Detect uses of anonymous structs/unions (a C2011 feature and GCC extension) and produce a diagnostic instead of ignoring them.

1 files changed, 14 insertions, 0 deletions

diff --git a/cparser/Elab.ml b/cparser/Elab.ml
index ae0ba17b..10af10a1 100644
--- a/cparser/Elab.ml
+++ b/cparser/Elab.ml
@@ -365,6 +365,14 @@ let typespec_rank = function (* Don't change this *)
 
 let typespec_order t1 t2 = compare (typespec_rank t1) (typespec_rank t2)
 
+(* Is a specifier an anonymous struct/union in the sense of ISO C2011? *)
+
+let is_anonymous_composite spec =
+  List.exists
+    (function SpecType(Tstruct_union(_, None, Some _, _)) -> true
+            | _ -> false)
+    spec
+
 (* Elaboration of a type specifier.  Returns 5-tuple:
      (storage class, "inline" flag, "typedef" flag, elaborated type, new env)
    Optional argument "only" is true if this is a standalone
@@ -617,6 +625,7 @@ and elab_init_name_group loc env (spec, namelist) =
 (* Elaboration of a field group *)
 
 and elab_field_group env (Field_group (spec, fieldlist, loc)) =
+
   let fieldlist = List.map (
     function
       | (None, x) -> (Name ("", JUSTBASE, [], cabslu), x)
@@ -629,6 +638,11 @@ and elab_field_group env (Field_group (spec, fieldlist, loc)) =
 
   if sto <> Storage_default then
     error loc "non-default storage in struct or union";
+  if fieldlist = [] then
+    if is_anonymous_composite spec then
+       error loc "ISO C99 does not support anonymous structs/unions"
+    else
+       warning loc "declaration does not declare any members";
 
   let elab_bitfield (Name (_, _, _, loc), optbitsize) (id, ty) =
     let optbitsize' =