Fix #14978: Valueflow: Missing buffer size for ::operator new (#8799)

Author: ludviggunne

lib/valueflow.cpp

@@ -7025,6 +7025,12 @@ static void valueFlowDynamicBufferSize(const TokenList& tokenlist, const SymbolD
     auto getBufferSizeFromNew = [&](const Token* newTok) -> MathLib::bigint {
         MathLib::bigint sizeValue = -1, numElem = -1;
 
+        // ::operator new(size_t size)
+        if (Token::Match(newTok->astOperand1(), "::| operatornew")) {
+            const Token *sizeTok = newTok->astOperand2();
+            return sizeTok->hasKnownIntValue() ? sizeTok->getKnownIntValue() : -1;
+        }
+
         if (newTok && newTok->astOperand1()) { // number of elements
             const Token* bracTok = nullptr, *typeTok = nullptr;
             if (newTok->astOperand1()->str() == "[")
@@ -7071,7 +7077,7 @@ static void valueFlowDynamicBufferSize(const TokenList& tokenlist, const SymbolD
             if (!rhs)
                 continue;
 
-            const bool isNew = rhs->isCpp() && rhs->str() == "new";
+            const bool isNew = rhs->isCpp() && (rhs->str() == "new" || Token::Match(rhs->astOperand1(), "::| operatornew"));
             if (!isNew && !Token::Match(rhs->previous(), "%name% ("))
                 continue;
 

test/testvalueflow.cpp

@@ -7932,6 +7932,13 @@ class TestValueFlow : public TestFixture {
                "  return x;\n"
                "}";
         ASSERT_EQUALS(true, testValueOfX(code, 4U, 4, ValueFlow::Value::ValueType::BUFFER_SIZE, &settingsCfg));
+
+        code = "void f()\n"
+               "{\n"
+               "    void *x = ::operator new(0);\n"
+               "    (void) x;\n"
+               "}\n";
+        ASSERT_EQUALS(true, testValueOfX(code, 4U, 0, ValueFlow::Value::ValueType::BUFFER_SIZE));
     }
 
     void valueFlowSafeFunctionParameterValues() {