Change Minimum GCC Version to 8 (Rippled Version: 1.7.0)

[septerr]

Issue Description

When trying to build from source, I encountered following compilation errors with GCC 7.5 on Ubuntu:

xrp core.dir unity_3_cxx.cxx:10:0: /build/rippled/src/ripple/protocol/impl/STInteger.cpp:28:10: fatal error: charconv: No such file or directory #include <charconv>

Using GCC 8, the build worked.

It appears the minimum required GCC version on Linux Build Instructions needs to be updated.

Steps to Reproduce

On Ubuntu, follow the steps from Linux Build Instructions , except when installing GCC use following:

apt-get update && apt-get install -y
apt-get update \
    && apt-get -y upgrade \
    && apt-get install -y wget git protobuf-compiler libprotobuf-dev \
      libssl-dev python-dev make pkg-config software-properties-common \
      build-essential curl fio \
    && add-apt-repository -y ppa:ubuntu-toolchain-r/test \
    && apt-get update \
    && apt-get install -y gcc-7 g++-7

update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-7 60 \
                        --slave /usr/bin/g++ g++ /usr/bin/g++-7

Expected Result

Expected a successful build.

Actual Result

Following build error:

xrp core.dir unity_3_cxx.cxx:10:0: /build/rippled/src/ripple/protocol/impl/STInteger.cpp:28:10: fatal error: charconv: No such file or directory #include <charconv>

Environment

Ubuntu (unsure of exact version)

Supporting Files

[MarkusTeufelberger]

Ubuntu (unsure of exact version)

What's the output of cat /etc/os-release on your build machine?

[septerr]

I believe the Ubuntu version is 16.04. We are building from source in a container with a base Ubuntu image. And from what I can tell the image is for Ubuntu 16.04. 🙏

[alloynetworks]

I confirm that this same behavior occurs on Ubuntu 18.04 when compiling 1.7.0+
It can be solved with:

sudo apt install g++-8 gcc-8 

In order to have it refer to the latest version, yet allow both GCC 7 and 8 directly, this helps:

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-7 700 --slave /usr/bin/g++ g++ /usr/bin/g++-7
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 800 --slave /usr/bin/g++ g++ /usr/bin/g++-8