Re: Re: Why does #include <cyg/io/eth/eth_drv> define a bunch of time-related symbols?

[Sergei Gavrikov <sergei dot gavrikov at gmail dot com>]

Hi Grant

On Tue, 25 Jun 2013, Grant Edwards wrote:

> On 2013-06-25, Grant Edwards <grant.b.edwards@gmail.com> wrote:
> 
> > I'm working on a new Ethernet driver.  eCos kernel/libs (including the
> > new drive) build fine. But, when I try to link an application I get a
> > bunch of errors because some time-related functions are defined twice.
> > They're defined in libtarget where they're supposed to be, but they're
> > also getting defined in the object file for my Ethernet driver [and I
> > can't figure out why].
 
I guess you catch some kind of "Library Issue"

  http://gcc.gnu.org/c99status.html

> It's cause by compiling the driver with the -std=gnu99 flag.  I a big
> fan of limiting the scope of variables and like to use this sort of
> construct:
> 
>   for (int i=0; i<whatever; ++i)
>     {
>       // "i" is only visible inside this block    
>     }
> 
> It appears that eCos header files don't work right when you compile
> with C99 semantics...

Not only libraries. Many people (me too) are surprised when they look at
this table http://en.wikipedia.org/wiki/C99#Implementations -- very few
compilers are ready for C99.

Of course, if you (your fingers :-) have a habit... Well, you know about
C and C++ mix in eCos. If you like for-scope declarations then you would
use standard C with a bit of C++ sugar instead C99, eCos way:

  % grep -Er '\<for\>\s+?\(\s+?\<int\>' $ECOS_REPOSITORY

Though then here and there human can miss the needed extern "C"
declarations and that is a penalty for the only one C99 habit.

Sergei

> -- 
> Grant Edwards               grant.b.edwards        Yow! I just forgot my whole
>                                   at               philosophy of life!!!
>                               gmail.com            
> 
> 
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