* Simon Perreault wrote on Wed, Mar 30, 2005 at 06:13:19PM CEST:
> On March 30, 2005 10:44, Ralf Wildenhues wrote:
> > > #include "../include/inc.h"
> >
> > which is not portable, by the way (but I can see if you don't care about
> > that part of the world).
>
> Why do you say that? That code is being ported from Microsoft's compiler, and
> I guess that if it works there and here then it ought to be portable.
IIRC some older compilers on Windows did not understand `/'.
Plus, I would consider using `..' and `include' in the actual path to be
bad style (not directory entries in general -- it's good to have
../include/foolib/foo1.h and use #include "foolib/foo1.h").
> > If you put this rule in several directories, it might lead to race
> > conditions with parallel make. (Your example suggests you might be
> > doing this.)
>
> Do you mean that if many make jobs try to make the same directory at the same
> time it will fail? I don't think so, since creating a directory is atomic and
> mkdir -p shouldn't fail if the directory is already created. But if mkdir is
> broken and fails because the directory was created between the time it
> checked for its existence and the time it tried to create it, then mkdir is
> broken and should be fixed. Anyway, that's off topic.
Well, using $(mkdir_p) fixes the `mkdir -p' part. But your header
creation might
- not be atomic, e.g. echo line1 > $@; echo line2 > $@
- not be allowed to be executed in parallel
(I *really* don't know whether parallel make works on cygwin. But
redirection into a file held open by another process fails there.)
> > - change the rule above to create a symlink to the current directory
> > or a central directory, for that matter
> > (be sure to look at $(LN_S) semantics in the Autoconf docs!).
> > Have `make clean' remove the links.
>
> Sorry, I don't understand your solution. Does that mean I should modify all
> the files including the built headers so that they point to the central
> directory?
No, why? Automake puts `-I.' in AM_CPPFLAGS. After you ensure that
../include/built.h exists, you have in Makefile.am
BUILT_SOURCES = built.h
built.h: ../include/built.h
rm -f $@ && $(LN_S) ../include/built.h $@
or easier, you have in the Makefile.am one level higher up:
BUILT_SOURCES = include/built.h
include/built.h:
$(mkdir_p) include
touch $@
for srcdir in $(some_dirs); do \
cd $$srcdir && { rm -f built.h; $(LN_S) ../include/built.h .; }; \
done
I'd probably extend that rule so that its output has modification times
updated only when necessary (look at `move-if-change'). Plus update
CLEANFILES and/or clean-local.
> If so, then I can't do that since the code I'm working on has to
> keep working on another build system.
SCons? :)
> If not, then can you explain a bit more?
HTH,
Ralf
