[BUG] `__call_location().file_name` returns incorrect information about mojo

[JoeLoser]

FYI @laszlokindrat

[carlca]

Following the new update to nightly/mojo, I've expended on the test code, taking into @Arthur Evans's wise words about not inlining the main fn 😮

Now we have...
from builtin._location import __call_location, _SourceLocation

fn main():
  test_fn()   # <== Reports this location!

@always_inline("nodebug")
fn test_fn():
  var file_name = __call_location().file_name
  var line = __call_location().line
  print(file_name)
  print(line)

# Output of test
# 
# [Fri May 10 2024 12:24PM (BST+0100)]  (main) [*] 🐍 v3.12.1   
# ~/Code/Mojo/ca_mojo/ca_lib/research  mojo main.mojo
# /Users/carlcaulkett/Code/Mojo/ca_mojo/ca_lib/research/main.mojo
# 4

The behaviour is improved, source location is now reported as the call point to the function. It's difference from how it used to be, but by chance this behaviour may suit me in my particular use case 😉

Note that this code still returns the baked in Modular source path...

from builtin._location import __call_location, _SourceLocation

@always_inline("nodebug")
fn main():
  var st = __call_location().file_name
  print(st)

[laszlokindrat]

Thanks for opening the ticket! Regarding the OP: this is sort of expected behavior, since the main you define in your file is indeed wrapped by some functions defined in _startup.mojo. I agree that it's not great that it returns the path on the machine the release was built. We don't think this is a huge risk, but we're evaluating what other ways this feature could be abused, so stay tuned!