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/JSON.h"
16#include "llvm/Support/raw_ostream.h"
17using namespace clang;
18
19namespace {
20class HeaderIncludesCallback : public PPCallbacks {
21 SourceManager &SM;
22 raw_ostream *OutputFile;
23 const DependencyOutputOptions &DepOpts;
24 unsigned CurrentIncludeDepth;
25 bool HasProcessedPredefines;
26 bool OwnsOutputFile;
27 bool ShowAllHeaders;
28 bool ShowDepth;
29 bool MSStyle;
30
31public:
32 HeaderIncludesCallback(const Preprocessor *PP, bool ShowAllHeaders_,
33 raw_ostream *OutputFile_,
34 const DependencyOutputOptions &DepOpts,
35 bool OwnsOutputFile_, bool ShowDepth_, bool MSStyle_)
36 : SM(PP->getSourceManager()), OutputFile(OutputFile_), DepOpts(DepOpts),
37 CurrentIncludeDepth(0), HasProcessedPredefines(false),
38 OwnsOutputFile(OwnsOutputFile_), ShowAllHeaders(ShowAllHeaders_),
39 ShowDepth(ShowDepth_), MSStyle(MSStyle_) {}
40
41 ~HeaderIncludesCallback() override {
42 if (OwnsOutputFile)
43 delete OutputFile;
44 }
45
46 HeaderIncludesCallback(const HeaderIncludesCallback &) = delete;
47 HeaderIncludesCallback &operator=(const HeaderIncludesCallback &) = delete;
48
49 void FileChanged(SourceLocation Loc, FileChangeReason Reason,
50 SrcMgr::CharacteristicKind FileType,
51 FileID PrevFID) override;
52
53 void FileSkipped(const FileEntryRef &SkippedFile, const Token &FilenameTok,
54 SrcMgr::CharacteristicKind FileType) override;
55
56private:
57 bool ShouldShowHeader(SrcMgr::CharacteristicKind HeaderType) {
58 if (!DepOpts.IncludeSystemHeaders && isSystem(CK: HeaderType))
59 return false;
60
61 // Show the current header if we are (a) past the predefines, or (b) showing
62 // all headers and in the predefines at a depth past the initial file and
63 // command line buffers.
64 return (HasProcessedPredefines ||
65 (ShowAllHeaders && CurrentIncludeDepth > 2));
66 }
67};
68
69/// A callback for emitting header usage information to a file in JSON. Each
70/// line in the file is a JSON object that includes the source file name and
71/// the list of headers directly or indirectly included from it. For example:
72///
73/// {"source":"/tmp/foo.c",
74/// "includes":["/usr/include/stdio.h", "/usr/include/stdlib.h"]}
75///
76/// To reduce the amount of data written to the file, we only record system
77/// headers that are directly included from a file that isn't in the system
78/// directory.
79class HeaderIncludesJSONCallback : public PPCallbacks {
80 SourceManager &SM;
81 raw_ostream *OutputFile;
82 bool OwnsOutputFile;
83 SmallVector<std::string, 16> IncludedHeaders;
84
85public:
86 HeaderIncludesJSONCallback(const Preprocessor *PP, raw_ostream *OutputFile_,
87 bool OwnsOutputFile_)
88 : SM(PP->getSourceManager()), OutputFile(OutputFile_),
89 OwnsOutputFile(OwnsOutputFile_) {}
90
91 ~HeaderIncludesJSONCallback() override {
92 if (OwnsOutputFile)
93 delete OutputFile;
94 }
95
96 HeaderIncludesJSONCallback(const HeaderIncludesJSONCallback &) = delete;
97 HeaderIncludesJSONCallback &
98 operator=(const HeaderIncludesJSONCallback &) = delete;
99
100 void EndOfMainFile() override;
101
102 void FileChanged(SourceLocation Loc, FileChangeReason Reason,
103 SrcMgr::CharacteristicKind FileType,
104 FileID PrevFID) override;
105
106 void FileSkipped(const FileEntryRef &SkippedFile, const Token &FilenameTok,
107 SrcMgr::CharacteristicKind FileType) override;
108};
109}
110
111static void PrintHeaderInfo(raw_ostream *OutputFile, StringRef Filename,
112 bool ShowDepth, unsigned CurrentIncludeDepth,
113 bool MSStyle) {
114 // Write to a temporary string to avoid unnecessary flushing on errs().
