Fix danmar#6933 FN uninitvar with POD struct and STL types (danmar#5713)

Co-authored-by: chrchr-github <chrchr@github>

Author: chrchr-github

lib/astutils.cpp

@@ -3257,6 +3257,11 @@ static ExprUsage getFunctionUsage(const Token* tok, int indirect, const Settings
         return ExprUsage::Used;
     } else if (ftok->str() == "{") {
         return indirect == 0 ? ExprUsage::Used : ExprUsage::Inconclusive;
+    } else if (ftok->variable() && ftok == ftok->variable()->nameToken()) { // variable init/constructor call
+        if (ftok->variable()->type() && ftok->variable()->type()->needInitialization == Type::NeedInitialization::True)
+            return ExprUsage::Used;
+        if (ftok->variable()->isStlType() || (ftok->variable()->valueType() && ftok->variable()->valueType()->container)) // STL types or containers don't initialize external variables
+            return ExprUsage::Used;
     } else {
         const bool isnullbad = settings->library.isnullargbad(ftok, argnr + 1);
         if (indirect == 0 && astIsPointer(tok) && !addressOf && isnullbad)

test/cfg/qt.cpp

@@ -321,6 +321,13 @@ void duplicateExpression_QString_Compare(QString style) //#8723
     {}
 }
 
+void QVector_uninit()
+{
+    int i;
+    // cppcheck-suppress [uninitvar, unreadVariable]
+    QVector<int> v(i);
+}
+
 void QStack1(QStack<int> intStackArg)
 {
     for (int i = 0; i <= intStackArg.size(); ++i) {

test/cfg/std.cpp

@@ -1043,8 +1043,8 @@ void uninitvar_isxdigit(void)
 void uninitvar_proj(void)
 {
     double d;
+    // cppcheck-suppress uninitvar
     const std::complex<double> dc(d,d);
-    // TODO cppcheck-suppress uninitvar
     (void)std::proj(dc);
 }
 

test/testuninitvar.cpp

@@ -7251,6 +7251,24 @@ class TestUninitVar : public TestFixture {
                       "[test.cpp:23]: (error) Uninitialized variable: s.t.j\n"
                       "[test.cpp:27]: (error) Uninitialized variable: s.t.j\n",
                       errout.str());
+
+        valueFlowUninit("struct S { int x; };\n"
+                        "void f() {\n"
+                        "    int i;\n"
+                        "    S s(i);\n"
+                        "}\n"
+                        "void g() {\n"
+                        "    int i;\n"
+                        "    S t{ i };\n"
+                        "}\n"
+                        "void h() {\n"
+                        "    int i;\n"
+                        "    std::vector<int> v(i);\n"
+                        "}\n");
+        ASSERT_EQUALS("[test.cpp:4]: (error) Uninitialized variable: i\n"
+                      "[test.cpp:8]: (error) Uninitialized variable: i\n"
+                      "[test.cpp:12]: (error) Uninitialized variable: i\n",
+                      errout.str());
     }
 
     void uninitvar_memberfunction() {