Fix T94116: Drivers can have multiple variables with same name

The RNA setter now ensures that driver variables are uniquely named
(within the scope of the driver).

Versioning code has been added to ensure this uniqueness. The last
variable with the non-unique name retains the original name; this
ensures that the driver will still evaluate to the same value as before
this fix.

This also introduces a new blenlib function `BLI_listbase_from_link()`,
which can be used to find the entire list from any item within the list.

Manifest Task: T94116

Reviewed By: mont29, JacquesLucke

Maniphest Tasks: T94116

Differential Revision: https://developer.blender.org/D13594

1 files changed, 7 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_fcurve_driver.h b/source/blender/blenkernel/BKE_fcurve_driver.h
index 18676dfcb38..7e4e0ad3c2a 100644
--- a/source/blender/blenkernel/BKE_fcurve_driver.h
+++ b/source/blender/blenkernel/BKE_fcurve_driver.h
@@ -105,6 +105,13 @@ void driver_change_variable_type(struct DriverVar *dvar, int type);
  */
 void driver_variable_name_validate(struct DriverVar *dvar);
 /**
+ * Ensure the driver variable's name is unique.
+ *
+ * Assumes the driver variable has already been assigned to the driver, so that
+ * the prev/next pointers can be used to find the other variables.
+ */
+void driver_variable_unique_name(struct DriverVar *dvar);
+/**
  * Add a new driver variable.
  */
 struct DriverVar *driver_add_new_variable(struct ChannelDriver *driver);