shiboken2: Use an AbstractMetaType for "void"

Previously, nullptr for an AbstractMetaType meant "void", particularly
for function return types. The problem with this is that it
causes unexpected crashes when dealing with template types
like QFuture<void> due to one of the instantiations of the
AbstractMetaType being nullptr. Use an AbstractMetaType based
on the existing "void" type entry for this.

Task-number: PYSIDE-1202
Change-Id: Ib06035cc7903480fd509f7e927d9114c55d51b62
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

4 files changed, 30 insertions, 34 deletions

diff --git a/sources/shiboken2/generator/shiboken2/cppgenerator.cpp b/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
index c1f1b21db..ea970331e 100644
--- a/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
+++ b/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
@@ -247,7 +247,7 @@ const AbstractMetaFunction *CppGenerator::boolCast(const AbstractMetaClass *meta
         return nullptr;
     // TODO: This could be configurable someday
     const AbstractMetaFunction *func = metaClass->findFunction(QLatin1String("isNull"));
-    if (!func || !func->type() || !func->type()->typeEntry()->isPrimitive() || !func->isPublic())
+    if (!func || func->isVoid() || !func->type()->typeEntry()->isPrimitive() || !func->isPublic())
         return nullptr;
     auto pte = static_cast<const PrimitiveTypeEntry *>(func->type()->typeEntry());
     while (pte->referencedTypeEntry())
@@ -892,9 +892,9 @@ QString CppGenerator::virtualMethodReturn(QTextStream &s,
                                           const AbstractMetaFunction *func,
                                           const FunctionModificationList &functionModifications)
 {
-    const AbstractMetaType *returnType = func->type();
-    if (!returnType)
+    if (func->isVoid())
         return QLatin1String("return;");
+    const AbstractMetaType *returnType = func->type();
     for (const FunctionModification &mod : functionModifications) {
         for (const ArgumentModification &argMod : mod.argument_mods) {
             if (argMod.index == 0 && !argMod.replacedDefaultExpression.isEmpty()) {
@@ -951,7 +951,7 @@ void CppGenerator::writeVirtualMethodNative(QTextStream &s,
         ((func->name() == QLatin1String("metaObject")) || (func->name() == QLatin1String("qt_metacall"))))
         return;
 
-    const TypeEntry *retType = func->type() ? func->type()->typeEntry() : nullptr;
+    const TypeEntry *retType = func->type()->typeEntry();
     const QString funcName = func->isOperatorOverload() ? pythonOperatorFunctionName(func) : func->name();
 
     QString prefix = wrapperName(func->ownerClass()) + QLatin1String("::");
@@ -994,7 +994,7 @@ void CppGenerator::writeVirtualMethodNative(QTextStream &s,
            << R"(] << '\n';)" << '\n';
     }
     // PYSIDE-803: Build a boolean cache for unused overrides.
-    const bool multi_line = retType == nullptr || !snips.isEmpty() || func->isAbstract();
+    const bool multi_line = func->isVoid() || !snips.isEmpty() || func->isAbstract();
     s << INDENT << "if (m_PyMethodCache[" << cacheIndex << "])" << (multi_line ? " {\n" : "\n");
     {
         Indentation indentation(INDENT);
@@ -1126,7 +1126,7 @@ void CppGenerator::writeVirtualMethodNative(QTextStream &s,
         }
         s << INDENT << "}\n";
 
-        if (retType) {
+        if (!func->isVoid()) {
             if (invalidateReturn)
                 s << INDENT << "bool invalidateArg0 = " << PYTHON_RETURN_VAR << "->ob_refcnt == 1;\n";
 
@@ -1211,7 +1211,7 @@ void CppGenerator::writeVirtualMethodNative(QTextStream &s,
         writeCodeSnips(s, snips, TypeSystem::CodeSnipPositionEnd, TypeSystem::NativeCode, func, lastArg);
     }
 
-    if (retType) {
+    if (!func->isVoid()) {
         s << INDENT << "return ";
         if (avoidProtectedHack() && retType->isEnum()) {
             const AbstractMetaEnum *metaEnum = findAbstractMetaEnum(retType);
@@ -2329,6 +2329,7 @@ void CppGenerator::writeTypeCheck(QTextStream &s, const AbstractMetaType *argTyp
 static void checkTypeViability(const AbstractMetaFunction *func, const AbstractMetaType *type, int argIdx)
 {
     if (!type
+        || type->isVoid()
         || !type->typeEntry()->isPrimitive()
         || type->indirections() == 0
         || (type->indirections() == 1 && type->typeUsagePattern() == AbstractMetaType::NativePointerAsArrayPattern)
@@ -2596,7 +2597,7 @@ void CppGenerator::writeConversionRule(QTextStream &s, const AbstractMetaFunctio
 
