Dynamic exception specification checking test.

Former-commit-id: 49119544e7723c472c51ae2423ca8ac6d6c3a9be

.gitattributes

@@ -20,6 +20,7 @@ cpp-examples/derived2_throw.cpp -text
 cpp-examples/derived3_throw.cpp -text
 cpp-examples/derived4_throw.cpp -text
 cpp-examples/derived_throw.cpp -text
+cpp-examples/dynamic_exception.cpp -text
 cpp-examples/hanoi++.cpp -text
 cpp-examples/newdel.cpp -text
 cpp-examples/newdel_broke1.cpp -text

cpp-examples/dynamic_exception.cpp

+#include <iostream>
+#include <exception>
+#include <cstdlib>
+
+using namespace std;
+ 
+class X {};
+class Y {};
+class Z : public X {};
+class W {};
+ 
+void f() throw(X, Y) 
+{
+    	const auto env=getenv("THROW_TYPE");
+	if(env==NULL)
+		return;
+    	const int n = atoi(env);
+    	if (n==0) throw X(); // OK
+    	if (n==1) throw Z(); // also OK
+    	if (n==2) throw Y(); // also OK
+    	throw W(); // will call std::unexpected()
+}
+ 
+int main() {
+	std::set_unexpected([]{
+		std::cout << "That was unexpected" << std::endl; // flush needed
+		std::abort();
+	});
+
+	try{
+  		f();
+		cout<<"No catch"<<endl;
+	}
+	catch(X x)
+	{
+		cout<<"Caught X (or maybe Z)"<<endl;
+	}
+	catch(Y Y)
+	{
+		cout<<"Caught Y"<<endl;
+	}
+}