Re: Multiple definition of gnulib symbols

[Bruno Haible]

Simon Josefsson wrote:
> But yes, gc-libgcrypt and gc-gnulib are intended to be two mutually  
> exclusive modules, since they provide the same symbols

... except for gc_hash_hmac_setkey.

> I had no idea that defining multiple symbols in a single object  
> file could lead to trouble.  Sigh.

That alone is not a problem. But if you have two object files with
_different_ but _overlapping_ set of symbols, you are in trouble.
Say,  first.o  defines 'aaa', and  second.o  defines 'aaa' and 'bbb'.
Then, when you link these:

     cc   (an object or library needing aaa) \
          (a library containing first.o) \
          (an object or library needing bbb) \
          (a library containing second.o)

you will get an error, because the linker will
  - see that it needs aaa, thus include first.o in the link,
  - see that it needs bbb, thus include second.o in the link,
  - and therefore give an error.
The linker does *not* remove first.o from the link when it decides to include
second.o.

Bruno