Re: [libcc1] Improve detection of triplet on compiler names

[Pedro Alves <palves at redhat dot com>]

On 08/23/2017 02:07 PM, Sergio Durigan Junior wrote:
> On Wednesday, August 23 2017, Pedro Alves wrote:
> 
>> On 08/23/2017 05:17 AM, Sergio Durigan Junior wrote:
>>> The GCC patch improves the libcc1::compiler_triplet_regexp::find and
>>> libcp1::compiler_triplet_regexp::find methods by first trying to match
>>> the triplet in the compiler name and correctly discarding the triplet
>>> part of the regexp if the matching succeeds.  I've had to do a few
>>> modifications on the way the regexp's are built, but I'll explain them
>>> in the patch itself.
>>>
>>> The GDB patch is very simple: it adds the trailing "-" in the triplet
>>> regexp.  Therefore, we will have a regexp that truly matches the full
>>> triplet (e.g., "^(x86_64|i.86)(-[^-]*)?-linux(-gnu)?-") instead of one
>>> that leaves the trailing "-" match to libcc1.
>>>
>>> I've tested this patch both on my Fedora and my Debian machines, and
>>> both now work as expected, independently of the presence of the triplet
>>> string in the compiler name.  I am sorry about the cross-post, but these
>>> patches are really dependent on one another.
>>
>> Is there a backward/forward compatibility impact?
> 
> Unfortunately, yes.
> 
>> Does new GDB work with old GCC?
> 
> No.  On Fedora systems, you would get:
> 
>   Could not find a compiler matching "^(x86_64|i.86)(-[^-]*)?-linux(-gnu)?--gcc$"
> 

That's a problem then.  Please read this:

 https://sourceware.org/gdb/wiki/GCCCompileAndExecute#How_to_extend_the_gdb.2BAC8-gcc_interface

> As can be seen, these failures are now happening because of the trailing
> dash that is now included in the triplet regexp by GDB.  I don't know if
> that warrants a change in the API, though.

Thanks,
Pedro Alves