diff --git a/bootstrap.py b/bootstrap.py
index c24f6e57..1d6a0b3b 100755
--- a/bootstrap.py
+++ b/bootstrap.py
@@ -37,6 +37,7 @@ parser = argparse.ArgumentParser()
 parser.add_argument('--debug', action='store_true', help='compile with debug flags')
 parser.add_argument('--cxx', metavar='<compiler>', help='compiler name to use (default: g++)', default='g++')
 parser.add_argument('--ci', action='store_true', help=argparse.SUPPRESS)
+parser.add_argument('--testing', action='store_true', help=argparse.SUPPRESS)
 parser.add_argument('--lua-dir', metavar='<dir>', help='directory lua is in with include and lib subdirectories')
 parser.add_argument('--install-dir', metavar='<dir>', help='directory to install the headers to', default=install_dir);
 parser.epilog = """In order to install sol, administrative privileges might be required.
@@ -80,6 +81,9 @@ if args.ci:
 else:
     ldflags.extend(libraries(['lua']))
 
+if args.testing:
+    cxxflags.append('-Wmissing-declarations')
+
 if 'linux' in sys.platform:
     ldflags.extend(libraries(['dl']))
 
diff --git a/sol/demangle.hpp b/sol/demangle.hpp
index 694a2be2..78f4dd4f 100644
--- a/sol/demangle.hpp
+++ b/sol/demangle.hpp
@@ -33,12 +33,12 @@
 namespace sol {
 namespace detail {
 #ifdef _MSC_VER
-std::string get_type_name(const std::type_info& id) {
+inline std::string get_type_name(const std::type_info& id) {
     return id.name();
 }
 
 #elif defined(__GNUC__) || defined(__clang__)
-std::string get_type_name(const std::type_info& id) {
+inline std::string get_type_name(const std::type_info& id) {
     int status;
     char* unmangled = abi::__cxa_demangle(id.name(), 0, 0, &status);
     std::string realname = unmangled;
@@ -50,7 +50,7 @@ std::string get_type_name(const std::type_info& id) {
 #error Compiler not supported for demangling
 #endif // compilers
 
-std::string demangle(const std::type_info& id) {
+inline std::string demangle(const std::type_info& id) {
     std::string realname = get_type_name(id);
     const static std::array<std::string, 2> removals = {{ "struct ", "class " }};
     const static std::array<std::string, 2> replacements = {{ "::", "_" }};
diff --git a/sol/resolve.hpp b/sol/resolve.hpp
index 0d849d0b..1f6f6066 100644
--- a/sol/resolve.hpp
+++ b/sol/resolve.hpp
@@ -28,66 +28,67 @@
 namespace sol {
 namespace detail {
 template<typename R, typename... Args, typename F, typename = typename std::result_of<Unqualified<F>(Args...)>::type>
-auto resolve_i(types<R(Args...)>, F&&)->R(Unqualified<F>::*)(Args...) {
+inline auto resolve_i(types<R(Args...)>, F&&) -> R(Unqualified<F>::*)(Args...) {
     using Sig = R(Args...);
     typedef Unqualified<F> Fu;
     return static_cast<Sig Fu::*>(&Fu::operator());
 }
 
 template<typename F, typename U = Unqualified<F>>
-auto resolve_f(std::true_type, F&& f) -> decltype(resolve_i(types<function_signature_t<decltype(&U::operator())>>(), std::forward<F>(f))) {
+inline auto resolve_f(std::true_type, F&& f)
+-> decltype(resolve_i(types<function_signature_t<decltype(&U::operator())>>(), std::forward<F>(f))) {
     return resolve_i(types<function_signature_t<decltype(&U::operator())>>(), std::forward<F>(f));
 }
 
 template<typename F>
-void resolve_f(std::false_type, F&&) {
+inline void resolve_f(std::false_type, F&&) {
     static_assert(has_deducible_signature<F>::value,
                   "Cannot use no-template-parameter call with an overloaded functor: specify the signature");
 }
 
 template<typename F, typename U = Unqualified<F>>
-auto resolve_i(types<>, F&& f) -> decltype(resolve_f(has_deducible_signature<U> {}, std::forward<F>(f))) {
+inline auto resolve_i(types<>, F&& f) -> decltype(resolve_f(has_deducible_signature<U> {}, std::forward<F>(f))) {
     return resolve_f(has_deducible_signature<U> {}, std::forward<F>(f));
 }
 
 template<typename... Args, typename F, typename R = typename std::result_of<F&(Args...)>::type>
-auto resolve_i(types<Args...>, F&& f) -> decltype( resolve_i(types<R(Args...)>(), std::forward<F>(f))) {
+inline auto resolve_i(types<Args...>, F&& f) -> decltype( resolve_i(types<R(Args...)>(), std::forward<F>(f))) {
     return resolve_i(types<R(Args...)>(), std::forward<F>(f));
 }
 
 template<typename Sig, typename C>
-Sig C::* resolve_v(std::false_type, Sig C::* mem_func_ptr) {
+inline Sig C::* resolve_v(std::false_type, Sig C::* mem_func_ptr) {
     return mem_func_ptr;
 }
 
 template<typename Sig, typename C>
-Sig C::* resolve_v(std::true_type, Sig C::* mem_variable_ptr) {
+inline Sig C::* resolve_v(std::true_type, Sig C::* mem_variable_ptr) {
     return mem_variable_ptr;
 }
 } // detail
 
 template<typename... Args, typename R>
-auto resolve(R fun_ptr(Args...)) -> R(*)(Args...) {
+inline auto resolve(R fun_ptr(Args...)) -> R(*)(Args...) {
     return fun_ptr;
 }
 
 template<typename Sig>
-Sig* resolve(Sig* fun_ptr) {
+inline Sig* resolve(Sig* fun_ptr) {
     return fun_ptr;
 }
 
 template<typename... Args, typename R, typename C>
-auto resolve(R(C::*mem_ptr)(Args...)) -> R(C::*)(Args...) {
+inline auto resolve(R(C::*mem_ptr)(Args...)) -> R(C::*)(Args...) {
     return mem_ptr;
 }
 
 template<typename Sig, typename C>
-Sig C::* resolve(Sig C::* mem_ptr) {
+inline Sig C::* resolve(Sig C::* mem_ptr) {
     return detail::resolve_v(std::is_member_object_pointer<Sig C::*>(), mem_ptr);
 }
 
 template<typename... Sig, typename F>
-auto resolve(F&& f) -> decltype(detail::resolve_i(types<Sig...>(), std::forward<F>(f))) {
+inline auto resolve(F&& f) -> decltype(detail::resolve_i(types<Sig...>(), std::forward<F>(f))) {
     return detail::resolve_i(types<Sig...>(), std::forward<F>(f));
 }
 } // sol