 void CppGenerator::writeNoneReturn(QTextStream &s, const AbstractMetaFunction *func, bool thereIsReturnValue)
 {
-    if (thereIsReturnValue && (!func->type() || func->argumentRemoved(0)) && !injectedCodeHasReturnValueAttribution(func)) {
+    if (thereIsReturnValue && (func->isVoid() || func->argumentRemoved(0)) && !injectedCodeHasReturnValueAttribution(func)) {
         s << INDENT << PYTHON_RETURN_VAR << " = Py_None;\n";
         s << INDENT << "Py_INCREF(Py_None);\n";
     }
@@ -3237,7 +3238,7 @@ QString CppGenerator::argumentNameFromIndex(const AbstractMetaFunction *func, in
     } else if (argIndex == 0) {
         AbstractMetaType *funcType = func->type();
         AbstractMetaType *returnType = getTypeWithoutContainer(funcType);
-        if (returnType) {
+        if (!returnType->isVoid()) {
             pyArgName = QLatin1String(PYTHON_RETURN_VAR);
             *wrappedClass = AbstractMetaClass::findClass(classes(), returnType->typeEntry());
         } else {
@@ -3560,7 +3561,7 @@ void CppGenerator::writeMethodCall(QTextStream &s, const AbstractMetaFunction *f
             if (isCtor) {
                 s << (useVAddr.isEmpty() ?
                       QString::fromLatin1("cptr = %1;").arg(methodCall) : useVAddr) << Qt::endl;
-            } else if (func->type() && !func->isInplaceOperator()) {
+            } else if (!func->isVoid() && !func->isInplaceOperator()) {
                 bool writeReturnType = true;
                 if (avoidProtectedHack()) {
                     const AbstractMetaEnum *metaEnum = findAbstractMetaEnum(func->type());
@@ -3598,7 +3599,7 @@ void CppGenerator::writeMethodCall(QTextStream &s, const AbstractMetaFunction *f
             // Convert result
             if (!func->conversionRule(TypeSystem::TargetLangCode, 0).isEmpty()) {
                 writeConversionRule(s, func, TypeSystem::TargetLangCode, QLatin1String(PYTHON_RETURN_VAR));
-            } else if (!isCtor && !func->isInplaceOperator() && func->type()
+            } else if (!isCtor && !func->isInplaceOperator() && !func->isVoid()
                 && !injectedCodeHasReturnValueAttribution(func, TypeSystem::TargetLangCode)) {
                 s << INDENT << PYTHON_RETURN_VAR << " = ";
                 if (isObjectTypeUsedAsValueType(func->type())) {
@@ -4696,7 +4697,7 @@ void CppGenerator::writeRichCompareFunction(QTextStream &s, const GeneratorConte
                     }
                     if (generateOperatorCode) {
                         s << INDENT;
-                        if (func->type())
+                        if (!func->isVoid())
                             s << func->type()->cppSignature() << " " << CPP_RETURN_VAR << " = ";
                         // expression
                         if (func->isPointerOperator())
@@ -4706,7 +4707,7 @@ void CppGenerator::writeRichCompareFunction(QTextStream &s, const GeneratorConte
                             s << '*';
                         s << CPP_ARG0 << ");\n";
                         s << INDENT << PYTHON_RETURN_VAR << " = ";
-                        if (func->type())
+                        if (!func->isVoid())
                             writeToPythonConversion(s, func->type(), metaClass, QLatin1String(CPP_RETURN_VAR));
                         else
                             s << "Py_None;\n" << INDENT << "Py_INCREF(Py_None)";
@@ -4830,7 +4831,7 @@ void CppGenerator::writeSignatureInfo(QTextStream &s, const AbstractMetaFunction
         if (multiple)
             s << idx-- << ':';
         s << funcName << '(' << args.join(QLatin1Char(',')) << ')';
-        if (f->type())
+        if (!f->isVoid())
             s << "->" << f->type()->pythonSignature();
         s << Qt::endl;
     }
@@ -6214,7 +6215,7 @@ void CppGenerator::writeReturnValueHeuristics(QTextStream &s, const AbstractMeta
     AbstractMetaType *type = func->type();
     if (!useReturnValueHeuristic()
         || !func->ownerClass()
-        || !type
+        || type->isVoid()
         || func->isStatic()
         || func->isConstructor()
         || !func->typeReplaced(0).isEmpty()) {
diff --git a/sources/shiboken2/generator/shiboken2/headergenerator.cpp b/sources/shiboken2/generator/shiboken2/headergenerator.cpp
index 36ccefb58..107e28a4a 100644
--- a/sources/shiboken2/generator/shiboken2/headergenerator.cpp
+++ b/sources/shiboken2/generator/shiboken2/headergenerator.cpp
@@ -239,7 +239,8 @@ void HeaderGenerator::writeFunction(QTextStream &s, const AbstractMetaFunction *
         s << INDENT << "inline " << (func->isStatic() ? "static " : "");
         s << functionSignature(func, QString(), QLatin1String("_protected"), Generator::EnumAsInts|Generator::OriginalTypeDescription)
             << " { ";
-        s << (func->type() ? "return " : "");
+        if (!func->isVoid())
+            s << "return ";
         if (!func->isAbstract())
             s << func->ownerClass()->qualifiedCppName() << "::";
         s << func->originalName() << '(';
@@ -637,8 +638,10 @@ void HeaderGenerator::writeInheritedOverloads(QTextStream &s)
 {
     for (const AbstractMetaFunction *func : qAsConst(m_inheritedOverloads)) {
         s << INDENT << "inline ";
-        s << functionSignature(func, QString(), QString(), Generator::EnumAsInts|Generator::OriginalTypeDescription) << " { ";
-        s << (func->type() ? "return " : "");
+        s << functionSignature(func, QString(), QString(), Generator::EnumAsInts|Generator::OriginalTypeDescription)
+            << " { ";
+        if (!func->isVoid())
+            s << "return ";
         s << func->ownerClass()->qualifiedCppName() << "::" << func->originalName() << '(';
         QStringList args;
         const AbstractMetaArgumentList &arguments = func->arguments();
diff --git a/sources/shiboken2/generator/shiboken2/overloaddata.cpp b/sources/shiboken2/generator/shiboken2/overloaddata.cpp
index 36725d3fc..9f79060da 100644
--- a/sources/shiboken2/generator/shiboken2/overloaddata.cpp
+++ b/sources/shiboken2/generator/shiboken2/overloaddata.cpp
@@ -579,10 +579,8 @@ QStringList OverloadData::returnTypes() const
     for (const AbstractMetaFunction *func : m_overloads) {
         if (!func->typeReplaced(0).isEmpty())
             retTypes << func->typeReplaced(0);
-        else if (func->type() && !func->argumentRemoved(0))
+        else if (!func->argumentRemoved(0))
             retTypes << func->type()->cppSignature();
-        else
-            retTypes << QLatin1String("void");
     }
     return retTypes.values();
 }
@@ -878,12 +876,9 @@ QString OverloadData::dumpGraph() const
         // Shows all function signatures
         s << "legend [fontsize=9 fontname=freemono shape=rect label=\"";
         for (const AbstractMetaFunction *func : m_overloads) {
-            s << "f" << functionNumber(func) << " : ";
-            if (func->type())
-                s << toHtml(func->type()->cppSignature());
-            else
-                s << "void";
-            s << ' ' << toHtml(func->minimalSignature()) << "\\l";
+            s << "f" << functionNumber(func) << " : "
+                << toHtml(func->type()->cppSignature())
+                << ' ' << toHtml(func->minimalSignature()) << "\\l";
         }
         s << "\"];\n";
 
