gcc-5

Build gcc-5 on Ubuntu 20.04 with gcc-9. Problems listed here are fixed and tested.

Prerequest

Make sure gcc-9 is installed on your distro. gcc other than version 9 and 11 are NOT tested.

gcc-11 is tested to be too new to build gcc-5 as discussed here. In practical, an error would be thrown:

use of an operand of type ‘bool’ in ‘operator++’ is forbidden in C++17

Usage

git clone https://github.com/AdorableJiang/gcc-5.4.0.git
cd gcc-5.4.0
./contrib/download_prerequisites
mkdir gcc-build-5.4.0
cd gcc-build-5.4.0
CC=[/path/to/gcc-9] CXX=[/path/to/g++-9] ../configure --prefix=/usr/local --enable-checking=release --enable-languages=c,c++ --disable-multilib

For explanation of gcc-5.4.0/configure options, check section Options specification of Installing GCC: Configuration.

Now you are all set to build gcc-5.

make -j$(nproc)
sudo make install

Validation

The built gcc-5 binaries should be installed to --prefix/gcc-5.4.0/bin,

$/usr/local/gcc-5.4.0/bin/gcc --version
gcc (GCC) 5.4.0
Copyright © 2015 Free Software Foundation, Inc.

and for g++

$/usr/local/gcc-5.4.0/bin/g++ --version
g++ (GCC) 5.4.0
Copyright © 2015 Free Software Foundation, Inc.

If you encountered problems using this repo, check here or cached offline reference/ubuntu_install_gcc5.4.html for help.

Uninstall

To uninstall gcc installed from source, run uninstall.sh under gcc build directory as root. That is gcc-build-5.4.0 if you follow the instructions above.

cp uninstall.sh gcc-build-5.4.0/ && cd gcc-build-5.4.0/
sudo bash uninstall.sh

Reference: How to uninstall gcc installed from source?