[Bug c/120353] Flex array struct referenced in the middle via type alias of forward declaration is not reported by -Wflex-array-member-not-at-end option

[qinzhao at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120353

--- Comment #2 from qinzhao at gcc dot gnu.org ---
the following patch fixes the issue:
[opc@qinzhao-aarch64-ol8 c]$ git diff
diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index ad66d7d258b..4733287eaf8 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -9891,6 +9891,7 @@ finish_struct (location_t loc, tree t, tree fieldlist,
tree attributes,
       C_TYPE_VARIABLE_SIZE (x) = C_TYPE_VARIABLE_SIZE (t);
       C_TYPE_VARIABLY_MODIFIED (x) = C_TYPE_VARIABLY_MODIFIED (t);
       C_TYPE_INCOMPLETE_VARS (x) = NULL_TREE;
+      TYPE_INCLUDES_FLEXARRAY (x) = TYPE_INCLUDES_FLEXARRAY (t);
     }

   /* Update type location to the one of the definition, instead of e.g.