Fix 10532: False negative: dangling string_view when using ternary operator (#4638)

* Fix 10532: False negative: dangling string_view when using ternary operator

* Format

* Update

Author: pfultz2

lib/astutils.cpp

@@ -397,12 +397,18 @@ bool isTemporary(bool cpp, const Token* tok, const Library* library, bool unknow
         return isTemporary(cpp, tok->astOperand2(), library);
     if (tok->isCast() || (cpp && isCPPCast(tok)))
         return isTemporary(cpp, tok->astOperand2(), library);
-    if (Token::Match(tok, "?|.|[|++|--|%name%|%assign%"))
+    if (Token::Match(tok, ".|[|++|--|%name%|%assign%"))
         return false;
     if (tok->isUnaryOp("*"))
         return false;
     if (Token::Match(tok, "&|<<|>>") && isLikelyStream(cpp, tok->astOperand1()))
         return false;
+    if (Token::simpleMatch(tok, "?")) {
+        const Token* branchTok = tok->astOperand2();
+        if (!branchTok->astOperand1()->valueType())
+            return false;
+        return !branchTok->astOperand1()->valueType()->isTypeEqual(branchTok->astOperand2()->valueType());
+    }
     if (Token::simpleMatch(tok, "(") && tok->astOperand1() &&
         (tok->astOperand2() || Token::simpleMatch(tok->next(), ")"))) {
         if (tok->valueType()) {

lib/symboldatabase.cpp

@@ -6386,14 +6386,26 @@ void SymbolDatabase::setValueType(Token* tok, const ValueType& valuetype, Source
             return;
         }
 
-        if (vt1->pointer != 0U && vt2 && vt2->pointer == 0U) {
-            setValueType(parent, *vt1);
-            return;
-        }
+        if (parent->isArithmeticalOp()) {
+            if (vt1->pointer != 0U && vt2 && vt2->pointer == 0U) {
+                setValueType(parent, *vt1);
+                return;
+            }
 
-        if (vt1->pointer == 0U && vt2 && vt2->pointer != 0U) {
-            setValueType(parent, *vt2);
-            return;
+            if (vt1->pointer == 0U && vt2 && vt2->pointer != 0U) {
+                setValueType(parent, *vt2);
+                return;
+            }
+        } else if (ternary) {
+            if (vt1->pointer != 0U && vt2 && vt2->pointer == 0U) {
+                setValueType(parent, *vt2);
+                return;
+            }
+
+            if (vt1->pointer == 0U && vt2 && vt2->pointer != 0U) {
+                setValueType(parent, *vt1);
+                return;
+            }
         }
 
         if (vt1->pointer != 0U) {
@@ -7309,6 +7321,8 @@ MathLib::bigint ValueType::typeSize(const cppcheck::Platform &platform, bool p)
 
 bool ValueType::isTypeEqual(const ValueType* that) const
 {
+    if (!that)
+        return false;
     auto tie = [](const ValueType* vt) {
         return std::tie(vt->type, vt->container, vt->pointer, vt->typeScope, vt->smartPointer);
     };

test/testautovariables.cpp

@@ -2757,6 +2757,15 @@ class TestAutoVariables : public TestFixture {
               "    return v[0];\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        // #10532
+        check("std::string f(std::string ss) {\n"
+              "  std::string_view sv = true ? \"\" : ss;\n"
+              "  std::string s = sv;\n"
+              "  return s;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:2] -> [test.cpp:3]: (error) Using object that is a temporary.\n",
+                      errout.str());
     }
 
     void danglingLifetimeUniquePtr()