Workaround for array<T,0> bug in MSVC

boostorg · Jan 29, 2024 · 37165ad · 37165ad
1 parent aee3750
commit 37165ad
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Showing 2 changed files with 25 additions and 3 deletions.
diff --git a/include/boost/mysql/detail/format_sql.hpp b/include/boost/mysql/detail/format_sql.hpp
@@ -14,6 +14,7 @@
 
 #include <boost/mysql/detail/writable_field_traits.hpp>
 
+#include <cstddef>
 #include <type_traits>
 
 namespace boost {
@@ -143,6 +144,28 @@ format_arg_descriptor make_format_arg_descriptor(const T& val)
     return {make_format_value(val), {}};
 }
 
+// std::array<T, 0> with non-default-constructible T has bugs in MSVC prior to 14.3
+template <std::size_t N>
+struct format_arg_store
+{
+    std::array<format_arg_descriptor, N> data;
+
+    template <class... Args>
+    format_arg_store(const Args&... args) noexcept : data{{make_format_arg_descriptor(args)...}}
+    {
+    }
+
+    span<const format_arg_descriptor> get() const noexcept { return data; }
+};
+
+template <>
+struct format_arg_store<0u>
+{
+    format_arg_store() = default;
+
+    span<const format_arg_descriptor> get() const noexcept { return {}; }
+};
+
 BOOST_MYSQL_DECL
 void vformat_sql_to(
     string_view format_str,

diff --git a/include/boost/mysql/format_sql.hpp b/include/boost/mysql/format_sql.hpp
@@ -177,10 +177,9 @@ inline detail::format_arg_descriptor arg(string_view name, const T& value) noexc
 template <BOOST_MYSQL_FORMATTABLE... Args>
 inline std::string format_sql(string_view format_str, const format_options& opts, const Args&... args)
 {
-    std::array<detail::format_arg_descriptor, sizeof...(Args)> desc{{detail::make_format_arg_descriptor(args
-    )...}};
+    detail::format_arg_store<sizeof...(Args)> store(args...);
     format_context ctx(opts);
-    detail::vformat_sql_to(format_str, ctx, desc);
+    detail::vformat_sql_to(format_str, ctx, store.get());
     return ctx.get().value();
 }