Fix #13196 FP negativeContainerIndex for non-empty container (#6948)

Author: chrchr-github

Diff for: lib/valueflow.cpp

@@ -5452,6 +5452,7 @@ void ValueFlow::setValues(TokenList& tokenlist,
         VFA(analyzeArrayBool(tokenlist, settings)),
         VFA(analyzeArrayElement(tokenlist, settings)),
         VFA(analyzeRightShift(tokenlist, settings)),
+        VFA_CPP(valueFlowCondition(ContainerConditionHandler{}, tokenlist, symboldatabase, errorLogger, settings, skippedFunctions)),
         VFA(valueFlowAfterAssign(tokenlist, symboldatabase, errorLogger, settings, skippedFunctions)),
         VFA_CPP(valueFlowAfterSwap(tokenlist, symboldatabase, errorLogger, settings)),
         VFA(valueFlowCondition(SimpleConditionHandler{}, tokenlist, symboldatabase, errorLogger, settings, skippedFunctions)),
@@ -5470,8 +5471,6 @@ void ValueFlow::setValues(TokenList& tokenlist,
             valueFlowCondition(IteratorConditionHandler{}, tokenlist, symboldatabase, errorLogger, settings, skippedFunctions)),
         VFA_CPP(analyzeIteratorInfer(tokenlist, settings)),
         VFA_CPP(valueFlowContainerSize(tokenlist, symboldatabase, errorLogger, settings, skippedFunctions)),
-        VFA_CPP(
-            valueFlowCondition(ContainerConditionHandler{}, tokenlist, symboldatabase, errorLogger, settings, skippedFunctions)),
         VFA(valueFlowSafeFunctions(tokenlist, symboldatabase, errorLogger, settings)),
     });
 

Diff for: test/teststl.cpp

@@ -2587,6 +2587,17 @@ class TestStl : public TestFixture {
               "int O::f() const { return v[c.h() - 1]; }\n");
         ASSERT_EQUALS("", errout_str());
 
+        check("void f(const std::vector<int>& v) {\n" // #13196
+              "    if (v.empty())\n"
+              "        return;\n"
+              "    int idx = -1;\n"
+              "    for (int i = 0; i < v.size(); ++i) {\n"
+              "        idx = i;\n"
+              "    }\n"
+              "    (void)v[idx];\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+
         const auto oldSettings = settings;
         settings.daca = true;