C: fix Strings.fromC/fromC16 methods

core/src/main/java/org/teavm/backend/c/CTarget.java

@@ -75,6 +75,7 @@ import org.teavm.backend.c.intrinsic.StringsIntrinsic;
 import org.teavm.backend.c.intrinsic.StructureIntrinsic;
 import org.teavm.backend.lowlevel.analyze.LowLevelInliningFilterFactory;
 import org.teavm.backend.lowlevel.dependency.ExceptionHandlingDependencyListener;
+import org.teavm.backend.lowlevel.dependency.StringsDependencyListener;
 import org.teavm.backend.lowlevel.dependency.WeakReferenceDependencyListener;
 import org.teavm.backend.lowlevel.generate.NameProvider;
 import org.teavm.backend.lowlevel.generate.NameProviderWithSpecialNames;
@@ -324,6 +325,7 @@ public class CTarget implements TeaVMTarget, TeaVMCHost {
         dependencyAnalyzer.linkClass(CallSiteLocation.class.getName());
 
         dependencyAnalyzer.addDependencyListener(new ExceptionHandlingDependencyListener());
+        dependencyAnalyzer.addDependencyListener(new StringsDependencyListener());
     }
 
     @Override

core/src/main/java/org/teavm/backend/lowlevel/dependency/StringsDependencyListener.java

@@ -0,0 +1,37 @@
+/*
+ *  Copyright 2020 konsoletyper.
+ *
+ *  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.lowlevel.dependency;
+
+import org.teavm.dependency.AbstractDependencyListener;
+import org.teavm.dependency.DependencyAgent;
+import org.teavm.dependency.MethodDependency;
+import org.teavm.model.MethodReference;
+
+public class StringsDependencyListener extends AbstractDependencyListener {
+    private static final String STRINGS_CLASS = "org.teavm.interop.Strings";
+
+    @Override
+    public void methodReached(DependencyAgent agent, MethodDependency method) {
+        MethodReference ref = method.getReference();
+        if (ref.getClassName().equals(STRINGS_CLASS)) {
+            switch (ref.getName()) {
+                case "fromC":
+                case "fromC16":
+                    method.getResult().propagate(agent.getType("java.lang.String"));
+            }
+        }
+    }
+}

core/src/main/java/org/teavm/backend/wasm/WasmTarget.java

@@ -32,6 +32,7 @@ import java.util.Properties;
 import java.util.Set;
 import org.teavm.ast.decompilation.Decompiler;
 import org.teavm.backend.lowlevel.analyze.LowLevelInliningFilterFactory;
+import org.teavm.backend.lowlevel.dependency.StringsDependencyListener;
 import org.teavm.backend.lowlevel.generate.NameProvider;
 import org.teavm.backend.lowlevel.generate.NameProviderWithSpecialNames;
 import org.teavm.backend.wasm.binary.BinaryWriter;
@@ -330,6 +331,8 @@ public class WasmTarget implements TeaVMTarget, TeaVMWasmHost {
                 dependencyAnalyzer.linkField(field.getReference());
             }
         }
+
+        dependencyAnalyzer.addDependencyListener(new StringsDependencyListener());
     }
 
     @Override