[PATCH] D119580: [LLVM][Support] Delete "copy" constructor of BumpPtrAllocatorImpl

[Zixu Wang via Phabricator via llvm-commits]

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Though the implicit copy constructor of BumpPtrAllocatorImpl is deleted
because of the presence of a user-defined move constructor, the
perfect-forwarding constructor will still match for lvalue reference of
BumpPtrAllocatorImpl, silently "copying" a BumpPtrAllocatorImpl
(actually just copy-constructing an underlying AllocatorT and
blank-constructing a BumpPtrAllocatorImpl).
This patch explicitly deletes the problematic specialization of the
forwarding constructor.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D119580

Files:
  llvm/include/llvm/Support/Allocator.h


Index: llvm/include/llvm/Support/Allocator.h
===================================================================
--- llvm/include/llvm/Support/Allocator.h
+++ llvm/include/llvm/Support/Allocator.h
@@ -79,6 +79,11 @@
   BumpPtrAllocatorImpl(T &&Allocator)
       : AllocatorT(std::forward<T &&>(Allocator)) {}
 
+  // BumpPtrAllocator shouldn't be copyable. Explicitly delete this
+  // specialization of the perfect-forwarding constructor above.
+  template <typename T>
+  BumpPtrAllocatorImpl(BumpPtrAllocatorImpl<T> &) = delete;
+
   // Manually implement a move constructor as we must clear the old allocator's
   // slabs as a matter of correctness.
   BumpPtrAllocatorImpl(BumpPtrAllocatorImpl &&Old)


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