Detect function template parameters through pointers and references.

Fixes #1541

Cython/Compiler/Nodes.py

@@ -545,6 +545,9 @@ class CPtrDeclaratorNode(CDeclaratorNode):
 
     child_attrs = ["base"]
 
+    def analyse_templates(self):
+        return self.base.analyse_templates()
+
     def analyse(self, base_type, env, nonempty=0):
         if base_type.is_pyobject:
             error(self.pos, "Pointer base type cannot be a Python object")
@@ -557,6 +560,9 @@ class CReferenceDeclaratorNode(CDeclaratorNode):
 
     child_attrs = ["base"]
 
+    def analyse_templates(self):
+        return self.base.analyse_templates()
+
     def analyse(self, base_type, env, nonempty=0):
         if base_type.is_pyobject:
             error(self.pos, "Reference base type cannot be a Python object")

tests/run/cpp_template_functions.pyx

@@ -10,6 +10,7 @@ cdef extern from "cpp_template_functions_helper.h":
         pair[T, U] method[U](T, U)
     cdef T nested_deduction[T](const T*)
     pair[T, U] pair_arg[T, U](pair[T, U] a)
+    cdef T* pointer_param[T](T*)
 
 def test_no_arg():
     """
@@ -63,3 +64,10 @@ def test_class_deductions(pair[long, double] x):
     """
     return pair_arg(x)
 
+def test_deduce_through_pointers(int k):
+    """
+    >>> test_deduce_through_pointers(5)
+    (5, 5.0)
+    """
+    cdef double x = k
+    return pointer_param(&k)[0], pointer_param(&x)[0]

tests/run/cpp_template_functions_helper.h

@@ -31,3 +31,8 @@ template <typename T, typename U>
 std::pair<T, U> pair_arg(std::pair<T, U> a) {
     return a;
 }
+
+template <typename T>
+T* pointer_param(T* param) {
+    return param;
+}