1//===--- DependencyFile.cpp - Generate dependency file --------------------===//
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// This code generates dependency files.
10//
11//===----------------------------------------------------------------------===//
12
13#include "clang/Basic/FileManager.h"
14#include "clang/Basic/SourceManager.h"
15#include "clang/Frontend/DependencyOutputOptions.h"
16#include "clang/Frontend/FrontendDiagnostic.h"
17#include "clang/Frontend/Utils.h"
18#include "clang/Lex/DirectoryLookup.h"
19#include "clang/Lex/ModuleMap.h"
20#include "clang/Lex/PPCallbacks.h"
21#include "clang/Lex/Preprocessor.h"
22#include "clang/Serialization/ASTReader.h"
23#include "llvm/ADT/StringSet.h"
24#include "llvm/Support/FileSystem.h"
25#include "llvm/Support/Path.h"
26#include "llvm/Support/raw_ostream.h"
27#include <optional>
28
29using namespace clang;
30
31namespace {
32struct DepCollectorPPCallbacks : public PPCallbacks {
33 DependencyCollector &DepCollector;
34 Preprocessor &PP;
35 DepCollectorPPCallbacks(DependencyCollector &L, Preprocessor &PP)
36 : DepCollector(L), PP(PP) {}
37
38 void LexedFileChanged(FileID FID, LexedFileChangeReason Reason,
39 SrcMgr::CharacteristicKind FileType, FileID PrevFID,
40 SourceLocation Loc) override {
41 if (Reason != PPCallbacks::LexedFileChangeReason::EnterFile)
42 return;
43
44 // Dependency generation really does want to go all the way to the
45 // file entry for a source location to find out what is depended on.
46 // We do not want #line markers to affect dependency generation!
47 if (std::optional<StringRef> Filename =
48 PP.getSourceManager().getNonBuiltinFilenameForID(FID))
49 DepCollector.maybeAddDependency(
50 Filename: llvm::sys::path::remove_leading_dotslash(path: *Filename),
51 /*FromModule*/ false, IsSystem: isSystem(CK: FileType), /*IsModuleFile*/ false,
52 /*IsMissing*/ false);
53 }
54
55 void FileSkipped(const FileEntryRef &SkippedFile, const Token &FilenameTok,
56 SrcMgr::CharacteristicKind FileType) override {
57 StringRef Filename =
58 llvm::sys::path::remove_leading_dotslash(path: SkippedFile.getName());
59 DepCollector.maybeAddDependency(Filename, /*FromModule=*/false,
60 /*IsSystem=*/isSystem(CK: FileType),
61 /*IsModuleFile=*/false,
62 /*IsMissing=*/false);
63 }
64
65 void EmbedDirective(SourceLocation, StringRef, bool,
66 OptionalFileEntryRef File,
67 const LexEmbedParametersResult &) override {
68 assert(File && "expected to only be called when the file is found");
69 StringRef FileName =
70 llvm::sys::path::remove_leading_dotslash(path: File->getName());
71 DepCollector.maybeAddDependency(Filename: FileName,
72 /*FromModule*/ false,
73 /*IsSystem*/ false,
74 /*IsModuleFile*/ false,
75 /*IsMissing*/ false);
76 }
77
78 void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
79 StringRef FileName, bool IsAngled,
80 CharSourceRange FilenameRange,
81 OptionalFileEntryRef File, StringRef SearchPath,
82 StringRef RelativePath, const Module *SuggestedModule,
83 bool ModuleImported,
84 SrcMgr::CharacteristicKind FileType) override {
85 if (!File)
86 DepCollector.maybeAddDependency(Filename: FileName, /*FromModule*/ false,
87 /*IsSystem*/ false,
88 /*IsModuleFile*/ false,
89 /*IsMissing*/ true);
90 // Files that actually exist are handled by FileChanged.
