Build fails with C++14 compiler; code uses <string_view> which is a C++17 header

[ryandesign]

Hi, the readme says tilemaker is written in C++14:

tilemaker/README.md

Line 48 in bf89810

tilemaker is written in C++14. The chief dependencies are:

However on OS X 10.11.6 with Apple Clang 8.0.0 (clang-800.0.42.1), which I've found hasn't implemented all of C++17, the build uses the flag -std=gnu++1z and it includes the <string_view> header, which doesn't exist in this compiler:

https://build.macports.org/builders/ports-10.11_x86_64-builder/builds/315537/steps/install-port/logs/stdio

In file included from /opt/local/var/macports/build/tilemaker-00870ee9/work/tilemaker-3.1.0/server/server.cpp:1:
In file included from /opt/local/var/macports/build/tilemaker-00870ee9/work/tilemaker-3.1.0/server/Simple-Web-Server/server_http.hpp:6:
/opt/local/var/macports/build/tilemaker-00870ee9/work/tilemaker-3.1.0/server/Simple-Web-Server/utility.hpp:26:10: fatal error: 'string_view' file not found
#include <string_view>
         ^

With newer versions of clang that have <string_view, the build uses the flag -std=gnu++17 and it succeeds.

So I wasn't sure if your stated requirement of C++14 should be changed to C++17 or whether you want to make any changes to maintain C++14 compatibility.

[systemed]

Hm. I think string_view is only used in tilemaker-server, rather than tilemaker itself. If you build with make tilemaker rather than make, is it happier?