Allow assignment of C function pointers with compatible exception declarations...

Allow assignment of C function pointers with compatible exception declarations (not only exact matches).

Cython/Compiler/ExprNodes.py

@@ -916,6 +916,7 @@ class ExprNode(Node):
             # in different pxi files.
             # TODO: Remove this hack and require shared declarations.
             if not (src.type == dst_type or str(src.type) == str(dst_type) or dst_type.assignable_from(src_type)):
+                print(src_type, dst_type)
                 self.fail_assignment(dst_type)
         return src
 

Cython/Compiler/PyrexTypes.py

@@ -2627,7 +2627,11 @@ class CFuncType(CType):
         return self.same_c_signature_as_resolved_type(
             other_type.resolve(), as_cmethod)
 
-    def same_c_signature_as_resolved_type(self, other_type, as_cmethod = 0, as_pxd_definition = 0):
+    def same_c_signature_as_resolved_type(self, other_type, as_cmethod=False, as_pxd_definition=False,
+                                          exact_semantics=True):
+        # If 'exact_semantics' is false, allow any C compatible signatures
+        # if the Cython semantics are compatible.
+
         #print "CFuncType.same_c_signature_as_resolved_type:", \
         #    self, other_type, "as_cmethod =", as_cmethod ###
         if other_type is error_type:
@@ -2656,12 +2660,15 @@ class CFuncType(CType):
         else:
             if not self.return_type.same_as(other_type.return_type):
                 return 0
+        if exact_semantics:
             if not self.same_calling_convention_as(other_type):
                 return 0
             if self.exception_check != other_type.exception_check:
                 return 0
             if not self._same_exception_value(other_type.exception_value):
                 return 0
+        else:
+            return self.compatible_signature_with_resolved_type(other_type, as_cmethod=as_cmethod)
         return 1
 
     def _same_exception_value(self, other_exc_value):
@@ -2770,13 +2777,14 @@ class CFuncType(CType):
         sc2 = other.calling_convention == '__stdcall'
         return sc1 == sc2
 
-    def same_as_resolved_type(self, other_type, as_cmethod = 0):
-        return self.same_c_signature_as_resolved_type(other_type, as_cmethod) \
+    def same_as_resolved_type(self, other_type, as_cmethod=False):
+        return self.same_c_signature_as_resolved_type(other_type, as_cmethod=as_cmethod) \
             and self.nogil == other_type.nogil
 
-    def pointer_assignable_from_resolved_type(self, other_type):
-        return self.same_c_signature_as_resolved_type(other_type) \
-            and not (self.nogil and not other_type.nogil)
+    def pointer_assignable_from_resolved_type(self, rhs_type):
+        # Accept compatible exception declarations for the RHS.
+        return rhs_type.same_c_signature_as_resolved_type(self, exact_semantics=False) \
+            and not (self.nogil and not rhs_type.nogil)
 
     def declaration_code(self, entity_code,
                          for_display = 0, dll_linkage = None, pyrex = 0,

tests/run/pxd_signature_excvalue.srctree

 PYTHON setup.py build_ext --inplace
 PYTHON -c "import foo"
-PYTHON -c "import a"
+PYTHON -c "import a; a.test()"
 
 ######## setup.py ########
 
@@ -15,6 +15,9 @@ setup(
 
 cdef int bar(int i) except *
 
+cdef int (*var_opt)(int) except? -1
+cdef int (*var_orig)(int) except *
+
 ######## foo.pyx ########
 
 cdef int bar(int i) except *:
@@ -22,10 +25,13 @@ cdef int bar(int i) except *:
         raise ValueError()
     return i + 1
 
+var_opt = bar   # by 'accident' of optimisation
+var_orig = bar  # by declaration
+
 ######## a.pyx ########
 
 cimport cython
-from foo cimport bar
+from foo cimport bar, var_orig, var_opt
 
 def test():
     assert bar(-2) == -1
@@ -34,4 +40,20 @@ def test():
     except ValueError:
         pass
     else:
-        assert False, "exception not raised"
+        assert False, "exception not raised in bar()"
+
+    assert var_orig(-2) == -1
+    try:
+        var_orig(10)
+    except ValueError:
+        pass
+    else:
+        assert False, "exception not raised in var_orig()"
+
+    assert var_opt(-2) == -1
+    try:
+        var_opt(10)
+    except ValueError:
+        pass
+    else:
+        assert False, "exception not raised in var_opt()"