Re: [RFC] Interim review: typedefs.h / structs.h splitting

On 03.10.2012 01:45, Kinkie wrote:
> On Sun, Sep 30, 2012 at 12:06 PM, Amos Jeffries
> <squid3_at_treenet.co.nz> wrote:
>> On 28/09/2012 4:10 a.m., Alex Rousskov wrote:
>>>
>>> On 09/27/2012 12:48 AM, Amos Jeffries wrote:
>>>>
>>>> On 26/09/2012 4:44 a.m., Kinkie wrote:
>>>>>
>>>>> Hi all,
>>>>> this new patch addresses the concerns that were raised.
>>>>> It stops short of removing typedefs.h (but structs.h is now
>>>>> gone).
>>>>>
>>>>> It doesn't break the build on the farm; it is in my opinion
>>>>> reasonably
>>>>> complete and it is for me a merge-candidate.
>>>>>
>>>>
>>>> I see a lot of externs being removed in .h files. All fine and
>>>> well for
>>>> statically linked .o files. But when these files are shuffled into
>>>> librares the ABI linking operates a little different and is known
>>>> to
>>>> strip away symbol references for "internal" objects (ie those with
>>>> no
>>>> explicit extern marking). Please be wary of that.
>>>
>>> Are you sure that such stripping happens in C++ context (rather
>>> than
>>> some old C context)? AFAIK, C++ function declarations have external
>>> C++
>>> linking scope by default, so they all should have "extern" marking
>>> from
>>> the linker point of view.
>>
>>
>> Moderately sure. I ran into it in trunk recently when moving
>> functions to
>> one of the libraries. I forget which.
>>
>> That might have been a fluke case, but think worth at least
>> checking up on
>> explicitly for the general case before doing this big merge.
>
>
> From
>
> http://stackoverflow.com/questions/1358400/what-is-external-linkage-and-internal-linkage-in-c
> :
>
> -----------------------
> You can explicitly control the linkage of a symbol by using the
> extern
> and static keywords and the default linkage is extern for non-const
> symbols and static (internal) for const symbols.
>
> // in namespace or global scope
> int i; // extern by default
> const int ci; // static by default
> extern const int eci; // explicitly extern
> static int si; // explicitly static
>
> // the same goes for functions (but there are no const functions)
> int foo(); // extern by default
> static int bar(); // explicitly static
> ------------------------
>
> We can of course explicitly mark functions as "extern", but this
> source agrees with Alex that it's not needed.
>
> If there's no objections, I plan to merge to trunk tomorrow.

Sure. Thank you for checking. +1.

Amos
Received on Tue Oct 02 2012 - 22:50:09 MDT