For many embedded C++ applications, compliance with the AUTOSAR or Misra rules is required. Among them is AUTOSAR Rule A18-5-5 which does not allow memory allocations with new. Since new and delete violate A18-5-5, the default STL containers must not be used in applications requiring AUTOSAR compliance. This holds for many embedded applications. With the allocators available since C++17 in the namespace std::pmr (polymorphic memory resources) these requirements can often be satisfied.

Target Audience: Architects, Developers, Project Leader
Prerequisites: Good C++ knowledge
Level: Advanced

Extended Abstract
For many embedded C++ applications, compliance with the AUTOSAR or Misra rules is required. Among them is AUTOSAR Rule A18-5-5.
Memory management functions shall ensure the following:
(a) deterministic behavior resulting with the existence of worst-case execution time,
(b) avoiding memory fragmentation,
(c) avoid running out of memory,
(d) avoiding mismatched allocations or deallocations,
(e) no dependence on non-deterministic calls to kernel.

This rule has far-reaching consequences, because per default the C++ standard library containers allocate their memory with new and free it with delete. These calls
• do not have deterministic execution times.
• can cause memory fragmentation.

Since new and delete violate A18-5-5, the default STL containers must not be used in applications requiring AUTOSAR compliance. This holds for many embedded applications.
With the allocators available since C++17 in the namespace std::pmr (polymorphic memory resources) these requirements can often be satisfied. This means that, for the first time in the history of C++, the containers and algorithms of the C++ standard library can be used in applications that require AUTOSAR Rule A18-5-5.