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

[Paul Koning <pkoning at equallogic dot com>]

Excerpt of message (sent 12 June 2002) by Zack Weinberg:
> Attached to this message is a huge list of macros used throughout gcc
> but not, as far as I can tell, defined anywhere.  The script that
> generated this list is limited to checking #if/#ifdef/#ifndef for
> uses, so it is not an exhaustive list; nor is it aware of macros
> defined by the Makefile, system headers, or compiler.  I have made an
> effort to remove false positives, but there may still be a few.  In
> some cases I left entries even though I knew or suspected that the
> macro was defined by one of these, if I thought the usage was bogus.

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?

A bunch of those things, like HOST_BITS_BIG_ENDIAN and ASM_OUTPUT_xxx
look like target hooks -- things that are currently not used but still
available in case some other target needs them?  Or leftover obsolete
hooks that no longer have value?

> I386
> config/darwin.c machopic_indirect_data_reference 524 #ifdef I386

Isn't that a target specific define that the compiler defines if it's
an i386 compiler?
 
> MIPSEL
> config/mips/mips.h <global> 1394 #if !defined(MIPSEL) && !defined(__MIPSEL__)

I think some compilers define MIPSEL and some define __MIPSEL__, at
least this reminds me of a problem I ran into at some point in the
past 6 months.

> OS2

Compiler builtin define for OS/2 target compiler?

> VAXC
> config/vax/xm-vms.h <global> 30 #if defined(VAXC) || defined(__DECC)
> config/vax/xm-vms.h <global> 113 #if defined(VAXC) || defined(__DECC)

I believe VAXC is defined by the DEC VAX C compiler.

  paul