From a2c868a098fcb51dcdf629045c5f5c0f68c2766f Mon Sep 17 00:00:00 2001
From: Jamie Liu <jamieliu@google.com>
Date: Tue, 11 Dec 2018 17:04:42 -0800
Subject: [PATCH] Add rvalue ref-qualified PosixErrorOr<T>::ValueOrDie()
 overloads.

This allows ValueOrDie() to be called on PosixErrorOr rvalues (e.g.
temporaries) holding move-only types without extraneous std::move()s.

PiperOrigin-RevId: 225098036
Change-Id: I662862e4f3562141f941845fc6e197edb27ce29b
---
 test/syscalls/linux/itimer.cc |  4 ++--
 test/util/posix_error.h       | 26 ++++++++++++++++++++------
 test/util/proc_util.h         |  2 +-
 3 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/test/syscalls/linux/itimer.cc b/test/syscalls/linux/itimer.cc
index ee5871cbe..5d42529e2 100644
--- a/test/syscalls/linux/itimer.cc
+++ b/test/syscalls/linux/itimer.cc
@@ -126,7 +126,7 @@ SignalTestResult ItimerSignalTest(int id, clock_t main_clock,
   sa.sa_handler = &SignalTestSignalHandler;
   sa.sa_flags = SA_RESTART;
   sigemptyset(&sa.sa_mask);
-  auto sigaction_cleanup = std::move(ScopedSigaction(signal, sa).ValueOrDie());
+  auto sigaction_cleanup = ScopedSigaction(signal, sa).ValueOrDie();
 
   int socketfds[2];
   TEST_PCHECK(socketpair(AF_UNIX, SOCK_STREAM, 0, socketfds) == 0);
@@ -167,7 +167,7 @@ SignalTestResult ItimerSignalTest(int id, clock_t main_clock,
   struct itimerval timer = {};
   timer.it_value = absl::ToTimeval(kPeriod);
   timer.it_interval = absl::ToTimeval(kPeriod);
-  auto cleanup_itimer = std::move(ScopedItimer(id, timer).ValueOrDie());
+  auto cleanup_itimer = ScopedItimer(id, timer).ValueOrDie();
 
   // Unblock th1.
   //
diff --git a/test/util/posix_error.h b/test/util/posix_error.h
index 8450be9b9..2dc5504fd 100644
--- a/test/util/posix_error.h
+++ b/test/util/posix_error.h
@@ -103,8 +103,10 @@ class ABSL_MUST_USE_RESULT PosixErrorOr {
   bool ok() const;
 
   // Returns a reference to our current value, or CHECK-fails if !this->ok().
-  const T& ValueOrDie() const;
-  T& ValueOrDie();
+  const T& ValueOrDie() const&;
+  T& ValueOrDie() &;
+  const T&& ValueOrDie() const&&;
+  T&& ValueOrDie() &&;
 
   // Ignores any errors. This method does nothing except potentially suppress
   // complaints from any tools that are checking that errors are not dropped on
@@ -179,17 +181,29 @@ bool PosixErrorOr<T>::ok() const {
 }
 
 template <typename T>
-const T& PosixErrorOr<T>::ValueOrDie() const {
+const T& PosixErrorOr<T>::ValueOrDie() const& {
   TEST_CHECK(absl::holds_alternative<T>(value_));
   return absl::get<T>(value_);
 }
 
 template <typename T>
-T& PosixErrorOr<T>::ValueOrDie() {
+T& PosixErrorOr<T>::ValueOrDie() & {
   TEST_CHECK(absl::holds_alternative<T>(value_));
   return absl::get<T>(value_);
 }
 
+template <typename T>
+const T&& PosixErrorOr<T>::ValueOrDie() const&& {
+  TEST_CHECK(absl::holds_alternative<T>(value_));
+  return std::move(absl::get<T>(value_));
+}
+
+template <typename T>
+T&& PosixErrorOr<T>::ValueOrDie() && {
+  TEST_CHECK(absl::holds_alternative<T>(value_));
+  return std::move(absl::get<T>(value_));
+}
+
 extern ::std::ostream& operator<<(::std::ostream& os, const PosixError& e);
 
 template <typename T>
@@ -399,7 +413,7 @@ IsPosixErrorOkAndHolds(InnerMatcher&& inner_matcher) {
   if (!posixerroror.ok()) {                                          \
     return (posixerroror.error());                                   \
   }                                                                  \
-  lhs = std::move(posixerroror.ValueOrDie())
+  lhs = std::move(posixerroror).ValueOrDie()
 
 #define EXPECT_NO_ERRNO(expression) \
   EXPECT_THAT(expression, IsPosixErrorOkMatcher())
@@ -419,7 +433,7 @@ IsPosixErrorOkAndHolds(InnerMatcher&& inner_matcher) {
   ({                                      \
     auto _expr_result = (expr);           \
     ASSERT_NO_ERRNO(_expr_result);        \
-    std::move(_expr_result.ValueOrDie()); \
+    std::move(_expr_result).ValueOrDie(); \
   })
 
 }  // namespace testing
diff --git a/test/util/proc_util.h b/test/util/proc_util.h
index f8021d92e..e1ee2db9c 100644
--- a/test/util/proc_util.h
+++ b/test/util/proc_util.h
@@ -115,7 +115,7 @@ MATCHER_P(ContainsMappings, mappings,
     return false;
   }
 
-  auto maps = std::move(maps_or.ValueOrDie());
+  auto maps = std::move(maps_or).ValueOrDie();
 
   // Does maps contain all elements in mappings? The comparator ignores
   // the major, minor, and inode fields.