Re: [BBv2] fix for response file regeneration

From: Reece Dunn (msclrhd_at_[hidden])
Date: 2005-10-22 15:06:17

David Abrahams wrote:
> Reece Dunn <msclrhd_at_[hidden]> writes:
>>David Abrahams <dave <at> boost-consulting.com> writes:
>>>Reece Dunn <msclrhd <at> hotmail.com> writes:
>>>>David Abrahams wrote:
>>>>>That just leads me to ask what's missing from the bjam core that we
>>>>>can't implement the same behavior without resorting to extending bjam
>>>>>specifically for response files?
>>
>>>>2. The main problem with the current response file code is that RSP 
>>>>files are being treated as a target, so if you specify to always 
>>>>generate the RSP file, it will recompile and relink the project that 
>>>>uses them.
>>>
>>>Isn't that what TEMPORARY is supposed to do? The idea is that you can
>>>delete TEMPORARY object files after creating a library without causing
>>>the library to be rebuilt.
>>
>>The problem is that if the target fails, the response file is kept around *but*
>>the action to regenerate the response file isn't called, so the old response
>>file is used.
> 
> Have you looked at the RMOLD rule?

I have tried:
TEMPORARY $(rsp) ;
RMOLD $(rsp) ;
and haven't noticed any change :(.

>>I am not too bothered about the rule+action interface, more the things that BBv2
>>adds like the features, toolsets, etc.
> 
> That stuff *is* BB, so any version on a new foundation would preserve
> it.

:)

>>So if I understand it:
>>* BJam will be BJam+Python allowing you to run Python code from
>>Jamfile/Sconsfile build scripts
>>* Scons will be responsible for the rule+action+target logic that Jam was
>>previously responsible for
>>* BBpy will add features, toolsets and all the fancy stuff I expect from BB :)
> 
> If we get to the point of replacing the build engine with Scons, yes.

:)

> Why would we want to keep the response files for failed targets? Oh,
> right, it's that whole mess with wanting to recreate the command
> manually :(

Would it be possible to do something like:
if (failed)
{
ECHO "== RESPONSE FILE ==" ;
ECHO $(rsp-contents) ;
ECHO "== END OF RESPONSE FILE ==" ;
RM $(rsp) ;
}
so we don't need to keep response files around, thus removing the 
problem, but still allowing users to recreate the command manually.

Or, use a --show-response-files option that will do an
ECHO $(rsp-contents) ;
when the response file is created, removing the need for any spercial 
failure detection. NOTE: This (or something similar) is what Matt's code 
does.

- Reece