rspec/rules/S1012/cfamily/rule.adoc

== Why is this an issue?

The use of ``++virtual++`` base classes can introduce a number of undefined and potentially confusing behaviours. Therefore, a base class shall only be declared ``++virtual++`` if that base class is to be used as a common base class in a diamond hierarchy.


=== Noncompliant code example

[source,cpp]
----
class A {};
class B1: public virtual A {}; // Compliant, A is a common base for C
class B2: public virtual A {}; // Compliant, A is a common base for C
class C: public B1, B2 {};
class D: public virtual A {}; // Noncompliant, D is not part of a diamond-shaped hierarchy.
----


== Resources

* MISRA {cpp}:2008, 10-1-2 - A base class shall only be declared virtual if it is used in a diamond hierarchy.


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