X on ctuple <- std::pair

Cython/Compiler/ExprNodes.py

@@ -855,7 +855,7 @@ class ExprNode(Node):
         for node in self.subexpr_nodes():
             node.annotate(code)
-    # ----------------- Coercion ----------------------
+    # ----------------- Coercion ----------------------         NOTE here
     def coerce_to(self, dst_type, env):
         #   Coerce the result so that it can be assigned to

Cython/Compiler/Pipeline.py

@@ -179,6 +179,7 @@ def create_pipeline(context, mode, exclude_classes=()):
     # code in pxd files. So it will be run multiple times in a
     # compilation stage.
     stages = [
+        #PrintTree(),
         NormalizeTree(context),
         PostParse(context),
         _specific_post_parse,
@@ -209,7 +210,11 @@ def create_pipeline(context, mode, exclude_classes=()):
         IntroduceBufferAuxiliaryVars(context),
         _check_c_declarations,
         InlineDefNodeCalls(context),
+
+        #PrintTree(),
         AnalyseExpressionsTransform(context),
+        #PrintTree(),
+
         FindInvalidUseOfFusedTypes(context),
         ExpandInplaceOperators(context),
         IterationTransform(context),

Cython/Compiler/PyrexTypes.py

@@ -4062,6 +4062,23 @@ class CTupleType(CType):
         env.use_utility_code(self._convert_from_py_code)
         return True
 
+    def assignable_from_resolved_type(self, src_type):
+        if src_type.is_cpp_class and src_type.cname == "std::pair" and len(src_type.templates) == 2:
+            # XXX len self.xxx == len src_type.templates
+            # XXX types are assignable
+
+            print
+            #from Cython.Compiler.Pipeline import dumptree
+            #dumptree(src_type)
+            print src_type
+            print src_type.name
+            print src_type.cname
+            print src_type.templates
+            print
+            return 1    # XXX check types match
+
+        return super(CTupleType, self).assignable_from_resolved_type(src_type)
+
 
 def c_tuple_type(components):
     components = tuple(components)

tests/run/cpp_ctuple.pyx

+# mode: run
+# tag: cpp
+
+from libcpp.utility cimport pair
+
+cdef (int, double) _coerce_from_pair(pair[int, double] pxy) nogil:
+    cdef (int, double) txy = pxy
+    return txy
+
+def coerce_from_pair(int x, double y):
+    """
+    >>> coerce_from_pair(1, 3.14)
+    (1, 3.14)
+    """
+    cdef pair[int, double] pxy = (x,y)
+    return _coerce_from_pair(pxy)