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Re: RFDiscussion: Macros used throughout gcc but not defined anywhere

From: Tim Hollebeek <tim at hollebeek dot com>
To: Paul Koning <pkoning at equallogic dot com>
Cc: zack at codesourcery dot com, gcc at gcc dot gnu dot org
Date: Thu, 13 Jun 2002 10:44:21 -0400
Subject: Re: RFDiscussion: Macros used throughout gcc but not defined anywhere
References: <20020613001207.GA10917@codesourcery.com> <15624.45052.470000.536840@gargle.gargle.HOWL>
Reply-to: tim at hollebeek dot com

> I would assume that a #if (as opposed to #ifdef or #ifndef) is
> referring to a symbol that's defined *somewhere* -- otherwise you'd
> get a compile error, right?

Nope.  Undefined symbols have value 0 in #if.  See the standard.

One of the really odd things about C, IMHO.

-Tim

References:
- RFDiscussion: Macros used throughout gcc but not defined anywhere
  - From: Zack Weinberg
- Re: RFDiscussion: Macros used throughout gcc but not defined anywhere
  - From: Paul Koning

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