Re: [libstdc++] libstdc++/7691, pass -Wabi, sanity checks

[Benjamin Kosnik <bkoz at redhat dot com>]

> 1)  As noted in PR 7691, --enable-cxx-flags can no longer take multiple
> options in a quoted string, like it used to, and like the documentation
> says.  Quoting the argument is now defeated by the higher-level configury
> at some point; the strings are just passed through too many layers of
> shell expansion to survive as a single word.

Hmm. The other option is just having people use CXXFLAGS directly, and
removing this enable flag.

ie

make CXXFLAGS="-fnot-an-idiot -fbigger-magic-wand" all

> The simple solution is to not use whitespace-seperated flags in the argument.
> Losing the quoting doesn't matter then.  I propose to require the flags to
> be colon-seperated, e.g, --enable-cxx-flags="-foo:-bar-:baz".  I considered
> comma-seperated instead, but that would wreak havoc when trying to pass
> -Wl or -Wa or -Wp options.

Hmm. I dunno about this. Is there something similar in libjava, or in
the gcc build/configure stuff? 

It seems like maybe more effort should be put into figuring why the
toplevel configure munges a whitespace-separated list of flags now, when
it didn't before.

> 2)  We now pass -Wabi all the time.

This is a great idea.

> 3)  Building libstdc++ has a standalone package (i.e., without the compiler)
> hasn't worked in a long time, and it's not supposed to work.  This checks
> to make sure that user isn't massively confused on that point.  I don't
> know whether we'll continue to release libstdc++ snapshots in the future,
> but if we do this might help and can't hurt in any case.

Great idea. I think removing all references to building libstdc++ as a
standalone package should be removed from the docs, if they are not already.

-benjamin