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421 :: How does one use endb to debug crashes?

• gradha (orginal) [2014-04-15T21:34:01+02:00] view original

  Given the following file testme.nim:

  
  proc test3(): string =
    ## Returns a string. Could be nil!
    echo "Test3 is going to be very bad!"
  
  proc test2() =
    echo "This is test2"
    echo test3()
  
  proc test1() =
    echo "This is test1"
    test2()
  
  when isMainModule:
    test1()
  Run

  I compile and run with the embedded debugger and when I run I get the expected crash:

  
  $ nimrod c --debugger:on -r testme.nim
  ...
  *** endb| testme.nim(14) testme ***
  *** endb| >>run
  This is test1
  This is test2
  Test3 is going to be very bad!
  Traceback (most recent call last)
  testme.nim(14)           testme
  testme.nim(11)           test1
  testme.nim(7)            test2
  SIGSEGV: Illegal storage access. (Attempt to read from nil?)
  Error: execution of an external program failed
  Run

  However the execution ends. I was expecting the debugger to leave me at the frame which crashed so I could poke variables and inspect stuff. How does one use the embedded nimrod debugger in such cases?

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• Araq (orginal) [2014-04-16T09:30:22+02:00] view original

  All I can say is that that used to work, but since our tester does not support anything that requires user input, we don't notice when we break things like these... Sad but true. I use endb only for its rather good watchpoint support these days.

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