9 files changed, 144 insertions, 40 deletions
diff --git a/sources/shiboken6_generator/ApiExtractor/abstractmetabuilder.cpp b/sources/shiboken6_generator/ApiExtractor/abstractmetabuilder.cpp
index 2413cc1ad..bf8d3246c 100644
--- a/sources/shiboken6_generator/ApiExtractor/abstractmetabuilder.cpp
+++ b/sources/shiboken6_generator/ApiExtractor/abstractmetabuilder.cpp
@@ -278,8 +278,35 @@ void AbstractMetaBuilderPrivate::registerToStringCapability(const FunctionModelI
     }
 }
 
+// Find "operator!=" matching an "operator==" in a scope.
+static bool hasOperatorNotEqual(const ScopeModelItem &scopeItem, const FunctionModelItem &operatorEqual)
+{
+    auto pred = [&operatorEqual](const FunctionModelItem &f) {
+        return f->isOperatorNotEqual() && operatorEqual->hasEquivalentArguments(*f);
+    };
+    return std::any_of(scopeItem->functions().cbegin(), scopeItem->functions().cend(), pred);
+}
+
+static ComparisonOperators synthesizedSpaceshipComparison(const AbstractMetaClassCPtr &currentClass,
+                                                          const FunctionModelItem &item)
+{
+    const auto te = currentClass->typeEntry();
+    // operator "<", ">" not for non-pair type containers
+    if (te->isContainer()) {
+        auto cTe = std::static_pointer_cast<const ContainerTypeEntry>(te);
+        if (cTe->containerKind() != ContainerTypeEntry::PairContainer)
+            return ComparisonOperatorType::EqualityMask;
+    }
+
+    // An == operator function is declared implicitly for each operator<=>
+    // defined as defaulted.
+    return item->attributes().testFlag(FunctionAttribute::Defaulted)
+        ? ComparisonOperatorType::AllMask : ComparisonOperatorType::OrderingMask;
+}
+
 // Traverse free operator functions (global/namespace)
 void AbstractMetaBuilderPrivate::traverseFreeOperatorFunction(const FunctionModelItem &item,
+                                                              const ScopeModelItem &scope,
                                                               const AbstractMetaClassPtr &currentClass)
 {
     Q_ASSERT(!currentClass || currentClass->isNamespace());
@@ -315,12 +342,6 @@ void AbstractMetaBuilderPrivate::traverseFreeOperatorFunction(const FunctionMode
         return;
     }
 
