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V822. Decreased performance. A new obje…
Analyzer diagnostics
General Analysis (C++)
General Analysis (C#)
General Analysis (Java)
Diagnosis of micro-optimizations (C++)
Diagnosis of 64-bit errors (Viva64, C++)
Customer specific requests (C++)
MISRA errors
AUTOSAR errors
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Contents

V822. Decreased performance. A new object is created, while a reference to an object is expected.

07 Nov 2019

The analyzer has detected an issue where a new object is created instead of a reference to an already existing object. The creation of an unnecessary object takes up some amount of time and memory.

Consider the following example, where a variable is cast to a reference in the right part of the expression while it is not declared as a reference in the left part:

auto test = static_cast<NotPOD &>(npod);

The right part of this expression contains a cast to a reference of type NotPOD, but no such cast is found in the left part. This results in copying the object instead of passing it by reference.

There are two ways to fix this code. The first is to replace auto with decltype(auto):

decltype(auto) test = static_cast<NotPOD &>(npod);

The '&' qualifier will now be deduced according to the right part, but this solution is too lengthy, so it would be better to just add the qualifier manually:

auto &test = static_cast<NotPOD &>(npod);

If you really wanted the object to be copied, you should remove the qualifier from the right part to make the code easier to read:

auto test = static_cast<NotPOD>(npod);
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