javac bug: defender method processing

[Jonathan Gibbons]

David,
> Unfortunately, a quick test shows that javac doesn't seem to fully
> implement JLS 6.7 in regards to unnamed packages
6.7 simply defines Fully Qualified Names and Canonical Names. It says 
nothing about the meaning of names. For that you need to read 6.5, and 
6.5.5.1 in particular:

http://java.sun.com/docs/books/jls/third_edition/html/names.html#6.5.5.1

If a type name consists of a single /Identifier/, then the identifier 
must occur in the scope of exactly one visible declaration of a type 
with this name, or a compile-time error occurs. The meaning of the type 
name is that type.

-- Jon




On 10/27/2010 06:45 PM, David Schlosnagle wrote:
> Brian,
>
> I don't believe this problem is specific to lambda, it is purely a
> combination of the interactions between the default visibility of the
> Impl type JLS 6.6.1 [1] and unnamed packages JLS 7.4.2 [2]. If you
> were to make the Impl class public, I would think you should be able
> to reference it using the fully qualified name 'Impl' per JLS 6.7 [3]:
>      The fully qualified name of a top level class or top level
> interface that is declared in an unnamed package is the simple name of
> the class or interface.
>
> Unfortunately, a quick test shows that javac doesn't seem to fully
> implement JLS 6.7 in regards to unnamed packages, all the more reason
> to not use unnamed packages!
>
> $ javac -fullversion
> javac full version "1.7.0-internal-david_2010_07_23_16_08-b00"
>
> $ cat Impl.java
> public class Impl {}
>
> $ cat test/TestUnnamedPackageVisibility.java
> package test;
> public class TestUnnamedPackageVisibility {
>      public static void main(String... args) {
>          System.out.println(Impl.class);
>      }
> }
>
> $ find . -name "*.java"
> ./Impl.java
> ./test/TestUnnamedPackageVisibility.java
>
> $ javac -d ../bin/ Impl.java test/TestUnnamedPackageVisibility.java
> test/TestUnnamedPackageVisibility.java:4: cannot find symbol
>          System.out.println(Impl.class);
>                             ^
>    symbol:   class Impl
>    location: class TestUnnamedPackageVisibility
> 1 error
>
>
> Also, Java 1.4 removed the ability to explicitly import a type from an
> unnamed package (per section 8 of the Java 1.4 compatibility [4]):
>      The compiler now rejects import statements that import a type from the
>      unnamed namespace. Previous versions of the compiler would accept such
>      import declarations, even though they were arguably not allowed by the
>      language (because the type name appearing in the import clause is not in
>      scope). The specification is being clarified to state clearly that you
>      cannot have a simple name in an import statement, nor can you import from
>      the unnamed namespace.
>
>
> References:
> [1]: http://java.sun.com/docs/books/jls/third_edition/html/names.html#6.6.1
> [2]: http://java.sun.com/docs/books/jls/third_edition/html/packages.html#7.4.2
> [3]: http://java.sun.com/docs/books/jls/third_edition/html/names.html#6.7
> [4]: http://java.sun.com/javase/compatibility_j2se1.4.html
>
> - Dave
>
>
> On Wed, Oct 27, 2010 at 5:43 PM, Brian Goetz<brian.goetz at oracle.com>  wrote:
>> I created this file:
>>
>> src/Impl.java (no package)
>>
>> class Impl {
>>      public static int one() { return 1 };
>> }
>>
>> and this test file:
>>
>> src/junit/SimpleDefenderTest.java:
>>
>> package junit;
>>
>> import junit.framework.TestCase;
>>
>> public class SimpleDefenderTest extends TestCase {
>>      private static interface A {
>>          public extension int get() default Impl.one;
>>      }
>>
>>      private static class C implements A {
>>      }
>>
>>      public void testSimpleWeave() {
>>          C c = new C();
>>          assertEquals(1, c.get());
>>      }
>> }
>>
>>
>> It failed to compile, with this error:
>>
>>      [javac] src/junit/SimpleDefenderTest.java:7: cannot find symbol
>>      [javac]         public extension int get() default Impl.one;
>>      [javac]                              ^
>>      [javac]   symbol:   variable Impl
>>      [javac]   location: interface A
>>      [javac] 1 error
>>
>>
>> The problem seems to be either that Impl was in the empty package, or maybe
>> that it was just in another package.  I moved it to the same package and it
>> worked.
>>
>>
>>
>>