From 7422cb9e3b45389529b5c067250f596dddc9a72f Mon Sep 17 00:00:00 2001
From: rbock <rbock@eudoxos.de>
Date: Sun, 25 Jun 2017 10:02:41 +0200
Subject: [PATCH] Compile with both, MSVC 2015 and 2017

Make MSVC 2017 accept the code as well

MSVC still has problems with variadic templates...

Adjust README, do not do debug build (reduce load for appveyor)
---
 .appveyor.yml               |  6 ++++--
 README.md                   |  2 +-
 include/sqlpp11/having.h    |  8 +++++++-
 include/sqlpp11/statement.h | 15 ++++++++++-----
 4 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/.appveyor.yml b/.appveyor.yml
index ba2387cf..adadfdb7 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -1,10 +1,12 @@
-os: Visual Studio 2015
+os:
+  - Visual Studio 2015
+  - Visual Studio 2017
 
 platform:
   - x64
 
 configuration:
-  - Debug
+  #- Debug
   - Release
 
 matrix:
diff --git a/README.md b/README.md
index d06ae11e..48839d43 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ See [Changes](ChangeLog.md)
 Status:
 -------
 
-Branch / Compiler | clang-3.4,  gcc-4.9, Xcode-7   |  MSVC 2015  | Test Coverage
+Branch / Compiler | clang-3.4,  gcc-4.9, Xcode-7   |  MSVC 2015/2017  | Test Coverage
 ------------------| -------------------------------|-------------|---------------
 master | [![Build Status](https://travis-ci.org/rbock/sqlpp11.svg?branch=master)](https://travis-ci.org/rbock/sqlpp11?branch=master) | [![Build status](https://ci.appveyor.com/api/projects/status/eid7mwqgavo0h61h/branch/master?svg=true)](https://ci.appveyor.com/project/rbock/sqlpp11/branch/master) | [![Coverage Status](https://coveralls.io/repos/rbock/sqlpp11/badge.svg?branch=master)](https://coveralls.io/r/rbock/sqlpp11?branch=master)
 develop | [![Build Status](https://travis-ci.org/rbock/sqlpp11.svg?branch=develop)](https://travis-ci.org/rbock/sqlpp11?branch=develop) | [![Build status](https://ci.appveyor.com/api/projects/status/eid7mwqgavo0h61h/branch/develop?svg=true)](https://ci.appveyor.com/project/rbock/sqlpp11/branch/develop) | [![Coverage Status](https://coveralls.io/repos/rbock/sqlpp11/badge.svg?branch=develop)](https://coveralls.io/r/rbock/sqlpp11?branch=develop)
diff --git a/include/sqlpp11/having.h b/include/sqlpp11/having.h
index a5fcfa6c..d2cd2e8b 100644
--- a/include/sqlpp11/having.h
+++ b/include/sqlpp11/having.h
@@ -181,6 +181,12 @@ namespace sqlpp
       static_check_t<not std::is_same<Database, void>::value, assert_having_dynamic_statement_dynamic_t>,
       check_having_t<Expression>>;
 
+  template <typename... Exprs>
+  constexpr auto are_all_parameters_expressions() -> bool
+  {
+    return logic::all_t<is_expression_t<Exprs>::value...>::value;
+  }
+
   // NO HAVING YET
   struct no_having_t
   {
@@ -237,7 +243,7 @@ namespace sqlpp
       //	  template <typename... T>
       //	  using _check = logic::all_t<is_expression_t<T>::value...>;
       template <typename... T>
-      struct _check : logic::all_t<is_expression_t<T>::value...>
+      struct _check : std::integral_constant<bool, are_all_parameters_expressions<T...>()>
       {
       };
 
diff --git a/include/sqlpp11/statement.h b/include/sqlpp11/statement.h
index 34af1dcc..f3fccf49 100644
--- a/include/sqlpp11/statement.h
+++ b/include/sqlpp11/statement.h
@@ -54,6 +54,12 @@ namespace sqlpp
 
   namespace detail
   {
+    template <typename... Policies>
+    constexpr auto is_any_policy_missing() -> bool
+    {
+      return logic::any_t<is_missing_t<Policies>::value...>::value;
+    }
+
     template <typename Db = void, typename... Policies>
     struct statement_policies_t
     {
@@ -122,11 +128,10 @@ namespace sqlpp
       }
 
       using _value_type =
-          typename std::conditional<logic::none_t<is_missing_t<Policies>::value...>::value,
-                                    value_type_of<_result_type_provider>,
-                                    no_value_t  // if a required statement part is missing (e.g. columns in a select),
-                                                // then the statement cannot be used as a value
-                                    >::type;
+          typename std::conditional<is_any_policy_missing<Policies...>(),
+                                    no_value_t,  // if a required statement part is missing (e.g. columns in a select),
+                                                 // then the statement cannot be used as a value
+                                    value_type_of<_result_type_provider>>::type;
 
       using _traits =
           make_traits<_value_type, tag_if<tag::is_expression, not std::is_same<_value_type, no_value_t>::value>>;