bugprone-unique-ptr-array-mismatch

Finds initializations of C++ unique pointers to non-array type that are initialized with an array.

If a pointer std::unique_ptr<T> is initialized with a new-expression new T[] the memory is not deallocated correctly. A plain delete is used in this case to deallocate the target memory. Instead a delete[] call is needed. A std::unique_ptr<T[]> uses the correct delete operator. The check does not emit warning if an unique_ptr with user-specified deleter type is used.

The check offers replacement of unique_ptr<T> to unique_ptr<T[]> if it is used at a single variable declaration (one variable in one statement).

Example:

std::unique_ptr<Foo> x(new Foo[10]); // -> std::unique_ptr<Foo[]> x(new Foo[10]);
//                     ^ warning: unique pointer to non-array is initialized with array
std::unique_ptr<Foo> x1(new Foo), x2(new Foo[10]); // no replacement
//                                   ^ warning: unique pointer to non-array is initialized with array

D d;
std::unique_ptr<Foo, D> x3(new Foo[10], d); // no warning (custom deleter used)

struct S {
  std::unique_ptr<Foo> x(new Foo[10]); // no replacement in this case
  //                     ^ warning: unique pointer to non-array is initialized with array
};

This check partially covers the CERT C++ Coding Standard rule MEM51-CPP. Properly deallocate dynamically allocated resources However, only the std::unique_ptr case is detected by this check.