[PATCH] D92480: [llvm] Add asserts in (ThreadSafe)?RefCountedBase destructors

[David Blaikie via Phabricator via cfe-commits]

dblaikie added inline comments.


================
Comment at: llvm/include/llvm/Support/ManagedStatic.h:25
+// that are const with no params.
+template <typename T> struct HasRetainRelease {
+private:
----------------
njames93 wrote:
> dblaikie wrote:
> > Are there many uses that rely on this? I don't think it's really worth all this infrastructure - compared to having it supported on an as-needed basis, such as directly in TrueMatcherImpl's ctor and dtor.
> It doesn't work in TrueMatcherImpl ctor/dtor due to the whole double free issue(See [[ https://reviews.llvm.org/D92480#inline-864517 | previous comment ]]). I can go back to just supporting it for TrueMatcherImpl by writing a single custom creator/deleter for that class.
> 
> This approach taken was a little overkill but likely a little more foolproof for someone using the library. I'll go ahead with whichever approach you would prefer. 
Ah, right - thanks for walking me through it again, now I better understand your previous comment - sorry for that erroneous suggestion/confusion.

Fair points all.

Given all that, I'm sort of leaning towards the idea that maybe the right solution here is for the `TrueMatcherInstance` bear the cost of the complexity here (if it's the only one) with something like:

```
struct TrueMatcherImplCreator {
  static void *call() {
    return new IntrusiveRefCntPtr<TrueMatcherImpl>(new TrueMatcherImpl());  
  }
};
static llvm::ManagedStatic<IntrusiveRefCntPtr<TrueMatcherImpl>, TrueMatcherImplCreator> TrueMatcherInstance;
```

I worry about creating a fairly generic extension point for customizing how elements in ManagedStatic can be constructed and destroyed via specialization rather than via explicit creator/destroyer parameters.

And while the custom destroyer is a bit simpler mechanically (doesn't involve dynamically allocating an IntrusiveCntPtr, which is unintuitive to say the least) - I think sticking to the "if you ever share ownership of a RefCountedBase object, you must've allocated it with 'new' and be really sharing ownership - no lies" is probably a healthier model for RefCountedBase/IntrusiveRefCntPtr.


Repository:
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  https://reviews.llvm.org/D92480/new/

https://reviews.llvm.org/D92480