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bpo-38631: Replace compiler fatal errors with exceptions #24369

Merged
merged 3 commits into from
Jan 30, 2021
Merged

bpo-38631: Replace compiler fatal errors with exceptions #24369

merged 3 commits into from
Jan 30, 2021

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vstinner
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@vstinner vstinner commented Jan 29, 2021 •
edited by bedevere-bot
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  • Replace Py_FatalError() calls with regular SystemError exceptions.
  • compiler_exit_scope() calls _PyErr_WriteUnraisableMsg() to log the
    PySequence_DelItem() failure.
  • compiler_unit_check() uses _PyMem_IsPtrFreed()
  • compiler_make_closure(): remove "(reftype == FREE)" comment since
    reftype can also be LOCAL or GLOBAL_EXPLICIT.

https://bugs.python.org/issue38631

@vstinner
bpo-38631: Replace compiler fatal errors with exceptions
da1adc4 
* Replace Py_FatalError() calls with regular SystemError exceptions.
* compiler_exit_scope() calls _PyErr_WriteUnraisableMsg() to log the
  PySequence_DelItem() failure.
* compiler_unit_check() uses _PyMem_IsPtrFreed()
* compiler_make_closure(): remove "(reftype == FREE)" comment since
  reftype can also be LOCAL or GLOBAL_EXPLICIT.
@vstinner vstinner requested a review from markshannon as a code owner January 29, 2021 17:07
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cc @isidentical @lysnikolaou @pablogsal

I injected bugs to check if the SystemError error message is formatted properly.

Error 1:

SystemError: PyST_GetScope(name='self') failed: unknown scope in unit update_sources_depends (31747488); symbols: {'self': 10260, 'moddirlist': 10242, 'os': 6160, 'headers': 2066, 'sysconfig': 6160, 'glob': 6160, 'escape': 6160, 'ext': 2066}; locals: {'self': 0}; globals: {'os': 0, 'path': 1, 'join': 2, 'srcdir': 3}

Error 2:

SystemError: compiler_lookup_arg(name='self') with reftype=5 failed in update_sources_depends; freevars of code '<listcomp>': ('self',)

Error 3:

SystemError: compiler stack_effect(opcode=116, arg=0) failed

It seems like if PySequence_DelItem() fails in compiler_exit_scope(), the compiler can crash. But I prefer to log the exception rather than exiting the whole process immediately. As written in the comment, since c_stack is a list, the function "shouldn't fail":

    /* we are deleting from a list so this really shouldn't fail */

pablogsal
pablogsal reviewed Jan 29, 2021
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Python/compile.c
arg = compiler_lookup_arg(c->u->u_cellvars, name);
else /* (reftype == FREE) */
}
else {
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Please, preserve the comment for the else branch: /* (reftype == FREE) */

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Please, preserve the comment for the else branch: /* (reftype == FREE) */

See the commit message: the comment is wrong. Try to convert the comment into an assertion.

pablogsal
pablogsal reviewed Jan 29, 2021
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pablogsal
pablogsal reviewed Jan 29, 2021
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vstinner and others added 2 commits January 30, 2021 01:03
@vstinner @pablogsal
Update Python/compile.c
9a9a07d 
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
@vstinner @pablogsal
Update Python/compile.c
6a23bb0 
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
@vstinner vstinner merged commit ba7a99d into python:master Jan 30, 2021
@vstinner vstinner deleted the compiler_fatal branch January 30, 2021 00:46
adorilson pushed a commit to adorilson/cpython that referenced this pull request Mar 13, 2021
@vstinner @adorilson
bpo-38631: Replace compiler fatal errors with exceptions (pythonGH-24369
bdadaff 
)

* Replace Py_FatalError() calls with regular SystemError exceptions.
* compiler_exit_scope() calls _PyErr_WriteUnraisableMsg() to log the
  PySequence_DelItem() failure.
* compiler_unit_check() uses _PyMem_IsPtrFreed().
* compiler_make_closure(): remove "(reftype == FREE)" comment since
  reftype can also be LOCAL or GLOBAL_EXPLICIT.
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@isidentical isidentical isidentical left review comments

@pablogsal pablogsal pablogsal approved these changes

@markshannon markshannon Awaiting requested review from markshannon

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@vstinner @pablogsal @isidentical @the-knights-who-say-ni @bedevere-bot