From 4e1ab4e7718a14d4cf043cc9c3f85395bd46e34b Mon Sep 17 00:00:00 2001
From: Yauheni Akhotnikau <eao197@gmail.com>
Date: Fri, 29 Nov 2019 19:10:48 +0300
Subject: [PATCH] A fix for issue #64.

---
 dev/restinio/cmake/target.cmake            |  2 +-
 dev/restinio/compiler_features.hpp         | 66 ++++++++++++++++++++++
 dev/restinio/impl/response_coordinator.hpp | 22 +++++---
 3 files changed, 81 insertions(+), 9 deletions(-)

diff --git a/dev/restinio/cmake/target.cmake b/dev/restinio/cmake/target.cmake
index 87dd8370..ed1724c8 100644
--- a/dev/restinio/cmake/target.cmake
+++ b/dev/restinio/cmake/target.cmake
@@ -1 +1 @@
-set(RESTINIO_VERSION "0.6.1")
+set(RESTINIO_VERSION "0.6.1.1")
diff --git a/dev/restinio/compiler_features.hpp b/dev/restinio/compiler_features.hpp
index f78fa3b9..f899f523 100644
--- a/dev/restinio/compiler_features.hpp
+++ b/dev/restinio/compiler_features.hpp
@@ -105,3 +105,69 @@
 #define RESTINIO_STATIC_ASSERT_NOT_NOEXCEPT(expr) \
 	static_assert(!noexcept(expr), #expr " is not expected to be noexcept" )
 
+namespace restinio
+{
+
+namespace static_if_details
+{
+
+template< bool Condition >
+struct static_if_impl;
+
+template<>
+struct static_if_impl<true>
+{
+	template<typename If_Part, typename Else_Part>
+	static decltype(auto)
+	call( If_Part && if_part, Else_Part && )
+	{
+		return if_part();
+	}
+};
+
+template<>
+struct static_if_impl<false>
+{
+	template<typename If_Part, typename Else_Part>
+	static decltype(auto)
+	call( If_Part &&, Else_Part && else_part )
+	{
+		return else_part();
+	}
+};
+
+} /* namespace static_if_details */
+
+//
+// static_if_else
+//
+/*!
+ * @brief An emulation of if constexpr for C++14.
+ *
+ * Usage example:
+ * @code
+ * static_if_else< noexcept(some-expression) >(
+ * 	[]() noexcept {
+ * 		... // Some action that doesn't throw.
+ * 	},
+ * 	[] {
+ * 		try {
+ * 			... // Some action that throws.
+ * 		}
+ * 		catch(...) {}
+ * 	});
+ * @endcode
+ *
+ * @since v.0.6.1.1
+ */
+template< bool Condition, typename If_Part, typename Else_Part >
+decltype(auto)
+static_if_else( If_Part && if_part, Else_Part && else_part )
+{
+	return static_if_details::static_if_impl<Condition>::call(
+			std::forward<If_Part>(if_part),
+			std::forward<Else_Part>(else_part) );
+}
+
+} /* namespace restinio */
+
diff --git a/dev/restinio/impl/response_coordinator.hpp b/dev/restinio/impl/response_coordinator.hpp
index 543220c8..6dc5c0f2 100644
--- a/dev/restinio/impl/response_coordinator.hpp
+++ b/dev/restinio/impl/response_coordinator.hpp
@@ -91,14 +91,20 @@ class response_context_t
 
 			write_group_t result{ std::move( m_write_groups.front() ) };
 
-			// We expect that m_write_groups.erase() isn't noexpect
-			// and because of that this call should be done via
-			// suppress_exceptions_quietly.
-			RESTINIO_STATIC_ASSERT_NOT_NOEXCEPT(
-					m_write_groups.erase(m_write_groups.begin()) );
-			restinio::utils::suppress_exceptions_quietly( [this] {
-					m_write_groups.erase( begin( m_write_groups ) );
-				} );
+			// Some STL implementation can have std::vector::erase that
+			// doesn't throw. So we use a kind of static if to select
+			// an appropriate behaviour.
+			static_if_else< noexcept(m_write_groups.erase(m_write_groups.begin())) >(
+					// This is for the case when std::vector::erase doesn't throw.
+					[this]() noexcept {
+						m_write_groups.erase( m_write_groups.begin() );
+					},
+					// This is for the case when std::vector::erase does throw.
+					[this]() {
+						restinio::utils::suppress_exceptions_quietly( [this] {
+								m_write_groups.erase( m_write_groups.begin() );
+						} );
+					} );
 
 			return result;
 		}