AUTOSAR C++14 Rule A7-1-6

The typedef specifier shall not be used

Description

Rule Definition

The typedef specifier shall not be used.

Rationale

The using syntax is a better alternative to typedef-s for defining aliases.

Since C++11, the using syntax allows you to define template aliases where the template arguments are not bound to a data type. For instance, the following statements define an alias vectorType for vector, where the argument T is not bound to a data type and can be substituted later:

template<class T, class Allocator = allocator<T>> class vector;
template<class T> using vectorType = vector<T, My_allocator<T>>;
vectorType<int> primes = {2,3,5,7,11,13,17,19,23,29};

The typedef keyword does not allow defining such template aliases.

Polyspace Implementation

The rule checker flags all uses of the typedef keyword.

If you do not want to remove certain instances of the typedef keyword, add a comment justifying those results. See:

• Address Results in Polyspace User Interface Through Bug Fixes or Justifications if you review results in the Polyspace user interface.

• Address Results in Polyspace Access Through Bug Fixes or Justifications (Polyspace Access) if you review results in a web browser.

• Annotate Code and Hide Known or Acceptable Results if you review results in an IDE.

Troubleshooting

If you expect a rule violation but Polyspace^® does not report it, see Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Examples

Use of typedef Keyword

#include <cstdint>
#include <type_traits>

typedef std::int32_t (*fptr1) (std::int32_t); //Noncompliant
using fptr2 = std::int32_t (*) (std::int32_t); //Compliant

template <class T> using fptr3 = std::int32_t (*) (T); //Compliant

The alias definitions for fptr1 and fptr2 are exactly equivalent. There is no typedef equivalent for the alias definition for fptr3.

The use of typedef-s violates this rule. The rule requires that you stick to the using syntax for consistency even when a typedef equivalent exists.

Check Information

Group: Declaration

Category: Required, Automated

Version History

Introduced in R2019a