Fix 9765: FP: knownConditionTrueFalse handling of template function with ternary operator (#3443)

Author: pfultz2

lib/valueflow.cpp

@@ -663,7 +663,7 @@ static void setTokenValue(Token* tok, ValueFlow::Value value, const Settings* se
                 if (std::find(values.begin(), values.end(), value) != values.end())
                     setTokenValue(parent, value, settings);
             }
-        } else {
+        } else if (!value.isImpossible()) {
             // is condition only depending on 1 variable?
             nonneg int varId = 0;
             bool ret = false;

test/testvalueflow.cpp

@@ -3223,6 +3223,14 @@ class TestValueFlow : public TestFixture {
                "}";
         ASSERT_EQUALS(false, testValueOfX(code, 4U, 13));
         ASSERT_EQUALS(true, testValueOfX(code, 4U, 26));
+
+        code = "void f(int* i) {\n"
+               "    if (!i) return;\n"
+               "    int * x = *i == 1 ? i : nullptr;\n"
+               "    int* a = x;\n"
+               "}\n";
+        ASSERT_EQUALS(true, testValueOfX(code, 4U, 0));
+        ASSERT_EQUALS(false, testValueOfXImpossible(code, 4U, 0));
     }
 
     void valueFlowForwardLambda() {