Re: [Boost-build] Problem with PCH

From: Bojan Resnik (resnikb_at_[hidden])
Date: 2006-09-24 03:41:32

My apologies to Vladimir, I accidentally sent this mail to his private address:

> >   A recent introduction of SORT in sequence.unique rule is causing PCH
> > generation to fail sometimes by attempting to compile the header file
> > instead of the source file. This happens in one of my projects, but I
> > have been unable to create a reproducible test case.
>
> I'm a bit unsure about sequence.unique changing the order of list elements, as
> there are cases where order matters.

 Me too, but this problem with pch could happen even if the order was
preserved in sequence.unique. The user could simply use
    lib a : [ pch apch : a.cpp [ cast _ pcheader : a.h ] ] ;
and make the source file first.

> And what if not?
> + if [ $(sources[2]).type ] = PCHEADER
> + {
> + cpp = $(sources[1]) ;
> + h = $(sources[2]) ;
> + }
>
> won't assign anything to 'cpp' and 'h' is the order is wrong, right? So PCH
> won't work?

 It would, because the two lines before the if are:
+        local cpp = $(sources[2]) ;
+        local h   = $(sources[1]) ;

--
Bojan Resnik