If you ever get an error message of “configure: error: C compiler cannot create executables” when executing brew install readline, then do what’s suggested in a related Homebrew issue:

1. brew edit readline
2. Comment out the line which starts with ENV.universal_binary.
3. Re-execute your previous brew install command.

The above also applies to the following packages:

• jpeg

Apparently the configuration specifying a Universal or PowerPC build target for libraries is in the library itself, not passed to it. If the library author wants to stop people using it on PowerPC, he/she can.