[SMTChecker] Refactor VariableUsage

test/libsolidity/smtCheckerTests/functions/function_inline_chain.sol

@@ -0,0 +1,41 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	uint x;
+	uint y;
+	uint z;
+
+	function f() public {
+		if (x == 1)
+			x = 2;
+		else
+			x = 1;
+		g();
+		assert(y == 1);
+	}
+
+	function g() public {
+		y = 1;
+		h();
+		assert(z == 1);
+	}
+
+	function h() public {
+		z = 1;
+		x = 1;
+		f();
+		// This fails for the following calls to the contract:
+		// h()
+		// g() h()
+		// It does not fail for f() g() h() because in that case
+		// h() will not inline f() since it already is in the callstack.
+		assert(x == 1);
+	}
+}
+// ----
+// Warning: (271-274): Assertion checker does not support recursive function calls.
+// Warning: (140-143): Assertion checker does not support recursive function calls.
+// Warning: (483-497): Assertion violation happens here
+// Warning: (201-204): Assertion checker does not support recursive function calls.
+// Warning: (483-497): Assertion violation happens here