cstyleCast

Message: C-style pointer casting

Category: Modernization

Severity: Style

Language: C++, not applicable for C code

Description

Many developers feel that it's best to replace C casts with C++ casts.

There are several advantages with C++ casts:

• they permit only certain conversions
• they express the intent
• they are easy to identify

This checker is about C casts that converts to/from a pointer or reference.

Note: More "noisy" warnings exists that warn about all C casts. For instance Clang has -Wold-style-cast and there is also such checking in Misra C++.

Dangerous conversions are covered by other warnings so this ID cstyleCast is primarily about writing warnings for casts that are currently safe.

Motivation

The motivation of this checker is to modernize c++ code.

How to fix

You can use C++ casts such as static_cast to fix these warnings.

The dynamic_cast should rarelly be used to fix these warnings because dangerousTypeCast is reported when that can be a good idea.

Before:

struct Base{};
struct Derived: public Base {};
void foo(Base* base) {
    Base *p = (Base*)derived; // <- cstyleCast, cast from derived object to base object is safe now
}

After:

struct Base{};
struct Derived: public Base {};
void foo(Base* base) {
    Derived *p = static_cast<Derived*>(base);
}

The static_cast ensures that there will not be loss of constness in the future.