lldb C local variable not printing -

value eval(value arg, table env) { if (arg.tag == conscell) {     value operator = car(arg);     value operands = cdr(arg); // <- debugger stopped here 

if print argument arg p arg, get:

(lldb) p arg (value) $0 = {   data = {     number = 1068272     list = 0x0000000100104cf0     symbol = 0x0000000100104cf0 "?l\x10"   }   tag = conscell } 

but if p operator, get:

(lldb) p operator error: expected type error: 1 errors parsing expression 

however, using frame variable operator works:

(lldb) frame variable operator (value) operator = {   data = {   number = 1068208   list = 0x0000000100104cb0   symbol = 0x0000000100104cb0 "\x10l\x10" }   tag = conscell } 

what's going wrong when i'm using p operator?

lldb evaluates expression in hybrid of c++ , objective-c. operator, name of variable, reserved keyword in c++. when use p command (which alias expression command), lldb passes expression clang parse , evaluate in c++/objective-c (or, if you're debugging swift method, parse , evaluate in swift). though program written in straight c, expressions evaluated c++ expressions , that's not valid c++ expression.

frame variable (fr v short) doesn't go through compiler evaluation, tries simple parsing of variable path provided. can simple dereferencing , following of pointers, can't cast values instance.