[libcxx-commits] [libcxx] [libc++] Add "using-if-exists" to timespec_get in modules (PR #78686)

[Dominik Wójt via libcxx-commits]

https://github.com/domin144 created https://github.com/llvm/llvm-project/pull/78686

Picolibc does not provide timespec_get function. Adding "using-if-exists" attribute fixes the modules.

This is a follow up patch for https://github.com/llvm/llvm-project/pull/78580

>From e3e526da0cf26f4e4258c47d3a134cdbb966a87f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20W=C3=B3jt?= <dominik.wojt at arm.com>
Date: Fri, 19 Jan 2024 09:12:50 +0100
Subject: [PATCH] [libc++] Add "using-if-exists" to timespec_get in modules

Picolibc does not provide timespec_get function. Adding
"using-if-exists" attribute fixes the modules.
---
 libcxx/modules/std.compat/ctime.inc         | 2 +-
 libcxx/modules/std/ctime.inc                | 2 +-
 libcxx/test/std/modules/std.compat.pass.cpp | 4 ----
 3 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/libcxx/modules/std.compat/ctime.inc b/libcxx/modules/std.compat/ctime.inc
index 92e3403a5e58e2..6e621f494348d7 100644
--- a/libcxx/modules/std.compat/ctime.inc
+++ b/libcxx/modules/std.compat/ctime.inc
@@ -24,5 +24,5 @@ export {
   using ::mktime;
   using ::strftime;
   using ::time;
-  using ::timespec_get;
+  using ::timespec_get _LIBCPP_USING_IF_EXISTS;
 } // export
diff --git a/libcxx/modules/std/ctime.inc b/libcxx/modules/std/ctime.inc
index c407ffc35e3fe3..c98cb28e649b85 100644
--- a/libcxx/modules/std/ctime.inc
+++ b/libcxx/modules/std/ctime.inc
@@ -24,5 +24,5 @@ export namespace std {
   using std::mktime;
   using std::strftime;
   using std::time;
-  using std::timespec_get;
+  using std::timespec_get _LIBCPP_USING_IF_EXISTS;
 } // namespace std
diff --git a/libcxx/test/std/modules/std.compat.pass.cpp b/libcxx/test/std/modules/std.compat.pass.cpp
index 9a2f330d722edd..a33ed3b6b64533 100644
--- a/libcxx/test/std/modules/std.compat.pass.cpp
+++ b/libcxx/test/std/modules/std.compat.pass.cpp
@@ -11,10 +11,6 @@
 // UNSUPPORTED: libcpp-has-no-std-modules
 // UNSUPPORTED: clang-modules-build
 
-// picolibc does not provide the required timespec_get function, and the
-// "using-if-exists" mechanism apparently did not work here.
-// XFAIL: LIBCXX-PICOLIBC-FIXME
-
 // A minimal test to validate import works.
 
 import std.compat;