Deprecated implicit conversion of enums to ints for consistency with scoped enums

include/fmt/core.h

@@ -140,6 +140,20 @@
 #  endif
 #endif
 
+#ifndef FMT_DEPRECATED
+#  if FMT_HAS_CPP14_ATTRIBUTE(deprecated) || FMT_MSC_VERSION >= 1900
+#    define FMT_DEPRECATED [[deprecated]]
+#  else
+#    if (defined(__GNUC__) && !defined(__LCC__)) || defined(__clang__)
+#      define FMT_DEPRECATED __attribute__((deprecated))
+#    elif FMT_MSC_VERSION
+#      define FMT_DEPRECATED __declspec(deprecated)
+#    else
+#      define FMT_DEPRECATED /* deprecated */
+#    endif
+#  endif
+#endif
+
 // [[noreturn]] is disabled on MSVC and NVCC because of bogus unreachable code
 // warnings.
 #if FMT_EXCEPTIONS && FMT_HAS_CPP_ATTRIBUTE(noreturn) && !FMT_MSC_VERSION && \
@@ -1420,9 +1434,9 @@ template <typename Context> struct arg_mapper {
   template <typename T,
             FMT_ENABLE_IF(
                 std::is_enum<T>::value&& std::is_convertible<T, int>::value &&
-                !has_formatter<T, Context>::value &&
+                !has_format_as<T>::value && !has_formatter<T, Context>::value &&
                 !has_fallback_formatter<T, char_type>::value)>
-  FMT_CONSTEXPR FMT_INLINE auto map(const T& val)
+  FMT_DEPRECATED FMT_CONSTEXPR FMT_INLINE auto map(const T& val)
       -> decltype(std::declval<arg_mapper>().map(
           static_cast<underlying_t<T>>(val))) {
     return map(static_cast<underlying_t<T>>(val));

include/fmt/format.h

@@ -118,20 +118,6 @@ FMT_END_NAMESPACE
 #  endif
 #endif
 
-#ifndef FMT_DEPRECATED
-#  if FMT_HAS_CPP14_ATTRIBUTE(deprecated) || FMT_MSC_VERSION >= 1900
-#    define FMT_DEPRECATED [[deprecated]]
-#  else
-#    if (defined(__GNUC__) && !defined(__LCC__)) || defined(__clang__)
-#      define FMT_DEPRECATED __attribute__((deprecated))
-#    elif FMT_MSC_VERSION
-#      define FMT_DEPRECATED __declspec(deprecated)
-#    else
-#      define FMT_DEPRECATED /* deprecated */
-#    endif
-#  endif
-#endif
-
 #ifndef FMT_USE_USER_DEFINED_LITERALS
 // EDG based compilers (Intel, NVIDIA, Elbrus, etc), GCC and MSVC support UDLs.
 #  if (FMT_HAS_FEATURE(cxx_user_literals) || FMT_GCC_VERSION >= 407 || \

test/format-test.cc

@@ -1756,6 +1756,7 @@ TEST(format_test, group_digits_view) {
 }
 
 enum test_enum { foo, bar };
+auto format_as(test_enum e) -> int { return e; }
 
 TEST(format_test, join) {
   using fmt::join;
@@ -1902,6 +1903,7 @@ TEST(format_test, formatter_not_specialized) {
 
 #if FMT_HAS_FEATURE(cxx_strong_enums)
 enum big_enum : unsigned long long { big_enum_value = 5000000000ULL };
+auto format_as(big_enum e) -> unsigned long long { return e; }
 
 TEST(format_test, strong_enum) {
   EXPECT_EQ("5000000000", fmt::format("{}", big_enum_value));
@@ -1983,9 +1985,7 @@ TEST(format_test, to_string) {
   EXPECT_EQ(fmt::to_string(reinterpret_cast<void*>(0x1234)), "0x1234");
   EXPECT_EQ(fmt::to_string(adl_test::fmt::detail::foo()), "foo");
   EXPECT_EQ(fmt::to_string(convertible_to_int()), "42");
-
-  enum foo : unsigned char { zero };
-  EXPECT_EQ(fmt::to_string(zero), "0");
+  EXPECT_EQ(fmt::to_string(foo), "0");
 
 #if FMT_USE_FLOAT128
   EXPECT_EQ(fmt::to_string(__float128(0.5)), "0.5");

test/ostream-test.cc

@@ -54,6 +54,7 @@ auto operator<<(std::ostream& os, streamable_enum) -> std::ostream& {
 }
 
 enum unstreamable_enum {};
+auto format_as(unstreamable_enum e) -> int { return e; }
 
 struct empty_test {};
 auto operator<<(std::ostream& os, empty_test) -> std::ostream& {

test/printf-test.cc

@@ -504,6 +504,7 @@ TEST(printf_test, pointer) {
 }
 
 enum test_enum { answer = 42 };
+auto format_as(test_enum e) -> int { return e; }
 
 TEST(printf_test, enum) {
   EXPECT_PRINTF("42", "%d", answer);

test/ranges-test.cc

@@ -224,6 +224,7 @@ TEST(ranges_test, range) {
 }
 
 enum test_enum { foo };
+auto format_as(test_enum e) -> int { return e; }
 
 TEST(ranges_test, enum_range) {
   auto v = std::vector<test_enum>{test_enum::foo};

test/xchar-test.cc

@@ -222,6 +222,7 @@ struct formatter<streamable_enum, wchar_t> : basic_ostream_formatter<wchar_t> {
 }  // namespace fmt
 
 enum unstreamable_enum {};
+auto format_as(unstreamable_enum e) -> int { return e; }
 
 TEST(xchar_test, enum) {
   EXPECT_EQ(L"streamable_enum", fmt::format(L"{}", streamable_enum()));