Re: [Buildroot] [PATCH] package/erlang-rebar: fix linking failure on shared library

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

Giulio, All,

On 2021-12-19 08:03 +0100, Giulio Benetti spake thusly:
> Add patch to fix linking failure while creating shared library. As
> explained in the patch itself, there is no specific variable for when we
> link a shared library and rebar itself rely on the default LDFLAGS. Since
> by default every CFLAGS is filled with -fPIC we need to make sure that
> every LDFLAGS is the same, so not having any other *_LDFLAGS variable to
> fille with -fPIC let's add it to the main LDFLAGS.
> 
> Fixes:
> http://autobuild.buildroot.net/results/602/60296a48210e7ffc6bc9fa50ee586441a8957e85/
> 
> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>

Even though I was not very happy with that solution, there is really no
better way, so: applied to master, thanks.

Regards,
Yann E. MORIN.

> ---
>  ...ompiler-add-fPIC-to-LDFLAGS-by-defau.patch | 35 +++++++++++++++++++
>  1 file changed, 35 insertions(+)
>  create mode 100644 package/erlang-rebar/0001-src-rebar_port_compiler-add-fPIC-to-LDFLAGS-by-defau.patch
> 
> diff --git a/package/erlang-rebar/0001-src-rebar_port_compiler-add-fPIC-to-LDFLAGS-by-defau.patch b/package/erlang-rebar/0001-src-rebar_port_compiler-add-fPIC-to-LDFLAGS-by-defau.patch
> new file mode 100644
> index 0000000000..a9c1670a1f
> --- /dev/null
> +++ b/package/erlang-rebar/0001-src-rebar_port_compiler-add-fPIC-to-LDFLAGS-by-defau.patch
> @@ -0,0 +1,35 @@
> +From 7f54d48ee5db037778ead310e0b8278f3fe70b41 Mon Sep 17 00:00:00 2001
> +From: Giulio Benetti <giulio.benetti@benettiengineering.com>
> +Date: Sun, 19 Dec 2021 07:52:55 +0100
> +Subject: [PATCH] src/rebar_port_compiler: add -fPIC to LDFLAGS by default
> +
> +Since both DRV_CFLAGS and EXE_CFLAGS list -fPIC we need also the LDFLAGS
> +to follow them. Unfortunately adding -fPIC only to DRV_LDFLAGS and
> +EXE_LDFLAGS is not sufficient, since when linking as a library(.so) it
> +doesn't take into account those variables. Since -fPIC is needed by default
> +by any kind of linking, let's add it to the general -fPIC. Rebar seems to
> +link libraries without taking into account any variable listed in:
> +src/rebar_port_compiler.erl
> +this after testing and tracing for every variable.
> +
> +Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
> +---
> + src/rebar_port_compiler.erl | 2 ++
> + 1 file changed, 2 insertions(+)
> +
> +diff --git a/src/rebar_port_compiler.erl b/src/rebar_port_compiler.erl
> +index 9679c80..bd08b21 100644
> +--- a/src/rebar_port_compiler.erl
> ++++ b/src/rebar_port_compiler.erl
> +@@ -645,6 +645,8 @@ default_env() ->
> +      {"OBJCOPY", get_tool(Arch, "objcopy", "objcopy")},
> +      {"OBJDUMP", get_tool(Arch, "objdump", "objdump")},
> + 
> ++     {"LDFLAGS", "-fPIC $LDFLAGS"},
> ++
> +      {"DRV_CXX_TEMPLATE",
> +       "$CXX -c $CXXFLAGS $DRV_CFLAGS $PORT_IN_FILES -o $PORT_OUT_FILE"},
> +      {"DRV_CC_TEMPLATE",
> +-- 
> +2.25.1
> +
> -- 
> 2.25.1
> 
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