1//===-- HeaderIncludeGen.cpp - Generate Header Includes -------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "clang/Frontend/DependencyOutputOptions.h"
10#include "clang/Frontend/Utils.h"
11#include "clang/Basic/SourceManager.h"
12#include "clang/Frontend/FrontendDiagnostic.h"
13#include "clang/Lex/Preprocessor.h"
14#include "llvm/ADT/SmallString.h"
15#include "llvm/Support/raw_ostream.h"
16using namespace clang;
17
18namespace {
19class HeaderIncludesCallback : public PPCallbacks {
20  SourceManager &SM;
21  raw_ostream *OutputFile;
22  const DependencyOutputOptions &DepOpts;
23  unsigned CurrentIncludeDepth;
24  bool HasProcessedPredefines;
25  bool OwnsOutputFile;
26  bool ShowAllHeaders;
27  bool ShowDepth;
28  bool MSStyle;
29
30public:
31  HeaderIncludesCallback(const Preprocessor *PP, bool ShowAllHeaders_,
32                         raw_ostream *OutputFile_,
33                         const DependencyOutputOptions &DepOpts,
34                         bool OwnsOutputFile_, bool ShowDepth_, bool MSStyle_)
35      : SM(PP->getSourceManager()), OutputFile(OutputFile_), DepOpts(DepOpts),
36        CurrentIncludeDepth(0), HasProcessedPredefines(false),
37        OwnsOutputFile(OwnsOutputFile_), ShowAllHeaders(ShowAllHeaders_),
38        ShowDepth(ShowDepth_), MSStyle(MSStyle_) {}
39
40  ~HeaderIncludesCallback() override {
41    if (OwnsOutputFile)
42      delete OutputFile;
43  }
44
45  void FileChanged(SourceLocation Loc, FileChangeReason Reason,
46                   SrcMgr::CharacteristicKind FileType,
47                   FileID PrevFID) override;
48
49  void FileSkipped(const FileEntryRef &SkippedFile, const Token &FilenameTok,
50                   SrcMgr::CharacteristicKind FileType) override;
51};
52}
53
54static void PrintHeaderInfo(raw_ostream *OutputFile, StringRef Filename,
55                            bool ShowDepth, unsigned CurrentIncludeDepth,
56                            bool MSStyle) {
57  // Write to a temporary string to avoid unnecessary flushing on errs().
58  SmallString<512> Pathname(Filename);
59  if (!MSStyle)
60    Lexer::Stringify(Pathname);
61
62  SmallString<256> Msg;
63  if (MSStyle)
64    Msg += "Note: including file:";
65
66  if (ShowDepth) {
67    // The main source file is at depth 1, so skip one dot.
68    for (unsigned i = 1; i != CurrentIncludeDepth; ++i)
69      Msg += MSStyle ? ' ' : '.';
70
71    if (!MSStyle)
72      Msg += ' ';
73  }
74  Msg += Pathname;
75  Msg += '\n';
76
77  *OutputFile << Msg;
78  OutputFile->flush();
79}
80
81void clang::AttachHeaderIncludeGen(Preprocessor &PP,
82                                   const DependencyOutputOptions &DepOpts,
83                                   bool ShowAllHeaders, StringRef OutputPath,
84                                   bool ShowDepth, bool MSStyle) {
85  raw_ostream *OutputFile = &llvm::errs();
86  bool OwnsOutputFile = false;
87
88  // Choose output stream, when printing in cl.exe /showIncludes style.
89  if (MSStyle) {
90    switch (DepOpts.ShowIncludesDest) {
91    default:
92      llvm_unreachable("Invalid destination for /showIncludes output!");
93    case ShowIncludesDestination::Stderr:
94      OutputFile = &llvm::errs();
95      break;
96    case ShowIncludesDestination::Stdout:
97      OutputFile = &llvm::outs();
98      break;
99    }
100  }
101
102  // Open the output file, if used.
