Another Java 8 Lambda bug report

[Luke De Gruchy]

Hi,

I have another bug to report.   I can't see why anybody would write new 
code that does this, but perhaps this would be the result of a 
refactoring of anonymous inner class code gone wrong.

As before, I'm running this code on RHEL 6 64-bit with the latest Java 8 
lambda build:

The following program, which combines anonymous inner classes and lambdas:

public class LambdaToAnon {
     public static void main( String[] args ) {
         Function<String,Function<String,String>> 
conditionalFunctionStartWithAnon =
         (aText) -> {
             if ( aText.length() > 3 ) {
                 return new Function<String,String>() {
                     @Override
                     public String apply(String newText) {
                         return newText;
                     }
                 };
             } else {
                 return new Function<String,String>() {
                     @Override
                     public String apply(String newText) {
                         return newText;
                     }
                 };
             }
         };
     }
}

Results in the following runtime error:

$ ~/Development/java/jdks/jdk1.8.0/bin/java LambdaToAnon
Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
Exception Details:
   Location:
     LambdaToAnon.main([Ljava/lang/String;)V @1: invokedynamic
   Reason:
     Type '[Ljava/lang/String;' (current frame, stack[0]) is not 
assignable to 'LambdaToAnon'
   Current Frame:
     bci: @1
     flags: { }
     locals: { '[Ljava/lang/String;' }
     stack: { '[Ljava/lang/String;' }
   Bytecode:
     0000000: 2aba 0002 0000 4cb1

     at java.lang.Class.getDeclaredMethods0(Native Method)
     at java.lang.Class.privateGetDeclaredMethods(Class.java:2443)
     at java.lang.Class.getMethod0(Class.java:2686)
     at java.lang.Class.getMethod(Class.java:1620)
     at 
sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:528)
     at 
sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:510)

Oddly enough, this program, which is a reverse of the previous program 
(anonymous inner classes calling lambdas, instead of the other way 
around), compiles and runs cleanly:

public class AnonToLambda {
     public static void main( String[] args ) {
         Function<String,Function<String,String>> 
conditionalFunctionStartWithAnon =
             new Function<String,Function<String,String>>() {
                 @Override
                 public Function<String,String> apply(String aText) {
                     if ( aText.length() > 3 ) {
                         return (text) -> ("My value");
                     } else {
                         return (text) -> (text);
                     }
                 }
         };
     };
}

Thanks,
Luke

-- 
Luke de Gruchy
Senior Software Developer
Intelerad Medical Systems Incorporated
895 de la Gauchetiere W, Suite 400
Montreal, Quebec, Canada H3B 4G1
luke.degruchy at intelerad.com
www.intelerad.com


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