package/brltty: use host pkg-config when building host tools

brltty builds host tools which rely on the expat library, and
pkg-config is used to detect the expat library.

Since commit cd16e18584066d2817d3acb3822e173f9f23455e ("pkgconf:
always keep system libs"), the wrapper script added
--keep-system-libs, which adds a -L$(STAGING_DIR)/usr/lib to the
pkg-config results instead of just -lexpat. So, previously, by chance,
the pkg-config result for the target expat was "good enough" for the
host expat as well. But now that -L$(STAGING_DIR)/usr/lib is added, it
breaks the build in all sort of ways as obviously building host
binaries with the library search path pointing to $(STAGING_DIR) is
not a good idea.

To fix that, this commit adjusts the brltty build system so that the
PKG_CONFIG_FOR_BUILD variable is used when using pkg-config to build
host binaries.

Fixes:

  http://autobuild.buildroot.net/results/5a64dfb845389882c366b6c91aaf5868c090a802/

Many thanks to the initial work from Fabrice Fontaine at
http://patchwork.ozlabs.org/patch/1238163/ which provided an initial
starting point for this investigation.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 ...ss-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch | 38 +++++++++++++++++++
 package/brltty/brltty.mk                      |  3 ++
 2 files changed, 41 insertions(+)
 create mode 100644 package/brltty/0003-mk4build-also-pass-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch

On Thu, 20 Feb 2020 00:37:47 +0100
Thomas Petazzoni <thomas.petazzoni@bootlin.com> wrote:

> brltty builds host tools which rely on the expat library, and
> pkg-config is used to detect the expat library.
> 
> Since commit cd16e18584066d2817d3acb3822e173f9f23455e ("pkgconf:
> always keep system libs"), the wrapper script added
> --keep-system-libs, which adds a -L$(STAGING_DIR)/usr/lib to the
> pkg-config results instead of just -lexpat. So, previously, by chance,
> the pkg-config result for the target expat was "good enough" for the
> host expat as well. But now that -L$(STAGING_DIR)/usr/lib is added, it
> breaks the build in all sort of ways as obviously building host
> binaries with the library search path pointing to $(STAGING_DIR) is
> not a good idea.
> 
> To fix that, this commit adjusts the brltty build system so that the
> PKG_CONFIG_FOR_BUILD variable is used when using pkg-config to build
> host binaries.
> 
> Fixes:
> 
>   http://autobuild.buildroot.net/results/5a64dfb845389882c366b6c91aaf5868c090a802/
> 
> Many thanks to the initial work from Fabrice Fontaine at
> http://patchwork.ozlabs.org/patch/1238163/ which provided an initial
> starting point for this investigation.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> ---
>  ...ss-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch | 38 +++++++++++++++++++
>  package/brltty/brltty.mk                      |  3 ++
>  2 files changed, 41 insertions(+)
>  create mode 100644 package/brltty/0003-mk4build-also-pass-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch

Applied to master, thanks.

Thomas

>>>>> "Thomas" == Thomas Petazzoni <thomas.petazzoni@bootlin.com> writes:

 > brltty builds host tools which rely on the expat library, and
 > pkg-config is used to detect the expat library.

 > Since commit cd16e18584066d2817d3acb3822e173f9f23455e ("pkgconf:
 > always keep system libs"), the wrapper script added
 > --keep-system-libs, which adds a -L$(STAGING_DIR)/usr/lib to the
 > pkg-config results instead of just -lexpat. So, previously, by chance,
 > the pkg-config result for the target expat was "good enough" for the
 > host expat as well. But now that -L$(STAGING_DIR)/usr/lib is added, it
 > breaks the build in all sort of ways as obviously building host
 > binaries with the library search path pointing to $(STAGING_DIR) is
 > not a good idea.

 > To fix that, this commit adjusts the brltty build system so that the
 > PKG_CONFIG_FOR_BUILD variable is used when using pkg-config to build
 > host binaries.

