string: fancy comparators should take only string_views

This reduces complications dealing with implicit casts from things like
'std::string' which are fairly common.

string.hpp

@@ -302,10 +302,9 @@ namespace cruft::string::compare {
     /// \tparam TransformV   A character transform function
     template <char (*TransformV)(char) noexcept>
     struct transform {
-        template <typename ContainerT>
         bool operator() (
-            ContainerT const &a,
-            ContainerT const &b
+            std::string_view const &a,
+            std::string_view const &b
         ) const noexcept {
             if (a.size () != b.size ())
                 return false;
@@ -316,18 +315,6 @@ namespace cruft::string::compare {
 
             return true;
         }
-
-
-        template <
-            typename CharT,
-            typename = std::void_t<
-                typename std::char_traits<CharT>::char_type
-            >
-        >
-        bool operator() (CharT const *a, CharT const *b) const noexcept
-        {
-            return (*this) (std::string_view (a), std::string_view (b));
-        }
     };
 
     using lower = transform<ascii::try_lower>;

test/string.cpp

@@ -210,15 +210,6 @@ void test_comparator_lower (cruft::TAP::logger &tap)
 
     for (auto const &t: TESTS) {
         tap.expect_eq (cmp (t.a, t.b), t.equal, "compare::lower, pointers, %!", t.message);
-        tap.expect_eq (
-            cmp (
-                cruft::view (t.a),
-                cruft::view (t.b)
-            ),
-            t.equal,
-            "compare::lower, views, %!",
-            t.message
-        );
     }
 }