Compiling ipopt with HSL on mac osx

[jtheinen]

I had a hard time compiling, to help others to fix the problem more quickly this were the steps that helped compile on big sur:

brew install gcc
This is necessary because clang does not support -fopenmd, check how the homebrew gcc is called to setup the flags. gcc --version outputs clang, the native compiler of mac, make sure you find the homebrew executable, which is usually gcc-$version$ (for me gcc-11)

brew install openblas
this makes a symlink in /usr/local/opt/openblas to use the native mac openblas tools

git clone https://github.com/coin-or-tools/ThirdParty-HSL.git
cd ThirdParty-HSL
./configure CXX=g++-11 CC=gcc-11 F77=gfortran-11 LDFLAGS="-L/usr/local/opt/openblas/lib" CPPFLAGS="-I/usr/local/opt/openblas/include"
make
sudo make install

Use your own version for -11

for ipopt:

git clone https://github.com/coin-or/Ipopt.git
cd Ipopt
./configure CXX=g++-11 CC=gcc-11 F77=gfortran-11 LDFLAGS="-L/usr/local/opt/openblas/lib" CPPFLAGS="-I/usr/local/opt/openblas/include"
make
sudo make install

Now ipopt is ready to use with HSL!