From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Example Ada calling Gnu Scientific Library (GSL)
Date: Sat, 08 Apr 2017 09:28:17 +0100
Organization: A noiseless patient Spider
Message-ID: <ly60if8fry.fsf@pushface.org>
References: <2b035819-e55e-4805-9ff1-a2cec09f13e0@googlegroups.com>
	<ek15faF6958U1@mid.individual.net>
	<obh45r$p0s$1@franka.jacob-sparre.dk>
	<ekihasFjum4U1@mid.individual.net> <lyefx695sm.fsf@pushface.org>
	<ekl1v6F4hvtU1@mid.individual.net> <lya87u803p.fsf@pushface.org>
	<ekq521F4gc3U1@mid.individual.net>
Mime-Version: 1.0
Content-Type: text/plain
Injection-Info: mx02.eternal-september.org;
 posting-host="2b83c84756a8be78cf5c0ef8aef783fb";
	logging-data="17213"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX1/GaaTzlpvkgAYmodRWfvVr9pjC0L18CLs="
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (darwin)
Cancel-Lock: sha1:tcN3fw9teLYg8qAJpprfKkdvvZ4=
	sha1:S8KceBgT4N8IJP1RcIDmFkLXK7s=
Xref: news.eternal-september.org comp.lang.ada:46541
Date: 2017-04-08T09:28:17+01:00
List-Id: <comp.lang.ada>

hreba <f_hreba@yahoo.com.br> writes:

> The missing function is declared in src/gsl_gsl_integration_h.ads as
>
>    function gsl_integration_qng
>      (f : access constant gsl_gsl_math_h.gsl_function;
>       a : double;
>       b : double;
>       epsabs : double;
>       epsrel : double;
>       result : access double;
>       abserr : access double;
>       neval : access stddef_h.size_t) return int;
>    pragma Import (C, gsl_integration_qng, "gsl_integration_qng");

What the pragma Import says is that gsl_integration_qng is imported from
some place else, presumably the C library you've asked gcc to generate a
skinny binding to.

Here, gsl 2.3, the symbol is in libgsl.

  nm -Aa libgl.a | grep gsl_integration_qng

says

  libgsl.a:qng.o: 00000000000000c0 T _gsl_integration_qng

I don't think the leading underscore is your problem, GNAT knows when
the platform (macOS here) needs the leading underscore.

I hate to ask this, but have you actually linked with -lgsl?