> Hi Bojan,
> I think it's possible to allow including PCH file
right into exe:
>
> exe hello : [ cast _ pchheader : pch.hpp ] main.cpp :
<define>ABC ;
The above does not work, but a similar line allows bjam to
build:
exe hello
: [ pch mypch : [ cast _ pcheader : pch.hpp ] pch.cpp ]
main.cpp
: <define>ABC ;
However, this still does not define ABC when compiling the
PCH (tried).
My current workaround for this issue is to have custom
my-lib and
my-exe rules which have an additional parameter - used
libraries. So
instead of
exe hello : mypch main.cpp ./other//other :
<define>ABC ;
I have
my-exe hello : precompiled.cpp main.cpp :
<define>ABC : ./other//other ;
The rule detects if precompiled.cpp is among the sources and
if it is
creates an inline pch target by applying all requirements
from above
and applying <use> to the dependencies:
exe hello: [ pch prec : [ cast _ pcheader : precompiled.hpp
] precompiled.cpp
: <define>ABC <use>/other//other
]
main.cpp /other//other
: <define>ABC
;
This adds most things to PCH. It does not, however,
propagate user
defined <cxxflags>.
> and in that case PCH will be created with right
properties. But this raises
> question about reusing of the same PCH by different
targets:
>
> pch mypch : [ cast _ pcheader : pch.hpp ] pch.cpp ;
> exe a : a.cpp mypch : <define>ABC ;
> exe b : b.cpp mypch : <define>ABC ;
>
> In which case we'd need either to propagate defines,
or manually add define to
> PCH. And what should happen in this case:
>
> pch mypch : [ cast _ pcheader : pch.hpp ] pch.cpp ;
> exe a : a.cpp mypch ;
> exe b : b.cpp mypch : <define>ABC ;
>
> Should it be an error?
>
> - Volodya
I believe it should, as it defeats the purpose of
precompiled
headers. The above pch must be recreated each time either a
or b is
compiled. After a is compiled it must be regenerated for b,
with
different compile settings. On the next build it must again
be
recreated for a.
--
Bojan Resnik
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