hg: jdk7/tl/langtools: 2 new changesets

Neal Gafter neal at gafter.com
Tue Jun 7 17:46:47 PDT 2011

One more thing: the casting conversion from "0" to "Byte" is also required
to be allowed by the draft JLS by this curious sentence:

The compile-time legality of a casting conversion is as follows:
• ...
• An expression of a primitive type can always be [sic] undergo casting
conversion to a reference type without error, by boxing conversion.

Since 0 is an expression of primitive type and Byte is a reference type, the
former can "always" undergo a casting conversion to the latter "without

On Tue, Jun 7, 2011 at 5:38 PM, Neal Gafter <neal at gafter.com> wrote:

> Regarding the fix for "bug" 7041730... I was under the impression that
> recent changes to the language and compiler were intended to allow
> assignment conversions as casting conversions too.  The conversion from the
> constant zero (0) to a Byte is among the assignment conversions.  Draft SE7
> JLS 5.2 (Assignment Conversion) says
> In addition, if the expression is a constant expression (§15.28) of type
> ... int ... a narrowing primitive conversion followed by a boxing conversion
> may be used if the type of the variable is ... Byte and the value of the
> constant expression is representable in the type byte...
> And 5.5 (Casting Conversion) says
> ...casting conversions are more inclusive than assignment or method
> invocation conversions: a cast can do any permitted conversion other than a
> string conversion or a capture conversion (§5.1.10).
> Yet this change claims to "fix" the bug 7041730, which requests that the
> casting conversion from "0" to "Byte" be illegal; that violates this JLS
> quote.
> Cheers,
> Neal
> On Wed, May 11, 2011 at 4:16 AM, <maurizio.cimadamore at oracle.com> wrote:
>> Changeset: 95fc7fd39be2
>> Author:    mcimadamore
>> Date:      2011-05-11 13:12 +0200
>> URL:       http://hg.openjdk.java.net/jdk7/tl/langtools/rev/95fc7fd39be2
>> 7041730: Regression: compiler accepts invalid cast from int to Byte
>> Summary: Implementation of cast conversion rules between primitive and
>> boxed types is too liberal
>> Reviewed-by: jjg
>> ! src/share/classes/com/sun/tools/javac/code/Types.java
>> ! test/tools/javac/types/BoxingConversionTest.java
>> ! test/tools/javac/types/CastTest.java
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