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"
16 using namespace clang;
17
18 namespace {
19 class 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
30 public:
HeaderIncludesCallback(const Preprocessor * PP,bool ShowAllHeaders_,raw_ostream * OutputFile_,const DependencyOutputOptions & DepOpts,bool OwnsOutputFile_,bool ShowDepth_,bool MSStyle_)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
~HeaderIncludesCallback()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 }
50
PrintHeaderInfo(raw_ostream * OutputFile,StringRef Filename,bool ShowDepth,unsigned CurrentIncludeDepth,bool MSStyle)51 static void PrintHeaderInfo(raw_ostream *OutputFile, StringRef Filename,
52 bool ShowDepth, unsigned CurrentIncludeDepth,
53 bool MSStyle) {
54 // Write to a temporary string to avoid unnecessary flushing on errs().
55 SmallString<512> Pathname(Filename);
56 if (!MSStyle)
57 Lexer::Stringify(Pathname);
58
59 SmallString<256> Msg;
60 if (MSStyle)
61 Msg += "Note: including file:";
62
63 if (ShowDepth) {
64 // The main source file is at depth 1, so skip one dot.
65 for (unsigned i = 1; i != CurrentIncludeDepth; ++i)
66 Msg += MSStyle ? ' ' : '.';
67
68 if (!MSStyle)
69 Msg += ' ';
70 }
71 Msg += Pathname;
72 Msg += '\n';
73
74 *OutputFile << Msg;
75 OutputFile->flush();
76 }
77
AttachHeaderIncludeGen(Preprocessor & PP,const DependencyOutputOptions & DepOpts,bool ShowAllHeaders,StringRef OutputPath,bool ShowDepth,bool MSStyle)78 void clang::AttachHeaderIncludeGen(Preprocessor &PP,
79 const DependencyOutputOptions &DepOpts,
80 bool ShowAllHeaders, StringRef OutputPath,
81 bool ShowDepth, bool MSStyle) {
82 raw_ostream *OutputFile = &llvm::errs();
83 bool OwnsOutputFile = false;
84
85 // Choose output stream, when printing in cl.exe /showIncludes style.
86 if (MSStyle) {
87 switch (DepOpts.ShowIncludesDest) {
88 default:
89 llvm_unreachable("Invalid destination for /showIncludes output!");
90 case ShowIncludesDestination::Stderr:
91 OutputFile = &llvm::errs();
92 break;
93 case ShowIncludesDestination::Stdout:
94 OutputFile = &llvm::outs();
95 break;
96 }
97 }
98
99 // Open the output file, if used.
100 if (!OutputPath.empty()) {
101 std::error_code EC;
102 llvm::raw_fd_ostream *OS = new llvm::raw_fd_ostream(
103 OutputPath.str(), EC,
104 llvm::sys::fs::OF_Append | llvm::sys::fs::OF_Text);
105 if (EC) {
106 PP.getDiagnostics().Report(clang::diag::warn_fe_cc_print_header_failure)
107 << EC.message();
108 delete OS;
109 } else {
110 OS->SetUnbuffered();
111 OutputFile = OS;
112 OwnsOutputFile = true;
113 }
114 }
115
116 // Print header info for extra headers, pretending they were discovered by
117 // the regular preprocessor. The primary use case is to support proper
118 // generation of Make / Ninja file dependencies for implicit includes, such
119 // as sanitizer blacklists. It's only important for cl.exe compatibility,
120 // the GNU way to generate rules is -M / -MM / -MD / -MMD.
121 for (const auto &Header : DepOpts.ExtraDeps)
122 PrintHeaderInfo(OutputFile, Header, ShowDepth, 2, MSStyle);
123 PP.addPPCallbacks(std::make_unique<HeaderIncludesCallback>(
124 &PP, ShowAllHeaders, OutputFile, DepOpts, OwnsOutputFile, ShowDepth,
125 MSStyle));
126 }
127
FileChanged(SourceLocation Loc,FileChangeReason Reason,SrcMgr::CharacteristicKind NewFileType,FileID PrevFID)128 void HeaderIncludesCallback::FileChanged(SourceLocation Loc,
129 FileChangeReason Reason,
130 SrcMgr::CharacteristicKind NewFileType,
131 FileID PrevFID) {
132 // Unless we are exiting a #include, make sure to skip ahead to the line the
133 // #include directive was at.
134 PresumedLoc UserLoc = SM.getPresumedLoc(Loc);
135 if (UserLoc.isInvalid())
136 return;
137
138 // Adjust the current include depth.
139 if (Reason == PPCallbacks::EnterFile) {
140 ++CurrentIncludeDepth;
141 } else if (Reason == PPCallbacks::ExitFile) {
142 if (CurrentIncludeDepth)
143 --CurrentIncludeDepth;
144
145 // We track when we are done with the predefines by watching for the first
146 // place where we drop back to a nesting depth of 1.
147 if (CurrentIncludeDepth == 1 && !HasProcessedPredefines) {
148 if (!DepOpts.ShowIncludesPretendHeader.empty()) {
149 PrintHeaderInfo(OutputFile, DepOpts.ShowIncludesPretendHeader,
150 ShowDepth, 2, MSStyle);
151 }
152 HasProcessedPredefines = true;
153 }
154
155 return;
156 } else
157 return;
158
159 // Show the header if we are (a) past the predefines, or (b) showing all
160 // headers and in the predefines at a depth past the initial file and command
161 // line buffers.
162 bool ShowHeader = (HasProcessedPredefines ||
163 (ShowAllHeaders && CurrentIncludeDepth > 2));
164 unsigned IncludeDepth = CurrentIncludeDepth;
165 if (!HasProcessedPredefines)
166 --IncludeDepth; // Ignore indent from <built-in>.
167 else if (!DepOpts.ShowIncludesPretendHeader.empty())
168 ++IncludeDepth; // Pretend inclusion by ShowIncludesPretendHeader.
169
170 // Dump the header include information we are past the predefines buffer or
171 // are showing all headers and this isn't the magic implicit <command line>
172 // header.
173 // FIXME: Identify headers in a more robust way than comparing their name to
174 // "<command line>" and "<built-in>" in a bunch of places.
175 if (ShowHeader && Reason == PPCallbacks::EnterFile &&
176 UserLoc.getFilename() != StringRef("<command line>")) {
177 PrintHeaderInfo(OutputFile, UserLoc.getFilename(), ShowDepth, IncludeDepth,
178 MSStyle);
179 }
180 }
181