shiboken2: Add attribute for generating "using namespace"

Make it possible to turn off the generation of
using namespace. This is required in Qt 6 to avoid
a clash between Qt3DCore::QBuffer and QBuffer used
in __repr__.

Task-number: PYSIDE-1339
Task-number: PYSIDE-904
Change-Id: Iaaf3e67f0ffaae86e2de82b9a1b8fe7d00c74e6b
Reviewed-by: Christian Tismer <tismer@stackless.com>

4 files changed, 18 insertions, 2 deletions

diff --git a/sources/shiboken2/ApiExtractor/typesystem.h b/sources/shiboken2/ApiExtractor/typesystem.h
index 9d97f5c93..b31cee9cd 100644
--- a/sources/shiboken2/ApiExtractor/typesystem.h
+++ b/sources/shiboken2/ApiExtractor/typesystem.h
@@ -1527,6 +1527,9 @@ public:
     void formatDebug(QDebug &d) const override;
 #endif
 
+    bool generateUsing() const { return m_generateUsing; }
+    void setGenerateUsing(bool generateUsing) { m_generateUsing = generateUsing; }
+
 protected:
     NamespaceTypeEntry(const NamespaceTypeEntry &);
 
@@ -1536,6 +1539,7 @@ private:
     TypeSystem::Visibility m_visibility = TypeSystem::Visibility::Auto;
     bool m_hasPattern = false;
     bool m_inlineNamespace = false;
+    bool m_generateUsing = true; // Whether to generate "using namespace" into wrapper
 };
 
 class ValueTypeEntry : public ComplexTypeEntry
diff --git a/sources/shiboken2/ApiExtractor/typesystemparser.cpp b/sources/shiboken2/ApiExtractor/typesystemparser.cpp
index 207c99c7a..a56c5c698 100644
--- a/sources/shiboken2/ApiExtractor/typesystemparser.cpp
+++ b/sources/shiboken2/ApiExtractor/typesystemparser.cpp
@@ -67,6 +67,7 @@ static inline QString flagsAttribute() { return QStringLiteral("flags"); }
 static inline QString forceAbstractAttribute() { return QStringLiteral("force-abstract"); }
 static inline QString forceIntegerAttribute() { return QStringLiteral("force-integer"); }
 static inline QString formatAttribute() { return QStringLiteral("format"); }
+static inline QString generateUsingAttribute() { return QStringLiteral("generate-using"); }
 static inline QString classAttribute() { return QStringLiteral("class"); }
 static inline QString generateAttribute() { return QStringLiteral("generate"); }
 static inline QString genericClassAttribute() { return QStringLiteral("generic-class"); }
@@ -1374,6 +1375,8 @@ NamespaceTypeEntry *
         } else if (attributeName == generateAttribute()) {
             if (!convertBoolean(attributes->takeAt(i).value(), generateAttribute(), true))
                 visibility = TypeSystem::Visibility::Invisible;
+        } else if (attributeName == generateUsingAttribute()) {
+            result->setGenerateUsing(convertBoolean(attributes->takeAt(i).value(), generateUsingAttribute(), true));
         }
     }
 
diff --git a/sources/shiboken2/doc/typesystem_specifying_types.rst b/sources/shiboken2/doc/typesystem_specifying_types.rst
index 27267faab..221519541 100644
--- a/sources/shiboken2/doc/typesystem_specifying_types.rst
+++ b/sources/shiboken2/doc/typesystem_specifying_types.rst
@@ -155,6 +155,7 @@ namespace-type
             <namespace-type name="..."
                 visible="true | auto | false"
                 generate="yes | no"
+                generate-using="yes | no"
                 package="..."
                 since="..."
                 revision="..." />
@@ -173,6 +174,13 @@ namespace-type
     The *optional* **generate** is a legacy attribute. Specifying
     **no** is equivalent to **visible="false"**.
 
+    The *optional* **generate-using** attribute specifies whether
+    ``using namespace`` is generated into the wrapper code for classes within
+    the namespace (default: **yes**). This ensures for example that not fully
+    qualified enumeration values of default argument values compile.
+    However, in rare cases, it might cause ambiguities and can then be turned
+    off.
+
     The **package** attribute can be used to override the package of the type system.
 
     The *optional*  **since** value is used to specify the API version of this type.
diff --git a/sources/shiboken2/generator/shiboken2/cppgenerator.cpp b/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
index d38463e2c..7a4f59cf3 100644
--- a/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
+++ b/sources/shiboken2/generator/shiboken2/cppgenerator.cpp
@@ -404,8 +404,9 @@ void CppGenerator::generateClass(QTextStream &s, const GeneratorContext &classCo
     {
         const AbstractMetaClass *context = metaClass->enclosingClass();
         while (context) {
-            if (context->isNamespace() && !context->enclosingClass()) {
-                s << "using namespace " << context->qualifiedCppName() << ";\n";
+            if (context->isNamespace() && !context->enclosingClass()
+                && static_cast<const NamespaceTypeEntry *>(context->typeEntry())->generateUsing()) {
+                s << "\nusing namespace " << context->qualifiedCppName() << ";\n";
                 break;
             }
             context = context->enclosingClass();