[Buildroot] [PATCH 1/2] package/Makefile.in should grab HOST_DIR headers using -isystem instead of -I.

[Yann E. MORIN <yann.morin.1998@free.fr>]

David, All,

[Please, wrap lines at ~72 chars; it's easier to read.]

On 2016-07-29 15:35 -0400, David Raeman spake thusly:
[--SNIP--]
> If the maintainers choose to back the patch out,

This is what I think is the best solution. Currently, all builds that
want to build a setuptools-based python package will fail; which means
that:

  - users will be very disapointed, and that's not good;

  - we are potentially missing on catching other build failures in our
    autobuilders, which is not good either, especially since we are soon
    to enter the stabilisation -rc phase in early August.

So, I think we should revert this patch (see below).

> I can find another way
> to resolve my original issue by submitting a patch to u-boot to ensure

U-Boot or Qemu? I thought you needed that for your custom Qemu...

So, because in Buildroot, we do not have a mean to use that custom Qemu,
we do not (yet?) have the issue, so we should not try to fix it. For now.

Also, it seems that a proper fix will be really complex, if at all
possible, given that systems (e.g. rolling or bleeding-edge distros)
with a gcc-6 are broken with this change (and not specifically because
of host-python).

And thus we should revert that patch. Will you send a patch to do the
revert, please?

> it prefers its modified copy of libfdt.h instead of the
> possibly-installed system copy.

I have had a similar issue quite recently, when working on the
linux-gpib package, especially the kernel parts.

Their buildsystem is not very clean, and they have headers with the same
names of other headers from the kernel, because they need to #define
legacy macros for backward compatibility, and then trampoline to the
original headers by way of #include_next.

Here is the patch I did (basically: rename the shadowing headers):

    https://gitlab.com/ymorin/buildroot/blob/yem/linux-gpib/package/linux-gpib/0005-drivers-gpib-rename-kernel-override-includes.patch

So, I think the best solution would be for U-Boot^WQemu to rename
their header.

Regards,
Yann E. MORIN.

> I still believe the use of -isystem here is correct in a strict technical
> sense, because "$(HOST_DIR)/usr/include" is truly a system include
> directory at a non-standard location.  But I understand that some packages incorrectly
> assume that -I is the only way to add include paths and don't anticipate
> the use of -isystem.  Case in point, the Python package I just submitted
> a patch for.
> 
> Cheers,
> David
> 
> 

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