Fix #13848 FP uninitStructMember with overloaded operator>> (danmar#7549)

Author: chrchr-github

lib/checkuninitvar.cpp

@@ -796,6 +796,9 @@ bool CheckUninitVar::checkScopeForVariable(const Token *tok, const Variable& var
 
 
             if (!membervar.empty()) {
+                if (mTokenizer->isCPP() && Token::simpleMatch(tok->astParent(), ">>"))
+                    return true;
+
                 if (isMemberVariableAssignment(tok, membervar)) {
                     checkRhs(tok, var, *alloc, number_of_if, membervar);
                     return true;

test/testuninitvar.cpp

@@ -4987,6 +4987,14 @@ class TestUninitVar : public TestFixture {
                        "    return s.i;\n"
                        "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        checkUninitVar("struct S { int a; };\n" // #13848
+                       "int f(std::istream& is) {\n"
+                       "    S s;\n"
+                       "    is >> s;\n"
+                       "    return s.a;\n"
+                       "}\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void uninitvar2_while() {