OK.
On Fri, Mar 3, 2017 at 9:34 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> Seems callers of cxx_eval_constant_expression don't really like if it
> returns NULL, which is what cxx_eval_statement_list returns for empty
> STATEMENT_LIST. In statement expressions we treat those the same
> as (void) 0 or any other statement with void value.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2017-03-03 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/79822
> * constexpr.c (cxx_eval_statement_list): Treat empty ({ }) like
> ({ (void) 0; }).
>
> * g++.dg/cpp0x/constexpr-79822.C: New test.
>
> --- gcc/cp/constexpr.c.jj 2017-02-22 23:03:12.000000000 +0100
> +++ gcc/cp/constexpr.c 2017-03-03 12:42:02.391773591 +0100
> @@ -3725,8 +3725,9 @@ cxx_eval_statement_list (const constexpr
> {
> tree_stmt_iterator i;
> tree local_target;
> - /* In a statement-expression we want to return the last value. */
> - tree r = NULL_TREE;
> + /* In a statement-expression we want to return the last value.
> + For empty statement expression return void_node. */
> + tree r = void_node;
> if (!jump_target)
> {
> local_target = NULL_TREE;
> --- gcc/testsuite/g++.dg/cpp0x/constexpr-79822.C.jj 2017-03-03
> 12:49:41.595614494 +0100
> +++ gcc/testsuite/g++.dg/cpp0x/constexpr-79822.C 2017-03-03
> 12:50:51.753673495 +0100
> @@ -0,0 +1,12 @@
> +// PR c++/79822
> +// { dg-do compile }
> +// { dg-options "" }
> +
> +bool
> +foo ()
> +{
> + bool a = ({ }) && false; // { dg-error "could not convert" }
> + bool b = ({ ; }) && false; // { dg-error "could not convert" }
> + bool c = ({ (void) 1; }) && false; // { dg-error "could not convert" }
> + return a && b && c;
> +}
>
> Jakub