@@ -903,12 +898,9 @@ QString OverloadData::dumpGraph() const
         s << "</td></tr>";
 
         // Function return type
-        s << "<tr><td bgcolor=\"gray\" align=\"right\">original type</td><td bgcolor=\"gray\" align=\"left\">";
-        if (rfunc->type())
-            s << toHtml(rfunc->type()->cppSignature());
-        else
-            s << "void";
-        s << "</td></tr>";
+        s << "<tr><td bgcolor=\"gray\" align=\"right\">original type</td><td bgcolor=\"gray\" align=\"left\">"
+            << toHtml(rfunc->type()->cppSignature())
+            << "</td></tr>";
 
         // Shows type changes for all function signatures
         for (const AbstractMetaFunction *func : m_overloads) {
diff --git a/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp b/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
index 8cea5aeda..3cd6b8e53 100644
--- a/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
+++ b/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
@@ -1862,7 +1862,7 @@ void ShibokenGenerator::writeCodeSnips(QTextStream &s,
     if (func->isConstructor()) {
         code.replace(QLatin1String("%0."), QLatin1String("cptr->"));
         code.replace(QLatin1String("%0"), QLatin1String("cptr"));
-    } else if (func->type()) {
+    } else if (!func->isVoid()) {
         QString returnValueOp = isPointerToWrapperType(func->type())
             ? QLatin1String("%1->") : QLatin1String("%1.");
         if (ShibokenGenerator::isWrapperType(func->type()))