91 }
92
93 void HasEmbed(SourceLocation, StringRef, bool,
94 OptionalFileEntryRef File) override {
95 if (!File)
96 return;
97 StringRef Filename =
98 llvm::sys::path::remove_leading_dotslash(path: File->getName());
99 DepCollector.maybeAddDependency(Filename,
100 /*FromModule=*/false, IsSystem: false,
101 /*IsModuleFile=*/false,
102 /*IsMissing=*/false);
103 }
104
105 void HasInclude(SourceLocation Loc, StringRef SpelledFilename, bool IsAngled,
106 OptionalFileEntryRef File,
107 SrcMgr::CharacteristicKind FileType) override {
108 if (!File)
109 return;
110 StringRef Filename =
111 llvm::sys::path::remove_leading_dotslash(path: File->getName());
112 DepCollector.maybeAddDependency(Filename, /*FromModule=*/false,
113 /*IsSystem=*/isSystem(CK: FileType),
114 /*IsModuleFile=*/false,
115 /*IsMissing=*/false);
116 }
117
118 void EndOfMainFile() override {
119 DepCollector.finishedMainFile(Diags&: PP.getDiagnostics());
120 }
121};
122
123struct DepCollectorMMCallbacks : public ModuleMapCallbacks {
124 DependencyCollector &DepCollector;
125 DepCollectorMMCallbacks(DependencyCollector &DC) : DepCollector(DC) {}
126
127 void moduleMapFileRead(SourceLocation Loc, FileEntryRef Entry,
128 bool IsSystem) override {
129 StringRef Filename = Entry.getName();
130 DepCollector.maybeAddDependency(Filename, /*FromModule*/ false,
131 /*IsSystem*/ IsSystem,
132 /*IsModuleFile*/ false,
133 /*IsMissing*/ false);
134 }
135};
136
137struct DepCollectorASTListener : public ASTReaderListener {
138 DependencyCollector &DepCollector;
139 FileManager &FileMgr;
140 DepCollectorASTListener(DependencyCollector &L, FileManager &FileMgr)
141 : DepCollector(L), FileMgr(FileMgr) {}
142 bool needsInputFileVisitation() override { return true; }
143 bool needsSystemInputFileVisitation() override {
144 return DepCollector.needSystemDependencies();
145 }
146 void visitModuleFile(StringRef Filename,
147 serialization::ModuleKind Kind) override {
148 DepCollector.maybeAddDependency(Filename, /*FromModule*/ true,
149 /*IsSystem*/ false, /*IsModuleFile*/ true,
150 /*IsMissing*/ false);
151 }
152 bool visitInputFile(StringRef Filename, bool IsSystem,
153 bool IsOverridden, bool IsExplicitModule) override {
154 if (IsOverridden || IsExplicitModule)
155 return true;
156
157 // Run this through the FileManager in order to respect 'use-external-name'
158 // in case we have a VFS overlay.
159 if (auto FE = FileMgr.getOptionalFileRef(Filename))
160 Filename = FE->getName();
161
162 DepCollector.maybeAddDependency(Filename, /*FromModule*/ true, IsSystem,
163 /*IsModuleFile*/ false,
164 /*IsMissing*/ false);
165 return true;
166 }
167};
168} // end anonymous namespace
169
170void DependencyCollector::maybeAddDependency(StringRef Filename,
171 bool FromModule, bool IsSystem,
172 bool IsModuleFile,
173 bool IsMissing) {
174 if (sawDependency(Filename, FromModule, IsSystem, IsModuleFile, IsMissing))
175 addDependency(Filename);
176}
177
178bool DependencyCollector::addDependency(StringRef Filename) {
179 StringRef SearchPath;
180#ifdef _WIN32
181 // Make the search insensitive to case and separators.
