Fix compilation issue on VS2019 (#1186) (#1191)

include/fmt/core.h

@@ -204,9 +204,10 @@ FMT_BEGIN_NAMESPACE
 template <bool B, class T = void>
 using enable_if_t = typename std::enable_if<B, T>::type;
 
-// An enable_if helper to be used in template parameters which results in much
+// enable_if helpers to be used in template parameters which results in much
 // shorter symbols: https://godbolt.org/z/sWw4vP.
-#define FMT_ENABLE_IF(...) enable_if_t<__VA_ARGS__, int> = 0
+// Also include fix for VS2019 compilation issue (see #1140 and #1186).
+#define FMT_ENABLE_IF(...) enable_if_t<(__VA_ARGS__), int> = 0
 
 namespace internal {
 

include/fmt/format-inl.h

@@ -674,7 +674,8 @@ template <int GRISU_VERSION> struct grisu_shortest_handler {
   }
 };
 
-template <typename Double, enable_if_t<sizeof(Double) == sizeof(uint64_t), int>>
+template <typename Double,
+          enable_if_t<(sizeof(Double) == sizeof(uint64_t)), int>>
 FMT_API bool grisu_format(Double value, buffer<char>& buf, int precision,
                           unsigned options, int& exp) {
   FMT_ASSERT(value >= 0, "value is negative");

include/fmt/format.h

@@ -2246,7 +2246,7 @@ FMT_CONSTEXPR bool do_check_format_string(basic_string_view<Char> s,
 }
 
 template <typename... Args, typename S,
-          enable_if_t<is_compile_string<S>::value, int>>
+          enable_if_t<(is_compile_string<S>::value), int>>
 void check_format_string(S format_str) {
   typedef typename S::char_type char_t;
   FMT_CONSTEXPR_DECL bool invalid_format =