Stackoverflow for parenthesized expr in conditionnal expr while searching assignment context

Issue #164 resolved
Loïc Girault created an issue

The following piece of code produces a stack overflow when trying to compile it :

package p;

class C {
    C(String str){}

    String getText(){return "";}

    void init(Object o){
        new C(o == null ? (getText()) : "");

Comments (5)

  1. Jesper Öqvist

    This error seems to be caused by a circular definition of the isPolyExpression and assignmentContext attributes. If this circularity can be removed that would be the preferred solution, but if the Java specification requires this to be a fixed-point computation then the attribute specifications need to be updated and declare the appropriate attributes as circular. This may require a new version of JastAdd to allow caching of non-circular attributes in a circular evaluation.

  2. Jesper Öqvist

    This test case implies that conditional expression operands have the same assignment context as the conditional expression itself:

    // Test type inference for lambda operands of conditional expression.
    // .result=COMPILE_PASS
    public class Test {
      public interface TestInterface<T> {
        public T functMethod(Integer a);
      public interface SubTestInterface<T> extends TestInterface<T> {
      public static void main(String[] args) {
        TestInterface<Integer> t = args.length == 3
            ? (SubTestInterface<Integer>) a -> a
            : b -> b.intValue() + 4;

    Updating the assignmentContext attribute so that conditional expression operands look further up in the tree for an assignment context removes the circularity and seems to fix this problem (and I don't see any regressions).

  3. Jesper Öqvist

    Remove circularity in assignmentContext attribute

    Fixed circular definitions of assignmentContext, invocationContext, and isPolyExpression, by letting ConditionalExpr operands receive the assignementContext/invocationContext of the ConditionalExpr itself.

    fixes #164 (bitbucket)

    → <<cset 42843acc9ed1>>

  4. Loïc Girault reporter

    You scared me when you mention the necessity of a new version of JastAdd ! Happy to see it so quickly fixed !

  5. Log in to comment