182 llvm::SmallString<256> TmpPath = Filename;
183 llvm::sys::path::native(TmpPath);
184 std::transform(TmpPath.begin(), TmpPath.end(), TmpPath.begin(), ::tolower);
185 SearchPath = TmpPath.str();
186#else
187 SearchPath = Filename;
188#endif
189
190 if (Seen.insert(key: SearchPath).second) {
191 Dependencies.push_back(x: std::string(Filename));
192 return true;
193 }
194 return false;
195}
196
197static bool isSpecialFilename(StringRef Filename) {
198 return Filename == "<built-in>";
199}
200
201bool DependencyCollector::sawDependency(StringRef Filename, bool FromModule,
202 bool IsSystem, bool IsModuleFile,
203 bool IsMissing) {
204 return !isSpecialFilename(Filename) &&
205 (needSystemDependencies() || !IsSystem);
206}
207
208DependencyCollector::~DependencyCollector() { }
209void DependencyCollector::attachToPreprocessor(Preprocessor &PP) {
210 PP.addPPCallbacks(C: std::make_unique<DepCollectorPPCallbacks>(args&: *this, args&: PP));
211 PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(
212 Callback: std::make_unique<DepCollectorMMCallbacks>(args&: *this));
213}
214void DependencyCollector::attachToASTReader(ASTReader &R) {
215 R.addListener(
216 L: std::make_unique<DepCollectorASTListener>(args&: *this, args&: R.getFileManager()));
217}
218
219DependencyFileGenerator::DependencyFileGenerator(
220 const DependencyOutputOptions &Opts)
221 : OutputFile(Opts.OutputFile), Targets(Opts.Targets),
222 IncludeSystemHeaders(Opts.IncludeSystemHeaders),
223 PhonyTarget(Opts.UsePhonyTargets),
224 AddMissingHeaderDeps(Opts.AddMissingHeaderDeps), SeenMissingHeader(false),
225 IncludeModuleFiles(Opts.IncludeModuleFiles),
226 OutputFormat(Opts.OutputFormat), InputFileIndex(0) {
227 for (const auto &ExtraDep : Opts.ExtraDeps) {
228 if (addDependency(Filename: ExtraDep.first))
229 ++InputFileIndex;
230 }
231}
232
233void DependencyFileGenerator::attachToPreprocessor(Preprocessor &PP) {
234 // Disable the "file not found" diagnostic if the -MG option was given.
235 if (AddMissingHeaderDeps)
236 PP.SetSuppressIncludeNotFoundError(true);
237
238 DependencyCollector::attachToPreprocessor(PP);
239}
240
241bool DependencyFileGenerator::sawDependency(StringRef Filename, bool FromModule,
242 bool IsSystem, bool IsModuleFile,
243 bool IsMissing) {
244 if (IsMissing) {
245 // Handle the case of missing file from an inclusion directive.
246 if (AddMissingHeaderDeps)
247 return true;
248 SeenMissingHeader = true;
249 return false;
250 }
251 if (IsModuleFile && !IncludeModuleFiles)
252 return false;
253
254 if (isSpecialFilename(Filename))
255 return false;
256
257 if (IncludeSystemHeaders)
258 return true;
259
260 return !IsSystem;
261}
262
263void DependencyFileGenerator::finishedMainFile(DiagnosticsEngine &Diags) {
264 outputDependencyFile(Diags);
265}
266
267/// Print the filename, with escaping or quoting that accommodates the three
268/// most likely tools that use dependency files: GNU Make, BSD Make, and
269/// NMake/Jom.
270///
271/// BSD Make is the simplest case: It does no escaping at all. This means
272/// characters that are normally delimiters, i.e. space and # (the comment
273/// character) simply aren't supported in filenames.
274///
275/// GNU Make does allow space and # in filenames, but to avoid being treated
276/// as a delimiter or comment, these must be escaped with a backslash. Because
277/// backslash is itself the escape character, if a backslash appears in a
278/// filename, it should be escaped as well. (As a special case, $ is escaped
279/// as $$, which is the normal Make way to handle the $ character.)
280/// For compatibility with BSD Make and historical practice, if GNU Make
281/// un-escapes characters in a filename but doesn't find a match, it will
282/// retry with the unmodified original string.
283///
284/// GCC tries to accommodate both Make formats by escaping any space or #
285/// characters in the original filename, but not escaping backslashes. The
286/// apparent intent is so that filenames with backslashes will be handled
287/// correctly by BSD Make, and by GNU Make in its fallback mode of using the
288/// unmodified original string; filenames with # or space characters aren't
289/// supported by BSD Make at all, but will be handled correctly by GNU Make
290/// due to the escaping.
291///
292/// A corner case that GCC gets only partly right is when the original filename
293/// has a backslash immediately followed by space or #. GNU Make would expect
294/// this backslash to be escaped; however GCC escapes the original backslash
295/// only when followed by space, not #. It will therefore take a dependency
296/// from a directive such as
297/// #include "a\ b\#c.h"
298/// and emit it as
299/// a\\\ b\\#c.h
300/// which GNU Make will interpret as
301/// a\ b\
302/// followed by a comment. Failing to find this file, it will fall back to the
303/// original string, which probably doesn't exist either; in any case it won't
304/// find
305/// a\ b\#c.h
306/// which is the actual filename specified by the include directive.
