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llvm-mirror/include/llvm/Support/Errno.h
Justin Lebar b77224b68f Use C++14-style return type deduction in LLVM.
Summary:
Simplifies the C++11-style "-> decltype(...)" return-type deduction.

Note that you have to be careful about whether the function return type
is `auto` or `decltype(auto)`.  The difference is that bare `auto`
strips const and reference, just like lambda return type deduction.  In
some cases that's what we want (or more likely, we know that the return
type is a value type), but whenever we're wrapping a templated function
which might return a reference, we need to be sure that the return type
is decltype(auto).

No functional change.

Subscribers: dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74383
2020-02-11 07:38:42 -08:00

47 lines
1.4 KiB
C++

//===- llvm/Support/Errno.h - Portable+convenient errno handling -*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file declares some portable and convenient functions to deal with errno.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_ERRNO_H
#define LLVM_SUPPORT_ERRNO_H
#include <cerrno>
#include <string>
#include <type_traits>
namespace llvm {
namespace sys {
/// Returns a string representation of the errno value, using whatever
/// thread-safe variant of strerror() is available. Be sure to call this
/// immediately after the function that set errno, or errno may have been
/// overwritten by an intervening call.
std::string StrError();
/// Like the no-argument version above, but uses \p errnum instead of errno.
std::string StrError(int errnum);
template <typename FailT, typename Fun, typename... Args>
inline decltype(auto) RetryAfterSignal(const FailT &Fail, const Fun &F,
const Args &... As) {
decltype(F(As...)) Res;
do {
errno = 0;
Res = F(As...);
} while (Res == Fail && errno == EINTR);
return Res;
}
} // namespace sys
} // namespace llvm
#endif // LLVM_SYSTEM_ERRNO_H