[all-commits] [llvm/llvm-project] 17c584: ADT: Add SFINAE to the generic IntrusiveRefCntPtr ...

[Duncan P. N. Exon Smith via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 17c584551d573f1693990773e29fbe6b4b6fa4f4
      https://github.com/llvm/llvm-project/commit/17c584551d573f1693990773e29fbe6b4b6fa4f4
  Author: Duncan P. N. Exon Smith <dexonsmith at apple.com>
  Date:   2021-01-28 (Thu, 28 Jan 2021)

  Changed paths:
    M llvm/include/llvm/ADT/IntrusiveRefCntPtr.h
    M llvm/unittests/ADT/IntrusiveRefCntPtrTest.cpp

  Log Message:
  -----------
  ADT: Add SFINAE to the generic IntrusiveRefCntPtr constructors

Add an `enable_if` to the generic `IntrusiveRefCntPtr` constructors so
that std::is_convertible gives an honest answer when the underlying
pointers cannot be converted. Added `static_assert`s to the test suite
to verify.

Also combine generic constructors from `IntrusiveRefCntPtr<X>&&` and
`const IntrusiveRefCntPtr<X>&`. At first glance this appears to be an
infinite loop, but the real copy/move constructors are spelled out
separately above. Added a unit test to verify.

Differential Revision: https://reviews.llvm.org/D95498