diff --git a/sphinx/domains/cpp.py b/sphinx/domains/cpp.py
index a6d0a2abe..e8990b235 100644
--- a/sphinx/domains/cpp.py
+++ b/sphinx/domains/cpp.py
@@ -915,8 +915,6 @@ class ASTNestedName(ASTBase):
         assert len(names) > 0
         self.names = names
         self.rooted = rooted
-        for i in range(len(names) - 1):
-            assert not names[i].is_operator()
 
     @property
     def name(self):
@@ -2123,17 +2121,13 @@ class Symbol(object):
             s = s.parent
         symbols.reverse()
         key = []
-        for s in symbols[:-1]:
-            assert s.identifier
-            nne = ASTNestedNameElement(s.identifier, s.templateArgs)
+        for s in symbols:
+            if s.identifier:
+                nne = ASTNestedNameElement(s.identifier, s.templateArgs)
+            else:
+                assert s.declaration
+                nne = s.declaration.name.names[-1]
             key.append((nne, s.templateParams))
-        s = symbols[-1]
-        if s.identifier:
-            nne = ASTNestedNameElement(s.identifier, s.templateArgs)
-        else:
-            assert self.declaration
-            nne = s.declaration.name.names[-1]
-        key.append((nne, s.templateParams))
         return key
 
     def get_full_nested_name(self):
diff --git a/tests/test_domain_cpp.py b/tests/test_domain_cpp.py
index 9d6b6c3e2..e0d5a3086 100644
--- a/tests/test_domain_cpp.py
+++ b/tests/test_domain_cpp.py
@@ -304,6 +304,15 @@ def test_templates():
           "void allow(F *f, typename func<F, B, G!=1>::type tt)",
           None, "I0E5allowP1FN4funcI1F1BXG!=1EE4typeE")
 
+    # from #2058
+    check('function',
+          "template<typename Char, typename Traits> "
+          "inline std::basic_ostream<Char, Traits> &operator<<("
+          "std::basic_ostream<Char, Traits> &os, "
+          "const c_string_view_base<const Char, Traits> &str)",
+          None, "I00ElsRNSt13basic_ostreamI4Char6TraitsEE"
+          "RK18c_string_view_baseIK4Char6TraitsE")
+
 
 def test_class():
     check('class', 'A final', 'A', '1A')