Added checking for function name in alternative signature.

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/AlternativeSignatureParsing.java

@@ -22,6 +22,7 @@ import com.intellij.psi.PsiErrorElement;
 import com.intellij.psi.PsiSubstitutor;
 import com.intellij.psi.PsiType;
 import com.intellij.util.Function;
+import com.intellij.util.containers.ComparatorUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.*;
@@ -304,5 +305,11 @@ class AlternativeSignatureParsing {
                                     syntaxErrors.size(), errorOffset, syntaxErrorDescription);
             throw new AlternativeSignatureMismatchException(errorText);
         }
+
+        if (!ComparatorUtil.equalsNullable(method.getName(), altFunDeclaration.getName())) {
+            throw new AlternativeSignatureMismatchException(String.format(
+                    "Function names mismatch, original: %s, alternative: %s",
+                    method.getName(), altFunDeclaration.getName()));
+        }
     }
 }