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8001109: arity mismatch on a call to spreader method handle should elicit IllegalArgumentException

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Document error conditions that may occur when calling a "spreader" method handle.  Use IAE in all cases.

Reviewed-by: twisti, vlivanov
This commit is contained in:
John R Rose 2013-10-05 05:30:39 -07:00
parent 77dc59f6ca
commit e4df9dc1ee
4 changed files with 20 additions and 9 deletions
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10
jdk/src/share/classes/java/lang/invoke/MethodHandle.java
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@ -804,6 +804,10 @@ public abstract class MethodHandle {
* to the target method handle.
* (The array may also be null when zero elements are required.)
* <p>
* If, when the adapter is called, the supplied array argument does
* not have the correct number of elements, the adapter will throw
* an {@link IllegalArgumentException} instead of invoking the target.
* <p>
* Here are some simple examples of array-spreading method handles:
* <blockquote><pre>{@code
MethodHandle equals = publicLookup()
@ -814,6 +818,12 @@ assert(!(boolean) equals.invokeExact("me", (Object)"thee"));
MethodHandle eq2 = equals.asSpreader(Object[].class, 2);
assert( (boolean) eq2.invokeExact(new Object[]{ "me", "me" }));
assert(!(boolean) eq2.invokeExact(new Object[]{ "me", "thee" }));
// try to spread from anything but a 2-array:
for (int n = 0; n <= 10; n++) {
Object[] badArityArgs = (n == 2 ? null : new Object[n]);
try { assert((boolean) eq2.invokeExact(badArityArgs) && false); }
catch (IllegalArgumentException ex) { } // OK
}
// spread both arguments from a String array:
MethodHandle eq2s = equals.asSpreader(String[].class, 2);
assert( (boolean) eq2s.invokeExact(new String[]{ "me", "me" }));

10
jdk/src/share/classes/java/lang/invoke/MethodHandleImpl.java
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@ -460,14 +460,8 @@ import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
}
static void checkSpreadArgument(Object av, int n) {
// FIXME: regression test for bug 7141637 erroneously expects an NPE, and other tests may expect IAE
// but the actual exception raised by an arity mismatch should be WMTE
final boolean RAISE_RANDOM_EXCEPTIONS = true; // FIXME: delete in JSR 292 M1
if (av == null) {
if (n == 0) return;
int len;
if (RAISE_RANDOM_EXCEPTIONS)
len = ((Object[])av).length; // throw NPE; but delete this after tests are fixed
} else if (av instanceof Object[]) {
int len = ((Object[])av).length;
if (len == n) return;
@ -476,9 +470,7 @@ import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
if (len == n) return;
}
// fall through to error:
if (RAISE_RANDOM_EXCEPTIONS)
throw newIllegalArgumentException("Array is not of length "+n);
throw new WrongMethodTypeException("Array is not of length "+n);
throw newIllegalArgumentException("array is not of length "+n);
}
/**

3
jdk/src/share/classes/java/lang/invoke/MethodHandles.java
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@ -1511,6 +1511,9 @@ return mh1;
* <p>
* Before invoking its target, the invoker will spread the final array, apply
* reference casts as necessary, and unbox and widen primitive arguments.
* If, when the invoker is called, the supplied array argument does
* not have the correct number of elements, the invoker will throw
* an {@link IllegalArgumentException} instead of invoking the target.
* <p>
* This method is equivalent to the following code (though it may be more efficient):
* <p><blockquote><pre>

6
jdk/test/java/lang/invoke/JavaDocExamplesTest.java
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@ -264,6 +264,12 @@ assert(!(boolean) equals.invokeExact("me", (Object)"thee"));
MethodHandle eq2 = equals.asSpreader(Object[].class, 2);
assert( (boolean) eq2.invokeExact(new Object[]{ "me", "me" }));
assert(!(boolean) eq2.invokeExact(new Object[]{ "me", "thee" }));
// try to spread from anything but a 2-array:
for (int n = 0; n <= 10; n++) {
Object[] badArityArgs = (n == 2 ? null : new Object[n]);
try { assert((boolean) eq2.invokeExact(badArityArgs) && false); }
catch (IllegalArgumentException ex) { } // OK
}
// spread both arguments from a String array:
MethodHandle eq2s = equals.asSpreader(String[].class, 2);
assert( (boolean) eq2s.invokeExact(new String[]{ "me", "me" }));