Fix #12961 FP passedByValue with std::bitset (#6635)

Author: chrchr-github

lib/checkother.cpp

@@ -1307,6 +1307,25 @@ void CheckOther::commaSeparatedReturnError(const Token *tok)
                 "macro is then used in a return statement, it is less likely such code is misunderstood.", CWE398, Certainty::normal);
 }
 
+static bool isLargeContainer(const Variable* var, const Settings* settings)
+{
+    const ValueType* vt = var->valueType();
+    if (vt->container->size_templateArgNo < 0)
+        return true;
+    const std::size_t maxByValueSize = 2 * settings->platform.sizeof_pointer;
+    if (var->dimensions().empty()) {
+        if (vt->container->startPattern == "std :: bitset <") {
+            if (vt->containerTypeToken->hasKnownIntValue())
+                return vt->containerTypeToken->getKnownIntValue() / 8 > maxByValueSize;
+        }
+        return false;
+    }
+    const ValueType vtElem = ValueType::parseDecl(vt->containerTypeToken, *settings);
+    const auto elemSize = std::max<std::size_t>(ValueFlow::getSizeOf(vtElem, *settings), 1);
+    const auto arraySize = var->dimension(0) * elemSize;
+    return arraySize > maxByValueSize;
+}
+
 void CheckOther::checkPassByReference()
 {
     if (!mSettings->severity.isEnabled(Severity::performance) || mTokenizer->isC())
@@ -1317,7 +1336,7 @@ void CheckOther::checkPassByReference()
     const SymbolDatabase * const symbolDatabase = mTokenizer->getSymbolDatabase();
 
     for (const Variable* var : symbolDatabase->variableList()) {
-        if (!var || !var->isClass() || var->isPointer() || var->isArray() || var->isReference() || var->isEnumType())
+        if (!var || !var->isClass() || var->isPointer() || (var->isArray() && !var->isStlType()) || var->isReference() || var->isEnumType())
             continue;
 
         const bool isRangeBasedFor = astIsRangeBasedForDecl(var->nameToken());
@@ -1335,6 +1354,8 @@ void CheckOther::checkPassByReference()
         bool inconclusive = false;
 
         const bool isContainer = var->valueType() && var->valueType()->type == ValueType::Type::CONTAINER && var->valueType()->container && !var->valueType()->container->view;
+        if (isContainer && !isLargeContainer(var, mSettings))
+            continue;
         if (!isContainer) {
             if (var->type() && !var->type()->isEnumType()) { // Check if type is a struct or class.
                 // Ensure that it is a large object.

test/cfg/std.cpp

@@ -5137,3 +5137,25 @@ void unusedvar_stringstream(const char* p)
     // cppcheck-suppress unreadVariable
     std::stringstream sstr(p);
 }
+
+int passedByValue_std_array1(std::array<int, 2> a)
+{
+    return a[0] + a[1];
+}
+
+// cppcheck-suppress passedByValue
+int passedByValue_std_array2(std::array<int, 200> a)
+{
+    return a[0] + a[1];
+}
+
+int passedByValue_std_bitset1(std::bitset<4> bs) // #12961
+{
+    return bs.size();
+}
+
+// cppcheck-suppress passedByValue
+int passedByValue_std_bitset2(std::bitset<256> bs)
+{
+    return bs.size();
+}