"Fix" root cause of T51260 Forward compatibility crash fter adding new IDProp type.

We unfortunately cannot fix this for previous versions of Blender, but
at least the issue (Blender crashing on unknown IDProp types) should now
be addressed for future.

Simply reset unknown IDProp types to integer one, and reset its value to zero.

1 files changed, 12 insertions, 1 deletions

diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index eabe2feb4d7..1d74e126d95 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -2107,8 +2107,19 @@ static void IDP_DirectLinkProperty(IDProperty *prop, int switch_endian, FileData
 				BLI_endian_switch_int32(&prop->data.val2);
 				BLI_endian_switch_int64((int64_t *)&prop->data.val);
 			}
-			
 			break;
+		case IDP_INT:
+		case IDP_FLOAT:
+		case IDP_ID:
+			break;  /* Nothing special to do here. */
+		default:
+			/* Unknown IDP type, nuke it (we cannot handle unknown types everywhere in code,
+			 * IDP are way too polymorphic to do it safely. */
+			printf("%s: found unknown IDProperty type %d, reset to Integer one !\n", __func__, prop->type);
+			/* Note: we do not attempt to free unknown prop, we have no way to know how to do that! */
+			prop->type = IDP_INT;
+			prop->subtype = 0;
+			IDP_Int(prop) = 0;
 	}
 }