fix: Incorporate Jason's patch for Visual Studio

pybind · Apr 23, 2018 · 9630d04 · 9630d04
1 parent fd937bb
commit 9630d04
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Showing 2 changed files with 10 additions and 4 deletions.
diff --git a/include/pybind11/detail/common.h b/include/pybind11/detail/common.h
@@ -799,6 +799,13 @@ class any_container {
     const std::vector<T> *operator->() const { return &v; }
 };
 
+template <int N, bool... Bool> struct first_true_impl : std::integral_constant<int, -1> {};
+template <int N, bool B, bool... BMore> struct first_true_impl<N, B, BMore...> :
+    std::integral_constant<int, B ? N : first_true_impl<N+1, BMore...>::value> {};
+/// Takes a parameter pack of bool values, return the index of the first one that is true or -1 if
+/// none of the template arguments are true.
+template <bool... B> using first_true_index = first_true_impl<0, B...>;
+
 NAMESPACE_END(detail)
 
 

diff --git a/include/pybind11/numpy.h b/include/pybind11/numpy.h
@@ -114,10 +114,9 @@ template <typename T> struct same_size {
 };
 
 // Lookup a type according to its size, and return a value corresponding to the NumPy typenum.
-template <typename Concrete, typename... Check>
-constexpr int platform_lookup(const std::array<int, sizeof...(Check)> codes) {
-    using code_index = std::integral_constant<int, constexpr_first<same_size<Concrete>::template as, Check...>()>;
-    static_assert(code_index::value != sizeof...(Check), "Unable to match type on this platform");
+template <typename Concrete, typename... Check, typename code_index = first_true_index<sizeof(Concrete) == sizeof(Check)...>>
+constexpr int platform_lookup(const std::array<int, sizeof...(Check)> &codes) {
+    static_assert(code_index::value >= 0, "Unable to match type on this platform");
     return codes[code_index::value];
 }