Merge pull request #39 from abayer/jenkins-46191

[FIXED JENKINS-46191] Do not cast empty declarations.

Author: abayer

src/main/java/org/kohsuke/groovy/sandbox/SandboxTransformer.java

@@ -27,6 +27,7 @@
 import org.codehaus.groovy.ast.expr.ClosureExpression;
 import org.codehaus.groovy.ast.expr.ConstantExpression;
 import org.codehaus.groovy.ast.expr.DeclarationExpression;
+import org.codehaus.groovy.ast.expr.EmptyExpression;
 import org.codehaus.groovy.ast.expr.Expression;
 import org.codehaus.groovy.ast.expr.ListExpression;
 import org.codehaus.groovy.ast.expr.MethodCallExpression;
@@ -716,7 +717,9 @@ public void visitExpressionStatement(ExpressionStatement es) {
                 DeclarationExpression de = (DeclarationExpression) exp;
                 Expression leftExpression = de.getLeftExpression();
                 if (leftExpression instanceof VariableExpression) {
-                    if (mightBePositionalArgumentConstructor((VariableExpression) leftExpression)) {
+                    // Only cast and transform if the RHS is *not* an EmptyExpression, i.e., "String foo;" would not be cast/transformed.
+                    if (!(de.getRightExpression() instanceof EmptyExpression) &&
+                            mightBePositionalArgumentConstructor((VariableExpression) leftExpression)) {
                         CastExpression ce = new CastExpression(leftExpression.getType(), de.getRightExpression());
                         ce.setCoerce(true);
                         es.setExpression(transform(new DeclarationExpression(leftExpression, de.getOperation(), ce)));

src/test/groovy/org/kohsuke/groovy/sandbox/TheTest.groovy

@@ -840,4 +840,15 @@ return cnt''')
                  '''
         )
     }
+
+    @Issue("JENKINS-46191")
+    void testEmptyDeclaration() {
+        assertIntercept([""],
+        "abc",
+        '''
+String a
+a = "abc"
+return a
+''')
+    }
 }