Getting stack traces when using the OCaml backend

There are two primary ways to get stack traces from a program compiled with the OCaml backend. Note that regardless of the method used most functions will have mangled names, i.e., they differ somewhat from the source code, but the connection is typically quite clear nonetheless. For example, a function typeCheckExpr in a language fragment ExtMCore might become something like camlDune__exe__Program__v_vExtMCore_typeCheckExpr_142839.

First, the OCAMLRUNPARAM environment flag can be set to b to instruct the OCaml runtime to emit a backtrace when it encounters an exception:

OCAMLRUNPARAM=b ./program

Second, the program can be run using a debugger such as gdb:

gdb ./program

# Once inside gdb:
run <program args>

# Use `bt` to get a backtrace when the program has crashed or been interrupted:
bt

tip

If the program prints an error and exits explicitly (e.g., via exit 1) rather than throwing an exception and crashing gdb can still extract a backtrace by adding a breakpoint to exit:

# Inside gdb, before running the program:
break exit
# Then run as usual, the program will break just before exiting, at which point you can run `bt`