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/DiagnosticFrontend.h"
14#include "clang/Basic/FileManager.h"
15#include "clang/Basic/SourceManager.h"
16#include "clang/Frontend/DependencyOutputOptions.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 bool EmbedFileNotFound(StringRef FileName) override {
79 DepCollector.maybeAddDependency(
80 Filename: llvm::sys::path::remove_leading_dotslash(path: FileName),
81 /*FromModule=*/false,
82 /*IsSystem=*/false,
83 /*IsModuleFile=*/false,
84 /*IsMissing=*/true);
85 // Return true to silence the file not found diagnostic.
86 return true;
87 }
88
89 void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
90 StringRef FileName, bool IsAngled,
91 CharSourceRange FilenameRange,
92 OptionalFileEntryRef File, StringRef SearchPath,
93 StringRef RelativePath, const Module *SuggestedModule,
94 bool ModuleImported,
95 SrcMgr::CharacteristicKind FileType) override {
96 if (!File)
97 DepCollector.maybeAddDependency(Filename: FileName, /*FromModule*/ false,
98 /*IsSystem*/ false,
99 /*IsModuleFile*/ false,
100 /*IsMissing*/ true);
101 // Files that actually exist are handled by FileChanged.
102 }
103
104 void HasEmbed(SourceLocation, StringRef, bool,
105 OptionalFileEntryRef File) override {
106 if (!File)
107 return;
108 StringRef Filename =
109 llvm::sys::path::remove_leading_dotslash(path: File->getName());
110 DepCollector.maybeAddDependency(Filename,
111 /*FromModule=*/false, IsSystem: false,
112 /*IsModuleFile=*/false,
113 /*IsMissing=*/false);
114 }
115
116 void HasInclude(SourceLocation Loc, StringRef SpelledFilename, bool IsAngled,
117 OptionalFileEntryRef File,
118 SrcMgr::CharacteristicKind FileType) override {
119 if (!File)
120 return;
121 StringRef Filename =
122 llvm::sys::path::remove_leading_dotslash(path: File->getName());
123 DepCollector.maybeAddDependency(Filename, /*FromModule=*/false,
124 /*IsSystem=*/isSystem(CK: FileType),
125 /*IsModuleFile=*/false,
126 /*IsMissing=*/false);
127 }
128
129 void EndOfMainFile() override {
130 DepCollector.finishedMainFile(Diags&: PP.getDiagnostics());
131 }
132};
133
134struct DepCollectorMMCallbacks : public ModuleMapCallbacks {
135 DependencyCollector &DepCollector;
136 DepCollectorMMCallbacks(DependencyCollector &DC) : DepCollector(DC) {}
137
138 void moduleMapFileRead(SourceLocation Loc, FileEntryRef Entry,
139 bool IsSystem) override {
140 StringRef Filename = Entry.getName();
141 DepCollector.maybeAddDependency(Filename, /*FromModule*/ false,
142 /*IsSystem*/ IsSystem,
143 /*IsModuleFile*/ false,
144 /*IsMissing*/ false);
145 }
146};
147
148struct DepCollectorASTListener : public ASTReaderListener {
149 DependencyCollector &DepCollector;
150 FileManager &FileMgr;
151 DepCollectorASTListener(DependencyCollector &L, FileManager &FileMgr)
152 : DepCollector(L), FileMgr(FileMgr) {}
153 bool needsInputFileVisitation() override { return true; }
154 bool needsSystemInputFileVisitation() override {
155 return DepCollector.needSystemDependencies();
156 }
157 void visitModuleFile(StringRef Filename,
158 serialization::ModuleKind Kind) override {
159 DepCollector.maybeAddDependency(Filename, /*FromModule*/ true,
160 /*IsSystem*/ false, /*IsModuleFile*/ true,
161 /*IsMissing*/ false);
162 }
163 bool visitInputFile(StringRef Filename, bool IsSystem,
164 bool IsOverridden, bool IsExplicitModule) override {
165 if (IsOverridden || IsExplicitModule)
166 return true;
167
168 // Run this through the FileManager in order to respect 'use-external-name'
169 // in case we have a VFS overlay.
170 if (auto FE = FileMgr.getOptionalFileRef(Filename))
171 Filename = FE->getName();
172
173 DepCollector.maybeAddDependency(Filename, /*FromModule*/ true, IsSystem,
174 /*IsModuleFile*/ false,
175 /*IsMissing*/ false);
176 return true;
177 }
178};
179} // end anonymous namespace
180
181void DependencyCollector::maybeAddDependency(StringRef Filename,
182 bool FromModule, bool IsSystem,
183 bool IsModuleFile,
184 bool IsMissing) {
185 if (sawDependency(Filename, FromModule, IsSystem, IsModuleFile, IsMissing))
186 addDependency(Filename);
187}
188
189bool DependencyCollector::addDependency(StringRef Filename) {
190 StringRef SearchPath;
191#ifdef _WIN32
192 // Make the search insensitive to case and separators.