 > Fixes:

 >   http://autobuild.buildroot.net/results/5a64dfb845389882c366b6c91aaf5868c090a802/

 > Many thanks to the initial work from Fabrice Fontaine at
 > http://patchwork.ozlabs.org/patch/1238163/ which provided an initial
 > starting point for this investigation.

 > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

Committed to 2019.11.x (patch does not apply to the version in
2019.02.x), thanks.

 > ---
 >  ...ss-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch | 38 +++++++++++++++++++
 >  package/brltty/brltty.mk                      |  3 ++
 >  2 files changed, 41 insertions(+)
 >  create mode 100644 package/brltty/0003-mk4build-also-pass-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch

 > diff --git a/package/brltty/0003-mk4build-also-pass-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch b/package/brltty/0003-mk4build-also-pass-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch
 > new file mode 100644
 > index 0000000000..5839f78f3f
 > --- /dev/null
 > +++ b/package/brltty/0003-mk4build-also-pass-PKG_CONFIG_FOR_BUILD-to-the-nativ.patch
 > @@ -0,0 +1,38 @@
 > +From 568e0d6070021a9b805ba1fe1543e4b43a073413 Mon Sep 17 00:00:00 2001
 > +From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
 > +Date: Thu, 20 Feb 2020 00:23:35 +0100
 > +Subject: [PATCH] mk4build: also pass PKG_CONFIG_FOR_BUILD to the native
 > + configure
 > +
 > +In commit 0414ad2b4e8978a14343d920a5a1f11da892eaf3, mk4build was
 > +modified to pass a number of *_FOR_BUILD variables down to the
 > +configure script called for building the native tools.
 > +
 > +However, this configure script also uses the pkg-config tool, and the
 > +pkg-config to use for the native build and the cross build may be
 > +different, so let's also pass PKG_CONFIG_FOR_BUILD down to the
 > +sub-configure, as PKG_CONFIG, following the same logic as the other
 > +variables.
 > +
 > +Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
 > +Upstream: https://github.com/brltty/brltty/pull/248
 > +[Upstream patch is different, due to other upstream changes.]
 > +---
 > + mk4build | 1 +
 > + 1 file changed, 1 insertion(+)
 > +
 > +diff --git a/mk4build b/mk4build
 > +index 3c64963b7..ad88ee69c 100755
 > +--- a/mk4build
 > ++++ b/mk4build
 > +@@ -73,6 +73,7 @@ then
 > +    CXXFLAGS=${CXXFLAGS_FOR_BUILD} \
 > +    LDFLAGS=${LDFLAGS_FOR_BUILD} \
 > +    LDLIBS=${LDLIBS_FOR_BUILD} \
 > ++   PKG_CONFIG=${PKG_CONFIG_FOR_BUILD} \
 > +    "${sourceRoot}/configure" \
 > +       --disable-api \
 > +       --disable-gpm \
 > +-- 
 > +2.24.1
 > +
 > diff --git a/package/brltty/brltty.mk b/package/brltty/brltty.mk
 > index 11b8c0d35f..acc172fab0 100644
 > --- a/package/brltty/brltty.mk
 > +++ b/package/brltty/brltty.mk
 > @@ -15,6 +15,9 @@ BRLTTY_LICENSE_FILES = LICENSE-LGPL README
 >  BRLTTY_DEPENDENCIES = $(TARGET_NLS_DEPENDENCIES) host-autoconf host-pkgconf \
 >  	$(if $(BR2_PACKAGE_AT_SPI2_CORE),at-spi2-core)
 
 > +BRLTTY_CONF_ENV = \
 > +	PKG_CONFIG_FOR_BUILD=$(HOST_DIR)/bin/pkgconf
 > +
 >  BRLTTY_CONF_OPTS = \
 >  	--disable-java-bindings \
 >  	--disable-lisp-bindings \
 > -- 
 > 2.24.1

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