On 14.09.21 21:22, Trent Piepho wrote:

On Tue, Sep 14, 2021 at 6:21 AM Ahmad Fatoum [off-list ref] wrote:

quoted

I've also run into downstream patches around broken toolchains that
change <libusb.h> to <libusb-1.0/libusb.h>, so the header is found.

How does this become a problem exactly?  If the toolchain has the file
in the location <includedir>/ibusb-1.0/libusb.h, then shouldn't
pkg-config --cflags have returned -I<includedir>/libusb-1.0 and it
would then find the file just fine?

Or is the problem really that the cross building setup does not have
correct .pc files?

I ran twice into downstream patches patching imx-usb-loader. So apparently

-lusb1.0 was returned but the CFLAGS were correctl set.

If it's the latter, then I'll point out that my previous email would
let someone put CROSS_LIBUSB_CFLAGS=-I<cross-include-dir>/libusb-1.0
on the make command line and get a build without having .pc files.
This is pretty much what you get with autoconf configure scripts when
you put headers in a non-standard place and don't have .pc files setup
to find them.  You need to supply CFLAGS, LDFLAGS, etc. variables with
the proper -L and -I options to find them.

I wrote this patch initially to support a pkg-config less build:
If CROSS_PKG_CONFIG wasn't set (no default), we would just use -lusb-1.0
and hope it works. For the header __has_include would try the two paths
that most probably would work.

Now that I dropped that fallback, I should probably drop this patch
as well and let people with broken pkg-config files just fix their
brokenness.

quoted

+++ b/scripts/libusb.h

By naming this libusb.h, it requires that "libusb.h" find this file
and <libusb.h> find a different header of the same name.  That's
certainly possible by being careful with the "" and <> search paths.
But it seems unnecessarily fragile.  I suggest using libusb-wrapper.h
for this file so you avoid name collisions with the real header file.

That's a good point. I'll drop this patch though for v2.

Thanks for your feedback,
Ahmad


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