Re: [rfa] teach lookup_symbol about namespace scope

[Paul Hilfinger <hilfingr at gnat dot com>]

David,

> > 2. We generally expect multiple symbol matches, rather than just taking
> >    the first match, and therefore our main lookup routine returns a list
> >    of symbols.

> We could probably use this feature in the non-Ada case, too, to get
> C++ right...

Perhaps a lookup procedure with a function parameter that serves as a 
callback.  The procedure would call its callback argument with each matching 
symbol (and the usual void* kludge ... uh, I mean ... argument for extra 
state information); the callback could return 0 or 1 to indicate whether to
stop.  The current lookup_symbol could simply use this routine.


> > 3. Linkage (mangled) names have the form 
> >         <prefix>__<simple name><optional suffic>
> >    and we need to be able to match this name given either
> >    either <prefix>__<simple name> or <simple name>.  
> 
> I'm curious: how frequent is this optional suffix?  Because this looks
> so simple that it seems like the time costs for demangling would be
> very small: all you have to do is skip "prefix__" and then check for
> the optional suffix (which I assume is easy to recognize?), and it
> seems to me that other costs in building symbol information would
> swamp that.  And we could design a scheme where, if the suffix was
> absent, the mangled and demangled names would share memory, since the
> demangled name is a final substring of the mangled name. 

Sorry; I was unclear.  The MANGLED names have the form shown, but
<prefix>__<simple name> is NOT the demangled name.  Binary operators
get renamed and "." goes to "__".  Hmm. We did the latter mangling
because of fear that some linkers or assemblers would not take kindly
to "."s in names.  Perhaps revisitation is in order; I honestly don't
know what the situation is these days vis-a-vis non-alphanumeric characters
in symbol names.

> Do Ada symbols have both the demangled and linkage name set?  Because
> if you're never setting the demangled name, I would think that you
> wouldn't have to use a special macro in the Ada case.  (By the way, we
> used to have a different macro called SYMBOL_SEARCH_NAME, but that's a
> separate issue.)

I'm not sure which of your macros then would yield the right value for 
all languages.  The idea was for SYMBOL_SEARCH_NAME to return the form 
of name for a symbol that a specific language does searches on.  We still
need SYMBOL_NATURAL_NAME and SYMBOL_PRINT_NAME to print out demangled
forms of the name (which for Ada would involve a procedure call).  

Paul