• d-bugmail puremagic.com (45/45) Oct 19 2018 https://issues.dlang.org/show_bug.cgi?id=19317

d-bugmail puremagic.com writes:

https://issues.dlang.org/show_bug.cgi?id=19317

          Issue ID: 19317
           Summary: dip1008 doesn't call the throwable's destructor in
                    _d_delThrowable
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: major
          Priority: P1
         Component: druntime
          Assignee: nobody puremagic.com
          Reporter: atila.neves gmail.com

The last assertion in the code below fails. This makes 1008 far less useful
than it could be. Exceptions have error messages, and the only way to construct
a useful message with runtime information is to allocate. Given that the
purpose of dip1008 is to avoid the GC and still be able to use exceptions, the
non error-prone way of doing this is to use an RAII string class.

However, that means that _d_delThrowable should call the class's destructor,
which it doesn't right now, resulting in a either a leak or the programmer
having to manually dispose of the memory.


---------------
class MyException: Exception {
    static int numInstances;
    this(string msg) {
        super(msg);
        ++numInstances;
    }

    ~this() {
        --numInstances;
    }
}

void main() {
    assert(MyException.numInstances == 0);

    try
        throw new MyException("oops");
    catch(MyException _)
        assert(MyException.numInstances == 1);

    assert(MyException.numInstances == 0);
}
---------------

% dmd -dip1008 -run exception.d
core.exception.AssertError exception.d(21): Assertion failure

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