rspec/rules/S2216/cfamily/rule.adoc

== Why is this an issue?

The values that can be represented by a signed bit field with a length of one bit may not meet developer expectations. For example, according to the C99 Standard, a single-bit signed bit-field has a single (one) sign bit and no (zero) value bits.


This rule does not apply to unnamed bit fields, as their values cannot be accessed.


=== Noncompliant code example

[source,cpp]
----
signed int f:1;  // Noncompliant; there's only room here for the sign
----


=== Compliant solution

[source,cpp]
----
unsigned int f:1;
----
or

[source,cpp]
----
signed int:1; // unnamed
----
or

[source,cpp]
----
signed int f:2;
----


== Resources

* MISRA C:2004, 6.5 - Bit fields of type signed int shall be at least 2 bits long
* MISRA C:2012, 6.2 - Single-bit named bit fields shall not be of a signed type
* MISRA {cpp}:2008, 9-6-4 - Named bit-fields with signed integer type shall have a length of more than one bit


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

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

=== Message

Review "X" declaration sign and size.


'''
== Comments And Links
(visible only on this page)

=== is duplicated by: S1010

=== on 9 Dec 2014, 20:58:20 Evgeny Mandrikov wrote:
\[~ann.campbell.2] could you please verify this description, which was built as a combination of MISRA C:2012 and MISRA {cpp}2008?

=== on 14 Dec 2014, 22:51:08 Evgeny Mandrikov wrote:
\[~ann.campbell.2] I was expecting that you'll also specify SQALE model and other parameters, but ok...

=== on 15 Dec 2014, 14:58:47 Ann Campbell wrote:
Sorry [~evgeny.mandrikov], I didn't notice the lack of SQALE &etc. I'll pay more attention next time.

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