On mac, g++ (clang) fails to search /usr/local/include and /usr/local/lib by default

I also use Homebrew and had a similar problem on Mac OSX Maverick 10.9.5 and Xcode 6.0.1, but it was solved by running:

xcode-select --install

Note that it doesn't work without the double hyphens given by the previous answer. This installs the command-line tools that also create /usr/lib/ and /usr/include/. I don't know why Homebrew doesn't automatically check this upon installation, since it does check for Xcode...

If you want to check exactly what folders your compiler is looking through for header files you can write:

cpp -v

A workaround would be to:

export C_INCLUDE_PATH=/usr/local/include
export CPLUS_INCLUDE_PATH=/usr/local/include

At least this tricked the pre-processor to behave here :)

Try running xcode-select --install

At least on Mavericks, I've found that if I install the Xcode application without installing the command-line tools, then the tools are sort of available, but normal unix-ey builds don't work correctly. One symptom is that /usr/local/include is not on the include search path. The command-line tools seem to resolve this issue.