std::unique_ptr and exception safety

Question

Do I need to wrap std::unique_ptr usage with try/catch in code which should be exception safe?
std::unique_ptr will hold a raw memory block created by ::malloc (with my custom deleter to call ::free ).

Answer 1

1. All of std::unique_ptr 's constructors * are noexcept
2. malloc won't throw any exception on failure... it will just return nullptr .
3. I believe your deleter's constructors won't throw anything either.

So you don't need to catch anything, since nothing will be thrown.

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*: See C++11 §20.7.1.2.1 unique_ptr constructors [unique.ptr.single.ctor]

Answer 2

As mentioned in the comments, this answer is relevant for C++14 only .

Despite the good answer from @keenyt, it's worth to say that std::make_unique<T> can throw, even though the constructors of std::unique_ptr are noexcept .
Actually, whether the above mentioned statement throws or not mostly depends on the constructors of the type T involved.

As an example from cppreference.com for std::make_unique :

May throw std::bad_alloc or any exception thrown by the constructor of T. If an exception is thrown, this function has no effect.

So, a refinement of the answer would be: no, you don't need a try/catch block, unless you are using std::make_unique and the constructors of your type T can throw.