llvm/clang/lib/Frontend/DependencyFile.cpp

//===--- DependencyFile.cpp - Generate dependency file --------------------===//
//
// 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 code generates dependency files.
//
//===----------------------------------------------------------------------===//

#include "clang/Frontend/Utils.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Frontend/DependencyOutputOptions.h"
#include "clang/Frontend/FrontendDiagnostic.h"
#include "clang/Lex/DirectoryLookup.h"
#include "clang/Lex/ModuleMap.h"
#include "clang/Lex/PPCallbacks.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Serialization/ASTReader.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <optional>

usingnamespaceclang;

namespace {
struct DepCollectorPPCallbacks : public PPCallbacks { … };

struct DepCollectorMMCallbacks : public ModuleMapCallbacks { … };

struct DepCollectorASTListener : public ASTReaderListener { … };
} // end anonymous namespace

void DependencyCollector::maybeAddDependency(StringRef Filename,
                                             bool FromModule, bool IsSystem,
                                             bool IsModuleFile,
                                             bool IsMissing) { … }

bool DependencyCollector::addDependency(StringRef Filename) { … }

static bool isSpecialFilename(StringRef Filename) { … }

bool DependencyCollector::sawDependency(StringRef Filename, bool FromModule,
                                        bool IsSystem, bool IsModuleFile,
                                        bool IsMissing) { … }

DependencyCollector::~DependencyCollector() { … }
void DependencyCollector::attachToPreprocessor(Preprocessor &PP) { … }
void DependencyCollector::attachToASTReader(ASTReader &R) { … }

DependencyFileGenerator::DependencyFileGenerator(
    const DependencyOutputOptions &Opts)
    : … { … }

void DependencyFileGenerator::attachToPreprocessor(Preprocessor &PP) { … }

bool DependencyFileGenerator::sawDependency(StringRef Filename, bool FromModule,
                                            bool IsSystem, bool IsModuleFile,
                                            bool IsMissing) { … }

void DependencyFileGenerator::finishedMainFile(DiagnosticsEngine &Diags) { … }

/// Print the filename, with escaping or quoting that accommodates the three
/// most likely tools that use dependency files: GNU Make, BSD Make, and
/// NMake/Jom.
///
/// BSD Make is the simplest case: It does no escaping at all.  This means
/// characters that are normally delimiters, i.e. space and # (the comment
/// character) simply aren't supported in filenames.
///
/// GNU Make does allow space and # in filenames, but to avoid being treated
/// as a delimiter or comment, these must be escaped with a backslash. Because
/// backslash is itself the escape character, if a backslash appears in a
/// filename, it should be escaped as well.  (As a special case, $ is escaped
/// as $$, which is the normal Make way to handle the $ character.)
/// For compatibility with BSD Make and historical practice, if GNU Make
/// un-escapes characters in a filename but doesn't find a match, it will
/// retry with the unmodified original string.
///
/// GCC tries to accommodate both Make formats by escaping any space or #
/// characters in the original filename, but not escaping backslashes.  The
/// apparent intent is so that filenames with backslashes will be handled
/// correctly by BSD Make, and by GNU Make in its fallback mode of using the
/// unmodified original string; filenames with # or space characters aren't
/// supported by BSD Make at all, but will be handled correctly by GNU Make
/// due to the escaping.
///
/// A corner case that GCC gets only partly right is when the original filename
/// has a backslash immediately followed by space or #.  GNU Make would expect
/// this backslash to be escaped; however GCC escapes the original backslash
/// only when followed by space, not #.  It will therefore take a dependency
/// from a directive such as
///     #include "a\ b\#c.h"
/// and emit it as
///     a\\\ b\\#c.h
/// which GNU Make will interpret as
///     a\ b\
/// followed by a comment. Failing to find this file, it will fall back to the
/// original string, which probably doesn't exist either; in any case it won't
/// find
///     a\ b\#c.h
/// which is the actual filename specified by the include directive.
///
/// Clang does what GCC does, rather than what GNU Make expects.
///
/// NMake/Jom has a different set of scary characters, but wraps filespecs in
/// double-quotes to avoid misinterpreting them; see
/// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info,
/// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
/// for Windows file-naming info.
static void PrintFilename(raw_ostream &OS, StringRef Filename,
                          DependencyOutputFormat OutputFormat) { … }

void DependencyFileGenerator::outputDependencyFile(DiagnosticsEngine &Diags) { … }

void DependencyFileGenerator::outputDependencyFile(llvm::raw_ostream &OS) { … }