diff --git a/libguile/vm-engine.c b/libguile/vm-engine.c index 7f4641a07..ff41ce4b6 100644 --- a/libguile/vm-engine.c +++ b/libguile/vm-engine.c @@ -140,6 +140,8 @@ VM_NAME (SCM vm, SCM program, SCM *argv, int nargs) goto vm_error; vm_error_unbound: + /* At this point FINISH_ARGS should be a one-element list containing + the name of the unbound variable. */ err_msg = scm_from_locale_string ("VM: Unbound variable: ~s"); goto vm_error; diff --git a/libguile/vm-i-system.c b/libguile/vm-i-system.c index 3af63082a..958f8b9c3 100644 --- a/libguile/vm-i-system.c +++ b/libguile/vm-i-system.c @@ -307,10 +307,13 @@ VM_DEFINE_INSTRUCTION (26, variable_ref, "variable-ref", 0, 1, 1) { SCM x = *sp; - if (!VARIABLE_BOUNDP (x)) + if (SCM_UNLIKELY (!VARIABLE_BOUNDP (x))) { - finish_args = scm_list_1 (x); - /* Was: finish_args = SCM_LIST1 (SCM_CAR (x)); */ + SCM var_name; + + /* Attempt to provide the variable name in the error message. */ + var_name = scm_module_reverse_lookup (scm_current_module (), x); + finish_args = scm_list_1 (scm_is_true (var_name) ? var_name : x); goto vm_error_unbound; } else