From mboxrd@z Thu Jan  1 00:00:00 1970
From: gsl-discuss@lists.thewrittenword.com
To: gsl-discuss@sources.redhat.com
Subject: Re: Problem building vector/reim_source.c
Date: Wed, 19 Dec 2001 13:20:00 -0000
Message-id: <20010818210249.E80313@oolong.il.thewrittenword.com>
References: <20010818202423.D80313@oolong.il.thewrittenword.com>
X-SW-Source: 2001/msg00404.html

On Sat, Aug 18, 2001 at 08:24:23PM -0500, gsl-discuss@lists.thewrittenword.com wrote:
> I don't think this is legal C89 code (from vector/reim_source.c):
> 
> QUALIFIED_REAL_VIEW(gsl_vector, view)
> FUNCTION(gsl_vector, real) (QUALIFIED_TYPE(gsl_vector) * v)
> {
>   REAL_TYPE(gsl_vector) s = NULL_VECTOR;
> 
>   s.data = v->data;
>   s.size = v->size;
>   s.stride = MULTIPLICITY * v->stride;
>   s.block = 0;  /* FIXME: should be v->block, but cannot point to
>                    block of different type */
>   s.owner = 0;
> 
>   {
>     QUALIFIED_REAL_VIEW(gsl_vector,view) view = NULL_VECTOR_VIEW;
>     ((REAL_VIEW(gsl_vector,view) *)(&view))->vector = s;
>     return view;
>   }
> }
> 
> The Solaris C compiler gives:
> 
> cc -DHAVE_CONFIG_H -I. -I. -I.. -I.. -I.. -mr -Qn -xstrconst -xO2
> -xtarget=generic -c reim.c  -KPIC -DPIC -o reim.o
> "./reim_source.c", line 35: left operand must be modifiable lvalue: op "="
> "./reim_source.c", line 53: left operand must be modifiable lvalue: op "="
> "./reim_source.c", line 35: left operand must be modifiable lvalue: op "="
> "./reim_source.c", line 53: left operand must be modifiable lvalue: op "="
> "./reim_source.c", line 35: left operand must be modifiable lvalue: op "="
> "./reim_source.c", line 53: left operand must be modifiable lvalue: op "="
> cc: acomp failed for reim.c
> 
> I don't believe you can cast an lvalue.

Ok, upon further investigation, the following code in vector/reim.c:

#define USE_QUALIFIER
#define QUALIFIER const

#define BASE_GSL_COMPLEX_LONG
#include "templates_on.h"
#include "reim_source.c"
#include "templates_off.h"
#undef  BASE_GSL_COMPLEX_LONG

causes the chunk above in vector/reim_source.c to cpp to:

gsl_vector_long_double_const_view 
gsl_vector_complex_long_double_const_real  (
	const gsl_vector_complex_long_double  * v)
{
  gsl_vector_long_double  s =  { 0 , 0 , 0 , 0 };

  s.data = v->data;
  s.size = v->size;
  s.stride =  2 * v->stride;
  s.block = 0;   
  s.owner = 0;

  {
     gsl_vector_long_double_const_view  view =  { { 0 , 0 , 0 , 0 } };
    (( gsl_vector_long_double_view  *)(&view))->vector = s;
    return view;
  }
}

So, the Solaris C compiler isn't allowing you to throw away the
const'ness of view (seems correct to me). I tried compiling with the
native compilers on Tru64 UNIX, IRIX, HP, and AIX and they all accept
the construct above.

-- 
albert chin (china@thewrittenword.com)