Only declare the C++ no-args constructor as "nogil" if the base classes allow it.

Closes #2157.

Cython/Compiler/ExprNodes.py

@@ -1729,12 +1729,7 @@ class NewExprNode(AtomicExprNode):
             self.type = error_type
             return
         self.cpp_check(env)
-        constructor = type.scope.lookup(u'<init>')
-        if constructor is None:
-            func_type = PyrexTypes.CFuncType(
-                type, [], exception_check='+', nogil=True)
-            type.scope.declare_cfunction(u'<init>', func_type, self.pos)
-            constructor = type.scope.lookup(u'<init>')
+        constructor = type.get_constructor(self.pos)
         self.class_type = type
         self.entry = constructor
         self.type = constructor.type

Cython/Compiler/PyrexTypes.py

@@ -3817,6 +3817,23 @@ class CppClassType(CType):
             func_type = func_type.base_type
         return func_type.return_type
 
+    def get_constructor(self, pos):
+        constructor = self.scope.lookup('<init>')
+        if constructor is not None:
+            return constructor
+
+        # Otherwise: automatically declare no-args default constructor.
+        # Make it "nogil" if the base classes allow it.
+        nogil = True
+        for base in self.base_classes:
+            base_constructor = base.scope.lookup('<init>')
+            if base_constructor and not base_constructor.type.nogil:
+                nogil = False
+                break
+
+        func_type = CFuncType(self, [], exception_check='+', nogil=nogil)
+        return self.scope.declare_cfunction(u'<init>', func_type, pos)
+
     def check_nullary_constructor(self, pos, msg="stack allocated"):
         constructor = self.scope.lookup(u'<init>')
         if constructor is not None and best_match([], constructor.all_alternatives()) is None:

tests/run/cpp_classes.pyx

@@ -9,7 +9,7 @@ cdef extern from "shapes.h" namespace "shapes":
         float area()
 
     cdef cppclass Ellipse(Shape):
-        Ellipse(int a, int b) except +
+        Ellipse(int a, int b) nogil except +
 
     cdef cppclass Circle(Ellipse):
         int radius
@@ -32,6 +32,7 @@ cdef extern from "shapes.h" namespace "shapes":
 
     int constructor_count, destructor_count
 
+
 def test_new_del():
     """
     >>> test_new_del()
@@ -45,6 +46,7 @@ def test_new_del():
     del rect, circ
     print constructor_count-c, destructor_count-d
 
+
 def test_default_constructor():
     """
     >>> test_default_constructor()
@@ -56,6 +58,20 @@ def test_default_constructor():
     finally:
         del shape
 
+
+def test_constructor_nogil():
+    """
+    >>> test_constructor_nogil()
+    True
+    """
+    with nogil:
+        shape = new Ellipse(4, 5)
+    try:
+        return 62 < shape.area() < 63 or shape.area()
+    finally:
+        del shape
+
+
 def test_rect_area(w, h):
     """
     >>> test_rect_area(3, 4)
@@ -67,6 +83,7 @@ def test_rect_area(w, h):
     finally:
         del rect
 
+
 def test_overload_bint_int():
     """
     >>> test_overload_bint_int()
@@ -83,6 +100,7 @@ def test_overload_bint_int():
         del rect1
         del rect2
 
+
 def test_square_area(w):
     """
     >>> test_square_area(15)
@@ -95,6 +113,7 @@ def test_square_area(w):
     finally:
         del sqr
 
+
 cdef double get_area(Rectangle s):
     return s.area()
 
@@ -110,6 +129,7 @@ def test_value_call(int w):
     finally:
         del sqr
 
+
 def get_destructor_count():
     return destructor_count
 
@@ -126,6 +146,7 @@ def test_stack_allocation(int w, int h):
     print rect.method(<int>5)
     return destructor_count
 
+
 cdef class EmptyHolder:
     cdef Empty empty
 
@@ -148,6 +169,7 @@ def test_class_member():
     assert destructor_count - start_destructor_count == 2, \
            destructor_count - start_destructor_count
 
+
 def test_derived_class_member():
     """
     >>> test_derived_class_member()
@@ -161,6 +183,7 @@ def test_derived_class_member():
     assert destructor_count - start_destructor_count == 2, \
            destructor_count - start_destructor_count
 
+
 cdef class TemplateClassMember:
     cdef vector[int] x
     cdef vector[vector[Empty]] vec
@@ -190,6 +213,9 @@ cdef int f(int x):
     return x
 
 def test_nested_del():
+    """
+    >>> test_nested_del()
+    """
     cdef vector[vector_int_ptr] v
     v.push_back(new vector[int]())
     del v[0]