Fix wantarray in eval STRING: pass outer context to apply()

EvalStringHandler.evalString() was hardcoding RuntimeContextType.SCALAR
when executing the eval body, so wantarray() inside eval STRING always
returned false (scalar) regardless of the actual call site context.

Fix: read registers[2] (the outer wantarray set by BytecodeInterpreter)
and pass it as callContext to evalString() and apply(), so wantarray()
inside the eval body correctly returns undef (void), false (scalar), or
true (list) matching the outer call site.

Result: op/eval.t passes 153/153 in both JVM and interpreter modes.

Author: fglock

src/main/java/org/perlonjava/backend/bytecode/EvalStringHandler.java

@@ -43,13 +43,15 @@ public class EvalStringHandler {
      * @param registers     Current register array (for variable access)
      * @param sourceName    Source name for error messages
      * @param sourceLine    Source line for error messages
+     * @param callContext   The calling context (VOID/SCALAR/LIST) for wantarray inside eval
      * @return RuntimeScalar result of evaluation (undef on error)
      */
     public static RuntimeScalar evalString(String perlCode,
                                           InterpretedCode currentCode,
                                           RuntimeBase[] registers,
                                           String sourceName,
-                                          int sourceLine) {
+                                          int sourceLine,
+                                          int callContext) {
         try {
             // Step 1: Clear $@ at start of eval
             GlobalVariable.getGlobalVariable("main::@").set("");
@@ -196,8 +198,10 @@ public static RuntimeScalar evalString(String perlCode,
             }
 
             // Step 6: Execute the compiled code
+            // Use the true outer call context so wantarray() inside the eval body
+            // returns the correct value (undef for void, false for scalar, true for list).
             RuntimeArray args = new RuntimeArray();  // Empty @_
-            RuntimeList result = evalCode.apply(args, RuntimeContextType.SCALAR);
+            RuntimeList result = evalCode.apply(args, callContext);
 
             // Step 7: Return scalar result
             return result.scalar();

src/main/java/org/perlonjava/backend/bytecode/SlowOpcodeHandler.java

@@ -252,13 +252,19 @@ public static int executeEvalString(
         }
         String perlCode = codeScalar.toString();
 
+        // Read outer wantarray from register 2 (set by BytecodeInterpreter from the call site context).
+        // This is the true calling context (VOID/SCALAR/LIST) that wantarray() inside the
+        // eval body must reflect — exactly as evalStringWithInterpreter receives callContext.
+        int callContext = ((RuntimeScalar) registers[2]).getInt();
+
         // Call EvalStringHandler to parse, compile, and execute
         RuntimeScalar result = EvalStringHandler.evalString(
             perlCode,
             code,           // Current InterpretedCode for context
             registers,      // Current registers for variable access
             code.sourceName,
-            code.sourceLine
+            code.sourceLine,
+            callContext     // True outer context for wantarray inside eval body
         );
 
         registers[rd] = result;