commit f28bfaea4feb996d22452ecb0ab2c11d2a0f429f
Author: Daniel Swanson <popcorn.tomato.dude@gmail.com>
Date:   Thu Aug 12 09:35:36 2021 -0500

    indexing issue in postchunk
    
    t1x & t2x are internally 0-indexed whereas t3x is 1-indexed (0 is the chunk), so `<get-case-from>` needs to convert the index, since it's calculated in the shared code.

diff --git a/apertium/postchunk.cc b/apertium/postchunk.cc
index 0707e14..81e0466 100644
--- a/apertium/postchunk.cc
+++ b/apertium/postchunk.cc
@@ -92,8 +92,8 @@ Postchunk::evalCachedString(xmlNode* element)
     break;
 
   case ti_get_case_from:
-    if (checkIndex(element, ti.getPos(), lword)) {
-      return copycase(word[ti.getPos()]->chunkPart(attr_items[ti.getContent()]),
+    if (checkIndex(element, ti.getPos()+1, lword)) {
+      return copycase(word[ti.getPos()+1]->chunkPart(attr_items[ti.getContent()]),
                       evalString(ti.getPointer()));
     }
     break;