Some final spec errata (ArrayType, AnnotationTypeElementDeclaration)

Alex Buckley alex.buckley at
Fri Feb 14 18:34:54 PST 2014

I received a private mail from a reader of the JLS8 draft, noting that 
the ArrayType and UnannArrayType productions show the square brackets to 
be optional:

   PrimitiveType {{Annotation} [ ]}
   ClassOrInterfaceType {{Annotation} [ ]}
   TypeVariable {{Annotation} [ ]}

This error, which makes the grammar ambiguous, has existed since the 
preview of Public Review in October 2013. Happily, implementations do 
the right thing.

Separately, I realized that JLS8 wrongly disallows annotations in an 
element of an annotation type declaration, on the legacy [] part:

   {AnnotationTypeElementModifier} UnannType Identifier ( ) {[ ]} 
[DefaultValue] ;

Because elements are really method declarations, and because method 
declarations allow annotations on a legacy [], javac allows annotations 
on the legacy [] in an element. (The rules of annotation types actually 
allow only one level of brackets here, despite the grammar allowing more.)

It is too late to correct the JLS in the Final Release of JSR 337 (Java 
SE 8), but the printed book and material will say:

   PrimitiveType Dims
   ClassOrInterfaceType Dims
   TypeVariable Dims

   {Annotation} [ ] {{Annotation} [ ]}

   {AnnotationTypeElementModifier} UnannType Identifier ( ) [Dims] 
[DefaultValue] ;


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