115 SmallString<512> Pathname(Filename);
116 if (!MSStyle)
117 Lexer::Stringify(Str&: Pathname);
118
119 SmallString<256> Msg;
120 if (MSStyle)
121 Msg += "Note: including file:";
122
123 if (ShowDepth) {
124 // The main source file is at depth 1, so skip one dot.
125 for (unsigned i = 1; i != CurrentIncludeDepth; ++i)
126 Msg += MSStyle ? ' ' : '.';
127
128 if (!MSStyle)
129 Msg += ' ';
130 }
131 Msg += Pathname;
132 Msg += '\n';
133
134 *OutputFile << Msg;
135 OutputFile->flush();
136}
137
138void clang::AttachHeaderIncludeGen(Preprocessor &PP,
139 const DependencyOutputOptions &DepOpts,
140 bool ShowAllHeaders, StringRef OutputPath,
141 bool ShowDepth, bool MSStyle) {
142 raw_ostream *OutputFile = &llvm::errs();
143 bool OwnsOutputFile = false;
144
145 // Choose output stream, when printing in cl.exe /showIncludes style.
146 if (MSStyle) {
147 switch (DepOpts.ShowIncludesDest) {
148 default:
149 llvm_unreachable("Invalid destination for /showIncludes output!");
150 case ShowIncludesDestination::Stderr:
151 OutputFile = &llvm::errs();
152 break;
153 case ShowIncludesDestination::Stdout:
154 OutputFile = &llvm::outs();
155 break;
156 }
157 }
158
159 // Open the output file, if used.
160 if (!OutputPath.empty()) {
161 std::error_code EC;
162 llvm::raw_fd_ostream *OS = new llvm::raw_fd_ostream(
163 OutputPath.str(), EC,
164 llvm::sys::fs::OF_Append | llvm::sys::fs::OF_TextWithCRLF);
165 if (EC) {
166 PP.getDiagnostics().Report(DiagID: clang::diag::warn_fe_cc_print_header_failure)
167 << EC.message();
168 delete OS;
169 } else {
170 OS->SetUnbuffered();
171 OutputFile = OS;
172 OwnsOutputFile = true;
173 }
174 }
175
176 switch (DepOpts.HeaderIncludeFormat) {
177 case HIFMT_None:
178 llvm_unreachable("unexpected header format kind");
179 case HIFMT_Textual: {
180 assert(DepOpts.HeaderIncludeFiltering == HIFIL_None &&
181 "header filtering is currently always disabled when output format is"
182 "textual");
183 // Print header info for extra headers, pretending they were discovered by
184 // the regular preprocessor. The primary use case is to support proper
185 // generation of Make / Ninja file dependencies for implicit includes, such
186 // as sanitizer ignorelists. It's only important for cl.exe compatibility,
187 // the GNU way to generate rules is -M / -MM / -MD / -MMD.
188 for (const auto &Header : DepOpts.ExtraDeps)
189 PrintHeaderInfo(OutputFile, Filename: Header.first, ShowDepth, CurrentIncludeDepth: 2, MSStyle);
190 PP.addPPCallbacks(C: std::make_unique<HeaderIncludesCallback>(
191 args: &PP, args&: ShowAllHeaders, args&: OutputFile, args: DepOpts, args&: OwnsOutputFile, args&: ShowDepth,
192 args&: MSStyle));
193 break;
194 }
195 case HIFMT_JSON: {
196 assert(DepOpts.HeaderIncludeFiltering == HIFIL_Only_Direct_System &&
197 "only-direct-system is the only option for filtering");
198 PP.addPPCallbacks(C: std::make_unique<HeaderIncludesJSONCallback>(
199 args: &PP, args&: OutputFile, args&: OwnsOutputFile));
200 break;
201 }
202 }
203}
204
205void HeaderIncludesCallback::FileChanged(SourceLocation Loc,
206 FileChangeReason Reason,
207 SrcMgr::CharacteristicKind NewFileType,
208 FileID PrevFID) {
209 // Unless we are exiting a #include, make sure to skip ahead to the line the
210 // #include directive was at.
211 PresumedLoc UserLoc = SM.getPresumedLoc(Loc);
212 if (UserLoc.isInvalid())
213 return;
214
215 // Adjust the current include depth.
216 if (Reason == PPCallbacks::EnterFile) {
217 ++CurrentIncludeDepth;
218 } else if (Reason == PPCallbacks::ExitFile) {
219 if (CurrentIncludeDepth)
220 --CurrentIncludeDepth;
221
222 // We track when we are done with the predefines by watching for the first
223 // place where we drop back to a nesting depth of 1.
