Comment why encoding check in appendAttributeValue is never true

Also add comment tag so lcov can ignore unreachable code

diff --git a/expat/lib/xmlparse.c b/expat/lib/xmlparse.c
index 73c7d39fd718f6ad98cac4b2b0191b336575b59a..d951154e20e04f1fb6fc8f0b5d0eed61041b9b3c 100644 (file)
--- a/expat/lib/xmlparse.c
+++ b/expat/lib/xmlparse.c
@@ -5595,8 +5595,26 @@ appendAttributeValue(XML_Parser parser, const ENCODING *enc, XML_Bool isCdata,
           break;
         }
         if (entity->open) {
-          if (enc == encoding)
-            eventPtr = ptr;
+          if (enc == encoding) {
+            /* It does not appear that this line can be executed.
+             *
+             * The "if (entity->open)" check catches recursive entity
+             * definitions.  In order to be called with an open
+             * entity, it must have gone through this code before and
+             * been through the recursive call to
+             * appendAttributeValue() some lines below.  That call
+             * sets the local encoding ("enc") to the parser's
+             * internal encoding (internal_utf8 or internal_utf16),
+             * which can never be the same as the principle encoding.
+             * It doesn't appear there is another code path that gets
+             * here with entity->open being TRUE.
+             *
+             * Since it is not certain that this logic is watertight,
+             * we keep the line and merely exclude it from coverage
+             * tests.
+             */
+            eventPtr = ptr; /* LCOV_EXCL_LINE */
+          }
           return XML_ERROR_RECURSIVE_ENTITY_REF;
         }
         if (entity->notation) {