# Extra Clang Tools 18.1.8 documentation

## clang-tidy - bugprone-shared-ptr-array-mismatch

# bugprone-shared-ptr-array-mismatch

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

If a shared pointer `std::shared_ptr<T>` is initialized with a new-expression `new T[]` the memory is not deallocated correctly. The pointer uses plain `delete` in this case to deallocate the target memory. Instead a `delete[]` call is needed. A `std::shared_ptr<T[]>` calls the correct delete operator.

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

Example:

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

    std::shared_ptr<Foo> x3(new Foo[10], [](const Foo *ptr) { delete[] ptr; }); // no warning

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

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