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

source code of clang/lib/Frontend/DependencyFile.cpp