Test whether a directory exists inside a makefile

Question

In his answer @Grundlefleck explains how to check whether a directory exists or not. I tried some to use this inside a makefile as follow:

foo.b         


        

Answer 1

There is a very different answer that allows you to use your if statements as you envisioned them in one shell:

.ONESHELL:
foo.bak: foo.bar
    echo "foo"
    if [ -d "~/Dropbox" ]; then
        echo "Dir exists"
    fi

Note that the only difference is the ONESHELL special target.