show argument types in docstring of wrapped C function

Cython/Compiler/PyrexTypes.py

@@ -2669,6 +2669,7 @@ class CFuncType(CType):
                 self.type = arg.type
                 self.type_name = 'TYPE%s' % ix
                 self.type_cname = self.type.declaration_code("")
+                self.type_displayname = self.type.declaration_code("", for_display=True)
                 if self.type.is_extension_type or self.type.is_builtin_type:
                     self.type_convert = '<%s>' % self.type_name
                 elif self.type.is_pyobject:

Cython/Utility/CFuncConvert.pyx

@@ -14,7 +14,7 @@ cdef extern from *:
 @cname("{{cname}}")
 cdef object {{cname}}({{return_type}} (*f)({{ ', '.join(arg.type_name for arg in args) }}) {{except_clause}}):
     def wrap({{ ', '.join(arg.name for arg in args) }}):
-        """wrap({{', '.join(arg.name for arg in args)}})"""
+        """wrap({{', '.join('{arg.name}: {arg.type_displayname!r}'.format(arg=arg) for arg in args)}})"""
         {{for arg in args}}
         {{arg.check_type()}}
         {{endfor}}

tests/run/cfunc_convert.pyx

@@ -38,7 +38,7 @@ def return_square_c():
     >>> square_c(x=4)
     16.0
     >>> square_c.__doc__   # FIXME: try to make original C function name available
-    'wrap(x)'
+    "wrap(x: 'double')"
     """
     return square_c
 
@@ -88,6 +88,16 @@ def call_abc(a, b, c):
     cdef object py_func = abc
     return py_func(a, b, c)
 
+def return_abc():
+    """
+    >>> abc = return_abc()
+    >>> abc(2, 3, 5)
+    False
+    >>> abc.__doc__
+    "wrap(a: 'long long', b: 'long long', c: 'long long')"
+    """
+    return abc
+
 
 ctypedef double foo
 cdef foo test_typedef_cfunc(foo x):