GDB (mis)behavior depends on DWARF DW_TAG_compile_unit data

[Maxim Grigoriev <maxim at tensilica dot com>]

Hello members,

I would like to hear your opinion on whether what I see is a compiler problem or a GDB misbehavior.

GDB session goes wrong, if my test case is compiled using a base name as a source file. Everything is fine, when an absolute path name is used instead. I checked several compilers ( all GCCs ). They seem to be consistent in generating DWARF DW_TAG_compile_unit information in this case.

Anyway, even if GDB treats this situation as a bad DWARF data it doesn't look decent to output misleading error messages, like 'No line 6 in file "test.c".', when there actually is the line number 6, and the test case was compiled with "-g".

				* * * * *

Here come the details:

1) The GDB version is: GNU gdb 6.6.50.20070312-cvs

2) The test program is:

001: extern int printf(const char *fmt,...);
002: 
003: int main()
004: {
005:   printf("Hello, World !\n");
006:   printf("Let's make DWARF consistent across all the tools !\n");
007: }

3) It was compiled with two different command line options:

gcc -g test.c -o basename_used.exe
gcc -g /home/maxim/W/BadgerPass/FSF_QUESTION/test.c -o full_path_used.exe

4) Freshly build GDB was run with the command file CMD_FILE:

break main
break test.c:6
quit

-- Good case:
> > > gdb full_path_used.exe --command=CMD_FILE
[ . . . . . ]
Breakpoint 1 at 0x40000970: file /home/maxim/W/BadgerPass/FSF_QUESTION/test.c, line 4.
Breakpoint 2 at 0x4000097c: file /home/maxim/W/BadgerPass/FSF_QUESTION/test.c, line 6.

-- Bad case:
> > > gdb basename_used.exe --command=CMD_FILE
[ . . . . . ]
Breakpoint 1 at 0x40000970: file /home/maxim/W/BadgerPass/FSF_QUESTION/test.c, line 4.
CMD_FILE:2: Error in sourced command file:
No line 6 in file "test.c".

5) The difference in DWARF info is :

-- Good case, full_path_used.exe:
[ . . . . ]
<0><c3>: Abbrev Number: 1 (DW_TAG_compile_unit)
    DW_AT_name        : /home/maxim/W/BadgerPass/FSF_QUESTION/test.c	
    DW_AT_comp_dir    : /home/maxim/W/BadgerPass/FSF_QUESTION

-- Bad case, basename_used.exe:
[ . . . . ]
<0><c3>: Abbrev Number: 1 (DW_TAG_compile_unit)
    DW_AT_name        : test.c	
    DW_AT_comp_dir    : /home/maxim/W/BadgerPass/FSF_QUESTION

Thanks in advance for any input on this,
-- Maxim