7904089: jextract cannot handle "void foo(int foo)"

src/main/java/org/openjdk/jextract/impl/HeaderFileBuilder.java

@@ -174,7 +174,10 @@ private void emitFunctionWrapper(String javaName, String nativeName, boolean nee
                 String.format("\"%1$s\", %2$s", nativeName, paramList);
         incrAlign();
         if (!isVarArg) {
-            String holderClass = newHolderClassName(javaName);
+            // function name may conflict with any of its parameter names.
+            boolean nameConflict = parameterNames.contains(javaName);
+            String holderName = nameConflict ? javaName + "$" : javaName;
+            String holderClass = newHolderClassName(holderName);
             appendLines("""
 
                 private static class %1$s {

test/jtreg/generator/nameConflict/TestNameConflict.java

@@ -0,0 +1,45 @@
+/* Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import org.testng.annotations.Test;
+
+import static org.testng.Assert.assertEquals;
+import static test.jextract.nameconflict.nameconflict_h.*;
+
+/*
+ * @test
+ * @bug 7904089
+ * @library /lib
+ * @build testlib.TestUtils
+ * @run main/othervm JtregJextract -l nameconflict --use-system-load-library -t test.jextract.nameconflict nameconflict.h
+ * @build TestNameConflict
+ * @run testng/othervm --enable-native-access=ALL-UNNAMED TestNameConflict
+ */
+public class TestNameConflict {
+
+    @Test
+    public void testNameConflict() {
+        foo(5d);
+        assertEquals(add(9,1), 10);
+        assertEquals(increment(10), 11);
+    }
+}

test/jtreg/generator/nameConflict/libnameconflict.c

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "nameconflict.h"
+
+EXPORT int increment(int increment){
+    return increment + 1;
+}
+
+EXPORT int add(int add2, int add){
+    return add + add2;
+}
+
+EXPORT void foo(double foo){
+    return ;
+}

test/jtreg/generator/nameConflict/nameconflict.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifdef _WIN64
+#define EXPORT __declspec(dllexport)
+#else
+#define EXPORT
+#endif
+
+EXPORT int increment(int increment);
+EXPORT int add(int add2, int add);
+EXPORT void foo(double foo);