OK.
On Fri, Mar 23, 2018 at 6:48 AM, Marek Polacek <pola...@redhat.com> wrote:
> In this test:
>
> struct S {
> enum { X };
> };
>
> int
> foo (struct S s)
> {
> return s.X;
> }
>
> unlike in C, lookup_member in C++ is able to find X in S. So in the following
> testcase finish_offsetof happily passes the CONST_DECL X down to
> fold_offsetof,
> which then crashes because fold_offsetof_1 doesn't handle CONST_DECLs. I
> think
> let's simply disallow 'em in finish_offsetof; we can't take their address
> anyway.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-03-23 Marek Polacek <pola...@redhat.com>
>
> PR c++/85033
> * semantics.c (finish_offsetof): Don't allow CONST_DECLs.
>
> * g++.dg/ext/builtin-offsetof2.C: New test.
>
> diff --git gcc/cp/semantics.c gcc/cp/semantics.c
> index 97fa57ae94e..035e3951574 100644
> --- gcc/cp/semantics.c
> +++ gcc/cp/semantics.c
> @@ -4072,6 +4072,11 @@ finish_offsetof (tree object_ptr, tree expr,
> location_t loc)
> }
> return error_mark_node;
> }
> + if (TREE_CODE (expr) == CONST_DECL)
> + {
> + error ("cannot apply %<offsetof%> to an enumerator %qD", expr);
> + return error_mark_node;
> + }
> if (REFERENCE_REF_P (expr))
> expr = TREE_OPERAND (expr, 0);
> if (!complete_type_or_else (TREE_TYPE (TREE_TYPE (object_ptr)),
> object_ptr))
> diff --git gcc/testsuite/g++.dg/ext/builtin-offsetof2.C
> gcc/testsuite/g++.dg/ext/builtin-offsetof2.C
> index e69de29bb2d..07cc55a65c1 100644
> --- gcc/testsuite/g++.dg/ext/builtin-offsetof2.C
> +++ gcc/testsuite/g++.dg/ext/builtin-offsetof2.C
> @@ -0,0 +1,7 @@
> +// PR c++/85033
> +
> +struct S {
> + enum { E };
> +};
> +
> +int b = __builtin_offsetof(S, E); // { dg-error "cannot apply .offsetof. to
> an enumerator" }
>
> Marek
