Fix #12428 FN objectIndex when accessing struct member (#8676)

Author: chrchr-github

lib/checkbufferoverrun.cpp

@@ -1086,9 +1086,11 @@ void CheckBufferOverrunImpl::objectIndex()
 
             std::vector<ValueFlow::Value> values = ValueFlow::getLifetimeObjValues(obj, false, -1);
             for (const ValueFlow::Value& v:values) {
-                if (v.lifetimeKind != ValueFlow::Value::LifetimeKind::Address)
+                if (v.lifetimeKind != ValueFlow::Value::LifetimeKind::Address && v.lifetimeKind != ValueFlow::Value::LifetimeKind::Object)
                     continue;
-                const Variable *var = v.tokvalue->variable();
+                const Token* varTok = nextAfterAstRightmostLeaf(v.tokvalue->astParent());
+                varTok = varTok ? varTok->previous() : nullptr;
+                const Variable *var = varTok ? varTok->variable() : nullptr;
                 if (!var)
                     continue;
                 if (var->isReference())

test/testbufferoverrun.cpp

@@ -5857,7 +5857,9 @@ class TestBufferOverrun : public TestFixture {
               "    (void)y[1];\n"
               "    (void)y[2];\n"
               "}\n");
-        TODO_ASSERT_EQUALS("error", "", errout_str());
+        ASSERT_EQUALS("[test.cpp:7:20] -> [test.cpp:9:12]: (error) The address of variable 's.a' is accessed at non-zero index. [objectIndex]\n"
+                      "[test.cpp:7:20] -> [test.cpp:10:12]: (error) The address of variable 's.a' is accessed at non-zero index. [objectIndex]\n",
+                      errout_str());
     }
 
     void checkPipeParameterSize() { // #3521