From 0fc7bd157381e2d28a0b3d37948faa461024b018 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sat, 28 Sep 2019 09:13:32 -0700
Subject: [PATCH] Fix ambiguity for types with dodgy conversions

---
 include/fmt/ranges.h |  3 ++-
 test/ranges-test.cc  | 21 +++++++++++++++++----
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/include/fmt/ranges.h b/include/fmt/ranges.h
index e031038a..6110fdaf 100644
--- a/include/fmt/ranges.h
+++ b/include/fmt/ranges.h
@@ -246,7 +246,8 @@ template <typename T, typename Char> struct is_range {
   static FMT_CONSTEXPR_DECL const bool value =
       internal::is_range_<T>::value &&
       !internal::is_like_std_string<T>::value &&
-      !std::is_convertible<T, std::basic_string<Char>>::value;
+      !std::is_convertible<T, std::basic_string<Char>>::value &&
+      !std::is_constructible<internal::std_string_view<Char>, T>::value;
 };
 
 template <typename RangeT, typename Char>
diff --git a/test/ranges-test.cc b/test/ranges-test.cc
index 56c8aa98..265f9acd 100644
--- a/test/ranges-test.cc
+++ b/test/ranges-test.cc
@@ -9,13 +9,13 @@
 // All Rights Reserved
 // {fmt} support for ranges, containers and types tuple interface.
 
-/// Check if  'if constexpr' is supported.
+#include "fmt/ranges.h"
+#include "gtest.h"
+
+// Check if  'if constexpr' is supported.
 #if (__cplusplus > 201402L) || \
     (defined(_MSVC_LANG) && _MSVC_LANG > 201402L && _MSC_VER >= 1910)
 
-#  include "fmt/ranges.h"
-#  include "gtest.h"
-
 #  include <array>
 #  include <map>
 #  include <string>
@@ -119,3 +119,16 @@ TEST(RangesTest, PathLike) {
 
 #endif  // (__cplusplus > 201402L) || (defined(_MSVC_LANG) && _MSVC_LANG >
         // 201402L && _MSC_VER >= 1910)
+
+#ifdef FMT_USE_STRING_VIEW
+struct string_like {
+  const char* begin();
+  const char* end();
+  explicit operator fmt::string_view() const { return "foo"; }
+  explicit operator std::string_view() const { return "foo"; }
+};
+
+TEST(RangesTest, FormatStringLike) {
+  EXPECT_EQ("foo", fmt::format("{}", string_like()));
+}
+#endif  // FMT_USE_STRING_VIEW