193 llvm::SmallString<256> TmpPath = Filename;
194 llvm::sys::path::native(TmpPath);
195 std::transform(TmpPath.begin(), TmpPath.end(), TmpPath.begin(), ::tolower);
196 SearchPath = TmpPath.str();
197#else
198 SearchPath = Filename;
199#endif
200
201 if (Seen.insert(key: SearchPath).second) {
202 Dependencies.push_back(x: std::string(Filename));
203 return true;
204 }
205 return false;
206}
207
208static bool isSpecialFilename(StringRef Filename) {
209 return Filename == "<built-in>";
210}
211
212bool DependencyCollector::sawDependency(StringRef Filename, bool FromModule,
213 bool IsSystem, bool IsModuleFile,
214 bool IsMissing) {
215 return !isSpecialFilename(Filename) &&
216 (needSystemDependencies() || !IsSystem);
217}
218
219DependencyCollector::~DependencyCollector() { }
220void DependencyCollector::attachToPreprocessor(Preprocessor &PP) {
221 PP.addPPCallbacks(C: std::make_unique<DepCollectorPPCallbacks>(args&: *this, args&: PP));
222 PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(
223 Callback: std::make_unique<DepCollectorMMCallbacks>(args&: *this));
224}
225void DependencyCollector::attachToASTReader(ASTReader &R) {
226 R.addListener(
227 L: std::make_unique<DepCollectorASTListener>(args&: *this, args&: R.getFileManager()));
228}
229
230DependencyFileGenerator::DependencyFileGenerator(
231 const DependencyOutputOptions &Opts)
232 : OutputFile(Opts.OutputFile), Targets(Opts.Targets),
233 IncludeSystemHeaders(Opts.IncludeSystemHeaders),
234 PhonyTarget(Opts.UsePhonyTargets),
235 AddMissingHeaderDeps(Opts.AddMissingHeaderDeps), SeenMissingHeader(false),
236 IncludeModuleFiles(Opts.IncludeModuleFiles),
237 OutputFormat(Opts.OutputFormat), InputFileIndex(0) {
238 for (const auto &ExtraDep : Opts.ExtraDeps) {
239 if (addDependency(Filename: ExtraDep.first))
240 ++InputFileIndex;
241 }
242}
243
244void DependencyFileGenerator::attachToPreprocessor(Preprocessor &PP) {
245 // Disable the "file not found" diagnostic if the -MG option was given.
246 if (AddMissingHeaderDeps)
247 PP.SetSuppressIncludeNotFoundError(true);
248
249 DependencyCollector::attachToPreprocessor(PP);
250}
251
252bool DependencyFileGenerator::sawDependency(StringRef Filename, bool FromModule,
253 bool IsSystem, bool IsModuleFile,
254 bool IsMissing) {
255 if (IsMissing) {
256 // Handle the case of missing file from an inclusion directive.
257 if (AddMissingHeaderDeps)
258 return true;
259 SeenMissingHeader = true;
260 return false;
261 }
262 if (IsModuleFile && !IncludeModuleFiles)
263 return false;
264
265 if (isSpecialFilename(Filename))
266 return false;
267
268 if (IncludeSystemHeaders)
269 return true;
270
271 return !IsSystem;
272}
273
274void DependencyFileGenerator::finishedMainFile(DiagnosticsEngine &Diags) {
275 outputDependencyFile(Diags);
276}
277
278/// Print the filename, with escaping or quoting that accommodates the three
279/// most likely tools that use dependency files: GNU Make, BSD Make, and
280/// NMake/Jom.
281///
282/// BSD Make is the simplest case: It does no escaping at all. This means
283/// characters that are normally delimiters, i.e. space and # (the comment
284/// character) simply aren't supported in filenames.
285///
286/// GNU Make does allow space and # in filenames, but to avoid being treated
287/// as a delimiter or comment, these must be escaped with a backslash. Because
288/// backslash is itself the escape character, if a backslash appears in a
289/// filename, it should be escaped as well. (As a special case, $ is escaped
290/// as $$, which is the normal Make way to handle the $ character.)
291/// For compatibility with BSD Make and historical practice, if GNU Make
292/// un-escapes characters in a filename but doesn't find a match, it will
293/// retry with the unmodified original string.
294///
295/// GCC tries to accommodate both Make formats by escaping any space or #
296/// characters in the original filename, but not escaping backslashes. The
297/// apparent intent is so that filenames with backslashes will be handled
298/// correctly by BSD Make, and by GNU Make in its fallback mode of using the
299/// unmodified original string; filenames with # or space characters aren't
300/// supported by BSD Make at all, but will be handled correctly by GNU Make
301/// due to the escaping.
