From ddd7caf38eeb281641f0881634c576b50c637c38 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sat, 13 Oct 2018 06:52:33 -0700
Subject: [PATCH] Fix locale-dependent formatting (#905)

---
 include/fmt/format.h | 14 ++++++++++----
 test/format-test.cc  |  2 ++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index f232be54..96774875 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -988,6 +988,8 @@ struct no_thousands_sep {
 
   template <typename Char>
   void operator()(Char *) {}
+
+  enum { size = 0 };
 };
 
 // A functor that adds a thousands separator.
@@ -1012,6 +1014,8 @@ class add_thousands_sep {
     std::uninitialized_copy(sep_.data(), sep_.data() + sep_.size(),
                             internal::make_checked(buffer, sep_.size()));
   }
+
+  enum { size = 1 };
 };
 
 template <typename Char>
@@ -1052,10 +1056,12 @@ template <typename OutChar, typename UInt, typename Iterator,
 inline Iterator format_decimal(
     Iterator out, UInt value, unsigned num_digits, ThousandsSep sep) {
   typedef typename ThousandsSep::char_type char_type;
-  // Buffer should be large enough to hold all digits (digits10 + 1) and null.
-  char_type buffer[std::numeric_limits<UInt>::digits10 + 2];
-  format_decimal(buffer, value, num_digits, sep);
-  return internal::copy_str<OutChar>(buffer, buffer + num_digits, out);
+  // Buffer should be large enough to hold all digits (<= digits10 + 1).
+  enum { max_size = std::numeric_limits<UInt>::digits10 + 1 };
+  FMT_ASSERT(ThousandsSep::size <= 1, "invalid separator");
+  char_type buffer[max_size + max_size / 3];
+  auto end = format_decimal(buffer, value, num_digits, sep);
+  return internal::copy_str<OutChar>(buffer, end, out);
 }
 
 template <typename OutChar, typename It, typename UInt>
diff --git a/test/format-test.cc b/test/format-test.cc
index dd3ed739..484fa21d 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -1378,6 +1378,8 @@ TEST(FormatterTest, FormatIntLocale) {
   EXPECT_EQ("123", format("{:n}", 123));
   EXPECT_EQ("1,234", format("{:n}", 1234));
   EXPECT_EQ("1,234,567", format("{:n}", 1234567));
+  EXPECT_EQ("4,294,967,295",
+            format("{:n}", std::numeric_limits<uint32_t>::max()));
 }
 
 struct ConvertibleToLongLong {