-    if (item->isSpaceshipOperator() && !item->isDeleted()) {
-        AbstractMetaClass::addSynthesizedComparisonOperators(baseoperandClass,
-                                                             InternalFunctionFlag::OperatorCpp20Spaceship);
-        return;
-    }
-
     // Do not synthesize reverse comparison operators. CPython swaps the
     // arguments for them by itself in Py_tp_richcompare.
     const bool reverseOperator = !firstArgumentIsSelf && !unaryOperator;
@@ -359,6 +380,27 @@ void AbstractMetaBuilderPrivate::traverseFreeOperatorFunction(const FunctionMode
     if (metaFunction->isComparisonOperator())
         metaFunction->setConstant(true);
     metaFunction->setAccess(Access::Public);
+    if (item->isSpaceshipOperator()) {
+        // For spaceship, the traverse mechanism is only used to handle rejections
+        // and get the argument type.
+        const auto ops = synthesizedSpaceshipComparison(baseoperandClass, item);
+        flags.setFlag(InternalFunctionFlag::OperatorCpp20Spaceship);
+        AbstractMetaClass::addSynthesizedComparisonOperators(baseoperandClass,
+                                                             metaFunction->arguments(),
+                                                             ops, flags);
+        return;
+    }
+
+    // C++20: Synthesize "!=" from "=="
+    if (clang::emulatedCompilerLanguageLevel() >= LanguageLevel::Cpp20
+        && item->isOperatorEqual()
+        && !item->hasPointerArguments() && !hasOperatorNotEqual(scope, item)) {
+        AbstractMetaClass::addSynthesizedComparisonOperators(
+            baseoperandClass, metaFunction->arguments(),
+            ComparisonOperatorType::OperatorNotEqual,
+            flags | InternalFunctionFlag::OperatorCpp20NonEquality);
+    }
+
     AbstractMetaClass::addFunction(baseoperandClass, metaFunction);
     ReportHandler::addGeneralMessage(msgSynthesizedFunction(metaFunction, item));
     if (!metaFunction->arguments().isEmpty()) {
@@ -676,11 +718,11 @@ void AbstractMetaBuilderPrivate::traverseDom(const FileModelItem &dom,
         case CodeModel::ArithmeticOperator:
         case CodeModel::BitwiseOperator:
         case CodeModel::LogicalOperator:
-            traverseFreeOperatorFunction(func, {});
+            traverseFreeOperatorFunction(func, dom, {});
             break;
         case CodeModel::ShiftOperator:
             if (!traverseStreamOperator(func, {}))
-                traverseFreeOperatorFunction(func, {});
+                traverseFreeOperatorFunction(func, dom, {});
         default:
             break;
         }
@@ -1465,7 +1507,7 @@ void AbstractMetaBuilderPrivate::traverseNameSpaceFunctions(const ScopeModelItem
     functions.reserve(scopeFunctionList.size());
     for (const FunctionModelItem &function : scopeFunctionList) {
         if (function->isOperator()) {
-            traverseFreeOperatorFunction(function, currentClass);
+            traverseFreeOperatorFunction(function, scopeItem, currentClass);
         } else if (auto metaFunction = traverseFunction(function, currentClass)) {
             metaFunction->setCppAttribute(FunctionAttribute::Static);
             functions.append(metaFunction);
@@ -1548,8 +1590,27 @@ void AbstractMetaBuilderPrivate::traverseClassFunction(const ScopeModelItem& sco
                                                        const AbstractMetaFunctionPtr &metaFunction,
                                                        const AbstractMetaClassPtr &metaClass) const
 {
-    Q_UNUSED(scopeItem)
-    Q_UNUSED(function)
+    if (function->isSpaceshipOperator()) {
+        // For spaceship, the traverse mechanism is only used to handle rejections
+        // and get the argument type.
+        if (!function->isDeleted()) {
+            const auto ops = synthesizedSpaceshipComparison(metaClass, function);
+            AbstractMetaClass::addSynthesizedComparisonOperators(metaClass,
+                                                                 metaFunction->arguments(),
+                                                                 ops, InternalFunctionFlag::OperatorCpp20Spaceship);
+        }
+        return;
+    }
+
+    // C++20: Synthesize "!=" from "=="
+    if (clang::emulatedCompilerLanguageLevel() >= LanguageLevel::Cpp20
+        && function->isOperatorEqual() && !hasOperatorNotEqual(scopeItem, function)) {
+        AbstractMetaClass::addSynthesizedComparisonOperators(
+            metaClass, metaFunction->arguments(),
+            ComparisonOperatorType::OperatorNotEqual,
+            InternalFunctionFlag::OperatorCpp20NonEquality);
+    }
+
     traverseClassFunction(metaFunction, metaClass);
 }
 
