How do you set breakpoints in the lldb terminal for swift? - swift

Question

I am trying to debug my swift program using lldb in terminal. I have compiled my code with the command
swiftc hello.swift
then I ran lldb using
lldb hello
in the lldb program I tried to set a break point using
(lldb) breakpoint set --file hello.swift --line 10
but I got the error
Breakpoint 2: no locations (pending).
WARNING: Unable to resolve breakpoint to any actual locations.
here is the code for hello.swift:
func answer()-> Int{
var value = 12
value = value + 9
return 4 * value
}
let arr = [0, 1, 2, 3, 4]
for _ in arr{
print(answer())
}
what am I doing wrong?

Answer 1

You should set the -g option when compiling the program. From swiftc --help:
-g Emit debug info. This is the preferred setting for debugging with LLDB.
Example session:
% swiftc -g hello.swift
% lldb hello
(lldb) target create "hello"
Current executable set to '/tmp/x/hello' (x86_64).
(lldb) breakpoint set --file hello.swift --line 10
Breakpoint 1: where = hello`main + 256 at hello.swift:10:11, address = 0x0000000100003bf0
(lldb) run
Process 15967 launched: '/tmp/x/hello' (x86_64)
Process 15967 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
frame #0: 0x0000000100003bf0 hello`main at hello.swift:10:11
7 let arr = [0, 1, 2, 3, 4]
8
9 for _ in arr{
-> 10 print(answer())
11 }
Target 0: (hello) stopped.