[Libguestfs] [PATCH nbdkit 2/2] golang: Compile against the local nbdkit build, not installed.

[Eric Blake]

On 4/23/20 1:04 PM, Richard W.M. Jones wrote:
> When compiling when an older nbdkit is installed, the build would fail
> because certain symbols such as .get_ready were not defined:
> 
>    ../../src/libguestfs.org/nbdkit/nbdkit.go:541:8: plugin.get_ready undefined (type _Ctype_struct_nbdkit_plugin has no field or method get_ready)
> 
> This happens because we were using the installed <nbdkit-plugin.h>
> rather than the local copy.
> 
> We don't want to modify the *.go files themselves as they might be
> copied into other projects.  Instead we can set PKG_CONFIG_PATH to
> point to the local nbdkit.pc which will return the correct CFLAGS.
> 
> Fixes: commit 1ff44288ae1cf95428283e252edd9474c3fe3b55
> Thanks: Dan Berrangé, Eric Blake
> ---
>   plugins/golang/Makefile.am | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/plugins/golang/Makefile.am b/plugins/golang/Makefile.am
> index f189184c..d8d19b7a 100644
> --- a/plugins/golang/Makefile.am
> +++ b/plugins/golang/Makefile.am
> @@ -66,18 +66,21 @@ noinst_DATA = \
>   examples/dump-plugin/nbdkit-godump-plugin.so: \
>   	    $(plugin_sources) examples/dump-plugin/dumpplugin.go
>   	cd examples/dump-plugin && \
> +	PKG_CONFIG_PATH="$(abs_builddir)/server/local" \

Shouldn't this be more like:

PKG_CONFIG_PATH="$(abs_builddir)/server/local$${PKG_CONFIG_PATH:-:$$PKG_CONFIG_PATH}"

so as to preserve any inherited override locations for other .pc files 
that might also be needed by cgo?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org