From dd69230f197ef58541dd7e81bf5d8b82979025d5 Mon Sep 17 00:00:00 2001
From: Glen Fraser <holaglen@gmail.com>
Date: Fri, 4 Sep 2020 11:27:52 +0200
Subject: [PATCH] Fix issues with Function_Params constructors (array and
 vector args)

- code (on MSVC) was asserting due to trying to dereference invalid
  pointers (dereferencing the end iterator, even if only to get its
  address!).
- when a Function_Params is constructed with an empty vector, you
  can't return the address of the vec.front() -- instead we use
  nullptr for the m_begin and m_end pointers.
---
 include/chaiscript/dispatchkit/function_params.hpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/chaiscript/dispatchkit/function_params.hpp b/include/chaiscript/dispatchkit/function_params.hpp
index c8afaaf89..249c41a76 100644
--- a/include/chaiscript/dispatchkit/function_params.hpp
+++ b/include/chaiscript/dispatchkit/function_params.hpp
@@ -30,13 +30,19 @@ namespace chaiscript {
       }
 
       explicit Function_Params(const std::vector<Boxed_Value> &vec)
-        : m_begin(&vec.front()), m_end(&vec.front() + vec.size())
+        : m_begin(vec.empty() ? nullptr : &vec.front()), m_end(vec.empty() ? nullptr : &vec.front() + vec.size())
       {
       }
 
       template<size_t Size>
       constexpr explicit Function_Params(const std::array<Boxed_Value, Size> &a)
-        : m_begin(&*std::begin(a)), m_end(&*std::end(a))
+        : m_begin(&a.front()), m_end(&a.front() + Size)
+      {
+      }
+
+      template<>
+      constexpr explicit Function_Params(const std::array<Boxed_Value, size_t{0}> &a)
+        : m_begin(nullptr), m_end(nullptr)
       {
       }