On 3/4/2012 6:31 PM, Chad J wrote:
class Bar
{
int foo;
}
void main()
{
Bar bar;
try {
bar.foo = 5;
} catch ( Exception e ) {
writefln("%s",e);
}
}
DMD 2.057 on Gentoo Linux, compiled with "-g -debug". It prints this:
Segmentation fault
Very frustrating!
This is what I get (I added in an import std.stdio;):
dmd foo -gc
gdb foo
GNU gdb (GDB) 7.2-ubuntu
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/walter/cbx/mars/foo...done.
(gdb) run
Starting program: /home/walter/cbx/mars/foo
[Thread debugging using libthread_db enabled]
Program received signal SIGSEGV, Segmentation fault.
0x0000000000401e45 in D main () at foo.d:13
13 bar.foo = 5;
(gdb) bt
#0 0x0000000000401e45 in D main () at foo.d:13
#1 0x000000000040aa9b in rt.dmain2.main() ()
#2 0x0000000000636010 in ?? ()
#3 0x00007ffff7fdeae0 in ?? ()
#4 0x00007fffffffeb30 in ?? ()
#5 0x00007fffffffea00 in ?? ()
#6 0x000000000040a41b in rt.dmain2.main() ()
#7 0x0000000000000001 in ?? ()
#8 0x0000000000000019 in ?? ()
#9 0x0000000000636020 in ?? ()
#10 0x00007fffffffeb30 in ?? ()
#11 0x00007ffff7ffe4c0 in ?? ()
#12 0x00007fffffffe8b0 in ?? ()
#13 0x00007fffffffeb30 in ?? ()
#14 0x00007fffffffea30 in ?? ()
#15 0x000000000040aaee in rt.dmain2.main() ()
#16 0x000000000040aa84 in rt.dmain2.main() ()
#17 0x00007fffffffeb30 in ?? ()
#18 0x00007fffffffea80 in ?? ()
#19 0x000000000040a41b in rt.dmain2.main() ()
#20 0x0000000000000001 in ?? ()
#21 0x0000000000000019 in ?? ()
#22 0x0000000000636020 in ?? ()
#23 0x0000000000000001 in ?? ()
#24 0x0000000000636020 in ?? ()
#25 0x00007fffffffee01 in ?? ()
#26 0x00007fffffffeb30 in ?? ()
#27 0x00007fffffffeb30 in ?? ()
#28 0x000000000040a3b3 in main ()
(gdb)
By running it under gdb (the debugger), it tells me what file and line it failed
on, and gives a lovely stack trace.
There really are only 3 gdb commands you need (and the only ones I remember):
run (run your program)
bt (print a backtrace)
quit (exit gdb)
Voila!
Also, a null pointer exception is only one of a whole menagerie of possible
hardware-detected errors. There's a limit on the compiler instrumenting code to
detect these. At some point, it really is worth learning how to use the debugger.
