# HG changeset patch
# User mcimadamore
# Date 1291994657 0
# Node ID e0a3aeefe4e7a8555a10be740fb64ec45dca3e26
# Parent  00834a375696d5ca6bdfda65582e000949a9fe75
6199075: Unambiguous varargs method calls flagged as ambiguous
Summary: javac does not implement overload resolution w.r.t. varargs methods as described in the JLS
Reviewed-by: jjg

diff -r 00834a375696 -r e0a3aeefe4e7 langtools/src/share/classes/com/sun/tools/javac/code/Types.java
--- a/langtools/src/share/classes/com/sun/tools/javac/code/Types.java	Fri Dec 10 15:23:42 2010 +0000
+++ b/langtools/src/share/classes/com/sun/tools/javac/code/Types.java	Fri Dec 10 15:24:17 2010 +0000
@@ -1318,6 +1318,13 @@
         }
     }
 
+    public Type elemtypeOrType(Type t) {
+        Type elemtype = elemtype(t);
+        return elemtype != null ?
+            elemtype :
+            t;
+    }
+
     /**
      * Mapping to take element type of an arraytype
      */
diff -r 00834a375696 -r e0a3aeefe4e7 langtools/src/share/classes/com/sun/tools/javac/comp/Resolve.java
--- a/langtools/src/share/classes/com/sun/tools/javac/comp/Resolve.java	Fri Dec 10 15:23:42 2010 +0000
+++ b/langtools/src/share/classes/com/sun/tools/javac/comp/Resolve.java	Fri Dec 10 15:24:17 2010 +0000
@@ -470,7 +470,9 @@
             throw inapplicableMethodException.setMessage("arg.length.mismatch"); // not enough args
 
         if (useVarargs) {
-            Type elt = types.elemtype(varargsFormal);
+            //note: if applicability check is triggered by most specific test,
+            //the last argument of a varargs is _not_ an array type (see JLS 15.12.2.5)
+            Type elt = types.elemtypeOrType(varargsFormal);
             while (argtypes.nonEmpty()) {
                 if (!types.isConvertible(argtypes.head, elt, warn))
                     throw inapplicableMethodException.setMessage("varargs.argument.mismatch",
@@ -827,24 +829,30 @@
         List<Type> fromArgs = from.type.getParameterTypes();
         List<Type> toArgs = to.type.getParameterTypes();
         if (useVarargs &&
-                toArgs.length() < fromArgs.length() &&
                 (from.flags() & VARARGS) != 0 &&
                 (to.flags() & VARARGS) != 0) {
-            //if we are checking a varargs method 'from' against another varargs
-            //method 'to' (where arity of 'to' < arity of 'from') then expand signature
-            //of 'to' to 'fit' arity of 'from' (this means adding fake formals to 'to'
-            //until 'to' signature has the same arity as 'from')
-            ListBuffer<Type> args = ListBuffer.lb();
             Type varargsTypeFrom = fromArgs.last();
             Type varargsTypeTo = toArgs.last();
-            while (fromArgs.head != varargsTypeFrom) {
-                args.append(toArgs.head == varargsTypeTo ? types.elemtype(varargsTypeTo) : toArgs.head);
-                fromArgs = fromArgs.tail;
-                toArgs = toArgs.head == varargsTypeTo ?
-                    toArgs :
-                    toArgs.tail;
+            ListBuffer<Type> args = ListBuffer.lb();
+            if (toArgs.length() < fromArgs.length()) {
+                //if we are checking a varargs method 'from' against another varargs
+                //method 'to' (where arity of 'to' < arity of 'from') then expand signature
+                //of 'to' to 'fit' arity of 'from' (this means adding fake formals to 'to'
+                //until 'to' signature has the same arity as 'from')
+                while (fromArgs.head != varargsTypeFrom) {
+                    args.append(toArgs.head == varargsTypeTo ? types.elemtype(varargsTypeTo) : toArgs.head);
+                    fromArgs = fromArgs.tail;
+                    toArgs = toArgs.head == varargsTypeTo ?
+                        toArgs :
+                        toArgs.tail;
+                }
+            } else {
+                //formal argument list is same as original list where last
+                //argument (array type) is removed
+                args.appendList(toArgs.reverse().tail.reverse());
             }
-            args.append(varargsTypeTo);
+            //append varargs element type as last synthetic formal
+            args.append(types.elemtype(varargsTypeTo));
             MethodSymbol msym = new MethodSymbol(to.flags_field,
                                                  to.name,
                                                  (Type)to.type.clone(), //see: 6990136
diff -r 00834a375696 -r e0a3aeefe4e7 langtools/test/tools/javac/varargs/6199075/T6199075.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/varargs/6199075/T6199075.java	Fri Dec 10 15:24:17 2010 +0000
@@ -0,0 +1,284 @@
+/*
+ * Copyright (c) 2010, 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.
