[Issue 13586] New: Destructors not run when argument list evaluation throws

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13586

          Issue ID: 13586
           Summary: Destructors not run when argument list evaluation
                    throws
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: blocker
          Priority: P1
         Component: DMD
          Assignee: nobody at puremagic.com
          Reporter: bugzilla at digitalmars.com

The following test case illustrates it - only s should be constructed, and when
throwit() throws, it should be destructed. It isn't.

------------------------------------------

import core.stdc.stdio;

struct S {
    static int count;
    ~this() { ++count; }
}

int throwit() { throw new Exception("whatevah"); }

void neverland(S s, int x, S t) { }

void main() {
    try {
        neverland(S(), throwit(), S());
    }
    catch (Exception e) {
        printf("%d\n", S.count);
        assert(S.count == 1);
    }
}

C:\cbx\mars>foo
0
core.exception.AssertError at foo.d(19): Assertion failure

-----------------------------------------------
The fix is similar to what Kenji did to ensure left to right order of
evaluation of arguments. If any arguments have destructors, then the argument
list has to be constructed before attempting to put the argument list on the
stack, because destructing them on a partially built stack is problematic. The
arguments are then blitted to the stack, because the blit operation cannot
throw.

Note that this solution relies on D's requirement that a struct instance cannot
have internal pointers to itself.

This bug blocks a reliable ref counting implementation.

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