"unknown Type Name 'decltype'": Installing Pyicu On Mac Failed, With Gcc Error

I ran the following command (because I have both python2 and python3 on my mac): $ CFLAGS=-I/usr/local/opt/icu4c/include LDFLAGS=-L/usr/local/opt/icu4c/lib sudo python3 -m pip ins

Solution 1:

According to @n.m., -std=c++11 needs to be added to CFLAGS.