+ */
+
+/*
+ * @test
+ * @bug 6199075
+ *
+ * @summary Unambiguous varargs method calls flagged as ambiguous
+ * @author mcimadamore
+ *
+ */
+
+import com.sun.source.util.JavacTask;
+import com.sun.tools.classfile.Instruction;
+import com.sun.tools.classfile.Attribute;
+import com.sun.tools.classfile.ClassFile;
+import com.sun.tools.classfile.Code_attribute;
+import com.sun.tools.classfile.ConstantPool.*;
+import com.sun.tools.classfile.Method;
+import com.sun.tools.javac.util.List;
+
+import java.io.File;
+import java.net.URI;
+import java.util.Arrays;
+import java.util.Locale;
+import javax.tools.Diagnostic;
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileObject;
+import javax.tools.SimpleJavaFileObject;
+import javax.tools.ToolProvider;
+
+public class T6199075 {
+
+    int checkCount = 0;
+    int bytecodeCheckCount = 0;
+
+    enum TypeKind {
+        BYTE("byte", "(byte)1", "[B", 0),
+        CHAR("char", "'c'", "[C", 1),
+        SHORT("short", "(short)1", "[S", 2),
+        INT("int", "1", "[I", 3),
+        LONG("long", "1L", "[J", 4),
+        FLOAT("float", "1.0F", "[F", 5),
+        DOUBLE("double", "1.0D", "[D", 6),
+        BOOLEAN("boolean", "true", "[Z", -1);
+
+        String typeString;
+        String valueString;
+        String bytecodeString;
+        private int subtypeTag;
+
+        TypeKind(String typeString, String valueString, String bytecodeString, int subtypeTag) {
+            this.typeString = typeString;
+            this.valueString = valueString;
+            this.bytecodeString = bytecodeString;
+            this.subtypeTag = subtypeTag;
+        }
+
+        boolean isSubtypeOf(TypeKind that) {
+            switch (this) {
+                case BOOLEAN:
+                    return that == BOOLEAN;
+                case BYTE:
+                case CHAR:
+                    return this.subtypeTag == that.subtypeTag ||
+                            this.subtypeTag + 2 <= that.subtypeTag;
+                default:
+                    return this.subtypeTag <= that.subtypeTag;
+            }
+        }
+    }
+
+    enum ArgumentsArity {
+        ZERO(0),
+        ONE(1),
+        TWO(2),
+        THREE(3);
+
+        int arity;
+
+        ArgumentsArity(int arity) {
+            this.arity = arity;
+        }
+
+        String asExpressionList(TypeKind type) {
+            StringBuilder buf = new StringBuilder();
+            String sep = "";
+            for (int i = 0; i < arity; i++) {
+                buf.append(sep);
+                buf.append(type.valueString);
+                sep = ",";
+            }
+            return buf.toString();
+        }
+    }
+
+    static class VarargsMethod {
+        TypeKind varargsElement;
+
+        VarargsMethod(TypeKind varargsElement) {
+            this.varargsElement = varargsElement;
+        }
+
+        @Override
+        public String toString() {
+            return "void m("+ varargsElement.typeString+ "... args) {}";
+        }
+
+        boolean isApplicable(TypeKind actual, ArgumentsArity argsArity) {
+            return argsArity == ArgumentsArity.ZERO ||
+                    actual.isSubtypeOf(varargsElement);
+        }
+
+        boolean isMoreSpecificThan(VarargsMethod that) {
+            return varargsElement.isSubtypeOf(that.varargsElement);
+        }
+    }
+
+    public static void main(String... args) throws Exception {
+        new T6199075().test();
+    }
+
+    void test() throws Exception {
+        for (TypeKind formal1 : TypeKind.values()) {
+            VarargsMethod m1 = new VarargsMethod(formal1);
+            for (TypeKind formal2 : TypeKind.values()) {
+                VarargsMethod m2 = new VarargsMethod(formal2);
+                for (TypeKind actual : TypeKind.values()) {
+                    for (ArgumentsArity argsArity : ArgumentsArity.values()) {
+                        compileAndCheck(m1, m2, actual, argsArity);
+                    }
+                }
+            }
+        }
+
+        System.out.println("Total checks made: " + checkCount);
+        System.out.println("Bytecode checks made: " + bytecodeCheckCount);
+    }
+
+    void compileAndCheck(VarargsMethod m1, VarargsMethod m2, TypeKind actual, ArgumentsArity argsArity) throws Exception {
+        final JavaCompiler tool = ToolProvider.getSystemJavaCompiler();
+        JavaSource source = new JavaSource(m1, m2, actual, argsArity);
+        ErrorChecker ec = new ErrorChecker();
+        JavacTask ct = (JavacTask)tool.getTask(null, null, ec,
+                null, null, Arrays.asList(source));
+        ct.generate();
+        check(source, ec, m1, m2, actual, argsArity);
+    }
+
+    void check(JavaSource source, ErrorChecker ec, VarargsMethod m1, VarargsMethod m2, TypeKind actual, ArgumentsArity argsArity) {
+        checkCount++;
+        boolean resolutionError = false;
+        VarargsMethod selectedMethod = null;
+
+        boolean m1_applicable = m1.isApplicable(actual, argsArity);
+        boolean m2_applicable = m2.isApplicable(actual, argsArity);
+
+        if (!m1_applicable && !m2_applicable) {
+            resolutionError = true;
+        } else if (m1_applicable && m2_applicable) {
+            //most specific
+            boolean m1_moreSpecific = m1.isMoreSpecificThan(m2);
+            boolean m2_moreSpecific = m2.isMoreSpecificThan(m1);
+            resolutionError = m1_moreSpecific == m2_moreSpecific;
+            selectedMethod = m1_moreSpecific ? m1 : m2;
+        } else {
+            selectedMethod = m1_applicable ?
