Fix overload ambiguity in arg_mapper

fmtlib · Aug 26, 2021 · 6d597e3 · 6d597e3
1 parent b9ce56d
commit 6d597e3
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Showing 2 changed files with 8 additions and 4 deletions.
diff --git 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
@@ -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));