On Mon, Dec 21, 2015 at 6:07 PM, Patrick Palka <patr...@parcs.ath.cx> wrote:
> We are currently failing to fold equality comparisons involving
> PTRMEM_CSTs since (I think) r229018 thus making this a GCC 6 regression.
> This regression shows up in the boost testsuite.
>
> Fixed in a straightforward way. OK to commit after bootstrap + regtest?
>
> gcc/cp/ChangeLog:
>
> * constexpr.c (cxx_eval_binary_expression): Expand
> the PTRMEM_CST operands of an equality comparison.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp0x/constexpr-ptrmem5.C: New test.
> ---
> gcc/cp/constexpr.c | 9 +++++++++
> gcc/testsuite/g++.dg/cpp0x/constexpr-ptrmem5.C | 14 ++++++++++++++
> 2 files changed, 23 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-ptrmem5.C
>
> diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
> index 208f43b..1ad87aa 100644
> --- a/gcc/cp/constexpr.c
> +++ b/gcc/cp/constexpr.c
> @@ -1630,6 +1630,15 @@ cxx_eval_binary_expression (const constexpr_ctx *ctx,
> tree t,
> location_t loc = EXPR_LOCATION (t);
> enum tree_code code = TREE_CODE (t);
> tree type = TREE_TYPE (t);
> +
> + if (code == EQ_EXPR || code == NE_EXPR)
> + {
> + if (TREE_CODE (lhs) == PTRMEM_CST && CONSTANT_CLASS_P (rhs))
> + lhs = cplus_expand_constant (lhs);
> + if (TREE_CODE (rhs) == PTRMEM_CST && CONSTANT_CLASS_P (lhs))
> + rhs = cplus_expand_constant (rhs);
> + }
> +
> r = fold_binary_loc (loc, code, type, lhs, rhs);
> if (r == NULL_TREE)
> {
> diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrmem5.C
> b/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrmem5.C
> new file mode 100644
> index 0000000..e28c917
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrmem5.C
> @@ -0,0 +1,14 @@
> +// { dg-do compile { target c++11 } }
> +
> +#define SA(x) static_assert ((x), #x)
> +
> +struct X { int a, b; };
> +
> +void
> +foo ()
> +{
> + SA (&X::a);
> + SA (&X::a == &X::a);
> + SA (&X::a != &X::b);
> + SA ((!&X::b) == 0);
> +}
> --
> 2.7.0.rc0.50.g1470d8f.dirty
>
Ping.
