Add test for #11534 (#5732)

Author: chrchr-github

test/testnullpointer.cpp

@@ -140,6 +140,7 @@ class TestNullPointer : public TestFixture {
         TEST_CASE(nullpointer99); // #10602
         TEST_CASE(nullpointer100);        // #11636
         TEST_CASE(nullpointer101);        // #11382
+        TEST_CASE(nullpointer102);
         TEST_CASE(nullpointer_addressOf); // address of
         TEST_CASE(nullpointerSwitch); // #2626
         TEST_CASE(nullpointer_cast); // #4692
@@ -2843,6 +2844,20 @@ class TestNullPointer : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
+    void nullpointer102()
+    {
+        check("struct S { std::string str; };\n" // #11534
+              "struct T { S s; };\n"
+              "struct U { T t[1]; };\n"
+              "void f(const T& t, const U& u, std::string& str) {\n"
+              "    if (str.empty())\n"
+              "        str = t.s.str;\n"
+              "    else\n"
+              "        str = u.t[0].s.str;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void nullpointer_addressOf() { // address of
         check("void f() {\n"
               "  struct X *x = 0;\n"