On Wed, 12 Jul 2023, Patrick Palka wrote:
> We're not checking constraints of pointer/reference-to-function conversion
> functions during overload resolution, which causes us to ICE on the first
> testcase and incorrectly reject the second testcase.
Er, I noticed [over.call.object] doesn't exactly say that surrogate
call functions inherit the constraints of the corresponding conversion
function, but I reckon that's the intent?
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk/13?
>
> PR c++/110535
>
> gcc/cp/ChangeLog:
>
> * call.cc (add_conv_candidate): Check constraints.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp2a/concepts-surrogate1.C: New test.
> * g++.dg/cpp2a/concepts-surrogate2.C: New test.
> ---
> gcc/cp/call.cc | 8 ++++++++
> gcc/testsuite/g++.dg/cpp2a/concepts-surrogate1.C | 12 ++++++++++++
> gcc/testsuite/g++.dg/cpp2a/concepts-surrogate2.C | 14 ++++++++++++++
> 3 files changed, 34 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-surrogate1.C
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-surrogate2.C
>
> diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
> index 15a3d6f2a1f..81935b83908 100644
> --- a/gcc/cp/call.cc
> +++ b/gcc/cp/call.cc
> @@ -2588,6 +2588,14 @@ add_conv_candidate (struct z_candidate **candidates,
> tree fn, tree obj,
> if (*candidates && (*candidates)->fn == totype)
> return NULL;
>
> + if (!constraints_satisfied_p (fn))
> + {
> + reason = constraint_failure ();
> + viable = 0;
> + return add_candidate (candidates, fn, obj, arglist, len, convs,
> + access_path, conversion_path, viable, reason,
> flags);
> + }
> +
> for (i = 0; i < len; ++i)
> {
> tree arg, argtype, convert_type = NULL_TREE;
> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-surrogate1.C
> b/gcc/testsuite/g++.dg/cpp2a/concepts-surrogate1.C
> new file mode 100644
> index 00000000000..e8481a31656
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-surrogate1.C
> @@ -0,0 +1,12 @@
> +// PR c++/110535
> +// { dg-do compile { target c++20 } }
> +
> +using F = int(int);
> +
> +template<bool B>
> +struct A {
> + operator F*() requires B;
> +};
> +
> +int i = A<true>{}(0); // OK
> +int j = A<false>{}(0); // { dg-error "no match" }
> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-surrogate2.C
> b/gcc/testsuite/g++.dg/cpp2a/concepts-surrogate2.C
> new file mode 100644
> index 00000000000..8bf8364beb7
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-surrogate2.C
> @@ -0,0 +1,14 @@
> +// PR c++/110535
> +// { dg-do compile { target c++20 } }
> +
> +using F = int(int);
> +using G = long(int);
> +
> +template<bool B>
> +struct A {
> + operator F&() requires B;
> + operator G&() requires (!B);
> +};
> +
> +int i = A<true>{}(0); // { dg-bogus "ambiguous" }
> +int j = A<false>{}(0); // { dg-bogus "ambiguous" }
> --
> 2.41.0.327.gaa9166bcc0
>
>
