[Bug breakpoints/15185] New: Dprintf should parse its string for validity right away

[Bug breakpoints/15185] New: Dprintf should parse its string for validity right away

[marc.khouzam at ericsson dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15185

             Bug #: 15185
           Summary: Dprintf should parse its string for validity right
                    away
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: breakpoints
        AssignedTo: unassigned@sourceware.org
        ReportedBy: marc.khouzam@ericsson.com
    Classification: Unclassified


No evaluation of the dprintf string is done by GDB.  This can be quite poor for
the user since it is only at run-time that an error will be given.

I think that a checking the expression early would much more user-friendly.


> gdb.7.6 ~/loopfirst
GNU gdb (GDB) 7.5.50.20130223-cvs
(gdb) dprintf 8,"hello$d",i
Dprintf 1 at 0x804855f: file loopfirst.cc, line 8.
(gdb) r
Starting program: /home/lmckhou/loopfirst 
warning: Cannot call inferior functions, you have broken Linux kernel i386 NX
(non-executable pages) support!
hellofriend
Wrong number of arguments for specified format-string
(gdb) bt
#0  main () at loopfirst.cc:8

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[Bug breakpoints/15185] Dprintf should parse its string for validity right away

[teawater at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15185

teawater <teawater at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |teawater at gmail dot com

--- Comment #1 from teawater <teawater at gmail dot com> ---
Could you post the src of loopfirst?

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[Bug breakpoints/15185] Dprintf should parse its string for validity right away

[marc.khouzam at ericsson dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15185

--- Comment #2 from Marc Khouzam <marc.khouzam at ericsson dot com> ---
GNU gdb (GDB) 7.6.50.20130627-cvs
Reading symbols from /home/lmckhou/loopfirst...done.
(gdb) l
warning: Source file is more recent than executable.
1       #include <unistd.h>
2       #include <stdio.h>
3
4       int main() {
5           int max = 900;
6           for (int i=0;i<max;i++) {
7               printf("i is %d\n",i);
8               sleep(1);
9           }
10          return 0;
11      }

(gdb) dprintf 7,"hello$d",i    <------------ Notice teh $d instead of %d

Dprintf 1 at 0x40055c: file loopfirst.cc, line 7.
(gdb) info b
Num     Type           Disp Enb Address            What
1       dprintf        keep y   0x000000000040055c in main() at loopfirst.cc:7
        printf "hello$d",i
(gdb) r
Starting program: /home/lmckhou/loopfirst 
Wrong number of arguments for specified format-string

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[Bug breakpoints/15185] Dprintf should parse its string for validity right away

[marc.khouzam at ericsson dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=15185

--- Comment #3 from Marc Khouzam <marc.khouzam at ericsson dot com> ---
Although it may seem like GDB cannot parse the string in advance because it
only knows the validity of a string at runtime, gdb seems to be able to do some
checking when we set conditions.  I was hoping we could do something similar?  

(gdb) b 9 if ii<0
No symbol "ii" in current context.

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