@@ -1559,10 +1620,7 @@ void AbstractMetaBuilderPrivate::traverseClassFunctions(const ScopeModelItem& sc
     Q_ASSERT(metaClass);
     AbstractMetaClass::Attributes constructorAttributes;
     for (const FunctionModelItem &function : scopeItem->functions()) {
-        if (function->isSpaceshipOperator() && !function->isDeleted()) {
-            AbstractMetaClass::addSynthesizedComparisonOperators(metaClass,
-                                                                 InternalFunctionFlag::OperatorCpp20Spaceship);
-        } else if (auto metaFunction = traverseFunction(function, metaClass)) {
+        if (auto metaFunction = traverseFunction(function, metaClass)) {
             traverseClassFunction(scopeItem, function, metaFunction, metaClass);
         } else if (!function->isDeleted() && function->functionType() == CodeModel::Constructor) {
             // traverseFunction() failed: mark rejected constructors
diff --git a/sources/shiboken6_generator/ApiExtractor/abstractmetabuilder_p.h b/sources/shiboken6_generator/ApiExtractor/abstractmetabuilder_p.h
index b503f4b33..0890eb752 100644
--- a/sources/shiboken6_generator/ApiExtractor/abstractmetabuilder_p.h
+++ b/sources/shiboken6_generator/ApiExtractor/abstractmetabuilder_p.h
@@ -116,7 +116,7 @@ public:
     void traverseFields(const ScopeModelItem &item, const AbstractMetaClassPtr &parent);
     bool traverseStreamOperator(const FunctionModelItem &functionItem,
                                 const AbstractMetaClassPtr &currentClass);
-    void traverseFreeOperatorFunction(const FunctionModelItem &item,
+    void traverseFreeOperatorFunction(const FunctionModelItem &item, const ScopeModelItem &scope,
                                       const AbstractMetaClassPtr &currentClass);
     AbstractMetaFunctionPtr
         traverseAddedFunctionHelper(const AddedFunctionPtr &addedFunc,
diff --git a/sources/shiboken6_generator/ApiExtractor/abstractmetalang.cpp b/sources/shiboken6_generator/ApiExtractor/abstractmetalang.cpp
index 837ce0d1a..14ed79644 100644
--- a/sources/shiboken6_generator/ApiExtractor/abstractmetalang.cpp
+++ b/sources/shiboken6_generator/ApiExtractor/abstractmetalang.cpp
@@ -920,35 +920,30 @@ static AbstractMetaType boolType()
     return result;
 }
 
-// Helper to synthesize comparison operators from a spaceship operator. Since
-// shiboken also generates code for comparing to different types, this fits
-// better than of handling it in the generator code.
+// Helper to synthesize comparison operators from a spaceship operator and equality operators.
+// Since shiboken also generates code for comparing to different types, this fits
+// better than handling it in the generator code.
 void AbstractMetaClass::addSynthesizedComparisonOperators(const AbstractMetaClassPtr &c,
+                                                          const AbstractMetaArgumentList &arguments,
+                                                          ComparisonOperators ops,
                                                           InternalFunctionFlags flags)
 {
     static const auto returnType = boolType();
 
-    AbstractMetaType selfType(c->typeEntry());
-    selfType.setConstant(true);
-    selfType.setReferenceType(LValueReference);
-    selfType.decideUsagePattern();
-    AbstractMetaArgument selfArgument;
-    selfArgument.setType(selfType);
-    selfArgument.setName(u"rhs"_s);
-    AbstractMetaArgumentList arguments(1, selfArgument);
-
-    static const char *operators[]
-        = {"operator==", "operator!=", "operator<", "operator<=", "operator>", "operator>="};
-    for (const auto *op : operators) {
-        auto *f = AbstractMetaClassPrivate::createFunction(QLatin1StringView(op),
-                                                           AbstractMetaFunction::ComparisonOperator,
-                                                           Access::Public, arguments,
-                                                           returnType, c);
-        f->setFlags(f->flags() | flags);
-        f->setConstant(true);
-        AbstractMetaFunctionCPtr newFunction(f);
-        c->d->addFunction(newFunction);
-        ReportHandler::addGeneralMessage(msgSynthesizedFunction(newFunction));
+    for (int mask = 0x1; (mask & int(ComparisonOperatorType::AllMask)) != 0; mask <<= 1) {
+        const auto op = ComparisonOperatorType(mask);
+        if (ops.testFlag(op)) {
+            const QString name = "operator"_L1 + QLatin1StringView(AbstractMetaFunction::cppComparisonOperator(op));
+            auto *f = AbstractMetaClassPrivate::createFunction(name,
+                                                               AbstractMetaFunction::ComparisonOperator,
+                                                               Access::Public, arguments,
+                                                               returnType, c);
+            f->setFlags(f->flags() | flags);
+            f->setConstant(true);
+            AbstractMetaFunctionCPtr newFunction(f);
+            c->d->addFunction(newFunction);
+            ReportHandler::addGeneralMessage(msgSynthesizedFunction(newFunction));
+        }
     }
 }
 
