Merge pull request #2615 from robertwb/cpp-py-exception

Allow catching both C++ and Python exceptions.

Cython/Compiler/ExprNodes.py

@@ -187,22 +187,35 @@ def infer_sequence_item_type(env, seq_node, index_node=None, seq_type=None):
             return item_types.pop()
     return None
 
+# Returns a block of code to translate the exception,
+# plus a boolean indicating whether to check for Python exceptions.
 def get_exception_handler(exception_value):
     if exception_value is None:
-        return "__Pyx_CppExn2PyErr();"
+        return "__Pyx_CppExn2PyErr();", False
+    elif (exception_value.type == PyrexTypes.c_char_type
+          and exception_value.value == '*'):
+        return "__Pyx_CppExn2PyErr();", True
     elif exception_value.type.is_pyobject:
         return 'try { throw; } catch(const std::exception& exn) { PyErr_SetString(%s, exn.what()); } catch(...) { PyErr_SetNone(%s); }' % (
             exception_value.entry.cname,
-            exception_value.entry.cname)
+            exception_value.entry.cname), False
     else:
-        return '%s(); if (!PyErr_Occurred()) PyErr_SetString(PyExc_RuntimeError , "Error converting c++ exception.");' % exception_value.entry.cname
+        return '%s(); if (!PyErr_Occurred()) PyErr_SetString(PyExc_RuntimeError , "Error converting c++ exception.");' % exception_value.entry.cname, False
+
+def maybe_check_py_error(code, check_py_exception, pos, nogil):
+    if check_py_exception:
+        if nogil:
+            code.putln(code.error_goto_if("__Pyx_ErrOccurredWithGIL()", pos))
+        else:
+            code.putln(code.error_goto_if("PyErr_Occurred()", pos))
 
 def translate_cpp_exception(code, pos, inside, py_result, exception_value, nogil):
-    raise_py_exception = get_exception_handler(exception_value)
+    raise_py_exception, check_py_exception = get_exception_handler(exception_value)
     code.putln("try {")
     code.putln("%s" % inside)
     if py_result:
       code.putln(code.error_goto_if_null(py_result, pos))
+    maybe_check_py_error(code, check_py_exception, pos, nogil)
     code.putln("} catch(...) {")
     if nogil:
         code.put_ensure_gil(declare_gilstate=True)
@@ -216,12 +229,14 @@ def translate_cpp_exception(code, pos, inside, py_result, exception_value, nogil
 # both have an exception declaration.
 def translate_double_cpp_exception(code, pos, lhs_type, lhs_code, rhs_code,
     lhs_exc_val, assign_exc_val, nogil):
-    handle_lhs_exc = get_exception_handler(lhs_exc_val)
-    handle_assignment_exc = get_exception_handler(assign_exc_val)
+    handle_lhs_exc, lhc_check_py_exc = get_exception_handler(lhs_exc_val)
+    handle_assignment_exc, assignment_check_py_exc = get_exception_handler(assign_exc_val)
     code.putln("try {")
     code.putln(lhs_type.declaration_code("__pyx_local_lvalue = %s;" % lhs_code))
+    maybe_check_py_error(code, lhc_check_py_exc, pos, nogil)
     code.putln("try {")
     code.putln("__pyx_local_lvalue = %s;" % rhs_code)
+    maybe_check_py_error(code, assignment_check_py_exc, pos, nogil)
     # Catch any exception from the overloaded assignment.
     code.putln("} catch(...) {")
     if nogil:

Cython/Compiler/Nodes.py

@@ -741,9 +741,11 @@ class CFuncDeclaratorNode(CDeclaratorNode):
                             and not exc_val_type.is_pyobject
                             and not (exc_val_type.is_cfunction
                                      and not exc_val_type.return_type.is_pyobject
-                                     and not exc_val_type.args)):
+                                     and not exc_val_type.args)
+                            and not (exc_val_type == PyrexTypes.c_char_type
+                                     and self.exception_value.value == '*')):
                         error(self.exception_value.pos,
-                              "Exception value must be a Python exception or cdef function with no arguments.")
+                              "Exception value must be a Python exception or cdef function with no arguments or *.")
                     exc_val = self.exception_value
                 else:
                     self.exception_value = self.exception_value.coerce_to(

Cython/Compiler/Parsing.py

@@ -2937,6 +2937,9 @@ def p_exception_value_clause(s):
                 name = s.systring
                 s.next()
                 exc_val = p_name(s, name)
+            elif s.sy == '*':
+                exc_val = ExprNodes.CharNode(s.position(), value=u'*')
+                s.next()
         else:
             if s.sy == '?':
                 exc_check = 1

docs/src/userguide/wrapping_CPlusPlus.rst

@@ -440,6 +440,13 @@ called, which allows one to do custom C++ to Python error "translations." If
 raise_py_error does not actually raise an exception a RuntimeError will be
 raised.
 
+There is also the special form::
+
+    cdef int raise_py_or_cpp() except +*
+
+for those functions that may raise either a Python or a C++ exception.
+
+
 Static member method
 --------------------
 

tests/run/cpp_exceptions.pyx

@@ -22,6 +22,7 @@ cdef extern from "cpp_exceptions_helper.h":
     cdef void raise_underflow() except +
 
     cdef raise_or_throw(bint py) except +
+    cdef int raise_or_throw_int(bint py) except +*
 
     cdef cppclass Foo:
         int bar_raw "bar"(bint fire) except +
@@ -113,6 +114,19 @@ def test_func_that_can_raise_or_throw(bint py):
     """
     raise_or_throw(py)
 
+def test_func_that_can_raise_or_throw_c_return(bint py):
+    """
+    >>> test_func_that_can_raise_or_throw_c_return(0)
+    Traceback (most recent call last):
+    ...
+    RuntimeError: oopsie
+    >>> test_func_that_can_raise_or_throw_c_return(1)
+    Traceback (most recent call last):
+    ...
+    ValueError: oopsie
+    """
+    raise_or_throw_int(py)
+
 def test_int_raw(bint fire):
     """
     >>> test_int_raw(False)

tests/run/cpp_exceptions_helper.h

@@ -70,3 +70,11 @@ PyObject *raise_or_throw(int py) {
     PyErr_SetString(PyExc_ValueError, "oopsie");
     return NULL;
 }
+
+int raise_or_throw_int(int py) {
+    if (!py) {
+        throw std::runtime_error("oopsie");
+    }
+    PyErr_SetString(PyExc_ValueError, "oopsie");
+    return -1;
+}