[processing] Fix API break in widget wrapper

Fixes #19820

Author: nyalldawson

python/gui/auto_generated/processing/qgsprocessingwidgetwrapper.sip.in

@@ -118,6 +118,8 @@ Returns the current wrapped label, if any.
 Returns the parameter definition associated with this wrapper.
 %End
 
+%Property( name = param, get = parameterDefinition )
+
     void setParameterValue( const QVariant &value, QgsProcessingContext &context );
 %Docstring
 Sets the current ``value`` for the parameter.

python/plugins/processing/gui/wrappers.py

@@ -155,7 +155,6 @@ def __init__(self, param, dialog, row=0, col=0, **kwargs):
         self.dialogType = dialogTypes.get(dialog.__class__.__name__, QgsProcessingGui.Standard)
         super().__init__(param, self.dialogType)
 
-        self.param = param
         self.dialog = dialog
         self.row = row
         self.col = col

scripts/sipify.pl

@@ -534,6 +534,13 @@ sub detect_non_method_member{
         write_output("COD", $LINE."\n");
         next;
     }
+    # do not process SIP code %Property
+    if ( $SIP_RUN == 1 && $LINE =~ m/^ *% *(Property)(.*)?$/ ){
+        $LINE = "%$1$2";
+        $COMMENT = '';
+        write_output("COD", $LINE."\n");
+        next;
+    }
 
     # Skip preprocessor stuff
     if ($LINE =~ m/^\s*#/){

src/gui/processing/qgsprocessingwidgetwrapper.h

@@ -139,6 +139,11 @@ class GUI_EXPORT QgsAbstractProcessingParameterWidgetWrapper : public QObject
      */
     const QgsProcessingParameterDefinition *parameterDefinition() const;
 
+    // TODO QGIS 4.0 -- remove
+#ifdef SIP_RUN
+    % Property( name = param, get = parameterDefinition )
+#endif
+
     /**
      * Sets the current \a value for the parameter.
      *