Using C++17 with clang++ on Ubuntu 16.04

Question

I can't for the life of me figure out how to get C++17 to work on Ubuntu 16.04.

This works on Ubuntu 18.04:

sudo apt-get update
sudo apt-get install clang-6.0

which installs the C++17 standard library headers in /usr/include/c++/7. However, when I run the same commands in Ubuntu 16.04, I get C++14 headers in /usr/include/c++/5, and C++17 features won't compile.

I tried following this as well to install clang-7, but that led to the following error: clang: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version 'GLIBCXX_3.4.22' not found (required by clang)

Apologies if this is a dumb question; I am new to this stuff and am probably missing something obvious.

Answer 1

I followed the same article but with little changes:

1. execute ldconfig after setting LD_LIBRARY_PATH.
2. change the "18.04" in the url to "16.04".

The installation was:

apt install build-essential xz-utils curl
curl -SL http://releases.llvm.org/7.0.1/clang+llvm-7.0.1-x86_64-linux-gnu-ubuntu-16.04.tar.xz | tar -xJC .
cp -r clang+llvm-7.0.1-x86_64-linux-gnu-ubuntu-16.04/ /usr/local/clang-7.0.1
export LD_LIBRARY_PATH=/usr/local/clang-7.0.1/lib:$LD_LIBRARY_PATH
export PATH=/usr/local/clang-7.0.1/bin:$PATH
ldconfig

Then created if_test.cpp:

#include <iostream>

int main() {
    // if block with init-statement:
    if(int a = 5; a < 8) {
        std::cout << "Local variable a is < 8\n";
    } else {
        std::cout << "Local variable a is >= 8\n";
    }
    return 0;
}

The source code was compiled by following instruction:

clang++ -std=c++17 -stdlib=libc++ -Wall -pedantic if_test.cpp -o if_test

Execution of object file will give correct output:

# ./if_test
Local variable a is < 8