224 if (CurrentIncludeDepth == 1 && !HasProcessedPredefines)
225 HasProcessedPredefines = true;
226
227 return;
228 } else {
229 return;
230 }
231
232 if (!ShouldShowHeader(HeaderType: NewFileType))
233 return;
234
235 unsigned IncludeDepth = CurrentIncludeDepth;
236 if (!HasProcessedPredefines)
237 --IncludeDepth; // Ignore indent from <built-in>.
238
239 // FIXME: Identify headers in a more robust way than comparing their name to
240 // "<command line>" and "<built-in>" in a bunch of places.
241 if (Reason == PPCallbacks::EnterFile &&
242 UserLoc.getFilename() != StringRef("<command line>")) {
243 PrintHeaderInfo(OutputFile, Filename: UserLoc.getFilename(), ShowDepth, CurrentIncludeDepth: IncludeDepth,
244 MSStyle);
245 }
246}
247
248void HeaderIncludesCallback::FileSkipped(const FileEntryRef &SkippedFile, const
249 Token &FilenameTok,
250 SrcMgr::CharacteristicKind FileType) {
251 if (!DepOpts.ShowSkippedHeaderIncludes)
252 return;
253
254 if (!ShouldShowHeader(HeaderType: FileType))
255 return;
256
257 PrintHeaderInfo(OutputFile, Filename: SkippedFile.getName(), ShowDepth,
258 CurrentIncludeDepth: CurrentIncludeDepth + 1, MSStyle);
259}
260
261void HeaderIncludesJSONCallback::EndOfMainFile() {
262 OptionalFileEntryRef FE = SM.getFileEntryRefForID(FID: SM.getMainFileID());
263 SmallString<256> MainFile(FE->getName());
264 SM.getFileManager().makeAbsolutePath(Path&: MainFile);
265
266 std::string Str;
267 llvm::raw_string_ostream OS(Str);
268 llvm::json::OStream JOS(OS);
269 JOS.object(Contents: [&] {
270 JOS.attribute(Key: "source", Contents: MainFile.c_str());
271 JOS.attributeArray(Key: "includes", Contents: [&] {
272 llvm::StringSet<> SeenHeaders;
273 for (const std::string &H : IncludedHeaders)
274 if (SeenHeaders.insert(key: H).second)
275 JOS.value(V: H);
276 });
277 });
278 OS << "\n";
279
280 if (OutputFile->get_kind() == raw_ostream::OStreamKind::OK_FDStream) {
281 llvm::raw_fd_ostream *FDS = static_cast<llvm::raw_fd_ostream *>(OutputFile);
282 if (auto L = FDS->lock())
283 *OutputFile << Str;
284 } else
285 *OutputFile << Str;
286}
287
288/// Determine whether the header file should be recorded. The header file should
289/// be recorded only if the header file is a system header and the current file
290/// isn't a system header.
291static bool shouldRecordNewFile(SrcMgr::CharacteristicKind NewFileType,
292 SourceLocation PrevLoc, SourceManager &SM) {
293 return SrcMgr::isSystem(CK: NewFileType) && !SM.isInSystemHeader(Loc: PrevLoc);
294}
295
296void HeaderIncludesJSONCallback::FileChanged(
297 SourceLocation Loc, FileChangeReason Reason,
298 SrcMgr::CharacteristicKind NewFileType, FileID PrevFID) {
299 if (PrevFID.isInvalid() ||
300 !shouldRecordNewFile(NewFileType, PrevLoc: SM.getLocForStartOfFile(FID: PrevFID), SM))
301 return;
302
303 // Unless we are exiting a #include, make sure to skip ahead to the line the
304 // #include directive was at.
305 PresumedLoc UserLoc = SM.getPresumedLoc(Loc);
306 if (UserLoc.isInvalid())
307 return;
308
309 if (Reason == PPCallbacks::EnterFile &&
310 UserLoc.getFilename() != StringRef("<command line>"))
311 IncludedHeaders.push_back(Elt: UserLoc.getFilename());
312}
313
314void HeaderIncludesJSONCallback::FileSkipped(
315 const FileEntryRef &SkippedFile, const Token &FilenameTok,
316 SrcMgr::CharacteristicKind FileType) {
317 if (!shouldRecordNewFile(NewFileType: FileType, PrevLoc: FilenameTok.getLocation(), SM))
318 return;
319
320 IncludedHeaders.push_back(Elt: SkippedFile.getName().str());
321}
322