[Bf-blender-cvs] [e862874606b] blender-v2.93-release: Fix slicing with negative indices

[Campbell Barton]

Commit: e862874606b9f1a8477c345b23fb39e53e4a9390
Author: Campbell Barton
Date:   Thu Aug 5 16:44:03 2021 +1000
Branches: blender-v2.93-release
https://developer.blender.org/rBe862874606b9f1a8477c345b23fb39e53e4a9390

Fix slicing with negative indices

Negative indices that remained negative after adding the sequence length
caused incorrect slicing.

With the default scene for example:

   bpy.context.scene.objects[-4:2]

Gave a different result to:

   tuple(bpy.context.scene.objects)[-4:2]

Clamp indices above zero so loops that step forward works as intended.

===================================================================

M	source/blender/python/bmesh/bmesh_py_types.c
M	source/blender/python/bmesh/bmesh_py_types_customdata.c
M	source/blender/python/bmesh/bmesh_py_types_select.c
M	source/blender/python/intern/bpy_rna.c

===================================================================

diff --git a/source/blender/python/bmesh/bmesh_py_types.c b/source/blender/python/bmesh/bmesh_py_types.c
index 3b6c5d5f280..ad5ee7b7604 100644
--- a/source/blender/python/bmesh/bmesh_py_types.c
+++ b/source/blender/python/bmesh/bmesh_py_types.c
@@ -3252,9 +3252,11 @@ static PyObject *bpy_bmelemseq_subscript(BPy_BMElemSeq *self, PyObject *key)
       const Py_ssize_t len = bpy_bmelemseq_length(self);
       if (start < 0) {
         start += len;
+        CLAMP_MIN(start, 0);
       }
       if (stop < 0) {
         stop += len;
+        CLAMP_MIN(stop, 0);
       }
     }
 
diff --git a/source/blender/python/bmesh/bmesh_py_types_customdata.c b/source/blender/python/bmesh/bmesh_py_types_customdata.c
index 78c43d18609..df02ee7f242 100644
--- a/source/blender/python/bmesh/bmesh_py_types_customdata.c
+++ b/source/blender/python/bmesh/bmesh_py_types_customdata.c
@@ -843,9 +843,11 @@ static PyObject *bpy_bmlayercollection_subscript(BPy_BMLayerCollection *self, Py
       const Py_ssize_t len = bpy_bmlayercollection_length(self);
       if (start < 0) {
         start += len;
+        CLAMP_MIN(start, 0);
       }
       if (stop < 0) {
         stop += len;
+        CLAMP_MIN(stop, 0);
       }
     }
 
diff --git a/source/blender/python/bmesh/bmesh_py_types_select.c b/source/blender/python/bmesh/bmesh_py_types_select.c
index 9bb9815f731..69f104c9959 100644
--- a/source/blender/python/bmesh/bmesh_py_types_select.c
+++ b/source/blender/python/bmesh/bmesh_py_types_select.c
@@ -282,9 +282,11 @@ static PyObject *bpy_bmeditselseq_subscript(BPy_BMEditSelSeq *self, PyObject *ke
       const Py_ssize_t len = bpy_bmeditselseq_length(self);
       if (start < 0) {
         start += len;
+        CLAMP_MIN(start, 0);
       }
       if (stop < 0) {
         stop += len;
+        CLAMP_MIN(stop, 0);
       }
     }
 
diff --git a/source/blender/python/intern/bpy_rna.c b/source/blender/python/intern/bpy_rna.c
index 1711637458a..eeb237a72cb 100644
--- a/source/blender/python/intern/bpy_rna.c
+++ b/source/blender/python/intern/bpy_rna.c
@@ -2785,9 +2785,11 @@ static PyObject *pyrna_prop_collection_subscript(BPy_PropertyRNA *self, PyObject
       const Py_ssize_t len = (Py_ssize_t)RNA_property_collection_length(&self->ptr, self->prop);
       if (start < 0) {
         start += len;
+        CLAMP_MIN(start, 0);
       }
       if (stop < 0) {
         stop += len;
+        CLAMP_MIN(stop, 0);
       }
     }
 
@@ -2915,9 +2917,11 @@ static int pyrna_prop_collection_ass_subscript(BPy_PropertyRNA *self,
         Py_ssize_t len = (Py_ssize_t)RNA_property_collection_length(&self->ptr, self->prop);
         if (start < 0) {
           start += len;
+          CLAMP_MIN(start, 0);
         }
         if (stop < 0) {
           stop += len;
+          CLAMP_MIN(stop, 0);
         }
       }