Incorrect type signature code

[berkus]

Hi!

The code in

jni.hpp/include/jni/type_signature.hpp

Lines 43 to 56 in 26cc577

	template < class R, class... Args >
	struct TypeSignature< R (Args...) >
	{
	private:
	template < class... T > void DoNothingWith( T&&... ) const {}
	std::string Compute() const
	{
	static std::string result("(");
	DoNothingWith( ( result += TypeSignature<Args>()() )... );
	result += ")";
	result += TypeSignature<R>()();
	return result;
	}

is incorrect.

It passes argument pack expansion as arguments to the function DoNothingWith(). Per standard compiler is free to arrange function arguments computation in any order - and gcc and clang disagree here. Clang computes arguments left to right, producing correct signature; android gcc 4.9 computes them right to left, producing completely invalid function signature.

You can verify it here

[jfirebaugh]

Thanks for the report! Since writing that code I learned a better technique for pack expansion but I forgot to port it to jni.hpp.

[berkus]

Yay, thanks for prompt fix!