- Exclude 'new' from 'drlIdentifier' because of 'primary' ambiguity

- Add tests

drools-drl/drools-drl-parser-tests/src/test/java/org/drools/drl/parser/antlr4/DRLExprParserTest.java

@@ -440,6 +440,30 @@ public void testExtraneousInput() {
         }
     }
 
+    @Test
+    public void testNoViableAlt() {
+        String source = "a~a";
+        parser.parse(source);
+
+        // Backward Compatibility Notes:
+        //   Old expr parser (DRL6Expressions) allows this expression and only takes "a" ignoring the invalid part "~a" without emitting an error.
+        //   This is rather a bug in the old parser, and the new parser (ANTLR4) correctly emits an error for this case.
+        //   Backward compatibility doesn't seem to be required in this case.
+        if (DrlParser.ANTLR4_PARSER_ENABLED) {
+            assertThat(parser.hasErrors()).isTrue();
+            assertThat(parser.getErrors()).hasSize(1);
+            DroolsParserException exception = parser.getErrors().get(0);
+            assertThat(exception.getErrorCode()).isEqualTo("ERR 101");
+            assertThat(exception.getLineNumber()).isEqualTo(1);
+            assertThat(exception.getColumn()).isEqualTo(2);
+            assertThat(exception.getOffset()).isEqualTo(2);
+            assertThat(exception.getMessage())
+                    .isEqualToIgnoringCase("[ERR 101] Line 1:2 no viable alternative at input 'a'");
+        } else {
+            assertThat(parser.hasErrors()).isFalse();
+        }
+    }
+
     @Test
     void orWithMethodCall() {
         String source = "value == 10 || someMethod() == 4";
@@ -541,4 +565,17 @@ void andWithMethodCallWithArg() {
         assertThat(left.getExpression()).isEqualTo("someMethod(value)");
         assertThat(right.getExpression()).isEqualTo("4");
     }
+
+    @Test
+    void newBigDecimal() {
+        String source = "$bd : new BigDecimal(30)";
+        ConstraintConnectiveDescr result = parser.parse(source);
+        assertThat(parser.hasErrors()).as(parser.getErrors().toString()).isFalse();
+
+        assertThat(result.getDescrs().size()).isEqualTo(1);
+
+        BindingDescr bind = (BindingDescr) result.getDescrs().get(0);
+        assertThat(bind.getVariable()).isEqualTo("$bd");
+        assertThat(bind.getExpression()).isEqualTo("new BigDecimal(30)");
+    }
 }

drools-drl/drools-drl-parser-tests/src/test/java/org/drools/drl/parser/antlr4/ParserTestUtils.java

@@ -25,12 +25,14 @@
 
 public class ParserTestUtils {
 
+    // 'new' is not included because it cannot be included in drlIdentifier.
+    // See https://github.com/apache/incubator-kie-drools/pull/5958
     public static List<String> javaKeywords =
             Arrays.asList(
                     "abstract", "assert", "boolean", "break", "byte", "case", "catch", "char", "class", "const",
                     "continue", "default", "do", "double", "else", "enum", "extends", "final", "finally", "float",
                     "for", "goto", "if", "implements", "import", "instanceof", "int", "interface", "long", "native",
-                    "new", "package", "private", "protected", "public", "return", "short", "static", "strictfp",
+                    "package", "private", "protected", "public", "return", "short", "static", "strictfp",
                     "super", "switch", "synchronized", "this", "throw", "throws", "transient", "try", "void", "volatile",
                     "while"
             );

drools-drl/drools-drl-parser/src/main/antlr4/org/drools/drl/parser/antlr4/DRL6Expressions.g4

@@ -193,7 +193,7 @@ drlIdentifier returns [Token token]
     | INTERFACE
     | LONG
     | NATIVE
-    | NEW
+//    | NEW     // avoid ambiguity with 'new_key creator' and 'drlIdentifier' in 'primary'
     | PACKAGE
     | PRIVATE
     | PROTECTED