[wpiutil] Vendor llvm and update to 13.0.0 (#4224)

wpiutil/src/test/native/cpp/llvm/ErrnoTest.cpp

@@ -0,0 +1,38 @@
+//===- ErrnoTest.cpp - Error handling unit tests --------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "wpi/Errno.h"
+#include "gtest/gtest.h"
+
+using namespace wpi::sys;
+
+TEST(ErrnoTest, RetryAfterSignal) {
+  EXPECT_EQ(1, RetryAfterSignal(-1, [] { return 1; }));
+
+  EXPECT_EQ(-1, RetryAfterSignal(-1, [] {
+    errno = EAGAIN;
+    return -1;
+  }));
+  EXPECT_EQ(EAGAIN, errno);
+
+  unsigned calls = 0;
+  EXPECT_EQ(1, RetryAfterSignal(-1, [&calls] {
+              errno = EINTR;
+              ++calls;
+              return calls == 1 ? -1 : 1;
+            }));
+  EXPECT_EQ(2u, calls);
+
+  EXPECT_EQ(1, RetryAfterSignal(-1, [](int x) { return x; }, 1));
+
+  std::unique_ptr<int> P(RetryAfterSignal(nullptr, [] { return new int(47); }));
+  EXPECT_EQ(47, *P);
+
+  errno = EINTR;
+  EXPECT_EQ(-1, RetryAfterSignal(-1, [] { return -1; }));
+}