Compiling cpp-ethereum on old MacBook Pros

I happen to still use a 2010 Macbook Pro for all my work and recently I’ve been researching dapps on the Ethereum blockchain. In attempting to have the full experience, I’ve installed go-ethereum and attempted (without success) to install cpp-ethereum as well.

While the precompiled OSX release should work, it crashes everytime I open it on my old MBP. The error is somewhat due to an illegal instruction - my guess is that, the release was compiled on more recent hardware with optimizations that use a more recent instruction set than that on mine. My last option was to compile it.

While the instructions for compiling cpp-ethereum are pretty straight forward, what it doesn’t tell you is that it would not work with the most recent version of qt5 (5.6 as of this writing); what you need is version 5.5. So rather than installing the most recent version of qt5, you should do the following instead:

brew install https://raw.githubusercontent.com/Homebrew/homebrew/f802822b0fa35ad362aebd0101ccf83a638bed37/Library/Formula/qt5.rb

Then you can proceed with the remaining steps to compile the package.