[llvm-bugs] [Bug 146324] [clang-tidy] `bugprone-unhandled-self-assignment` doesn't know about allocator arguments to copy/move constructors

[LLVM Bugs via llvm-bugs]

Issue	146324
Summary	[clang-tidy] `bugprone-unhandled-self-assignment` doesn't know about allocator arguments to copy/move constructors
Labels	clang-tidy
Assignees
Reporter	MikeWeller

    I may have copy/move constructors that take an additional allocator argument (similar to `vector( const vector& other, const Allocator& alloc );`). Additionally, the type may use the [leading-allocator convention](https://en.cppreference.com/w/cpp/memory/uses_allocator.html) with `std::allocator_arg_t`.

If I call one of these "extended" copy/move constructors in my copy/move-and-swap idiom, `bugprone-unhandled-self-assignment` doesn't recognize it and produces a false positive warning (copy-and-swap/move should not trigger the warning).

A rough test:

```
// REQUIRES: static-analyzer
// RUN: clang-tidy -checks='-*,bugprone-unhandled-self-assignment' %s -- | FileCheck %s

namespace std {
  namespace pmr {
    template <typename TYPE = void>
    class allocator {};
  }

  struct allocator_arg_t {} allocator_arg;
};

#define LEADING_STYLE 1

class MyValueType
{
  // pointer member to trigger bugprone-unhandled-self-assignment
  void *foo = nullptr;

  public:
    using allocator_type = std::pmr::allocator<>;

 MyValueType(const MyValueType& other)
    {
    }

#ifdef LEADING_STYLE
    MyValueType(std::allocator_arg_t, const allocator_type& alloc, const MyValueType& other)
    {
    }
#else
    MyValueType(const MyValueType& other, const allocator_type& alloc)
    {
 }
#endif

#ifdef LEADING_STYLE
    // CHECK-NOT: warning
 MyValueType& operator=(const MyValueType& other)
    {
        MyValueType tmp(std::allocator_arg, get_allocator(), other);
        swap(tmp);
 return *this;
    }
#else
    // CHECK-NOT: warning
    MyValueType& operator=(const MyValueType& other)
    {
        MyValueType tmp(other, get_allocator());
        swap(tmp);
        return *this;
 }
#endif

    void swap(MyValueType& other) noexcept {
    }

 allocator_type get_allocator() const {
        return allocator_type();
 }
};
```

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