Fix for a failing case of template reference arguments

with some improvements to previously committed test case

Cython/Compiler/ExprNodes.py

@@ -600,7 +600,7 @@ class ExprNode(Node):
         if self.check_for_coercion_error(dst_type):
             return self
 
-        if dst_type.is_reference:
+        if dst_type.is_reference and not src_type.is_reference:
             dst_type = dst_type.ref_base_type
 
         if src_type.is_fused or dst_type.is_fused:

tests/bugs.txt

@@ -8,7 +8,6 @@ missing_baseclass_in_predecl_T262
 cfunc_call_tuple_args_T408
 compile.cpp_operators
 cpp_templated_ctypedef
-cpp_template_args
 cpp_structs
 function_as_method_T494
 closure_inside_cdef_T554

tests/compile/cpp_template_args.pyx

-
-cdef extern from "template_args.h":
-
-    cdef cppclass Bar [T]:
-        Bar()
-
-    cdef cppclass Foo [T]:
-        Foo()
-        void set_bar(Bar[size_t] & bar)
-
-cpdef func():
-    cdef Foo[int] foo
-    cdef Bar[size_t] bar
-    cdef Bar[size_t] & bref = bar
-
-    foo.set_bar(bref)
-

tests/compile/template_args.h → tests/run/cpp_template_ref_args.h

@@ -3,11 +3,13 @@
 
 template <typename T>
 struct Bar {
+    Bar & ref() { return *this; }
+    T value;
 };
 
 template <typename T>
 struct Foo {
-    void set_bar(const Bar[size_t] & bar) {}
+    int bar_value(const Bar<int> & bar) { return bar.value; }
 };
 
 #endif

tests/run/cpp_template_ref_args.pyx

+# tag: cpp
+
+
+cdef extern from "cpp_template_ref_args.h":
+
+    cdef cppclass Bar[T]:
+        Bar()
+        Bar[T] & ref()
+        T value
+
+    cdef cppclass Foo[T]:
+        Foo()
+        int bar_value(Bar[int] & bar)
+
+
+def test_template_ref_arg(int x):
+    """
+    >>> test_template_ref_arg(4)
+    4
+    """
+
+    # Templated reference parameters in method
+    # of templated classes were not properly coalesced.
+
+    cdef Foo[size_t] foo
+    cdef Bar[int] bar
+
+    bar.value = x
+
+    return foo.bar_value(bar.ref())