wasm gc: add classes that are not directly reachable, but are mention…

…ed in method signatures

Rationale: it can be that some function `foo` declares that it takes class C, but class C is never reachable from code (e.g. never get instantiated, and `foo` only takes nulls). In this case it can be that class C has no representation in Wasm module, which can lead to type validation errors.

core/src/main/java/org/teavm/backend/wasm/gc/WasmGCDependencies.java

@@ -45,6 +45,7 @@ public void contribute() {
         analyzer.addDependencyListener(new WasmGCReferenceQueueDependency());
         analyzer.addDependencyListener(new WasmGCResourceDependency());
         analyzer.addDependencyListener(new SystemArrayCopyDependencySupport());
+        analyzer.addDependencyListener(new WasmGCSignatureDependencyListener());
         handleReferences();
     }
 

core/src/main/java/org/teavm/backend/wasm/gc/WasmGCSignatureDependencyListener.java

@@ -0,0 +1,45 @@
+/*
+ *  Copyright 2025 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.backend.wasm.gc;
+
+import org.teavm.dependency.AbstractDependencyListener;
+import org.teavm.dependency.DependencyAgent;
+import org.teavm.dependency.FieldDependency;
+import org.teavm.dependency.MethodDependency;
+import org.teavm.model.ValueType;
+
+public class WasmGCSignatureDependencyListener extends AbstractDependencyListener {
+    @Override
+    public void methodReached(DependencyAgent agent, MethodDependency method) {
+        for (var i = 0; i < method.getMethod().parameterCount(); ++i) {
+            linkType(agent, method.getMethod().parameterType(i));
+        }
+        linkType(agent, method.getMethod().getResultType());
+    }
+
+    @Override
+    public void fieldReached(DependencyAgent agent, FieldDependency field) {
+        linkType(agent, field.getField().getType());
+    }
+
+    private void linkType(DependencyAgent agent, ValueType type) {
+        if (type instanceof ValueType.Object) {
+            agent.linkClass(((ValueType.Object) type).getClassName());
+        } else if (type instanceof ValueType.Array) {
+            linkType(agent, ((ValueType.Array) type).getItemType());
+        }
+    }
+}