Fix todo test for returning a dangling reference (#3284)

lib/checkautovariables.cpp

@@ -30,6 +30,7 @@
 #include "tokenize.h"
 #include "valueflow.h"
 
+#include <algorithm>
 #include <list>
 
 //---------------------------------------------------------------------------
@@ -434,7 +435,14 @@ static int getPointerDepth(const Token *tok)
 {
     if (!tok)
         return 0;
-    return tok->valueType() ? tok->valueType()->pointer : 0;
+    if (tok->valueType())
+        return tok->valueType()->pointer;
+    int n = 0;
+    std::pair<const Token*, const Token*> decl = Token::typeDecl(tok);
+    for (const Token* tok2 = decl.first; tok2 != decl.second; tok2 = tok2->next())
+        if (Token::simpleMatch(tok, "*"))
+            n++;
+    return n;
 }
 
 static bool isDeadTemporary(bool cpp, const Token* tok, const Token* expr, const Library* library)

lib/symboldatabase.cpp

@@ -34,9 +34,10 @@
 #include <algorithm>
 #include <cassert>
 #include <cstring>
-#include <limits>
 #include <iomanip>
 #include <iostream>
+#include <limits>
+#include <string>
 #include <unordered_map>
 //---------------------------------------------------------------------------
 
@@ -6906,7 +6907,12 @@ ValueType::MatchResult ValueType::matchParameter(const ValueType *call, const Va
     if (callVar && ((res == ValueType::MatchResult::SAME && call->container) || res == ValueType::MatchResult::UNKNOWN)) {
         const std::string type1 = getTypeString(callVar->typeStartToken());
         const std::string type2 = getTypeString(funcVar->typeStartToken());
-        if (type1 != type2)
+        const bool templateVar =
+            funcVar->scope() && funcVar->scope()->function && funcVar->scope()->function->templateDef;
+        if (type1 == type2)
+            return ValueType::MatchResult::SAME;
+        if (!templateVar && type1.find("auto") == std::string::npos && type2.find("auto") == std::string::npos &&
+            type1 != type2)
             return ValueType::MatchResult::NOMATCH;
     }
     return res;

lib/valueflow.cpp

@@ -2896,6 +2896,8 @@ static bool isLifetimeBorrowed(const ValueType *vt, const ValueType *vtParent)
         return false;
     if (!vt)
         return false;
+    if (vt->pointer > 0 && vt->pointer == vtParent->pointer)
+        return true;
     if (vt->type != ValueType::UNKNOWN_TYPE && vtParent->type != ValueType::UNKNOWN_TYPE && vtParent->container == vt->container) {
         if (vtParent->pointer > vt->pointer)
             return true;

test/testautovariables.cpp

@@ -2146,9 +2146,8 @@ private:
               "    return get_default(m, k, &x);\n"
               "}\n",
               true);
-        TODO_ASSERT_EQUALS(
+        ASSERT_EQUALS(
             "[test.cpp:9] -> [test.cpp:9] -> [test.cpp:8] -> [test.cpp:9]: (error, inconclusive) Returning pointer to local variable 'x' that will be invalid when returning.\n",
-            "",
             errout.str());
 
         check("std::vector<int> g();\n"