Fix uninitdata regression (#5179)

Author: chrchr-github

lib/checkuninitvar.cpp

@@ -1253,7 +1253,7 @@ const Token* CheckUninitVar::isVariableUsage(bool cpp, const Token *vartok, cons
                 const Token* deref = derefValue->astOperand1();
                 while (deref && deref->isCast())
                     deref = deref->astOperand1();
-                if (deref == vartok)
+                if (deref == vartok || Token::simpleMatch(deref, "+"))
                     return nullptr;
             }
             if (alloc != NO_ALLOC && astIsRhs(valueExpr))

test/testuninitvar.cpp

@@ -2080,6 +2080,13 @@ class TestUninitVar : public TestFixture {
                        "    return p;\n"
                        "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        checkUninitVar("void f(int n) {\n"
+                       "    int* p = (int*)malloc(n * sizeof(int));\n"
+                       "    for (int i = 0; i < n; ++i)\n"
+                       "        *(p + i) = 0;\n"
+                       "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     // class / struct..