103  if (!OutputPath.empty()) {
104    std::error_code EC;
105    llvm::raw_fd_ostream *OS = new llvm::raw_fd_ostream(
106        OutputPath.str(), EC,
107        llvm::sys::fs::OF_Append | llvm::sys::fs::OF_TextWithCRLF);
108    if (EC) {
109      PP.getDiagnostics().Report(clang::diag::warn_fe_cc_print_header_failure)
110          << EC.message();
111      delete OS;
112    } else {
113      OS->SetUnbuffered();
114      OutputFile = OS;
115      OwnsOutputFile = true;
116    }
117  }
118
119  // Print header info for extra headers, pretending they were discovered by
120  // the regular preprocessor. The primary use case is to support proper
121  // generation of Make / Ninja file dependencies for implicit includes, such
122  // as sanitizer blacklists. It's only important for cl.exe compatibility,
123  // the GNU way to generate rules is -M / -MM / -MD / -MMD.
124  for (const auto &Header : DepOpts.ExtraDeps)
125    PrintHeaderInfo(OutputFile, Header.first, ShowDepth, 2, MSStyle);
126  PP.addPPCallbacks(std::make_unique<HeaderIncludesCallback>(
127      &PP, ShowAllHeaders, OutputFile, DepOpts, OwnsOutputFile, ShowDepth,
128      MSStyle));
129}
130
131void HeaderIncludesCallback::FileChanged(SourceLocation Loc,
132                                         FileChangeReason Reason,
133                                         SrcMgr::CharacteristicKind NewFileType,
134                                         FileID PrevFID) {
135  // Unless we are exiting a #include, make sure to skip ahead to the line the
136  // #include directive was at.
137  PresumedLoc UserLoc = SM.getPresumedLoc(Loc);
138  if (UserLoc.isInvalid())
139    return;
140
141  // Adjust the current include depth.
142  if (Reason == PPCallbacks::EnterFile) {
143    ++CurrentIncludeDepth;
144  } else if (Reason == PPCallbacks::ExitFile) {
145    if (CurrentIncludeDepth)
146      --CurrentIncludeDepth;
147
148    // We track when we are done with the predefines by watching for the first
149    // place where we drop back to a nesting depth of 1.
150    if (CurrentIncludeDepth == 1 && !HasProcessedPredefines) {
151      if (!DepOpts.ShowIncludesPretendHeader.empty()) {
152        PrintHeaderInfo(OutputFile, DepOpts.ShowIncludesPretendHeader,
153                        ShowDepth, 2, MSStyle);
154      }
155      HasProcessedPredefines = true;
156    }
157
158    return;
159  } else
160    return;
161
162  // Show the header if we are (a) past the predefines, or (b) showing all
163  // headers and in the predefines at a depth past the initial file and command
164  // line buffers.
165  bool ShowHeader = (HasProcessedPredefines ||
166                     (ShowAllHeaders && CurrentIncludeDepth > 2));
167  unsigned IncludeDepth = CurrentIncludeDepth;
168  if (!HasProcessedPredefines)
169    --IncludeDepth; // Ignore indent from <built-in>.
170  else if (!DepOpts.ShowIncludesPretendHeader.empty())
171    ++IncludeDepth; // Pretend inclusion by ShowIncludesPretendHeader.
172
173  if (!DepOpts.IncludeSystemHeaders && isSystem(NewFileType))
174    ShowHeader = false;
175
176  // Dump the header include information we are past the predefines buffer or
177  // are showing all headers and this isn't the magic implicit <command line>
178  // header.
179  // FIXME: Identify headers in a more robust way than comparing their name to
180  // "<command line>" and "<built-in>" in a bunch of places.
181  if (ShowHeader && Reason == PPCallbacks::EnterFile &&
182      UserLoc.getFilename() != StringRef("<command line>")) {
183    PrintHeaderInfo(OutputFile, UserLoc.getFilename(), ShowDepth, IncludeDepth,
184                    MSStyle);
185  }
186}
187
188void HeaderIncludesCallback::FileSkipped(const FileEntryRef &SkippedFile, const
189                                         Token &FilenameTok,
190                                         SrcMgr::CharacteristicKind FileType) {
191  if (!DepOpts.ShowSkippedHeaderIncludes)
192    return;
193
194  if (!DepOpts.IncludeSystemHeaders && isSystem(FileType))
195    return;
196
197  PrintHeaderInfo(OutputFile, SkippedFile.getName(), ShowDepth,
198                  CurrentIncludeDepth + 1, MSStyle);
199}
200