[Swig-devel] [ swig-Bugs-3597854 ] std_except.i and bug with SWIG_STD_EXCEPTIONS_AS_CLASSES

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Bugs item #3597854, was opened at 2012-12-20 11:02
Message generated for change (Settings changed) made by ptomulik
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Category: None
Group: None
Status: Open
Resolution: None
>Priority: 4
Private: No
Submitted By: Paweł Tomulik (ptomulik)
>Assigned to: William Fulton (wsfulton)
Summary: std_except.i and bug with SWIG_STD_EXCEPTIONS_AS_CLASSES

Initial Comment:
Hello,

I need to use standard exceptions as classes in python and can't make it work.

With following simple module:

---- 8< ------------------------------
%module std_except_mod

%inline %{
void foo() { throw std::logic_error("Hi there"); }
%}

%import  <std_string.i>
#define SWIG_STD_EXCEPTIONS_AS_CLASSES
%include <std_except.i>

void foo() { throw std::logic_error("Hi there"); }
---- 8< ------------------------------

I get a bunch of warnings when running swig on it and %exceptionclass is not applied to the standard exceptions classes being wrapped
(so, I'm not able to catch them properly in python code).

Compilation log says:

------- 8< ---------------------------------------------------------------------------
swig -c++ -python std_except_mod.i && g++ -shared -fPIC -I . -I /usr/include/python2.7 -o _std_except_mod.so std_except_mod_wrap.cxx
/usr/share/swig2.0/typemaps/std_except.swg:41: Warning 302: Identifier 'exception' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:13: Warning 302: previous definition of 'exception'.
/usr/share/swig2.0/typemaps/std_except.swg:47: Warning 302: Identifier 'bad_exception' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:19: Warning 302: previous definition of 'bad_exception'.
/usr/share/swig2.0/typemaps/std_except.swg:51: Warning 302: Identifier 'logic_error' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:23: Warning 302: previous definition of 'logic_error'.
/usr/share/swig2.0/typemaps/std_except.swg:56: Warning 302: Identifier 'domain_error' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:28: Warning 302: previous definition of 'domain_error'.
/usr/share/swig2.0/typemaps/std_except.swg:61: Warning 302: Identifier 'invalid_argument' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:33: Warning 302: previous definition of 'invalid_argument'.
/usr/share/swig2.0/typemaps/std_except.swg:66: Warning 302: Identifier 'length_error' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:38: Warning 302: previous definition of 'length_error'.
/usr/share/swig2.0/typemaps/std_except.swg:71: Warning 302: Identifier 'out_of_range' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:43: Warning 302: previous definition of 'out_of_range'.
/usr/share/swig2.0/typemaps/std_except.swg:76: Warning 302: Identifier 'runtime_error' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:48: Warning 302: previous definition of 'runtime_error'.
/usr/share/swig2.0/typemaps/std_except.swg:81: Warning 302: Identifier 'range_error' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:53: Warning 302: previous definition of 'range_error'.
/usr/share/swig2.0/typemaps/std_except.swg:86: Warning 302: Identifier 'overflow_error' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:58: Warning 302: previous definition of 'overflow_error'.
/usr/share/swig2.0/typemaps/std_except.swg:91: Warning 302: Identifier 'underflow_error' redefined (ignored),
/usr/share/swig2.0/std/std_except.i:63: Warning 302: previous definition of 'underflow_error'.
------- 8< ---------------------------------------------------------------------------

In my opinion, the problem sits in 'typemap/std_except.swg'. I'll post a patch proposition soon.

Simple test in python interpreter reveals that the exception classes are not handled properly:

ptomulik@barakus:$ python
Python 2.7.3 (default, Sep  9 2012, 17:41:34) 
[GCC 4.7.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from std_except_mod import *
>>> try: foo()
... except exception: pass
... 
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
SystemError: 'finally' pops bad exception

IHMO, the exception should be caught above.

Attached is a mini-project to replicate the bug and possible patch.
After patching, the project compiles without warnings and exceptions
seem to be caughr correctly.


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