From df66516ed35c1a22231f283cc8e4a2dbc8d57c13 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sat, 14 Nov 2020 09:02:14 -0800
Subject: [PATCH] Workaround an issue with mixing std versions in gcc (#2017)

---
 include/fmt/format.h | 14 +++-----------
 test/format-test.cc  |  7 ++++---
 2 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index b967afea..1a037b02 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1145,8 +1145,8 @@ template <typename T = void> struct null {};
 template <typename Char> struct fill_t {
  private:
   enum { max_size = 4 };
-  Char data_[max_size];
-  unsigned char size_;
+  Char data_[max_size] = {Char(' '), Char(0), Char(0), Char(0)};
+  unsigned char size_ = 1;
 
  public:
   FMT_CONSTEXPR void operator=(basic_string_view<Char> s) {
@@ -1166,13 +1166,6 @@ template <typename Char> struct fill_t {
   FMT_CONSTEXPR const Char& operator[](size_t index) const {
     return data_[index];
   }
-
-  static FMT_CONSTEXPR fill_t<Char> make() {
-    auto fill = fill_t<Char>();
-    fill[0] = Char(' ');
-    fill.size_ = 1;
-    return fill;
-  }
 };
 }  // namespace detail
 
@@ -1204,8 +1197,7 @@ template <typename Char> struct basic_format_specs {
         type(0),
         align(align::none),
         sign(sign::none),
-        alt(false),
-        fill(detail::fill_t<Char>::make()) {}
+        alt(false) {}
 };
 
 using format_specs = basic_format_specs<char>;
diff --git a/test/format-test.cc b/test/format-test.cc
index 5626fa28..d3f21b47 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -2423,17 +2423,17 @@ TEST(FormatTest, CharTraitsIsNotAmbiguous) {
 #endif
 }
 
+#if __cplusplus > 201103L
 struct custom_char {
   int value;
   custom_char() = default;
 
-  template <typename T> custom_char(T val) : value(static_cast<int>(val)) {}
+  template <typename T>
+  constexpr custom_char(T val) : value(static_cast<int>(val)) {}
 
   operator int() const { return value; }
 };
 
-int to_ascii(custom_char c) { return c; }
-
 FMT_BEGIN_NAMESPACE
 template <> struct is_char<custom_char> : std::true_type {};
 FMT_END_NAMESPACE
@@ -2444,6 +2444,7 @@ TEST(FormatTest, FormatCustomChar) {
   EXPECT_EQ(result.size(), 1);
   EXPECT_EQ(result[0], custom_char('x'));
 }
+#endif
 
 // Convert a char8_t string to std::string. Otherwise GTest will insist on
 // inserting `char8_t` NTBS into a `char` stream which is disabled by P1423.