From 6d597e39c3397da39e8dd9b84df958e8589afa1a Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@fb.com>
Date: Thu, 26 Aug 2021 16:54:27 -0700
Subject: [PATCH] Fix overload ambiguity in arg_mapper

---
 include/fmt/core.h | 8 ++++----
 test/xchar-test.cc | 4 ++++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/fmt/core.h b/include/fmt/core.h
index 3097feee..bb67a9ea 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -1270,7 +1270,8 @@ template <typename Context> struct arg_mapper {
   FMT_CONSTEXPR FMT_INLINE auto map(const char_type* val) -> const char_type* {
     return val;
   }
-  template <typename T, FMT_ENABLE_IF(is_string<T>::value)>
+  template <typename T,
+            FMT_ENABLE_IF(is_string<T>::value && !std::is_pointer<T>::value)>
   FMT_CONSTEXPR FMT_INLINE auto map(const T& val)
       -> basic_string_view<char_type> {
     static_assert(std::is_same<char_type, char_t<T>>::value,
@@ -1324,9 +1325,8 @@ template <typename Context> struct arg_mapper {
 
   // We use SFINAE instead of a const T* parameter to avoid conflicting with
   // the C array overload.
-  template <typename T>
-  FMT_CONSTEXPR auto map(T)
-      -> enable_if_t<std::is_pointer<T>::value, unformattable_pointer> {
+  template <typename T, FMT_ENABLE_IF(std::is_pointer<T>::value)>
+  FMT_CONSTEXPR auto map(T) -> unformattable_pointer {
     return {};
   }
 
diff --git a/test/xchar-test.cc b/test/xchar-test.cc
index 4e837aab..106840e6 100644
--- a/test/xchar-test.cc
+++ b/test/xchar-test.cc
@@ -87,6 +87,10 @@ TEST(xchar_test, format) {
   EXPECT_EQ(L"abc1", fmt::format(L"{}c{}", L"ab", 1));
 }
 
+TEST(xchar_test, is_formattable) {
+  static_assert(!fmt::is_formattable<const wchar_t*>::value, "");
+}
+
 TEST(xchar_test, compile_time_string) {
 #if defined(FMT_USE_STRING_VIEW) && __cplusplus >= 201703L
   EXPECT_EQ(L"42", fmt::format(FMT_STRING(std::wstring_view(L"{}")), 42));