On Sun, Dec 27, 2015 at 12:14 PM, Patrick Palka <patr...@parcs.ath.cx> wrote:
> In try_one_overload(), it should not be a deduction failure if we
> deduced more arguments of an argument pack than were explicitly
> specified (as long as the arguments are otherwise equivalent).
>
> This patch makes try_one_overload() manually check the argument packs,
> to permit such a case.
>
> Bootstrap + regtest in progress on x86_64-pc-linux-gnu, will also test
> against Boost. Is this OK to commit if testing succeeds?
>
> gcc/cp/ChangeLog:
>
> PR c++/69056
> * pt.c (try_one_overload): Handle comparing argument packs so
> that there is no conflict if we deduced more arguments of an
> argument pack than were explicitly specified.
>
> gcc/testsuite/ChangeLog:
>
> PR c++/69056
> g++.dg/cpp0x/pr69056.C: New test.
> ---
> gcc/cp/pt.c | 22 ++++++++++++++++++++++
> gcc/testsuite/g++.dg/cpp0x/pr69056.C | 30 ++++++++++++++++++++++++++++++
> 2 files changed, 52 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/pr69056.C
>
> diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
> index ff16b7c..e8cf1fa 100644
> --- a/gcc/cp/pt.c
> +++ b/gcc/cp/pt.c
> @@ -18694,6 +18694,28 @@ try_one_overload (tree tparms,
> template args used in the function parm list with our own
> template parms. Discard them. */
> TREE_VEC_ELT (tempargs, i) = NULL_TREE;
> + else if (oldelt && ARGUMENT_PACK_P (oldelt))
> + {
> + /* Check that the argument at each index of the deduced argument
> pack
> + is equivalent to the corresponding explicitly specified argument.
> + We may have deduced more arguments than were explicitly
> specified,
> + and that's OK. */
> + gcc_assert (ARGUMENT_PACK_INCOMPLETE_P (oldelt));
> + gcc_assert (ARGUMENT_PACK_ARGS (oldelt)
> + == ARGUMENT_PACK_EXPLICIT_ARGS (oldelt));
> +
> + tree explicit_pack = ARGUMENT_PACK_ARGS (oldelt);
> + tree deduced_pack = ARGUMENT_PACK_ARGS (elt);
> +
> + if (TREE_VEC_LENGTH (deduced_pack)
> + < TREE_VEC_LENGTH (explicit_pack))
> + return 0;
> +
> + for (int j = 0; j < TREE_VEC_LENGTH (explicit_pack); j++)
> + if (!template_args_equal (TREE_VEC_ELT (explicit_pack, j),
> + TREE_VEC_ELT (deduced_pack, j)))
> + return 0;
> + }
> else if (oldelt && !template_args_equal (oldelt, elt))
> return 0;
> }
> diff --git a/gcc/testsuite/g++.dg/cpp0x/pr69056.C
> b/gcc/testsuite/g++.dg/cpp0x/pr69056.C
> new file mode 100644
> index 0000000..ab4e071
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/pr69056.C
> @@ -0,0 +1,30 @@
> +// { dg-do compile { target c++11 } }
> +// PR c++/69056
> +
> +template <typename T, typename... Args>
> +void resolver(int (*) (T, Args...));
> +
> +int funcA(int, float) { return 0; }
> +int funcA(double) { return 0; }
> +
> +int funcB(int, float, char) { return 0; }
> +int funcB(int, bool) { return 0; }
> +int funcB(double) { return 0; }
> +
> +int funcC(int) { return 0; }
> +int funcC(double) { return 0; }
> +
> +void
> +foo (void)
> +{
> + resolver (&funcA); // { dg-error "no match" }
> + resolver<int> (&funcA);
> + resolver<double> (&funcA);
> +
> + resolver<int> (&funcB); // { dg-error "no match" }
> + resolver<int, char> (&funcB); // { dg-error "no match" }
> + resolver<int, float> (&funcB);
> +
> + resolver<int> (&funcC);
> + resolver<int, float> (&funcC); // { dg-error "no match" }
> +}
> --
> 2.7.0.rc1.98.gacf58d0.dirty
>
Ping.
