allow struct constructors to coerce directly to Python dicts without intermediate assignment

CHANGES.rst

@@ -32,6 +32,9 @@ Bugs fixed
 * Relative cimports could accidentally fall back to trying an absolute cimport
   on failure.
 
+* The result of calling a C struct constructor no longer requires an intermediate
+  assignment when coercing to a Python dict.
+
 * Runtime reported file paths of source files (e.g for profiling and tracing)
   are now relative to the build root directory instead of the main source file.
 

Cython/Compiler/ExprNodes.py

@@ -7164,6 +7164,13 @@ class DictNode(ExprNode):
     def coerce_to(self, dst_type, env):
         if dst_type.is_pyobject:
             self.release_errors()
+            if self.type.is_struct_or_union:
+                if not dict_type.subtype_of(dst_type):
+                    error(self.pos, "Cannot interpret struct as non-dict type '%s'" % dst_type)
+                return DictNode(self.pos, key_value_pairs=[
+                    DictItemNode(item.pos, key=item.key.coerce_to_pyobject(env),
+                                 value=item.value.coerce_to_pyobject(env))
+                    for item in self.key_value_pairs])
             if not self.type.subtype_of(dst_type):
                 error(self.pos, "Cannot interpret dict as type '%s'" % dst_type)
         elif dst_type.is_struct_or_union:

tests/run/struct_conversion.pyx

@@ -13,6 +13,17 @@ def test_constructor(x, y, color):
     cdef Point p = Point(x, y, color)
     return p
 
+
+def return_constructor(x, y, color):
+    """
+    >>> sorted(return_constructor(1,2,255).items())
+    [('color', 255), ('x', 1.0), ('y', 2.0)]
+    >>> try: return_constructor(1, None, 255)
+    ... except TypeError: pass
+    """
+    return Point(x, y, color)
+
+
 def test_constructor_kwds(x, y, color):
     """
     >>> sorted(test_constructor_kwds(1.25, 2.5, 128).items())
@@ -25,6 +36,19 @@ def test_constructor_kwds(x, y, color):
     cdef Point p = Point(x=x, y=y, color=color)
     return p
 
+
+def return_constructor_kwds(x, y, color):
+    """
+    >>> sorted(return_constructor_kwds(1.25, 2.5, 128).items())
+    [('color', 128), ('x', 1.25), ('y', 2.5)]
+    >>> return_constructor_kwds(1.25, 2.5, None)
+    Traceback (most recent call last):
+    ...
+    TypeError: an integer is required
+    """
+    return Point(x=x, y=y, color=color)
+
+
 def test_dict_construction(x, y, color):
     """
     >>> sorted(test_dict_construction(4, 5, 64).items())