shiboken: Refactor code generating multiple inheritance

- Remove the check function hasMultipleInheritanceInAncestry(),
  which is nearly identical to getMultipleInheritingClass().
- Modernize the generated code to use C++ casts, uintptr_t and streamline

Change-Id: I68f52c2cbf1a589fd31c9c73919365176c56932e
Reviewed-by: Christian Tismer <tismer@stackless.com>

3 files changed, 20 insertions, 34 deletions

diff --git a/sources/shiboken2/generator/shiboken2/cppgenerator.cpp b/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
index 67f8f1a7b..4b0b99317 100644
--- a/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
+++ b/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
@@ -330,8 +330,8 @@ void CppGenerator::generateClass(QTextStream &s, GeneratorContext &classContext)
 
     // The multiple inheritance initialization function
     // needs the 'set' class from C++ STL.
-    if (hasMultipleInheritanceInAncestry(metaClass))
-        s << "#include <set>" << endl;
+    if (getMultipleInheritingClass(metaClass) != nullptr)
+        s << "#include <algorithm>\n#include <set>\n";
     if (metaClass->generateExceptionHandling())
         s << "#include <exception>" << endl;
 
@@ -3553,11 +3553,18 @@ QStringList CppGenerator::getAncestorMultipleInheritance(const AbstractMetaClass
     const AbstractMetaClassList &baseClases = getBaseClasses(metaClass);
     if (!baseClases.isEmpty()) {
         for (const AbstractMetaClass *baseClass : baseClases) {
-            result.append(QString::fromLatin1("((size_t) static_cast<const %1*>(class_ptr)) - base")
-                                              .arg(baseClass->qualifiedCppName()));
-            result.append(QString::fromLatin1("((size_t) static_cast<const %1*>((%2*)((void*)class_ptr))) - base")
-                                              .arg(baseClass->qualifiedCppName(), metaClass->qualifiedCppName()));
+            QString offset;
+            QTextStream(&offset) << "reinterpret_cast<uintptr_t>(static_cast<const "
+                << baseClass->qualifiedCppName() << "*>(class_ptr)) - base";
+            result.append(offset);
+            offset.clear();
+            QTextStream(&offset) << "reinterpret_cast<uintptr_t>(static_cast<const "
+                << baseClass->qualifiedCppName() << "*>(static_cast<const "
+                << metaClass->qualifiedCppName()
+                << "*>(static_cast<const void*>(class_ptr)))) - base";
+            result.append(offset);
         }
+
         for (const AbstractMetaClass *baseClass : baseClases)
             result.append(getAncestorMultipleInheritance(baseClass));
     }
@@ -3579,25 +3586,17 @@ void CppGenerator::writeMultipleInheritanceInitializerFunction(QTextStream& s, c
     {
         Indentation indent(INDENT);
         s << INDENT << "std::set<int> offsets;" << endl;
-        s << INDENT << "std::set<int>::iterator it;" << endl;
-        s << INDENT << "const " << className << "* class_ptr = reinterpret_cast<const " << className << "*>(cptr);" << endl;
-        s << INDENT << "size_t base = (size_t) class_ptr;" << endl;
+        s << INDENT << "const auto* class_ptr = reinterpret_cast<const " << className << "*>(cptr);" << endl;
+        s << INDENT << "const auto base = reinterpret_cast<uintptr_t>(class_ptr);" << endl;
 
         for (const QString &ancestor : ancestors)
-            s << INDENT << "offsets.insert(" << ancestor << ");" << endl;
+            s << INDENT << "offsets.insert(int(" << ancestor << "));" << endl;
 
         s << endl;
         s << INDENT << "offsets.erase(0);" << endl;
         s << endl;
 
-        s << INDENT << "int i = 0;" << endl;
-        s << INDENT << "for (it = offsets.begin(); it != offsets.end(); it++) {" << endl;
-        {
-            Indentation indent(INDENT);
-            s << INDENT << "mi_offsets[i] = *it;" << endl;
-            s << INDENT << "i++;" << endl;
-        }
-        s << INDENT << '}' << endl;
+        s << INDENT << "std::copy(offsets.cbegin(), offsets.cend(), mi_offsets);\n";
     }
     s << INDENT << '}' << endl;
     s << INDENT << "return mi_offsets;" << endl;
@@ -3748,8 +3747,6 @@ void CppGenerator::writeExtendedConverterInitialization(QTextStream& s, const Ty
 
 QString CppGenerator::multipleInheritanceInitializerFunctionName(const AbstractMetaClass* metaClass)
 {
-    if (!hasMultipleInheritanceInAncestry(metaClass))
-        return QString();
     return cpythonBaseName(metaClass->typeEntry()) + QLatin1String("_mi_init");
 }
 
diff --git a/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp b/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
index 12efb68c3..44405c700 100644
--- a/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
+++ b/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
@@ -2178,15 +2178,6 @@ bool ShibokenGenerator::injectedCodeUsesArgument(const AbstractMetaFunction* fun
     return false;
 }
 
-bool ShibokenGenerator::hasMultipleInheritanceInAncestry(const AbstractMetaClass* metaClass)
-{
-    if (!metaClass || metaClass->baseClassNames().isEmpty())
-        return false;
-    if (metaClass->baseClassNames().size() > 1)
-        return true;
-    return hasMultipleInheritanceInAncestry(metaClass->baseClass());
-}
-
 bool ShibokenGenerator::classNeedsGetattroFunction(const AbstractMetaClass* metaClass)
 {
     return getGeneratorClassInfo(metaClass).needsGetattroFunction;
@@ -2269,7 +2260,7 @@ AbstractMetaClassList ShibokenGenerator::getBaseClasses(const AbstractMetaClass*
 const AbstractMetaClass* ShibokenGenerator::getMultipleInheritingClass(const AbstractMetaClass* metaClass)
 {
     if (!metaClass || metaClass->baseClassNames().isEmpty())
-        return 0;
+        return nullptr;
     if (metaClass->baseClassNames().size() > 1)
         return metaClass;
     return getMultipleInheritingClass(metaClass->baseClass());
diff --git a/sources/shiboken2/generator/shiboken2/shibokengenerator.h b/sources/shiboken2/generator/shiboken2/shibokengenerator.h
index ebfc059de..f5f291526 100644
--- a/sources/shiboken2/generator/shiboken2/shibokengenerator.h
+++ b/sources/shiboken2/generator/shiboken2/shibokengenerator.h
@@ -183,8 +183,8 @@ protected:
                               Options options = NoOption,
                               int arg_count = -1) const;
 
-    /// Returns true if there are cases of multiple inheritance in any of its ancestors.
-    bool hasMultipleInheritanceInAncestry(const AbstractMetaClass* metaClass);
+    /// Returns the top-most class that has multiple inheritance in the ancestry.
+    static const AbstractMetaClass *getMultipleInheritingClass(const AbstractMetaClass* metaClass);
 
     /// Returns true if the class needs to have a getattro function.
     bool classNeedsGetattroFunction(const AbstractMetaClass* metaClass);
@@ -198,8 +198,6 @@ protected:
     /// Returns a list of parent classes for a given class.
     AbstractMetaClassList getBaseClasses(const AbstractMetaClass* metaClass) const;
 
-    const AbstractMetaClass* getMultipleInheritingClass(const AbstractMetaClass* metaClass);
-
     void writeToPythonConversion(QTextStream& s, const AbstractMetaType* type,
                                  const AbstractMetaClass* context, const QString& argumentName);
     void writeToCppConversion(QTextStream& s, const AbstractMetaType* type, const AbstractMetaClass* context, const QString& inArgName, const QString& outArgName);