From 8a06ca84c7995a1b6966845ecb4d376e6fde4ea0 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@fb.com>
Date: Thu, 5 Mar 2020 11:43:33 -0800
Subject: [PATCH] Fix ambiguous overloads of format & format_to

---
 include/fmt/compile.h | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/include/fmt/compile.h b/include/fmt/compile.h
index 2e166b5c..ca8b4285 100644
--- a/include/fmt/compile.h
+++ b/include/fmt/compile.h
@@ -351,6 +351,8 @@ template <int N, typename... Args> struct get_type_impl<N, type_list<Args...>> {
 template <int N, typename T>
 using get_type = typename get_type_impl<N, T>::type;
 
+template <typename T> struct is_static_compiled_format : std::false_type {};
+
 template <typename Char> struct text {
   basic_string_view<Char> data;
   using char_type = Char;
@@ -362,6 +364,9 @@ template <typename Char> struct text {
   }
 };
 
+template <typename Char>
+struct is_static_compiled_format<text<Char>> : std::true_type {};
+
 template <typename Char>
 constexpr text<Char> make_text(basic_string_view<Char> s, size_t pos,
                                size_t size) {
@@ -407,6 +412,9 @@ template <typename Char, typename T, int N> struct field {
   }
 };
 
+template <typename Char, typename T, int N>
+struct is_static_compiled_format<field<Char, T, N>> : std::true_type {};
+
 template <typename L, typename R> struct concat {
   L lhs;
   R rhs;
@@ -419,6 +427,9 @@ template <typename L, typename R> struct concat {
   }
 };
 
+template <typename L, typename R>
+struct is_static_compiled_format<concat<L, R>> : std::true_type {};
+
 template <typename L, typename R>
 constexpr concat<L, R> make_concat(L lhs, R rhs) {
   return {lhs, rhs};
@@ -507,19 +518,19 @@ constexpr auto compile(S format_str) {
   }
 }
 
-template <typename CompiledFormat, typename... Args,
-          typename Char = typename CompiledFormat::char_type,
-          FMT_ENABLE_IF(!std::is_base_of<internal::basic_compiled_format,
-                                         CompiledFormat>::value)>
+template <
+    typename CompiledFormat, typename... Args,
+    typename Char = typename CompiledFormat::char_type,
+    FMT_ENABLE_IF(internal::is_static_compiled_format<CompiledFormat>::value)>
 std::basic_string<Char> format(const CompiledFormat& cf, const Args&... args) {
   basic_memory_buffer<Char> buffer;
   cf.format(std::back_inserter(buffer), args...);
   return to_string(buffer);
 }
 
-template <typename OutputIt, typename CompiledFormat, typename... Args,
-          FMT_ENABLE_IF(!std::is_base_of<internal::basic_compiled_format,
-                                         CompiledFormat>::value)>
+template <
+    typename OutputIt, typename CompiledFormat, typename... Args,
+    FMT_ENABLE_IF(internal::is_static_compiled_format<CompiledFormat>::value)>
 OutputIt format_to(OutputIt out, const CompiledFormat& cf,
                    const Args&... args) {
   return cf.format(out, args...);