[Bug debug/21828] [4.0/4.1 Regression] debug info omitted for uninitialized variables

["mark at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From mark at codesourcery dot com  2005-07-08 01:56 -------
Subject: Re:  [4.0/4.1 Regression] debug info omitted for
 uninitialized variables

wilson at specifix dot com wrote:

> I think you are just compounding the mistake created by Mark Mitchell's 
> patch for PR 18556.  I mentioned this in comment #8, which unfortunately 
> didn't get sent to the gcc-bugs mailing list.

I agree that, in the abstract, the debug information should match the 
source program.  However, the problem was that we generated debug 
information that referenced a non-existant symbol, which is clearly a 
major problem.  I'm not sure why the debug generator did that; perhaps 
that's the real bug, as you suggest.

My change essentially restored the behavior of check_global_declarations 
to its historical state; clearing DECL_RTL (as this code used to do) was 
essentially supposed to turn off generation of debugging information for 
the variable.  If information was still emitted, that was somewhat by 
accident, judging by the comment there.

Since this bug does not affect the C++ front end, it's clear that it's 
possible to write a front end in which things work as expected.

So, there would be seem to be two ways to potential ways to fix things: 
(1) change the debug generators, as you suggest; (2) change the C front end.

I'd be happy to help with either approach; this is certainly my fault, 
independently of where the fix lies.  However, as you've volunteered to 
look at the debug generators, I'm going to leave this bug aside until 
you report back.  If you don't have time to look soon, would you please 
let me know?

Thanks,



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21828