307///
308/// Clang does what GCC does, rather than what GNU Make expects.
309///
310/// NMake/Jom has a different set of scary characters, but wraps filespecs in
311/// double-quotes to avoid misinterpreting them; see
312/// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info,
313/// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
314/// for Windows file-naming info.
315static void PrintFilename(raw_ostream &OS, StringRef Filename,
316 DependencyOutputFormat OutputFormat) {
317 // Convert filename to platform native path
318 llvm::SmallString<256> NativePath;
319 llvm::sys::path::native(path: Filename.str(), result&: NativePath);
320
321 if (OutputFormat == DependencyOutputFormat::NMake) {
322 // Add quotes if needed. These are the characters listed as "special" to
323 // NMake, that are legal in a Windows filespec, and that could cause
324 // misinterpretation of the dependency string.
325 if (NativePath.find_first_of(Chars: " #${}^!") != StringRef::npos)
326 OS << '\"' << NativePath << '\"';
327 else
328 OS << NativePath;
329 return;
330 }
331 assert(OutputFormat == DependencyOutputFormat::Make);
332 for (unsigned i = 0, e = NativePath.size(); i != e; ++i) {
333 if (NativePath[i] == '#') // Handle '#' the broken gcc way.
334 OS << '\\';
335 else if (NativePath[i] == ' ') { // Handle space correctly.
336 OS << '\\';
337 unsigned j = i;
338 while (j > 0 && NativePath[--j] == '\\')
339 OS << '\\';
340 } else if (NativePath[i] == '$') // $ is escaped by $$.
341 OS << '$';
342 OS << NativePath[i];
343 }
344}
345
346void DependencyFileGenerator::outputDependencyFile(DiagnosticsEngine &Diags) {
347 if (SeenMissingHeader) {
348 llvm::sys::fs::remove(path: OutputFile);
349 return;
350 }
351
352 std::error_code EC;
353 llvm::raw_fd_ostream OS(OutputFile, EC, llvm::sys::fs::OF_TextWithCRLF);
354 if (EC) {
355 Diags.Report(DiagID: diag::err_fe_error_opening) << OutputFile << EC.message();
356 return;
357 }
358
359 outputDependencyFile(OS);
360}
361
362void DependencyFileGenerator::outputDependencyFile(llvm::raw_ostream &OS) {
363 // Write out the dependency targets, trying to avoid overly long
364 // lines when possible. We try our best to emit exactly the same
365 // dependency file as GCC>=10, assuming the included files are the
366 // same.
367 const unsigned MaxColumns = 75;
368 unsigned Columns = 0;
369
370 for (StringRef Target : Targets) {
371 unsigned N = Target.size();
372 if (Columns == 0) {
373 Columns += N;
374 } else if (Columns + N + 2 > MaxColumns) {
375 Columns = N + 2;
376 OS << " \\\n ";
377 } else {
378 Columns += N + 1;
379 OS << ' ';
380 }
381 // Targets already quoted as needed.
382 OS << Target;
383 }
384
385 OS << ':';
386 Columns += 1;
387
388 // Now add each dependency in the order it was seen, but avoiding
389 // duplicates.
390 ArrayRef<std::string> Files = getDependencies();
391 for (StringRef File : Files) {
392 if (File == "<stdin>")
393 continue;
394 // Start a new line if this would exceed the column limit. Make
395 // sure to leave space for a trailing " \" in case we need to
396 // break the line on the next iteration.
397 unsigned N = File.size();
398 if (Columns + (N + 1) + 2 > MaxColumns) {
399 OS << " \\\n ";
400 Columns = 2;
401 }
402 OS << ' ';
403 PrintFilename(OS, Filename: File, OutputFormat);
404 Columns += N + 1;
405 }
406 OS << '\n';
407
408 // Create phony targets if requested.
409 if (PhonyTarget && !Files.empty()) {
410 unsigned Index = 0;
411 for (auto I = Files.begin(), E = Files.end(); I != E; ++I) {
412 if (Index++ == InputFileIndex)
413 continue;
414 PrintFilename(OS, Filename: *I, OutputFormat);
415 OS << ":\n";
416 }
417 }
418}
419