[libcxx-commits] [libcxx] 2ae3f7c - [libc++][test] Close LWG3238 and add tests (#93043)

[via libcxx-commits]

Author: Hui
Date: 2024-05-29T01:34:29+01:00
New Revision: 2ae3f7c29c1149098827df7edafa761e3e3eb420

URL: https://github.com/llvm/llvm-project/commit/2ae3f7c29c1149098827df7edafa761e3e3eb420
DIFF: https://github.com/llvm/llvm-project/commit/2ae3f7c29c1149098827df7edafa761e3e3eb420.diff

LOG: [libc++][test] Close LWG3238 and add tests (#93043)

Added: 
    

Modified: 
    libcxx/docs/Status/Cxx20Issues.csv
    libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.pass.cpp

Removed: 
    libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.verify.cpp


################################################################################
diff  --git a/libcxx/docs/Status/Cxx20Issues.csv b/libcxx/docs/Status/Cxx20Issues.csv
index 6fc40270af158..54517ab002b86 100644
--- a/libcxx/docs/Status/Cxx20Issues.csv
+++ b/libcxx/docs/Status/Cxx20Issues.csv
@@ -202,7 +202,7 @@
 "`3226 <https://wg21.link/LWG3226>`__","``zoned_time``\  constructor from ``string_view``\  should accept ``zoned_time<Duration2, TimeZonePtr2>``\ ","Prague","","","|chrono|"
 "`3233 <https://wg21.link/LWG3233>`__","Broken requirements for ``shared_ptr``\  converting constructors","Prague","|Complete|","19.0"
 "`3237 <https://wg21.link/LWG3237>`__","LWG 3038 and 3190 have inconsistent PRs","Prague","|Complete|","16.0"
-"`3238 <https://wg21.link/LWG3238>`__","Insufficiently-defined behavior of ``std::function``\  deduction guides","Prague","",""
+"`3238 <https://wg21.link/LWG3238>`__","Insufficiently-defined behavior of ``std::function``\  deduction guides","Prague","|Nothing To Do|",""
 "`3242 <https://wg21.link/LWG3242>`__","``std::format``\ : missing rules for ``arg-id``\  in ``width``\  and ``precision``\ ","Prague","|Complete|","14.0","|format|"
 "`3243 <https://wg21.link/LWG3243>`__","``std::format``\  and negative zeroes","Prague","|Complete|","14.0","|format|"
 "`3247 <https://wg21.link/LWG3247>`__","``ranges::iter_move``\  should perform ADL-only lookup of ``iter_move``\ ","Prague","|Complete|","15.0","|ranges|"

diff  --git a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.pass.cpp b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.pass.cpp
index ef43ab9b64b5b..381bcda761700 100644
--- a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.pass.cpp
+++ b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.pass.cpp
@@ -118,10 +118,14 @@ int main(int, char**) {
 // Make sure we fail in a SFINAE-friendly manner when we try to deduce
 // from a type without a valid call operator.
 template <typename F, typename = decltype(std::function{std::declval<F>()})>
-constexpr bool can_deduce() { return true; }
+constexpr bool can_deduce_test(int) { return true; }
 template <typename F>
-constexpr bool can_deduce(...) { return false; }
+constexpr bool can_deduce_test(...) { return false; }
 
+template <typename F>
+constexpr bool can_deduce = can_deduce_test<F>(0);
+
+struct valid { int operator()() const; };
 struct invalid1 { };
 struct invalid2 {
   template <typename ...Args>
@@ -131,6 +135,22 @@ struct invalid3 {
   void operator()(int);
   void operator()(long);
 };
-static_assert(!can_deduce<invalid1>());
-static_assert(!can_deduce<invalid2>());
-static_assert(!can_deduce<invalid3>());
+static_assert( can_deduce<valid>);
+static_assert(!can_deduce<invalid1>);
+static_assert(!can_deduce<invalid2>);
+static_assert(!can_deduce<invalid3>);
+
+
+// LWG 3238. Insufficiently-defined behavior of std::function deduction guides
+// https://cplusplus.github.io/LWG/issue3238
+// The deduction guides for std::function do not handle rvalue-ref qualified
+// call operators and C-style variadics. It also doesn't deduce from nullptr_t.
+// Make sure we stick to the specification.
+
+struct invalid_rvalue_ref { R operator()() && { return {}; } };
+struct invalid_c_vararg { R operator()(int, ...) { return {}; } };
+
+static_assert(!can_deduce<invalid_rvalue_ref>);
+static_assert(!can_deduce<invalid_c_vararg>);
+static_assert(!can_deduce<std::nullptr_t>);
+

diff  --git a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.verify.cpp b/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.verify.cpp
deleted file mode 100644
index 8a42d3be3571c..0000000000000
--- a/libcxx/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_F.verify.cpp
+++ /dev/null
@@ -1,30 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-// <functional>
-
-// template<class F>
-// function(F) -> function<see-below>;
-
-// UNSUPPORTED: c++03, c++11, c++14
-
-// The deduction guides for std::function do not handle rvalue-ref qualified
-// call operators and C-style variadics. It also doesn't deduce from nullptr_t.
-// Make sure we stick to the specification.
-
-#include <functional>
-
-struct R { };
-struct f0 { R operator()() && { return {}; } };
-struct f1 { R operator()(int, ...) { return {}; } };
-
-void f() {
-    std::function f = f0{}; // expected-error{{no viable constructor or deduction guide for deduction of template arguments of 'function'}}
-    std::function g = f1{}; // expected-error{{no viable constructor or deduction guide for deduction of template arguments of 'function'}}
-    std::function h = nullptr; // expected-error{{no viable constructor or deduction guide for deduction of template arguments of 'function'}}
-}