From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jim Blandy <jimb@zwingli.cygnus.com>
To: Eli Zaretskii <eliz@is.elta.co.il>
Cc: Jim Blandy <jimb@cygnus.com>, gdb-patches@sources.redhat.com, msnyder@cygnus.com
Subject: Re: RFA: don't try to compare IEEE NaN's
Date: Wed, 06 Jun 2001 10:37:00 -0000
Message-id: <npn17l4ife.fsf@zwingli.cygnus.com>
References: <Pine.SUN.3.91.1010606184023.18730A-100000@is>
X-SW-Source: 2001-06/msg00081.html

Eli Zaretskii <eliz@is.elta.co.il> writes:
> My assumption was that whoever wrote the test wanted to see that GDB 
> doesn't lose bits due to all kinds of conversions that are going under 
> the hood.  If that is true, you want to make sure the value you work with 
> has the same bit pattern you wanted it to have.  If not, you don't really 
> know what you are testing here; for example, imagine an (absurdly 
> unrealistic) case that the compiler turns your literal constant into an 
> all-zero bit pattern, or into a NaN.  Then you are back to square
> one.

What you're saying is that, between this:

        union {
          float f;
          char bytes[80];
        } u;

        for (i = 0; i < 80; i++)
          u.bytes[i] = something interesting;

and this:

        u.f = 2.7182818284590452354;

that you're more concerned that the latter will put a NaN in u.f than
the former.  When, in fact, the exact problem I'm trying to fix is
that someone's first shot at the former strategy produced a NaN.

This seems silly.