== Why is this an issue?

Because ``++reinterpret_cast++`` ignores the type system, it is capable of performing dangerous conversions between unrelated types which can lead to undefined behavior.


This rule reports an issue for two problematic uses of ``++reinterpret_cast++``:

* when it is used to make the compiler believe that an object in memory is from a different type from its real type (for instance, casting a ``++long*++`` to ``++double*++``, because accessing a ``++long++`` as if it was a ``++double++`` is undefined behavior (even if ``++sizeof(long) == sizeof(double)++``),
* when it is used to cast between different levels of a complex inheritance hierarchy (a ``++static_cast++`` would apply pointer offsets to take into account multiple inheritance, for instance, but ``++reinterpret_cast++`` does not)


=== Noncompliant code example

[source,cpp]
----
class X {};
class Y : virtual X {};

void test() {
  long l;
  auto a = reinterpret_cast<double&>(l); // Noncompliant: undefined behavior

  Y* y;
  auto x = reinterpret_cast<X*>(y); // Noncompliant
}
----

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

reinterpret_cast from "XXX" to "YYY" has undefined behavior


endif::env-github,rspecator-view[]