From 1f3ef3bedbaa2828574a6f75814a127bab61d368 Mon Sep 17 00:00:00 2001
From: Ethan Slattery <crustyauklet@gmail.com>
Date: Mon, 27 Sep 2021 15:14:11 -0700
Subject: [PATCH] Fixes #9 - unable to pack into spans

with span-lite this currently breaks on MSVC (but not gcc). Waiting to see response to bug report in span-lite
---
 conanfile.py                    |  2 +-
 include/bitpacker/bitstruct.hpp | 14 +++++++-------
 tests/python_common.hpp         |  1 +
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/conanfile.py b/conanfile.py
index 8e1092d..30bed2d 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -32,7 +32,7 @@ def validate(self):
 
     def requirements(self):
         if not tools.valid_min_cppstd(self, "20"):
-            self.requires("span-lite/0.7.0")
+            self.requires("span-lite/0.10.1")
 
     def build_requirements(self):
         if tools.get_env("CONAN_RUN_TESTS", True) or self.develop:
diff --git a/include/bitpacker/bitstruct.hpp b/include/bitpacker/bitstruct.hpp
index 7bcc133..7704d56 100644
--- a/include/bitpacker/bitstruct.hpp
+++ b/include/bitpacker/bitstruct.hpp
@@ -410,7 +410,8 @@ namespace bitpacker {
 
         /// helper function to pack types into the given buffer
         template<typename Fmt, size_type N, size_type... Items, typename... Args>
-        constexpr void pack(std::array<byte_type, N>& output, const size_type start_bit, std::index_sequence<Items...> /*unused*/, Args&&... args) {
+        constexpr void pack(span<byte_type, N> output, const size_type start_bit, std::index_sequence<Items...> /*unused*/, Args&&... args) {
+            static_assert(calcbytes(Fmt{}) <= N, "bitpacker::pack : format larger than given array, not even counting the offset!");
             static_assert(sizeof...(args) == sizeof...(Items), "pack expected items for packing != sizeof...(args) passed");
             constexpr auto byte_order = impl::get_byte_order(Fmt{});
             static_assert(byte_order == impl::Endian::big, "Unpacking little endian byte order not supported yet...");
@@ -501,21 +502,20 @@ namespace bitpacker {
     template<typename Fmt, typename... Args>
     constexpr auto pack(Fmt /*unused*/, Args&&... args) {
         std::array<byte_type, calcbytes(Fmt{})> output{};
-        impl::pack<Fmt>(output, 0, std::make_index_sequence<impl::count_non_padding(Fmt{})>(), std::forward<Args>(args)...);
+        impl::pack<Fmt>(span(output), 0, std::make_index_sequence<impl::count_non_padding(Fmt{})>(), std::forward<Args>(args)...);
         return output;
     }
 
     /**
      * Pack Args... into data, starting at given bit offset offset, according to given format string fmt.
      * @param fmt [IN] format string created with macro `BP_STRING()`
-     * @param data [IN/OUT] reference to existing std::array of bytes to pack into
+     * @param data [IN/OUT] reference to a fixed size span of bytes to pack into
      * @param offset [IN] bit index to start unpacking from
      * @param args... [IN] list of arguments to pack into the format string
      */
-    template<typename Fmt, size_type N, typename... Args>
-    constexpr void pack_into(Fmt /*unused*/, std::array<byte_type, N>& data, const size_type offset, Args&&... args) {
-        static_assert(calcbytes(Fmt{}) <= N, "bitpacker::pack_into : format larger than given array, not even counting the offset!");
-        impl::pack<Fmt>(data, offset, std::make_index_sequence<impl::count_non_padding(Fmt{})>(), std::forward<Args>(args)...);
+    template<typename Fmt, typename Output, typename... Args>
+    constexpr void pack_into(Fmt /*unused*/, Output& data, const size_type offset, Args&&... args) {
+        impl::pack<Fmt>(span(data), offset, std::make_index_sequence<impl::count_non_padding(Fmt{})>(), std::forward<Args>(args)...);
     }
 
 }  // namespace bitpacker
diff --git a/tests/python_common.hpp b/tests/python_common.hpp
index c354c3f..b186cb4 100644
--- a/tests/python_common.hpp
+++ b/tests/python_common.hpp
@@ -13,6 +13,7 @@
 
 #define CATCH_CONFIG_ENABLE_TUPLE_STRINGMAKER
 #include "test_common.hpp"
+#include "bitpacker/bitstruct.hpp"
 
 template < typename T >
 std::string escapeString(const T &val)