shiboken6: Enable adding modifications to declare-function

Amends 40483a4249306b62029987d03e7de57d456954b2.

Task-number: PYSIDE-1627
Change-Id: I1521e7436749fb95f282a07539310257dca3918f
Reviewed-by: Shyamnath Premnadh <Shyamnath.Premnadh@qt.io>
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>
(cherry picked from commit d375273ba0d6fed567a5b8cc386395b10f5f2bda)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 11 insertions, 7 deletions

diff --git a/sources/shiboken6/ApiExtractor/typesystemparser.cpp b/sources/shiboken6/ApiExtractor/typesystemparser.cpp
index a4ad9ea7a..2db8300ba 100644
--- a/sources/shiboken6/ApiExtractor/typesystemparser.cpp
+++ b/sources/shiboken6/ApiExtractor/typesystemparser.cpp
@@ -920,7 +920,8 @@ bool TypeSystemParser::endElement(StackElement element)
     }
     break;
 
-    case StackElement::AddFunction: {
+    case StackElement::AddFunction:
+    case StackElement::DeclareFunction: {
         // Leaving add-function: Assign all modifications to the added function
         const int modIndex = top->addedFunctionModificationIndex;
         top->addedFunctionModificationIndex = -1;
@@ -2221,10 +2222,11 @@ bool TypeSystemParser::parseModifyArgument(const ConditionalStreamReader &,
                                   StackElement topElement, QXmlStreamAttributes *attributes)
 {
     if (topElement != StackElement::ModifyFunction
-            && topElement != StackElement::AddFunction) {
-        m_error = QString::fromLatin1("argument modification requires function"
-                                      " modification as parent, was %1")
-                                      .arg(tagFromElement(topElement));
+        && topElement != StackElement::AddFunction
+        && topElement != StackElement::DeclareFunction) {
+        m_error = u"Argument modification requires <modify-function>,"
+                  " <add-function> or <declare-function> as parent, was "_qs
+                  + tagFromElement(topElement).toString();
         return false;
     }
 
diff --git a/sources/shiboken6/doc/typesystem_manipulating_objects.rst b/sources/shiboken6/doc/typesystem_manipulating_objects.rst
index 79add6d57..653de7718 100644
--- a/sources/shiboken6/doc/typesystem_manipulating_objects.rst
+++ b/sources/shiboken6/doc/typesystem_manipulating_objects.rst
@@ -261,6 +261,7 @@ add-function
     language, and it is a child of an :ref:`object-type` or :ref:`value-type` nodes if the
     function is supposed to be a method, or :ref:`namespace` and :ref:`typesystem` if
     the function is supposed to be a function inside a namespace or a global function.
+    It may contain :ref:`modify-argument` nodes.
 
     Typically when adding a function some code must be injected to provide the function
     logic. This can be done using the :ref:`inject-code` node.
@@ -303,7 +304,7 @@ declare-function
     the type and it is a child of an :ref:`object-type` or :ref:`value-type` nodes
     if the function is supposed to be a method, or :ref:`namespace` and
     :ref:`typesystem` if the function is supposed to be a function inside a
-    namespace or a global function.
+    namespace or a global function. It may contain :ref:`modify-argument` nodes.
 
     .. code-block:: xml
 
diff --git a/sources/shiboken6/doc/typesystem_modify_function.rst b/sources/shiboken6/doc/typesystem_modify_function.rst
index d7cb50dd6..19d0f211a 100644
--- a/sources/shiboken6/doc/typesystem_modify_function.rst
+++ b/sources/shiboken6/doc/typesystem_modify_function.rst
@@ -9,7 +9,8 @@ modify-argument
 ^^^^^^^^^^^^^^^
 
     Function modifications consist of a list of ``modify-argument`` nodes
-    contained in a :ref:`modify-function` node.  Use the :ref:`remove-argument`,
+    contained in :ref:`modify-function`, :ref:`add-function` or
+    :ref:`declare-function` nodes. Use the :ref:`remove-argument`,
     :ref:`replace-default-expression`, :ref:`remove-default-expression`,
     :ref:`replace-type`, :ref:`reference-count` and :ref:`define-ownership`
     nodes to specify the details of the modification.