From: greve AT rs1 DOT thch DOT uni-bonn DOT de (Thomas Greve)
Subject: Complex -- compiler bug?
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Date: Wed, 1 Jul 92 15:55:48 NFT

After Stuart M Lichtenthal has asked me about the `Complex' class,
i've tried it myself now and i've made the following experiences:
- the program *compiles* fine, BUT at the linking stage, there remain
  `undefined symbols'.

- The errors I get upon linking are like:
  complex.o: Undefined symbol _hypot referenced from text.
  complex.o: Undefined symbol _atan2 referenced from text.

  I had a whole bunch of them. Even though i included libm (this is
  where these functions -- exp, log, sin, cos too -- reside) and
  -- yes -- i told gcc *correctly* ;-).

- Recompiling (and ar[chive?]ing) libm changes *nothing*.

- Then i tried to use one of these functions elsewhere:
  void dummy( void ) { double x = cos(3.14); }

  Afterwards -- surprize! -- the warning about `undefined _cos' had
  vanished... 

- calling the other undefined functions from that dummy function
  made the remaining linker errors disappear: the program linked fine,
  and it worked.

Summary: obviously, g++ has a bug, that lets the linker forget to link
functions called by unused methods (this is sort of an optimization ;-)
and complain about them missing afterwards... (this is a bug).

Please, could someone forward this to the appropriate GNU address? 
(This has nothing to do with DJ's work, i guess...)

				- Thomas

   greve AT rs1 DOT thch DOT uni-bonn DOT de
   unt145 AT dbnrhrz1