Mac brew bundle adds gcc@6, build needs gcc@8

Describe the bug The README-mac.md and the Brewfile will use gcc@6, but the build requires gcc@8

To Reproduce Build without gcc@8 installed. The build will fail: configure: error: C++ compiler cannot create executables

Expected behavior The build should begin.

Desktop (please complete the following information):

OS: MacOS Catalina

Additional context Configure checks for g++-8. This is from the config.log:

configure:4526: checking whether the C++ compiler works configure:4548: g++-8 -pipe -O1 -arch x86_64 -I/usr/local/Cellar/gcc\@8/8.3.0/include/c++/8.3.0/ -I$PREFIX/include -fwrapv -fno-strict-aliasing -Wno-builtin-declaration-mismatch -Werror -g -Wl,-undefined -Wl,dynamic_lookup -I/Users/brian/Projects/pirate/depends/x86_64-apple-darwin19.6.0/share/../include/ -I/Users/brian/Projects/pirate/depends/x86_64-apple-darwin19.6.0/include -arch x86_64 -L/Users/brian/Projects/pirate/depends/x86_64-apple-darwin19.6.0/share/../lib -L/Users/brian/Projects/pirate/depends/x86_64-apple-darwin19.6.0/lib -arch x86_64 -Wl,-no_pie conftest.cpp >&5 ./configure: line 4550: g++-8: command not found configure:4552: $? = 127 configure:4592: result: no

PirateNetwork / pirate

Mac brew bundle adds gcc@6, build needs gcc@8 #55