diff --git a/sources/shiboken6_generator/ApiExtractor/abstractmetalang.h b/sources/shiboken6_generator/ApiExtractor/abstractmetalang.h
index 8cc2f71f8..fd9b89443 100644
--- a/sources/shiboken6_generator/ApiExtractor/abstractmetalang.h
+++ b/sources/shiboken6_generator/ApiExtractor/abstractmetalang.h
@@ -128,6 +128,8 @@ public:
     bool isCopyConstructible() const;
 
     static void addSynthesizedComparisonOperators(const AbstractMetaClassPtr &c,
+                                                  const AbstractMetaArgumentList &arguments,
+                                                  ComparisonOperators ops,
                                                   InternalFunctionFlags flags);
 
     bool generateExceptionHandling() const;
diff --git a/sources/shiboken6_generator/ApiExtractor/clangparser/clangbuilder.cpp b/sources/shiboken6_generator/ApiExtractor/clangparser/clangbuilder.cpp
index 407a7a9e7..8e262d6d8 100644
--- a/sources/shiboken6_generator/ApiExtractor/clangparser/clangbuilder.cpp
+++ b/sources/shiboken6_generator/ApiExtractor/clangparser/clangbuilder.cpp
@@ -397,6 +397,7 @@ FunctionModelItem BuilderPrivate::createMemberFunction(const CXCursor &cursor,
     result->setAttribute(FunctionAttribute::Static, clang_CXXMethod_isStatic(cursor) != 0);
     result->setAttribute(FunctionAttribute::Virtual, clang_CXXMethod_isVirtual(cursor) != 0);
     result->setAttribute(FunctionAttribute::Abstract, clang_CXXMethod_isPureVirtual(cursor) != 0);
+    result->setAttribute(FunctionAttribute::Defaulted, clang_CXXMethod_isDefaulted(cursor) != 0);
     return result;
 }
 
diff --git a/sources/shiboken6_generator/ApiExtractor/parser/codemodel.cpp b/sources/shiboken6_generator/ApiExtractor/parser/codemodel.cpp
index 8cbca7bc9..bfccacbac 100644
--- a/sources/shiboken6_generator/ApiExtractor/parser/codemodel.cpp
+++ b/sources/shiboken6_generator/ApiExtractor/parser/codemodel.cpp
@@ -846,6 +846,13 @@ void _ArgumentModelItem::setScopeResolution(bool v)
     m_scopeResolution = v;
 }
 
+bool _ArgumentModelItem::isEquivalent(const _ArgumentModelItem &rhs) const
+{
+    return m_scopeResolution == rhs.m_scopeResolution && m_defaultValue == rhs.m_defaultValue
+        && m_defaultValueExpression == rhs.m_defaultValueExpression
+        && m_type == rhs.m_type;
+}
+
 #ifndef QT_NO_DEBUG_STREAM
 void _ArgumentModelItem::formatDebug(QDebug &d) const
 {
@@ -991,6 +998,16 @@ bool _FunctionModelItem::isOperator() const
     return result;
 }
 
+static bool isPointerArgument(const ArgumentModelItem &a)
+{
+    return !a->type().indirectionsV().isEmpty();
+}
+
+bool _FunctionModelItem::hasPointerArguments() const
+{
+    return std::any_of(m_arguments.cbegin(), m_arguments.cend(), isPointerArgument);
+}
+
 ExceptionSpecification _FunctionModelItem::exceptionSpecification() const
 {
     return m_exceptionSpecification;
@@ -1075,6 +1092,19 @@ QString _FunctionModelItem::typeSystemSignature() const  // For dumping out type
     return result;
 }
 
