[Bug ada/18819] [4.1/4.2 Regression] ACATS cdd2a01 cdd2a02 fail at runtime

["ebotcazou at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #17 from ebotcazou at gcc dot gnu dot org  2006-01-22 11:43 -------
> No real solution as of this writing, only a poor workaround: not compiling the
> support files with -gnato (overflow checks).

Well, I may have spoken too soon. :-)  We are calling Remove_Side_Effects on:

N_Type_Conversion (Node_Id=1679) (analyzed)
 Rewritten: original node = N_Op_Add "Oadd" (Node_Id=39499)
 Parent = N_Range (Node_Id=1681)
 Sloc = 7611  fdd2a00.adb:6:38
 Etype = N_Defining_Identifier "Tstream_element_offsetB" (Entity_Id=2017)
 Subtype_Mark = N_Identifier "Tstream_element_offsetB" (Node_Id=39497)
 Expression = N_Function_Call (Node_Id=39496)
 Conversion_OK = True

It turns out that the fix is already present in the front-end, but inhibited:

      --  If this is a type conversion, leave the type conversion and remove
      --  the side effects in the expression. This is important in several
      --  circumstances: for change of representations, and also when this
      --  is a view conversion to a smaller object, where gigi can end up
      --  creating its own temporary of the wrong size.

      --  ??? this transformation is inhibited for elementary types that are
      --  not involved in a change of representation because it causes
      --  regressions that are not fully understood yet.

      elsif Nkind (Exp) = N_Type_Conversion
        and then (not Is_Elementary_Type (Underlying_Type (Exp_Type))
                   or else Nkind (Parent (Exp)) = N_Assignment_Statement)
      then
         Remove_Side_Effects (Expression (Exp), Name_Req, Variable_Ref);
         Scope_Suppress := Svg_Suppress;
         return;

However, another possible fix is to make a copy when we know we will not be
able to use a renaming.  Tentative patch to be attached.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18819