Use <cerrno> explicitly

[chapuni]

Summary

D146395 has hidden errno in LLVM_ENABLE_MODULES.

[chapuni]

Could you reconfirm they are expected?

[ldionne]

In D149513#4307343, @chapuni wrote:

Could you reconfirm they are expected?

I don't understand the question. If these files use content from <errno.h>, they should include that or <cerrno>. I think you might be hitting a case of code not including what it uses previously, and D146395 made the compiler catch the issue.

[chapuni]

@ldionne Thanks. It is what I would like to ask you.

llvm/lib/Object/ArchiveWriter.cpp

 #include "llvm/Support/Errc.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/SmallVectorMemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 
+#include <cerrno>
 #include <map>
 
 #if !defined(_MSC_VER) && !defined(__MINGW32__)
 #include <unistd.h>
 #else
 #include <io.h>
 #endif
 

llvm/lib/Support/JSON.cpp

 //=== JSON.cpp - JSON value, parsing and serialization - 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
 //
 //===---------------------------------------------------------------------===//
 
 #include "llvm/Support/JSON.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/NativeFormatting.h"
 #include <cctype>
+#include <cerrno>
 #include <optional>
 
 namespace llvm {
 namespace json {
 
 Value &Object::operator[](const ObjectKey &K) {
   return try_emplace(K, nullptr).first->getSecond();
 }

llvm/lib/Support/Path.cpp

 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
 #include <cctype>
+#include <cerrno>
 
 #if !defined(_MSC_VER) && !defined(__MINGW32__)
 #include <unistd.h>
 #else
 #include <io.h>
 #endif
 
 using namespace llvm;