+static inline bool equivalentArguments(const ArgumentModelItem &lhs,
+                                       const ArgumentModelItem &rhs)
+{
+    return lhs->isEquivalent(*rhs);
+}
+
+bool _FunctionModelItem::hasEquivalentArguments(const _FunctionModelItem &rhs) const
+{
+    return m_arguments.size() == rhs.m_arguments.size()
+        && std::equal(m_arguments.cbegin(), m_arguments.cend(), rhs.m_arguments.cbegin(), rhs.m_arguments.cend(),
+                         equivalentArguments);
+}
+
 using NameFunctionTypeHash = QHash<QStringView, CodeModel::FunctionType>;
 
 static const NameFunctionTypeHash &nameToOperatorFunction()
diff --git a/sources/shiboken6_generator/ApiExtractor/parser/codemodel.h b/sources/shiboken6_generator/ApiExtractor/parser/codemodel.h
index 8d757e635..7ff0a88e2 100644
--- a/sources/shiboken6_generator/ApiExtractor/parser/codemodel.h
+++ b/sources/shiboken6_generator/ApiExtractor/parser/codemodel.h
@@ -380,6 +380,8 @@ public:
     bool scopeResolution() const;
     void setScopeResolution(bool v);
 
+    bool isEquivalent(const _ArgumentModelItem &rhs) const; // Compare all except name
+
 #ifndef QT_NO_DEBUG_STREAM
     void formatDebug(QDebug &d) const override;
 #endif
@@ -502,6 +504,7 @@ public:
     bool isSpaceshipOperator() const;
     bool isOperatorEqual() const;
     bool isOperatorNotEqual() const;
+    bool hasPointerArguments() const;
 
     bool isSimilar(const FunctionModelItem &other) const;
 
@@ -515,6 +518,9 @@ public:
     QString classQualifiedSignature() const;
     QString typeSystemSignature() const; // For dumping out type system files
 
+    // Compare all except names
+    bool hasEquivalentArguments(const _FunctionModelItem &rhs) const;
+
     // Private, for usage by the clang builder.
     void _determineType();
 
diff --git a/sources/shiboken6_generator/ApiExtractor/parser/codemodel_enums.h b/sources/shiboken6_generator/ApiExtractor/parser/codemodel_enums.h
index 358195799..272140ae3 100644
--- a/sources/shiboken6_generator/ApiExtractor/parser/codemodel_enums.h
+++ b/sources/shiboken6_generator/ApiExtractor/parser/codemodel_enums.h
@@ -53,6 +53,7 @@ enum class FunctionAttribute : std::uint8_t {
     Final      = 0x00000010,
     Deprecated = 0x00000020, // Code annotation
     Explicit   = 0x00000040, // Constructor
+    Defaulted  = 0x00000080
 };
 
 Q_DECLARE_FLAGS(FunctionAttributes, FunctionAttribute)
diff --git a/sources/shiboken6_generator/ApiExtractor/typedatabase.cpp b/sources/shiboken6_generator/ApiExtractor/typedatabase.cpp
index 91d39f835..ae06fb140 100644
--- a/sources/shiboken6_generator/ApiExtractor/typedatabase.cpp
+++ b/sources/shiboken6_generator/ApiExtractor/typedatabase.cpp
@@ -1739,6 +1739,17 @@ void TypeDatabasePrivate::addBuiltInPrimitiveTypes()
                                          root, rootPackage,
                                          pyUnicodeCustomEntry);
     }
+
+    // Prevent rejection of operator<=>() due to mismatched return type.
+    if (clang::emulatedCompilerLanguageLevel() >= LanguageLevel::Cpp20) {
+        for (const QString &ordering : {u"std::strong_ordering"_s, u"std::partial_ordering"_s}) {
+            if (!m_entries.contains(ordering)) {
+                    auto entry = std::make_shared<CustomTypeEntry>(ordering, QVersionNumber{}, root);
+                    entry->setTargetLangPackage(rootPackage);
+                    m_entries.insert(ordering, entry);
+            }
+        }
+    }
 }
 
 QDebug operator<<(QDebug d, const TypeDatabase &db)