I want to prevent the project from compiling when I run an Ant task, how is this done?
Eclipse build setting is not automatic but the build still remains running before any ant task be launched.
You can turn off "Build (if required) before launch"
You have turned rebuild off for resource modification but I believe you haven't turned off "Build (if required) before launch"
Go to:
Window > Preferences > Run/Debug > Launching -> Build (if required) before launching
On older versions of eclipse:
Window > Preferences > Run/Debug > Build (if required) before launching