llvm dev - Sep 2015 - Why does clang build native llvm-config? Is there any way to avoid it?

I'm cross compiling llvm/libclang.  About halfway through a libclang build
cmake always runs another configure step in the NATIVE directory.

This causes problems with configuration settings and pre-compiler
definitions.  For instance I can't get __STRICT_ANSI__ to stay unset
through CMAKE_CXX_FLAGS.  It works for first 49% of the build but after
that reconfigure at the 50% mark in the NATIVE dir __STRICT_ANSI__ gets set
again causing the build to error out on  isascii calls.

After patching that I ran into a bunch of other issues including missing
strsignal and am beginning to wonder why we need a native llvm-config and
why we can't just point to it like we do native tablegen
(-DLLVM_TABLEGEN=path/to/llvm-tablegen)

Any thoughts?  Any way to avoid this step?  Any ideas where to start poking
around to understand how to get my includes setup properly for this native
build portion while not screwing with the cross compile?

P.S. The llvmdev at cs.uiuc.edu email that used to work to post to the list
and the one posted here no longer works and is bouncing:
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev  Looks like an alias was
taken down in early August if that archive cutting off then is a sign.

Thanks!
Ed
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Ed,

The native llvm-config isn’t needed by the build, but it is included as part of
the ‘all’ target. The idea is that if you’re cross compiling you’ll want a
host-executable llvm-config to configure clients using the cross-built LLVM from
your host.

Since the CMake build doesn’t actually use llvm-config, we could probably make
an option to exclude it from the ‘all’ target, but we probably don’t want that
to be the default behavior because it is very useful.

-Chris
> On Sep 10, 2015, at 2:37 PM, ed at modk.it via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> I'm cross compiling llvm/libclang.  About halfway through a libclang
build cmake always runs another configure step in the NATIVE directory.
> 
> This causes problems with configuration settings and pre-compiler
definitions.  For instance I can't get __STRICT_ANSI__ to stay unset through
CMAKE_CXX_FLAGS.  It works for first 49% of the build but after that reconfigure
at the 50% mark in the NATIVE dir __STRICT_ANSI__ gets set again causing the
build to error out on  isascii calls.
> 
> After patching that I ran into a bunch of other issues including missing
strsignal and am beginning to wonder why we need a native llvm-config and why we
can't just point to it like we do native tablegen
(-DLLVM_TABLEGEN=path/to/llvm-tablegen)
> 
> Any thoughts?  Any way to avoid this step?  Any ideas where to start poking
around to understand how to get my includes setup properly for this native build
portion while not screwing with the cross compile?
> 
> P.S. The llvmdev at cs.uiuc.edu <mailto:llvmdev at cs.uiuc.edu> email
that used to work to post to the list and the one posted here no longer works
and is bouncing:  http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
<http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>  Looks like an alias
was taken down in early August if that archive cutting off then is a sign.
> 
> Thanks!
> Ed
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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