Fix losing the default value when the type altered

The changes influence, for instance, the following line:
```python
@staticmethod
def translate(
    context: str,
    key: str,
    disambiguation: Optional[str] = ...,
    n: int = ...
) -> str: ...
```
Namely, the `disambiguation` argument now indicates
that it has a default value.

It seems that the `pyi-type` attribute of the modify-argument tag
eats the argument default value.
The commit should add the omitted values if they're provided.

Initial-patch-by: Anton Yablokov (stsav012@gmail.com)
Change-Id: Ie3914c3ef13578ef8cfff9ecb8c6c64f167b5360
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>
(cherry picked from commit e82812a17888e8bbf30908f790b16433b086a4ef)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 6 insertions, 8 deletions

diff --git a/sources/shiboken6/generator/shiboken/cppgenerator.cpp b/sources/shiboken6/generator/shiboken/cppgenerator.cpp
index e56982b6c..74a9d8e91 100644
--- a/sources/shiboken6/generator/shiboken/cppgenerator.cpp
+++ b/sources/shiboken6/generator/shiboken/cppgenerator.cpp
@@ -5003,12 +5003,6 @@ QString CppGenerator::signatureParameter(const AbstractMetaArgument &arg) const
     if (size > 1)
         s << ']';
 
-    if (!arg.defaultValueExpression().isEmpty()) {
-        s << '=';
-        QString e = arg.defaultValueExpression();
-        e.replace(u"::"_s, u"."_s);
-        s << e;
-    }
     return result;
 }
 
@@ -5029,14 +5023,18 @@ void CppGenerator::writeSignatureInfo(TextStream &s, const OverloadData &overloa
         const auto &arguments = f->arguments();
         for (qsizetype i = 0, size = arguments.size(); i < size; ++i) {
             const auto n = i + 1;
+            const auto &arg = arguments.at(i);
             if (!f->argumentRemoved(n)) {
                 QString t = f->pyiTypeReplaced(n);
                 if (t.isEmpty()) {
-                    t = signatureParameter(arguments.at(i));
+                    t = signatureParameter(arg);
                 } else {
                     t.prepend(u':');
-                    t.prepend(arguments.at(i).name());
+                    t.prepend(arg.name());
                 }
+                QString defaultValue = arg.defaultValueExpression();
+                if (!defaultValue.isEmpty())
+                    t += u'=' + defaultValue.replace(u"::"_s, u"."_s);
                 args.append(t);
             }
         }