C compilation questions

[Drew Parsons <dparsons@emerall.com>]

I've agreed to adopt meschach, and have been trying to recompile it.
It hasn't been recompiled for a year-and-a-half, and specified that it
requires egcc rather than gcc.  However, I suspect that since that time egcc
has been merged into gcc proper (they took over development, didn't they?),
and I think I have some ansi C questions to resolve.  I've currently got gcc
2.95.2-20.  The previous compilation must have been done while gcc 2.7.2
reigned, or something, and egcc is no longer available as a separate package.

Now there are two issues I'd like to ask about, one of which halts
compilation. 

The first problem comes from a typedef using a struct.  meschach wants to
define complex numbers using (from zmatrix.h):
typedef struct  { 
         Real re, im; 
 } complex;                 

(Real is defined elsewhere as double).

This generates the compiler warning:
zmatrix.h:41: warning: useless keyword or type name in empty declaration
zmatrix.h:41: warning: unnamed struct/union that defines no instances

At the point where the struct is actually being used (the or .re .im field is
referred to), I find the error:

zmachine.c:62: request for member `re' in something not a structure or union
zmachine.c:62: request for member `im' in something not a structure or union

and compilation ceases.

If I instead use 

typedef struct  { 
         Real re, im; 
 } complexNum;                 
 
then it appears to compile OK, but this is a poor solution since I'd have to
then change all references from type complex to type complexNum.

So the problem seems to be some conflict over the name "complex", but I
don't understand what the conflict is exactly.  gcc supports the keyword
"__complex__" via complex.h, but that's different to just defining
"complex", isn't it?   Any ideas?


================
The second problem seems to be one of policy.  I get a warning:
In file included from /usr/include/math.h:33,
from lufactor.c:37:
/usr/include/bits/huge_val.h:37: warning: HUGE_VAL' redefined
 machine.h:216: warning: this is the location of the previous definition

This happens because the source file in question has: 
#include        "matrix.h" 
#include        <math.h> 

Meschach header file matrix.h defines HUGE_VAL if it isn't already defined,
while the standard header math.h also defines it.  This can of course be
resolved by simply changing the order:
#include        <math.h> 
#include        "matrix.h" 

So my question here is how much of a problem is this?  Should it be (or is
it) official policy somewhere that standard headers should always be given
before local headers?


Thanks for any words of wisdom,

Drew

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