+                m1 : m2;
+        }
+
+        if (ec.errorFound != resolutionError) {
+            throw new Error("invalid diagnostics for source:\n" +
+                    source.getCharContent(true) +
+                    "\nExpected resolution error: " + resolutionError +
+                    "\nFound error: " + ec.errorFound +
+                    "\nCompiler diagnostics:\n" + ec.printDiags());
+        } else if (!resolutionError) {
+            verifyBytecode(selectedMethod);
+        }
+    }
+
+    void verifyBytecode(VarargsMethod selected) {
+        bytecodeCheckCount++;
+        File compiledTest = new File("Test.class");
+        try {
+            ClassFile cf = ClassFile.read(compiledTest);
+            Method testMethod = null;
+            for (Method m : cf.methods) {
+                if (m.getName(cf.constant_pool).equals("test")) {
+                    testMethod = m;
+                    break;
+                }
+            }
+            if (testMethod == null) {
+                throw new Error("Test method not found");
+            }
+            Code_attribute ea = (Code_attribute)testMethod.attributes.get(Attribute.Code);
+            if (testMethod == null) {
+                throw new Error("Code attribute for test() method not found");
+            }
+
+            for (Instruction i : ea.getInstructions()) {
+                if (i.getMnemonic().equals("invokevirtual")) {
+                    int cp_entry = i.getUnsignedShort(1);
+                    CONSTANT_Methodref_info methRef =
+                            (CONSTANT_Methodref_info)cf.constant_pool.get(cp_entry);
+                    String type = methRef.getNameAndTypeInfo().getType();
+                    if (!type.contains(selected.varargsElement.bytecodeString)) {
+                        throw new Error("Unexpected type method call: " + type);
+                    }
+                    break;
+                }
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+            throw new Error("error reading " + compiledTest +": " + e);
+        }
+    }
+
+    static class JavaSource extends SimpleJavaFileObject {
+
+        static final String source_template = "class Test {\n" +
+                "   #V1\n" +
+                "   #V2\n" +
+                "   void test() { m(#E); }\n" +
+                "}";
+
+        String source;
+
+        public JavaSource(VarargsMethod m1, VarargsMethod m2, TypeKind actual, ArgumentsArity argsArity) {
+            super(URI.create("myfo:/Test.java"), JavaFileObject.Kind.SOURCE);
+            source = source_template.replaceAll("#V1", m1.toString()).
+                    replaceAll("#V2", m2.toString()).
+                    replaceAll("#E", argsArity.asExpressionList(actual));
+        }
+
+        @Override
+        public CharSequence getCharContent(boolean ignoreEncodingErrors) {
+            return source;
+        }
+    }
+
+    static class ErrorChecker implements javax.tools.DiagnosticListener<JavaFileObject> {
+
+        boolean errorFound;
+        List<String> errDiags = List.nil();
+
+        public void report(Diagnostic<? extends JavaFileObject> diagnostic) {
+            if (diagnostic.getKind() == Diagnostic.Kind.ERROR) {
+                errDiags = errDiags.append(diagnostic.getMessage(Locale.getDefault()));
+                errorFound = true;
+            }
+        }
+
+        String printDiags() {
+            StringBuilder buf = new StringBuilder();
+            for (String s : errDiags) {
+                buf.append(s);
+                buf.append("\n");
+            }
+            return buf.toString();
+        }
+    }
+}