gdb_assert when resetting breakpoints

[Roland Schwingel <roland dot schwingel at onevision dot de>]

Hi...

When using current gdb cvs head sources I encounter a gdb_assert() in 
breakpoint.c line 7451.
This is in function breakpoint_re_set_one().
Let me tell you what I am doing to get it (reproduceably). I am not a 
guru to gdb's internals so
please forgive me if I conclude something wrong.

I am having a mixed C and Objective C application. I am running on 
windows using GNUstep
for my ObjC Foundation classes. GNUstep-base is a shared library loaded 
lazy.
Due to the nature of this bug I assume that this will also appear on 
other platforms like linux
(according to my analysis). So it is not windows specific.

I start gdb and set a breakpoint to main() using "b main". Then I run my 
app using "r".
A few seconds later I get the assert in breakpoint.c:7451 
gdb_assert(sals.nelts==1).
When I debug into it sals.nelts == 2. The assert happens when the 
gnustep-base shared
library was loaded.

What has happenend: In breakpoint.c line 7417 you find:
sals = decode_line_1 (&s, 1, (struct symtab *) NULL, 0, (char ***) 
NULL,not_found_ptr);
s points to "main" at that moment as found in the breakpoint structure 
supplied to breakpoint_re_set_one().

sals (returned from decode_line_1) contains 2 entries.
Sals entry 0 points to the ObjectiveC METHOD main of the foundation base 
class NSThread
(written in ObjC notation -[NSThread main]). This is a real ObjC 
baseclass not something
from my own code. It has also nothing to do with an application's 
entrypoint. It also perfectly
legal in ObjectiveC to name methods like C functions. They do not collide.
Sals entry 1 points to the function "main()" of my application. This is 
the entry which I think is
the correct one to use here.

Obviously decode_line_1 returns every symbol matching a certain string 
independant of
its language. As far as I understand gdb at the moment this appears to 
be ok.

So what is the correct behaviour here to fix this problem? I assume that 
there might be more
areas of symbol duplicates that can occur not only main() vs -[NSThread 
main].

Maybe the assert should be replaced by a loop over the sals entries 
matching the infos from the
breakpoint structure passed to breakpoint_re_set_one() and the 
individual symtab entry of one
sals entry by filename(?) matching?

Thanks in advance for your help,

Roland