commit 9118ac819a67b9da728a7b057bf0b3671102ebee
author Daniele Di Proietto <ddiproietto@google.com> Wed Aug 02 14:47:29 2023 +0000
committer Daniele Di Proietto <ddiproietto@google.com> Wed Aug 02 14:55:28 2023 +0000
tree 40c51c18b7023399e4d2070d10c654c607674bc8
parent e78b30d80b733d50944df18358efaae7cba6ea3f

ipc: Remove wrong DeferredBase constructor.

DeferredBase had a constructor that accepted a Deferred<T> and moved its
callback to the new DeferredBase.

The problem with moving an std::function is that what's left in the
original is unspecified (but valid): a copy of the original callback
could be stuck there and it could be called when the formal parameter (a
copy) would be destroyed.

With this commit, we use the non inline DeferredBase(DeferredBase&&)
move constructor (it works, since Deferred<T> is a DeferredBase).
There's actually already a comment in deferred.cc that explains that:

```
// Can't just use "= default" here because the default move operator for
// std::function doesn't necessarily swap and hence can leave a copy of the
// bind state around, which is undesirable.
```

Since the problem is based on unspecified behavior, we only managed to
trigger it in CI in conjuction with https://r.android.com/2686526

This also seems to reduce the binary size of the libperfetto_c.so by a
couple of kilobytes.

Change-Id: I787cd4a5f1722f7c83492bd3581b2c9e8e7f56f0