCanAdd();