[GROOVY-8337] STC: instanceof in ternary expression not propagating type info to true expression

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.0.0-alpha-4, 2.5.3
• Component/s: Static Type Checker
• Assignee: Daniel Sun
• Reporter: Eric Milles
• Created: 02/Oct/17 01:00
• Updated: 13/Dec/18 10:05
• Resolved: 26/Aug/18 02:08

Description

@CompileStatic
class Static {
  private Number n
  BigDecimal meth() {
    return n == null || n instanceof BigDecimal ? n : new BigDecimal(n.toString())
  }
}

StaticTypeCheckingVisitor is missing the temporary type of the true expression part of the ternary expression because it pops before accessing the type. One possible solution:

    @Override
    public void visitTernaryExpression(final TernaryExpression expression) {
        Map<VariableExpression, List<ClassNode>> oldTracker = pushAssignmentTracking();
        // create a new temporary element in the if-then-else type info
        typeCheckingContext.pushTemporaryTypeInfo();
        expression.getBooleanExpression().visit(this);
        Expression trueExpression = expression.getTrueExpression();
        Expression falseExpression = expression.getFalseExpression();
        trueExpression.visit(this);
        // GRECLIPSE add
        final ClassNode typeOfTrue = findCurrentInstanceOfClass(trueExpression, getType(trueExpression));
        // GRECLIPSE end
        // pop if-then-else temporary type info
        typeCheckingContext.popTemporaryTypeInfo();
        falseExpression.visit(this);
        ClassNode resultType;
        if (isNullConstant(trueExpression) || isNullConstant(falseExpression)) {
            BinaryExpression enclosingBinaryExpression = typeCheckingContext.getEnclosingBinaryExpression();
            if (enclosingBinaryExpression != null && enclosingBinaryExpression.getRightExpression()==expression) {
                resultType = getType(enclosingBinaryExpression.getLeftExpression());
            } else if (isNullConstant(trueExpression) && isNullConstant(falseExpression)) {
                resultType = OBJECT_TYPE;
            } else if (isNullConstant(trueExpression)) {
                resultType = wrapTypeIfNecessary(getType(falseExpression));
            } else {
                resultType = wrapTypeIfNecessary(getType(trueExpression));
            }
        } else {
            // store type information
            // GRECLIPSE edit
            //final ClassNode typeOfTrue = getType(trueExpression);
            // GRECLIPSE end
            final ClassNode typeOfFalse = getType(falseExpression);
            resultType = lowestUpperBound(typeOfTrue, typeOfFalse);
        }
        storeType(expression, resultType);
        popAssignmentTracking(oldTracker);
    }