Added example program demonstrating NPE when removing empty method.

src/test/java/dk/camelot64/kickc/test/TestProgramsFast.java

@@ -9,6 +9,12 @@ import java.io.IOException;
  */
 public class TestProgramsFast extends TestPrograms {
 
+   /* Fix problem where removing empty method can cause NPE (because a local variable in the method is still used)
+   @Test
+   public void testStructOptimizeProblem() throws IOException {
+      compileAndCompare("struct-optimize-problem.c",log().verboseSSAOptimize());
+   }
+    */
 
    @Test
    public void testTmpZpProblem() throws IOException {

src/test/kc/struct-optimize-problem.c

@@ -0,0 +1,20 @@
+// Re-create problem where removing empty method can cause NPE (because a local variable in the method is still used)
+struct line_t {
+  char buf[10];
+  char pos;
+};
+
+struct line_t lines[10];
+
+char *lined_line(struct line_t *l) {
+  return (l->buf);
+}
+
+void main() {
+    struct line_t* line = lines;
+    for(char i=0;i<10;i++) {
+        char* buf = lined_line(line);
+        *buf = 'a';
+        line++;
+    }
+}