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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Help: Ada in NetBSD
Date: Sun, 29 Aug 2021 19:25:05 +0100
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Fernando Oleo Blanco <irvise_ml@irvise.xyz> writes:

>> On NetBSD there are several symbols that are replaced by the virtue
>> of including a C header.
>> If you include correctly the C header, the correct symbol is used
>> and you don't get the linker warning.
>
> That is what I did by adding the indicated header files to the NetBSD
> section of the init.c file. No other systems have them there (or 
> anywhere in some cases). I expected that to fix the issue, but it did not.

The problem can't be fixed by including C headers, because ...

>> For gettimeofday the symbol is replaced by __gettimeofday50.
>> These symbols are marked with __RENAME(XXX) macros in the C headers.

The C header is (I got this from the net, so beware)

int	gettimeofday(struct timeval * __restrict, void *__restrict)
    __RENAME(__gettimeofday50);

so when you say, in Ada,

   function gettimeofday
     (tv : not null access struct_timeval;
      tz : struct_timezone_ptr) return Integer;
   pragma Import (C, gettimeofday, "gettimeofday");

the linker looks for a symbol gettimeofday (or maybe _gettimeofday) and
gives you the warning that you report. Since it's just a warning, it may
actually work - for the moment, anyway.

The Ada needs to change to

   function gettimeofday
     (tv : not null access struct_timeval;
      tz : struct_timezone_ptr) return Integer;
   pragma Import (C, gettimeofday, "gettimeofday50");

(or maybe "_gettimeofday50", or even "__gettimeofday50" - nm will be
your friend).