I tried compiling this example from ch6 with llvm-project/build/bin/toyc-ch6 obtained from Getting Started - MLIR
$ echo ‘def main() { print([[1, 2], [3, 4]]); }’ | ./bin/toyc-ch6 -emit=jit
JIT invocation failed
Program aborted due to an unhandled Error:
Symbols not found: [ _mlir__mlir_ciface_main ]
Aborted (core dumped)