48cd9d9dd8
Summary: If the output filename was specified as "-", the ToolOutputFile class would create a brand new raw_ostream object referring to the stdout. This patch changes it to reuse the llvm::outs() singleton. At the moment, this change should be "NFC", but it does enable other enhancements, like the automatic stdout/stderr synchronization as discussed on D80803. I've checked the history, and I did not find any indication that this class *has* to use a brand new stream object instead of outs() -- indeed, it is special-casing "-" in a number of places already, so this change fits the pattern pretty well. I suspect the main reason for the current state of affairs is that the class was originally introduced (r111595, in 2010) as a raw_fd_ostream subclass, which made any other solution impossible. Another potential benefit of this patch is that it makes it possible to move the raw_ostream class out of the business of special-casing "-" for stdout handling. That state of affairs does not seem appropriate because "-" is a valid filename (albeit hard to access with a lot of command line tools) on most systems. Handling "-" in ToolOutputFile seems more appropriate. To make this possible, this patch changes the return type of llvm::outs() and errs() to raw_fd_ostream&. Previously the functions were constructing objects of that type, but returning a generic raw_ostream reference. This makes it possible for new ToolOutputFile and other code to use raw_fd_ostream methods like error() on the outs() object. This does not seem like a bad thing (since stdout is a file descriptor which can be redirected to anywhere, it makes sense to ask it whether the writing was successful or if it supports seeking), and indeed a lot of code was already depending on this fact via the ToolOutputFile "back door". Reviewers: dblaikie, JDevlieghere, MaskRay, jhenderson Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D81078
68 lines
2.2 KiB
C++
68 lines
2.2 KiB
C++
//===- ToolOutputFile.h - Output files for compiler-like tools -----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the ToolOutputFile class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_TOOLOUTPUTFILE_H
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#define LLVM_SUPPORT_TOOLOUTPUTFILE_H
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#include "llvm/ADT/Optional.h"
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#include "llvm/Support/raw_ostream.h"
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namespace llvm {
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/// This class contains a raw_fd_ostream and adds a few extra features commonly
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/// needed for compiler-like tool output files:
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/// - The file is automatically deleted if the process is killed.
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/// - The file is automatically deleted when the ToolOutputFile
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/// object is destroyed unless the client calls keep().
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class ToolOutputFile {
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/// This class is declared before the raw_fd_ostream so that it is constructed
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/// before the raw_fd_ostream is constructed and destructed after the
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/// raw_fd_ostream is destructed. It installs cleanups in its constructor and
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/// uninstalls them in its destructor.
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class CleanupInstaller {
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/// The name of the file.
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std::string Filename;
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public:
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/// The flag which indicates whether we should not delete the file.
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bool Keep;
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explicit CleanupInstaller(StringRef Filename);
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~CleanupInstaller();
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} Installer;
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/// Storage for the stream, if we're owning our own stream. This is
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/// intentionally declared after Installer.
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Optional<raw_fd_ostream> OSHolder;
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/// The actual stream to use.
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raw_fd_ostream *OS;
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public:
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/// This constructor's arguments are passed to raw_fd_ostream's
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/// constructor.
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ToolOutputFile(StringRef Filename, std::error_code &EC,
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sys::fs::OpenFlags Flags);
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ToolOutputFile(StringRef Filename, int FD);
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/// Return the contained raw_fd_ostream.
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raw_fd_ostream &os() { return *OS; }
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/// Indicate that the tool's job wrt this output file has been successful and
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/// the file should not be deleted.
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void keep() { Installer.Keep = true; }
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};
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} // end llvm namespace
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#endif
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