Re: Debug source lookup question

> On Wednesday 19 November 2008 17:52:46 Mikhail Khodjaiants wrote:
>
> Hi Mikhail,
>
>> As far as I remember this functionality was added in attempt to
>> "synchronize" the external (CDT) source lookup with GDB. I haven't been
>> aware it has such an effect. What's the purpose of this command then?
>
> The answer is somewhat long. Most often, binaries compiled with gcc
> and typical build systems have two bits of information for every source
> file:
>
> - the name of the file (without directory)
> - the compilation directory
>
> The GDB search path is a list of directories, and may include special
> '$cdir' element. When GDB wants to find the fullname of a file, it
> checks for it each directory in the search path. If $cdir is found,
> it checks in the compilation directory from the debug info.
>
> The default search path includes $cdir already, so if you don't do
> any explicit 'dir' commands only compilation directory and current
> directory are searched.
>
> The problem is that paths passed via 'dir' or '-environment-directory'
> are added in front of the search path. So, it overrides the compilation
> directory. And if you have file name a.c in two different directories,
> and you add both those directories via -environment-directory, you're
> out of luck. Note that adding $cdir in the front will not work, in
> general, for example if the binary is run on a different system from where
> it was compiled.  I think this is the fundamental limitation of a system
> where N source directories are specified and searched in order. The best
> approach is
> - Not used 'dir' at all when application is built and debugged
> on the same system
> - Use GDB path substitution mechanisms otherwise, documented at
> http://sourceware.org/gdb/current/onlinedocs/gdb_9.html#SEC63
> This is only available in recent versions of GDB.
>
> I'm also not quite sure how this all meshes with the CDT model. Probably,
> search path should not include any directories by default. Then users
> would add it if all the standard mechanisms in GDB fail.
>
>> Regarding getSourcePaths: it was added to get the source lookup
>> information from GDB and populate the CDT source lookup. But the idea
>> has never materialized. I am not aware of any future plans for it.
>
> Should this maybe be dropped from source code? The only possible use case
> for this is detecting when user typed 'dir' in GDB console, which does not
> seem like a very important use case.
>
> Thanks,
> Volodya
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