Re: [Qemu-devel] [PATCH] HACKING: Clarify the paragraph about typedefs

[Cédric Le Goater]

On 1/11/19 11:38 AM, Paolo Bonzini wrote:
> On 11/01/19 09:42, Thomas Huth wrote:
>>  2.3. Typedefs
>> -Typedefs are used to eliminate the redundant 'struct' keyword.
>> +Typedefs can be used to eliminate the redundant 'struct' keyword. This is
>> +especially helpful for common types that are used all over the place. Since
>> +certain C compilers choke on duplicated typedefs, you should avoid them and
>> +declare a typedef only in one header file. For common types, you can use
>> +"include/qemu/typedefs.h" for example. Note that it is also perfectly fine 
>> to
>> +use forward struct definitions without typedefs for references in headers
>> +to avoid the problem with duplicated typedefs.
>>  
> 
> I agree 100% with the wording after "Since".  However, I think the first
> part should be made stronger, not weaker.
> 
> Typedefs are use to eliminate the redundant 'struct' keyword, since type
> names have a different style than other identifiers ("CamelCase" versus
> "snake_case").  Each struct should have a CamelCase name and a
> corresponding typedef.
> 
> Since certain C compilers choke on duplicated typedefs, you should avoid
> them and declare a typedef only in one header file.  For common types,
> you can use "include/qemu/typedefs.h" for example.  However, as a metter
> of convenience it is also perfectly fine to use forward struct
> definitions instead of typedefs in headers and function prototypes; this
> avoids problems with duplicated typedefs and reduces the need to include
> headers from other headers.

I suppose this is difficult to check with checkpatch ? It's easy to
cross the border as I have proven many times. 
 
> And, I would move it to CODING_STYLE since we are at it. :)

yes.

C.