New: Can't find libmpfr.so.4 when using external toolchain on ubuntu 18.04/18.10

https://bugs.busybox.net/show_bug.cgi?id=11451

Bug ID: 11451
Summary: Can't find libmpfr.so.4 when using external toolchain
on ubuntu 18.04/18.10
Product: buildroot
Version: unspecified
Hardware: All
OS: Linux
Status: NEW
Severity: critical
Priority: P5
Component: Other
Assignee: unassigned at buildroot.uclibc.org
Reporter: lgnice at sina.com
CC: buildroot at uclibc.org
Target Milestone: ---

Created attachment 7836
--> https://bugs.busybox.net/attachment.cgi?id=7836&action=edit
libzlib configure error

When I upgraded ubuntu from 16.04 to 18.04, output/build/libzlib-1.2.11 will have a compilation error, because I used the toolchain provided by the bsp vendor.

The reason is: ubuntu 18.04/18.10 removed
Libgmpv4-dev - Multiprecision arithmetic library developers tools (GCC 4.x compatible)

Only reserved: libmpfr6 - multiple precision floating-point computation

However, I found that all toolchains provide libmpfr.so by themselves:

/opt/Vatics/vtcs_toolchain/arm-eabi-uclibc/usr/lib/libmpfr.so /opt/ralink/arm-buildroot-gcc463-for-ibox/usr/lib/libmpfr.so /opt/ralink/buildroot-gcc463/usr/lib/libmpfr.so /opt/mtk_mipsel_gcc-4.6.3_uclibc-0.9.33/usr/lib/libmpfr.so /opt/GrainMedia/gm813x/toolchain_gnueabi-4.4.0_ARMv5TE/usr/lib/libmpfr.so /opt/mipsel-24kec-linux-uclibc-4.9-2017.07/usr/lib/libmpfr.so /opt/960A/buildroot-gcc463/usr/lib/libmpfr.so

?Just set the environment variable LD_LIBRARY_PATH to solve it.

Export LD_LIBRARY_PATH=/opt/mipsel-24kec-linux-uclibc-4.9-2017.07/usr/lib:$LD_LIBRARY_PATH

but, once LD_LIBRARY_PATH is set, an error will be reported in buildroot:

You seem to have the current working directory in your LD_LIBRARY_PATH environment variable. This doesn't work.
Make: *** [support/dependencies/dependencies.mk:25: core-dependencies] Error 1

How to solve it?

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https://bugs.busybox.net/show_bug.cgi?id=11451

--- Comment #1 from galen <[email protected]> ---
Created attachment 7841
--> https://bugs.busybox.net/attachment.cgi?id=7841&action=edit
add LD_LIBRARY_PATH

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https://bugs.busybox.net/show_bug.cgi?id=11451

Thomas Petazzoni <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------

         Resolution|---                         |WONTFIX
             Status|NEW                         |RESOLVED

--- Comment #2 from Thomas Petazzoni <[email protected]> --- If the programs in your external toolchain use libmpfr.so, but it is not provided by the external toolchain, then the external toolchain is broken.

Your patch causes two problems:

(1) libmpfr.so is not guaranteed to be installed $(HOST_DIR)/lib. Buildroot
only builds/installs host-mpfr if needed, and a typical configuration that uses an external toolchain will not build/install host-mpfr.

(2) Passing LD_LIBRARY_PATH pointing to some host libraries will very likely
confuse the cross-compilation of some packages. We tried a while ago to use LD_LIBRARY_PATH, and it was a total failure.

So, here, you really need to fix the external toolchain itself.

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