Name: vpR10072 Date: 11/13/2003



The "Autoboxing and Auto-unboxing support for Java^tm Programming Language"
document reads in JLS 15.25 Conditional Operator ? :

   ...
   The type of a conditional expression is determined as follows:

    * If the second and third operands have the same type (which may be
      the null type), then that is the type of the conditional expression.
    * Otherwise, if the second and third operands have types that are
      convertible to numeric types, then there are several cases:
          o If one of the operands is of type byte and the other is
            of type short, then the type of the conditional expression
            is short.
!!! o If one of the operands is of type T where T is byte, short,
            or char, and the other operand is a constant expression
            of type int whose value is representable in type T, then
            the type of the conditional expression is T.
          o Otherwise, binary numeric promotion (?5.6.2) is applied to the
            operand types, and the type of the conditional expression
            is the promoted type of the second and third operands.
            Note that binary numeric promotion performs unboxing
            conversion (5.1.8) and value set conversion (?5.1.8).

The marked bullet does not specify the situation when values of types
Byte, Short, or Character are used with the other operand which is a
constant expression of type int whose value is representable in other
operand type.

However the javac compiler (jdk1.5.0-b28) performs this conversion.

To demonstrate this, see the following testcase:

% cat test.java
--------------------------------------------------cut here
public class test {
    static final int TByte = 0;
    static final int TShort = 1;
    static final int TChar = 2;
    static final int TInt = 3;
    static final int TLong = 4;
    static final int TFloat = 5;
    static final int TDouble = 6;
    static final int TBoolean = 7;
    static final int TRef = 8;

    static int getType(byte b) {return TByte;}
    static int getType(short s) {return TShort;}
    static int getType(char c) {return TChar;}
    static int getType(int i) {return TInt;}
    static int getType(long l) {return TLong;}
    static int getType(float f) {return TFloat;}
    static int getType(double d) {return TDouble;}
    static int getType(boolean t) {return TBoolean;}
    static int getType(Object o) {return TRef;}

    public static void main(String args[]) {
        boolean f = false, t = true;
        Byte b = new Byte((byte)0x0F);
        Short s = new Short((short)0x0FF0);
        Character c = new Character('a');
        Integer i = new Integer(127);

        if (getType(t ? 1 : b) != TInt)
            System.out.println("got " + getType(t ? 1 : b) + " FAIL#:" + 1);
        if (getType(t ? 2 : s) != TInt)
            System.out.println("got " + getType(t ? 2 : s) + " FAIL#:" + 2);
        if (getType(t ? 3 : c) != TInt)
            System.out.println("got " + getType(t ? 3 : c) + " FAIL#:" + 3);
        if (getType(t ? 4 : i) != TInt)
            System.out.println("got " + getType(t ? 4 : i) + " FAIL#:" + 4);
        if (getType(t ? (byte)0x5 : i) != TInt)
            System.out.println("got " + getType(t ? (byte)0x5 : i) + " FAIL#:" + 5);
        if (getType(t ? (short)0x6 : i) != TInt)
            System.out.println("got " + getType(t ? (short)0x6 : i) + " FAIL#:" + 6);
        if (getType(t ? 'c' : i) != TInt)
            System.out.println("got " + getType(t ? 'c' : i) + " FAIL#:" + 7);
        if (getType(t ? 7 : i) != TInt)
            System.out.println("got " + getType(t ? 7 : i) + " FAIL#:" + 8);
        if (getType(t ? b : i) != TInt)
            System.out.println("got " + getType(t ? b : i) + " FAIL#:" + 9);
        if (getType(t ? s : i) != TInt)
            System.out.println("got " + getType(t ? s : i) + " FAIL#:" + 10);
        if (getType(t ? c : i) != TInt)
            System.out.println("got " + getType(t ? c : i) + " FAIL#:" + 11);
    }
}
--------------------------------------------------cut here

% java -version
java version "1.5.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-beta-b28)
Java HotSpot(TM) Client VM (build 1.5.0-beta-b28, mixed mode)

% javac -source 1.5 test.java

% java test

got 0 FAIL#:1 !!! got type byte
got 1 FAIL#:2 !!! got type short
got 2 FAIL#:3 !!! got type char

The JCK test
    lang/EXPR/expr539/expr53901/expr53901.html
fails due to this bug.

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