python -m pdb error.py: stuck in unexitable infinite prompt loop

[59062004-5199-4539-afa5-e89c3bd56d93]

BPO	24957
Nosy	@birkenfeld, @terryjreedy, @shlomif
Superseder	bpo-16180: cannot quit pdb when there is a syntax error in the debuggee (must kill it)
Files	euler-234-v1.py

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields: ```python assignee = None closed_at = created_at = labels = ['type-bug', 'library'] title = 'python -m pdb error.py: stuck in unexitable infinite prompt loop' updated_at = user = 'https://github.com/shlomif' ``` bugs.python.org fields: ```python activity = actor = 'terry.reedy' assignee = 'none' closed = True closed_date = closer = 'terry.reedy' components = ['Library (Lib)'] creation = creator = 'shlomif' dependencies = [] files = ['40292'] hgrepos = [] issue_num = 24957 keywords = [] message_count = 3.0 messages = ['249319', '249320', '249794'] nosy_count = 3.0 nosy_names = ['georg.brandl', 'terry.reedy', 'shlomif'] pr_nums = [] priority = 'normal' resolution = 'duplicate' stage = 'resolved' status = 'closed' superseder = '16180' type = 'behavior' url = 'https://bugs.python.org/issue24957' versions = ['Python 2.7', 'Python 3.4', 'Python 3.5', 'Python 3.6'] ```

[59062004-5199-4539-afa5-e89c3bd56d93]

I tried Ctrl+C, Ctrl+D, "quit" and "exit", and "q" - nothing exits from the infinite prompt loop.

shlomif@telaviv1:~/Docs/homepage/homepage/trunk$ cd /home/shlomif/progs/riddles/project-euler/hg/project-euler/234
shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$ ls
brute-force.pl   euler-234-description.txt   euler-234-v1.py
brute-force.pl~  euler-234-description.txt~  euler-234-v1.py~
shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$ python3 euler-234-v1.py 
  File "euler-234-v1.py", line 21
    print "Found[] = ", n
                     ^
SyntaxError: Missing parentheses in call to 'print'
shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$ python3 -mpdb euler-234-v1.py 1000
Traceback (most recent call last):
  File "/usr/lib64/python3.4/pdb.py", line 1661, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib64/python3.4/pdb.py", line 1542, in _runscript
    self.run(statement)
  File "/usr/lib64/python3.4/bdb.py", line 431, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "/home/shlomif/progs/riddles/project-euler/hg/project-euler/234/euler-234-v1.py", line 21
    print "Found[] = ", n
                     ^
SyntaxError: Missing parentheses in call to 'print'
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> <string>(1)<module>()
(Pdb) 
(Pdb) exit
Post mortem debugger finished. The euler-234-v1.py will be restarted
Traceback (most recent call last):
  File "/usr/lib64/python3.4/pdb.py", line 1661, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib64/python3.4/pdb.py", line 1542, in _runscript
    self.run(statement)
  File "/usr/lib64/python3.4/bdb.py", line 431, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "/home/shlomif/progs/riddles/project-euler/hg/project-euler/234/euler-234-v1.py", line 21                                                                
    print "Found[] = ", n                                                       
                     ^                                                          
SyntaxError: Missing parentheses in call to 'print'                             
Uncaught exception. Entering post mortem debugging                              
Running 'cont' or 'step' will restart the program                               
> <string>(1)<module>()                                                         
(Pdb) quit                                                                      
Post mortem debugger finished. The euler-234-v1.py will be restarted            
Traceback (most recent call last):                                              
  File "/usr/lib64/python3.4/pdb.py", line 1661, in main                        
    pdb._runscript(mainpyfile)                                                  
  File "/usr/lib64/python3.4/pdb.py", line 1542, in _runscript                  
    self.run(statement)                                                         
  File "/usr/lib64/python3.4/bdb.py", line 431, in run                          
    exec(cmd, globals, locals)                                                  
  File "<string>", line 1, in <module>                                          
  File "/home/shlomif/progs/riddles/project-euler/hg/project-euler/234/euler-234-v1.py", line 21
    print "Found[] = ", n
                     ^
SyntaxError: Missing parentheses in call to 'print'
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> <string>(1)<module>()
(Pdb) 
Post mortem debugger finished. The euler-234-v1.py will be restarted
Traceback (most recent call last):
  File "/usr/lib64/python3.4/pdb.py", line 1661, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib64/python3.4/pdb.py", line 1542, in _runscript
    self.run(statement)
  File "/usr/lib64/python3.4/bdb.py", line 431, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "/home/shlomif/progs/riddles/project-euler/hg/project-euler/234/euler-234-v1.py", line 21
    print "Found[] = ", n
                     ^
SyntaxError: Missing parentheses in call to 'print'
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> <string>(1)<module>()
(Pdb) --KeyboardInterrupt--
(Pdb) --KeyboardInterrupt--
(Pdb) exit
Post mortem debugger finished. The euler-234-v1.py will be restarted
Traceback (most recent call last):
  File "/usr/lib64/python3.4/pdb.py", line 1661, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib64/python3.4/pdb.py", line 1542, in _runscript
    self.run(statement)
  File "/usr/lib64/python3.4/bdb.py", line 431, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "/home/shlomif/progs/riddles/project-euler/hg/project-euler/234/euler-234-v1.py", line 21
    print "Found[] = ", n
                     ^
SyntaxError: Missing parentheses in call to 'print'
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> <string>(1)<module>()
(Pdb) quit
Post mortem debugger finished. The euler-234-v1.py will be restarted
Traceback (most recent call last):
  File "/usr/lib64/python3.4/pdb.py", line 1661, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib64/python3.4/pdb.py", line 1542, in _runscript
    self.run(statement)
  File "/usr/lib64/python3.4/bdb.py", line 431, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "/home/shlomif/progs/riddles/project-euler/hg/project-euler/234/euler-234-v1.py", line 21
    print "Found[] = ", n
                     ^
SyntaxError: Missing parentheses in call to 'print'
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> <string>(1)<module>()
(Pdb) 
[1]+  Stopped                 python3 -mpdb euler-234-v1.py 1000
shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$ kill %1

[1]+ Stopped python3 -mpdb euler-234-v1.py 1000 shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$ [1]+ Terminated python3 -mpdb euler-234-v1.py 1000 shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$ shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$ shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$ jobs shlomif@telaviv1:~/progs/riddles/project-euler/hg/project-euler/234$

[59062004-5199-4539-afa5-e89c3bd56d93]

I should note that I am using python3-3.4.3-6.mga6 on Mageia Linux x86-64 6/Cauldron.

[terryjreedy]

Pdb says "Running 'cont' or 'step' will restart the program" but it seems to restart on any recognized command other than 'h' and traps everything else. I verified behavior on Win7 with ordinary syntax error 'a = = 1' on installed 2.7.10 and 3.4.3. Removed qualifiers from title.

Doc says ''' python3 -m pdb myscript.py

When invoked as a script, pdb will automatically enter post-mortem debugging if the program being debugged exits abnormally. After post-mortem debugging (or after normal exit of the program), pdb will restart the program.'''

But not being able to exit could not have been the intention. Looking at the code.