302///
303/// A corner case that GCC gets only partly right is when the original filename
304/// has a backslash immediately followed by space or #. GNU Make would expect
305/// this backslash to be escaped; however GCC escapes the original backslash
306/// only when followed by space, not #. It will therefore take a dependency
307/// from a directive such as
308/// #include "a\ b\#c.h"
309/// and emit it as
310/// a\\\ b\\#c.h
311/// which GNU Make will interpret as
312/// a\ b\
313/// followed by a comment. Failing to find this file, it will fall back to the
314/// original string, which probably doesn't exist either; in any case it won't
315/// find
316/// a\ b\#c.h
317/// which is the actual filename specified by the include directive.
318///
319/// Clang does what GCC does, rather than what GNU Make expects.
320///
321/// NMake/Jom has a different set of scary characters, but wraps filespecs in
322/// double-quotes to avoid misinterpreting them; see
323/// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info,
324/// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
325/// for Windows file-naming info.
326static void PrintFilename(raw_ostream &OS, StringRef Filename,
327 DependencyOutputFormat OutputFormat) {
328 // Convert filename to platform native path
329 llvm::SmallString<256> NativePath;
330 llvm::sys::path::native(path: Filename.str(), result&: NativePath);
331
332 if (OutputFormat == DependencyOutputFormat::NMake) {
333 // Add quotes if needed. These are the characters listed as "special" to
334 // NMake, that are legal in a Windows filespec, and that could cause
335 // misinterpretation of the dependency string.
336 if (NativePath.find_first_of(Chars: " #${}^!") != StringRef::npos)
337 OS << '\"' << NativePath << '\"';
338 else
339 OS << NativePath;
340 return;
341 }
342 assert(OutputFormat == DependencyOutputFormat::Make);
343 for (unsigned i = 0, e = NativePath.size(); i != e; ++i) {
344 if (NativePath[i] == '#') // Handle '#' the broken gcc way.
345 OS << '\\';
346 else if (NativePath[i] == ' ') { // Handle space correctly.
347 OS << '\\';
348 unsigned j = i;
349 while (j > 0 && NativePath[--j] == '\\')
350 OS << '\\';
351 } else if (NativePath[i] == '$') // $ is escaped by $$.
352 OS << '$';
353 OS << NativePath[i];
354 }
355}
356
357void DependencyFileGenerator::outputDependencyFile(DiagnosticsEngine &Diags) {
358 if (SeenMissingHeader) {
359 llvm::sys::fs::remove(path: OutputFile);
360 return;
361 }
362
363 std::error_code EC;
364 llvm::raw_fd_ostream OS(OutputFile, EC, llvm::sys::fs::OF_TextWithCRLF);
365 if (EC) {
366 Diags.Report(DiagID: diag::err_fe_error_opening) << OutputFile << EC.message();
367 return;
368 }
369
370 outputDependencyFile(OS);
371}
372
373void DependencyFileGenerator::outputDependencyFile(llvm::raw_ostream &OS) {
374 // Write out the dependency targets, trying to avoid overly long
375 // lines when possible. We try our best to emit exactly the same
376 // dependency file as GCC>=10, assuming the included files are the
377 // same.
378 const unsigned MaxColumns = 75;
379 unsigned Columns = 0;
380
381 for (StringRef Target : Targets) {
382 unsigned N = Target.size();
383 if (Columns == 0) {
384 Columns += N;
385 } else if (Columns + N + 2 > MaxColumns) {
386 Columns = N + 2;
387 OS << " \\\n ";
388 } else {
389 Columns += N + 1;
390 OS << ' ';
391 }
392 // Targets already quoted as needed.
393 OS << Target;
394 }
395
396 OS << ':';
397 Columns += 1;
398
399 // Now add each dependency in the order it was seen, but avoiding
400 // duplicates.
401 ArrayRef<std::string> Files = getDependencies();
402 for (StringRef File : Files) {
403 if (File == "<stdin>")
404 continue;
405 // Start a new line if this would exceed the column limit. Make
406 // sure to leave space for a trailing " \" in case we need to
407 // break the line on the next iteration.
408 unsigned N = File.size();
409 if (Columns + (N + 1) + 2 > MaxColumns) {
410 OS << " \\\n ";
411 Columns = 2;
412 }
413 OS << ' ';
414 PrintFilename(OS, Filename: File, OutputFormat);
415 Columns += N + 1;
416 }
417 OS << '\n';
418
419 // Create phony targets if requested.
420 if (PhonyTarget && !Files.empty()) {
421 unsigned Index = 0;
422 for (auto I = Files.begin(), E = Files.end(); I != E; ++I) {
423 if (Index++ == InputFileIndex)
424 continue;
425 PrintFilename(OS, Filename: *I, OutputFormat);
426 OS << ":\n";
427 }
428 }
429}
430