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Subject: Re: [boost] preprocess operation problems
From: Peter Dimov (lists_at_[hidden])
Date: 2015-01-28 13:07:58

Fletcher, John P wrote:
> These do not look like links to me:
> fletcher_at_fletcher-desktop:~/boost_maintenance/modular-boost/boost$ ls -l
> int*.hpp
> -rw-rw-r-- 1 fletcher fletcher 4617 Jan 19 2014 integer_fwd.hpp
> -rw-rw-r-- 1 fletcher fletcher 11314 Jan 19 2014 integer.hpp
> -rw-rw-r-- 1 fletcher fletcher 8317 Jan 20 2014 integer_traits.hpp

Nope, they look like straight copies.

> > The workaround is usually to delete boost/ and recreate it with b2
> > headers, but this shouldn't be necessary, at least in theory.
> I could try this, but what does it do with the files in /boost which are
> not links? Is there a file somewhere which tells it which things to copy?
> I have run ./b2 headers on my present setup and that runs clean.

This is a Boost.Build issue and I don't understand it very well.

I have a rough idea what happens though. Boost.Build checks if it can use
symlinks, which is this part of its output:

    Performing configuration checks

        - symlinks supported : no (cached)
        - junctions supported : yes (cached)
        - hardlinks supported : yes (cached)

I'm on Windows (without symlink rights), so it detects that it can't
symlink. For you, the output would probably be

    Performing configuration checks

        - symlinks supported : yes (cached)
        - hardlinks supported : yes (cached)

Now, it goes to check whether to copy/hardlink/symlink boost/integer_fwd.hpp
to libs/integer/include/boost/integer_fwd.hpp.

It sees that it can symlink, so it assumes that the existing
boost/integer_fwd.hpp is already a symlink and doesn't need to be updated.

Your existing boost/integer_fwd.hpp is a file for some reason though. I
don't know why. It's possible that when you originally ran b2 headers, it
did not yet support symlinks, but that's just a guess, as I really don't

This can be considered a bug in the part of Boost.Build that is responsible
for the header links, but if it is, I don't know how or whether it should be

Either way, if you delete your existing boost/ header directory and rerun b2
headers, the files there should now be symbolic links. I think.

> My mental model has been that if I run these commands I am up to date on
> develop.
> git checkout develop
> git pull --recurse-submodules
> git submodule update --init | added to check for new libraries.
> git submodule foreach git checkout develop
> git submodule foreach git pull | to bring everything up to date.

Yes, in theory. But there have been many occasions when the header
copies/links do not update automatically, so it's still a problem from time
to time.

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