From 5934a281244126e4728d3519a1f690f1c836eea2 Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkrystian@gmail.com>
Date: Fri, 6 Mar 2020 22:26:06 -0500
Subject: [PATCH] Fix operator+ for non-full arrays

---
 include/boost/static_string/static_string.hpp | 16 ++++++--------
 test/static_string.cpp                        | 22 +++++++++++++++++--
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/include/boost/static_string/static_string.hpp b/include/boost/static_string/static_string.hpp
index 47641ef..09cd0ce 100644
--- a/include/boost/static_string/static_string.hpp
+++ b/include/boost/static_string/static_string.hpp
@@ -5544,36 +5544,34 @@ operator+(
     std::size_t(0), 1, lhs);
 }
 
-// Add a null-terminated character array to a string.
+// Add a null terminated character array to a string.
 template<
   std::size_t N, std::size_t M,
   typename CharT, typename Traits>
 BOOST_STATIC_STRING_CPP14_CONSTEXPR
 inline
-basic_static_string<(N + M) - 1, CharT, Traits>
+basic_static_string<N + M, CharT, Traits>
 operator+(
   const basic_static_string<N, CharT, Traits>& lhs,
   const CharT(&rhs)[M])
 {
-  // Subtract 1 to account for the null terminator, as "hello" is a char[6]
-  return basic_static_string<(N + M) - 1, CharT, Traits>(lhs).append(+rhs, M - 1);
+  return basic_static_string<N + M, CharT, Traits>(lhs).append(+rhs);
 }
 
-// Add a string to a null-terminated character array.
+// Add a string to a null terminated character array.
 template<
   std::size_t N, std::size_t M,
   typename CharT, typename Traits>
 BOOST_STATIC_STRING_CPP14_CONSTEXPR
 inline
-basic_static_string<(N + M) - 1, CharT, Traits>
+basic_static_string<N + M, CharT, Traits>
 operator+(
   const CharT(&lhs)[N],
   const basic_static_string<M, CharT, Traits>& rhs)
 {
-  // Subtract 1 to account for the null terminator, as "hello" is a char[6]
   // The cast to std::size_t is needed here since 0 is a null pointer constant
-  return basic_static_string<(N + M) - 1, CharT, Traits>(rhs).insert(
-    std::size_t(0), +lhs, N - 1);
+  return basic_static_string<N + M, CharT, Traits>(rhs).insert(
+    std::size_t(0), +lhs);
 }
 
 //------------------------------------------------------------------------------
diff --git a/test/static_string.cpp b/test/static_string.cpp
index 119b9ef..f4e8ce5 100644
--- a/test/static_string.cpp
+++ b/test/static_string.cpp
@@ -7096,7 +7096,7 @@ testOperatorPlus()
   {
     auto res = s1 + "world";
     BOOST_TEST(res == "helloworld");
-    BOOST_TEST(res.capacity() == 15);
+    BOOST_TEST(res.capacity() == 16);
     BOOST_TEST(res.size() == 10);
   }
 
@@ -7104,7 +7104,25 @@ testOperatorPlus()
   {
     auto res = "hello" + s2;
     BOOST_TEST(res == "helloworld");
-    BOOST_TEST(res.capacity() == 15);
+    BOOST_TEST(res.capacity() == 16);
+    BOOST_TEST(res.size() == 10);
+  }
+
+  // operator+(static_string, CharT(&)[N]), no null
+  {
+    char arr[10] = {'w', 'o', 'r', 'l', 'd'};
+    auto res = s1 + arr;
+    BOOST_TEST(res == "helloworld");
+    BOOST_TEST(res.capacity() == 20);
+    BOOST_TEST(res.size() == 10);
+  }
+
+  // operator+(CharT(&)[N], static_string), no null
+  {
+    char arr[10] = {'h', 'e', 'l', 'l', 'o'};
+    auto res = arr + s2;
+    BOOST_TEST(res == "helloworld");
+    BOOST_TEST(res.capacity() == 20);
     BOOST_TEST(res.size() == 10);
   }
 }