Re: Address MISRA C:2012 Rule 8.4

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

>> 3. Variables that are either extern or not, such as 'acpi_gbl_FADT' in
>> 'xen/include/acpi/acglobal.h', depending on
>>     DEFINE_ACPI_GLOBALS
>> 
>> Below are the proposed resolution strategies:

> 
>> 3. One possible resolution pattern is including 'acglobal.h' twice
>> (either directly or indirectly trough acpi.h, if
>>     the latter does not cause other issues) like so:
>> 
>>     (assuming DEFINE_ACPI_GLOBALS is undefined here)
>>     #include "acglobal.h"
>>     #define DEFINE_ACPI_GLOBALS
>>     #include  "acglobal.h"
>> 
>>    this way, the rule is followed properly, though it's not the 
>> prettiest
>> pattern and also clashes with the objectives
>>    of D4.10 ("Precautions shall be taken in order to prevent the 
>> contents
>> of a header file being included
>>    more than once"), but then a motivated exception is allowed there.
> 
> Not really sure about this one.
> 
> Jan

If you can tell me more about why that header is defined the way it is 
(i.e. why it's used twice with
DEFINE_ACPI_GLOBALS #defined and the other times without), maybe we can 
come up
with better alternatives.

-- 
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)