Allow calling internal functions of libraries.

Internal functions of libraries can be called as if the library were a
base contract of the calling contract. As the calling convention for
internal functions is to not create a new call context, the code of
these functions will be pulled into the context of the caller,
duplicating their code. This might pull in code of further internal or
even private functions.

The use case for such functions is to allow libraries which can operate
on memory types such that these types can also be modified in place.

test/libsolidity/SolidityEndToEndTest.cpp

@@ -6633,6 +6633,83 @@ BOOST_AUTO_TEST_CASE(delete_on_array_of_structs)
 	BOOST_CHECK(callContractFunction("f()") == encodeArgs(true));
 }
 
+BOOST_AUTO_TEST_CASE(internal_library_function)
+{
+	// tests that internal library functions can be called from outside
+	// and retain the same memory context (i.e. are pulled into the caller's code)
+	char const* sourceCode = R"(
+		library L {
+			function f(uint[] _data) internal {
+				_data[3] = 2;
+			}
+		}
+		contract C {
+			function f() returns (uint) {
+				uint[] memory x = new uint[](7);
+				x[3] = 8;
+				L.f(x);
+				return x[3];
+			}
+		}
+	)";
+	// This has to work without linking, because everything will be inlined.
+	compileAndRun(sourceCode, 0, "C");
+	BOOST_CHECK(callContractFunction("f()") == encodeArgs(u256(2)));
+}
+
+BOOST_AUTO_TEST_CASE(internal_library_function_calling_private)
+{
+	// tests that internal library functions that are called from outside and that
+	// themselves call private functions are still able to (i.e. the private function
+	// also has to be pulled into the caller's code)
+	char const* sourceCode = R"(
+		library L {
+			function g(uint[] _data) private {
+				_data[3] = 2;
+			}
+			function f(uint[] _data) internal {
+				g(_data);
+			}
+		}
+		contract C {
+			function f() returns (uint) {
+				uint[] memory x = new uint[](7);
+				x[3] = 8;
+				L.f(x);
+				return x[3];
+			}
+		}
+	)";
+	// This has to work without linking, because everything will be inlined.
+	compileAndRun(sourceCode, 0, "C");
+	BOOST_CHECK(callContractFunction("f()") == encodeArgs(u256(2)));
+}
+
+BOOST_AUTO_TEST_CASE(internal_library_function_bound)
+{
+	char const* sourceCode = R"(
+		library L {
+			struct S { uint[] data; }
+			function f(S _s) internal {
+				_s.data[3] = 2;
+			}
+		}
+		contract C {
+			using L for L.S;
+			function f() returns (uint) {
+				L.S memory x;
+				x.data = new uint[](7);
+				x.data[3] = 8;
+				x.f();
+				return x.data[3];
+			}
+		}
+	)";
+	// This has to work without linking, because everything will be inlined.
+	compileAndRun(sourceCode, 0, "C");
+	BOOST_CHECK(callContractFunction("f()") == encodeArgs(u256(2)));
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }