When building and executing a rule that is written in MVEL dialect and contains a statement ending with a new line character (not semi-colon) in action part with executable model enabled, we sometimes encounter some compilation error or unexpected result.

• Example 1 (rule "rule22a1" in reproducer_model_compiler_22a)
  This rule (*1) contains a statement ending with a new line character (*1-1). When building this rule, model compiler generates java code like (*2) from the action part and the generated code causes a compilation error like (*3).
  (*1)

  package com.example.reproducer
  
  import java.math.BigDecimal
  
  dialect "mvel"
  
  rule "rule22a1"
      when
          $bus : Bus( $weight : weight != 0 )
      then
          System.out.println("***** Action of rule22a1: " + $bus + ", $weight = " + $weight);
          $weight = $weight    // .......... (*1-1)
          BigDecimal bd1 = 0;
          modify($bus) {
              weight = bd1
          }
  end
  

  (*2)

          System.out.println("***** Action of rule22a1: " + $bus + ", $weight = " + $weight);
          $weight = new java.math.BigDecimal(0);    // ..... (*2-1)
          $bus.setWeight(bd1);
          drools.update($bus, mask_$bus);
  

  (*3)

  17:28:50.182 [INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile-1) @ reproducer_model_compiler_22a ---
  17:28:50.185 [INFO] Changes detected - recompiling the module!
  17:28:50.186 [INFO] Compiling 9 source files to /work2/testdir/reproducer_model_compiler_22a/target/classes
  17:28:50.459 [INFO] -------------------------------------------------------------
  17:28:50.459 [ERROR] COMPILATION ERROR : 
  17:28:50.459 [INFO] -------------------------------------------------------------
  17:28:50.459 [ERROR] /work2/testdir/reproducer_model_compiler_22a/target/generated-sources/drools-model-compiler/main/java/com/example/reproducer/P7C/LambdaConsequence7CD56D82A4775FB5FC32E4022E4511B5.java:[25,24] cannot find symbol
    symbol:   variable bd1
    location: class com.example.reproducer.P7C.LambdaConsequence7CD56D82A4775FB5FC32E4022E4511B5
  17:28:50.460 [INFO] 1 error
  17:28:50.460 [INFO] -------------------------------------------------------------
  

• Example 2 (rule "rule22a2" in reproducer_model_compiler_22a)
  This rule (*4) contains a statement ending with a new line character (*4-1). When building this rule, model compiler generates java code like (*5) from the action part. The generated code does not cause a compilation error but causes unexpected result at runtime like (*6).
  (*4)

  rule "rule22a2"
      when
          $bus : Bus( $weight : weight != 0, $capacity : capacity != 0 )
      then
          System.out.println("***** Action of rule22a2: " + $bus + ", $weight = " + $weight + ", $capacity = " + $capacity);
          $weight = $weight    // .......... (*4-1)
          BigDecimal bd1 = $capacity;
          modify($bus) {
              weight = $weight
          }
  end
  

  (*5)

          System.out.println("***** Action of rule22a2: " + $bus + ", $weight = " + $weight + ", $capacity = " + $capacity);
          $weight = new java.math.BigDecimal($capacity);    ..... (*5-1)
          $bus.setWeight($weight);
          drools.update($bus, mask_$bus);
  

  (*6)

  ***** start
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 12000, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** Action of rule22a2: com.example.reproducer.Bus@7b64240d, $weight = 25, $capacity = 25
  ***** end
  

Java code generated by model compiler (*2-1) and (*5-1) are both $weight = <RHS of the next assignment statement> and incorrect.

In plain drl, both of these examples are successfully built and executed as expected.