For mac :

1. Install Abseil using Homebrew: Bash L brew update brew install abseil

2. Try installing google-re2 without explicitly setting compiler flags
first: Bash python3 -m pip install google-re2 Often, the build system will automatically detect and use a suitable C++ standard if Abseil is found.

3. If you still face build issues and suspect the C++ standard is the problem, try setting CXXFLAGS : Bash CXXFLAGS='-std=c++17' python3 -m pip install google-re2