Pending breakpoints on lines that don't exist

Pedro Alves alves.ped@gmail.com
Thu Jan 5 12:56:00 GMT 2012


On 01/04/2012 08:49 PM, Tom Tromey wrote:
>>>>>> "Marc" == Marc Khouzam<marc.khouzam@ericsson.com>  writes:
>
> Marc>  (gdb) b 2
> Marc>  No line 2 in the current file.
> Marc>  Make breakpoint pending on future shared library load? (y or [n]) y
> Marc>  Breakpoint 1 (2) pending.
>
> This is intended, but I wonder whether it would make sense to have
> different behavior in the case where the file is implicit.
>
> That is, "b 2" would just give the old error, but "b currentfile.c:2"
> would prompt for a pending breakpoint.
>
> The rationale for this would be that, in the implicit filename case, the
> user is presumably asking for exactly the current file.

It sounds tempting, but it goes back to guessing user's intentions?

I'm left wondering if the real problem isn't that

 >  No line 2 in the current file.
 >  Make breakpoint pending on future shared library load? (y or [n]) y
 >  Breakpoint 1 (2) pending.

Isn't super clear that "2" doesn't actually mean "line 2 in any file",
but currentfile.c:2.  Or does it not?

Note (debugging gdb):

(top-gdb) b 56
No line 56 in the current file.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 4 (56) pending.
(top-gdb) info breakpoints
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x00000000006a419a in internal_error at ../../src/gdb/utils.c:1046
2       breakpoint     keep y   0x00000000004ccc49 in info_command at ../../src/gdb/cli/cli-cmds.c:229
         silent
         return
4       breakpoint     keep y   <PENDING>          56
(top-gdb)

When read this, I go "where will breakpoint 4 resolve again?".  It feels like gdb should show
the (normalized) spec back to the user.  "What" isn't exactly that.

I find myself confused like that with e.g., `*' breakpoints.  As in,
was that a * breakpoint I set there, or not?:

(top-gdb) b *main
Breakpoint 5 at 0x455314: file ../../src/gdb/gdb.c, line 26.
(top-gdb) info breakpoints 5
Num     Type           Disp Enb Address            What
5       breakpoint     keep y   0x0000000000455314 in main at ../../src/gdb/gdb.c:26
(top-gdb) b main
Breakpoint 6 at 0x455323: file ../../src/gdb/gdb.c, line 29.
(top-gdb) info breakpoints 5-6
Num     Type           Disp Enb Address            What
5       breakpoint     keep y   0x0000000000455314 in main at ../../src/gdb/gdb.c:26
6       breakpoint     keep y   0x0000000000455323 in main at ../../src/gdb/gdb.c:29

-- 
Pedro Alves



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