Gcc build fails with test_real_width is negative

[Mr Dini <mrdini@protonmail.com>]

Hi,

I am trying to build a native gcc binary for a pre-existing rootfs of my smart TV. The vendor has provided a toolchain for x86_64 hosts:

root@hal-9000:~# arm-webos-linux-gnueabi-gcc --version
arm-webos-linux-gnueabi-gcc (GCC) 6.2.0
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

As for the building I have tried building on an ubuntu 16.04 host with gcc version 5.3.1 and Ubuntu 20.04 with gcc version 9.3.0. The issue is always the same.

I have also tried to build the latest gcc release, 9.3.0, 9.2.0, 5.4.0 and 6.2.0.

Here is the error: https://pastebin.com/raw/Cr4amNCJ

To quote the specific part:

In file included from ../.././gcc/rtl.h:27,
                 from ../.././gcc/genoutput.c:90:
../.././gcc/real.h:74:76: error: narrowing conversion of '-1' from 'int' to 'long unsigned int' [-Wnarrowing]
   74 |   [sizeof (REAL_VALUE_TYPE) <= REAL_WIDTH * sizeof (HOST_WIDE_INT) ? 1 : -1];
      |                                                                            ^

Also, it looks like when gcc is building this specific component, make does a cd to host-armv7a-linux-gnueabi/gcc yet it uses the g++ of the host and completely ignores the CXX variable I have set when I configure gcc:

CC="arm-webos-linux-gnueabi-gcc -march=armv7-a -mfpu=neon -mfloat-abi=softfp --sysroot=/opt/webos-sdk-x86_64/1.0.g/sysroots/armv7a-neon-webos-linux-gnueabi" CXX="arm-webos-linux-gnueabi-g++ -march=armv7-a -mfpu=neon -mfloat-abi=softfp --sysroot=/opt/webos-sdk-x86_64/1.0.g/sysroots/armv7a-neon-webos-linux-gnueabi" ./configure --prefix=/opt/webos-sdk-x86_64/1.0.g/sysroots/armv7a-neon-webos-linux-gnueabi --with-mpfr=/opt/webos-sdk-x86_64/1.0.g/sysroots/armv7a-neon-webos-linux-gnueabi --host=armv7a-linux-gnueabi --target=armv7a-linux-gnueabi --build=x86_64-linux-gnu

Any ideas what can I do?

Thank you so much!