Re: [ob] Remove initializations of memset'd structure

[Elena Zannoni <ezannoni at redhat dot com>]

Daniel Jacobowitz writes:
 > On Tue, Feb 17, 2004 at 02:33:27PM -0500, Elena Zannoni wrote:
 > > Eli Zaretskii writes:
 > >  > > From: Elena Zannoni <ezannoni@redhat.com>
 > >  > > Date: Tue, 17 Feb 2004 09:30:06 -0500
 > >  > >  > >  
 > >  > >  > > -    MSYMBOL_TYPE (m) = mst_unknown;
 > >  > >  > 
 > >  > >  > This part of the patch seems to assume that mst_unknown has the value
 > >  > >  > zero.  Should we have such assumptions in the code?
 > >  > > 
 > >  > > Yes, in symtab.h mst_unknown is 0.
 > >  > 
 > >  > I know that, I looked it up in symtab.h.  The question is, should the
 > >  > code rely on the fact that zeroing out the struct causes the
 > >  > MSYMBOL_TYPE member to become mst_unknown.  Suppose we change the
 > >  > enumeration some day, that would break the code.
 > >  > 
 > > 
 > > Oh, I see. I misunderstood you. 
 > > 
 > >  > So I think a comment is not enough, we should leave that line alone.
 > >  > In general, it is my opinion that code should not assume anything
 > >  > about the numerical values of enumerated types.
 > > 
 > > That's true. It would be safer to leave the line alone. I'll change
 > > it back. Also language_unknown is used similarly.
 > > 
 > > I've committed this.
 > 
 > Thanks.  The only downside is that this suggests the type of the
 > terminating symbol can ever be read without being in error, which is
 > incorrect; the minimal symbol table's end appears to be marked by
 > otherwise by SYMBOL_LINKAGE_NAME (msym) == NULL.  Other minimal symbols
 > may have type mst_unknown.
 > 

I am not sure I follow your sentence. If you are worried that the
value 0 can indicate a perfectly legal msymbol, this is no different
from the situation we end up with when just using the memset. You can
always add a new enum value of mst_bogus (pick your name) and use that
in the terminating msym. BTW, there is almost identical code in
minsyms.c:install_minimal_symbols.