aboutsummaryrefslogtreecommitdiff
path: root/clang/tools/clang-scan-deps/ClangScanDeps.cpp
blob: 036e57c8d213b45e703de5d711c779dfdc9cef61 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
//===- ClangScanDeps.cpp - Implementation of clang-scan-deps --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "clang/Driver/Compilation.h"
#include "clang/Driver/Driver.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/TextDiagnosticPrinter.h"
#include "clang/Tooling/CommonOptionsParser.h"
#include "clang/Tooling/DependencyScanning/DependencyScanningService.h"
#include "clang/Tooling/DependencyScanning/DependencyScanningTool.h"
#include "clang/Tooling/DependencyScanning/DependencyScanningWorker.h"
#include "clang/Tooling/JSONCompilationDatabase.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/JSON.h"
#include "llvm/Support/LLVMDriver.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/ThreadPool.h"
#include "llvm/Support/Threading.h"
#include "llvm/Support/Timer.h"
#include "llvm/TargetParser/Host.h"
#include <mutex>
#include <optional>
#include <thread>

#include "Opts.inc"

using namespace clang;
using namespace tooling::dependencies;

namespace {

using namespace llvm::opt;
enum ID {
  OPT_INVALID = 0, // This is not an option ID.
#define OPTION(...) LLVM_MAKE_OPT_ID(__VA_ARGS__),
#include "Opts.inc"
#undef OPTION
};

#define PREFIX(NAME, VALUE)                                                    \
  constexpr llvm::StringLiteral NAME##_init[] = VALUE;                         \
  constexpr llvm::ArrayRef<llvm::StringLiteral> NAME(                          \
      NAME##_init, std::size(NAME##_init) - 1);
#include "Opts.inc"
#undef PREFIX

const llvm::opt::OptTable::Info InfoTable[] = {
#define OPTION(...) LLVM_CONSTRUCT_OPT_INFO(__VA_ARGS__),
#include "Opts.inc"
#undef OPTION
};

class ScanDepsOptTable : public llvm::opt::GenericOptTable {
public:
  ScanDepsOptTable() : GenericOptTable(InfoTable) {
    setGroupedShortOptions(true);
  }
};

enum ResourceDirRecipeKind {
  RDRK_ModifyCompilerPath,
  RDRK_InvokeCompiler,
};

static std::string OutputFileName = "-";
static ScanningMode ScanMode = ScanningMode::DependencyDirectivesScan;
static ScanningOutputFormat Format = ScanningOutputFormat::Make;
static ScanningOptimizations OptimizeArgs;
static std::string ModuleFilesDir;
static bool EagerLoadModules;
static unsigned NumThreads = 0;
static std::string CompilationDB;
static std::string ModuleName;
static std::vector<std::string> ModuleDepTargets;
static bool DeprecatedDriverCommand;
static ResourceDirRecipeKind ResourceDirRecipe;
static bool Verbose;
static bool PrintTiming;
static llvm::BumpPtrAllocator Alloc;
static llvm::StringSaver Saver{Alloc};
static std::vector<const char *> CommandLine;

#ifndef NDEBUG
static constexpr bool DoRoundTripDefault = true;
#else
static constexpr bool DoRoundTripDefault = false;
#endif

static bool RoundTripArgs = DoRoundTripDefault;

static void ParseArgs(int argc, char **argv) {
  ScanDepsOptTable Tbl;
  llvm::StringRef ToolName = argv[0];
  llvm::opt::InputArgList Args =
      Tbl.parseArgs(argc, argv, OPT_UNKNOWN, Saver, [&](StringRef Msg) {
        llvm::errs() << Msg << '\n';
        std::exit(1);
      });

  if (Args.hasArg(OPT_help)) {
    Tbl.printHelp(llvm::outs(), "clang-scan-deps [options]", "clang-scan-deps");
    std::exit(0);
  }
  if (Args.hasArg(OPT_version)) {
    llvm::outs() << ToolName << '\n';
    llvm::cl::PrintVersionMessage();
    std::exit(0);
  }
  if (const llvm::opt::Arg *A = Args.getLastArg(OPT_mode_EQ)) {
    auto ModeType =
        llvm::StringSwitch<std::optional<ScanningMode>>(A->getValue())
            .Case("preprocess-dependency-directives",
                  ScanningMode::DependencyDirectivesScan)
            .Case("preprocess", ScanningMode::CanonicalPreprocessing)
            .Default(std::nullopt);
    if (!ModeType) {
      llvm::errs() << ToolName
                   << ": for the --mode option: Cannot find option named '"
                   << A->getValue() << "'\n";
      std::exit(1);
    }
    ScanMode = *ModeType;
  }

  if (const llvm::opt::Arg *A = Args.getLastArg(OPT_format_EQ)) {
    auto FormatType =
        llvm::StringSwitch<std::optional<ScanningOutputFormat>>(A->getValue())
            .Case("make", ScanningOutputFormat::Make)
            .Case("p1689", ScanningOutputFormat::P1689)
            .Case("experimental-full", ScanningOutputFormat::Full)
            .Default(std::nullopt);
    if (!FormatType) {
      llvm::errs() << ToolName
                   << ": for the --format option: Cannot find option named '"
                   << A->getValue() << "'\n";
      std::exit(1);
    }
    Format = *FormatType;
  }

  std::vector<std::string> OptimizationFlags =
      Args.getAllArgValues(OPT_optimize_args_EQ);
  OptimizeArgs = ScanningOptimizations::None;
  for (const auto &Arg : OptimizationFlags) {
    auto Optimization =
        llvm::StringSwitch<std::optional<ScanningOptimizations>>(Arg)
            .Case("none", ScanningOptimizations::None)
            .Case("header-search", ScanningOptimizations::HeaderSearch)
            .Case("system-warnings", ScanningOptimizations::SystemWarnings)
            .Case("vfs", ScanningOptimizations::VFS)
            .Case("canonicalize-macros", ScanningOptimizations::Macros)
            .Case("all", ScanningOptimizations::All)
            .Default(std::nullopt);
    if (!Optimization) {
      llvm::errs()
          << ToolName
          << ": for the --optimize-args option: Cannot find option named '"
          << Arg << "'\n";
      std::exit(1);
    }
    OptimizeArgs |= *Optimization;
  }
  if (OptimizationFlags.empty())
    OptimizeArgs = ScanningOptimizations::Default;

  if (const llvm::opt::Arg *A = Args.getLastArg(OPT_module_files_dir_EQ))
    ModuleFilesDir = A->getValue();

  if (const llvm::opt::Arg *A = Args.getLastArg(OPT_o))
    OutputFileName = A->getValue();

  EagerLoadModules = Args.hasArg(OPT_eager_load_pcm);

  if (const llvm::opt::Arg *A = Args.getLastArg(OPT_j)) {
    StringRef S{A->getValue()};
    if (!llvm::to_integer(S, NumThreads, 0)) {
      llvm::errs() << ToolName << ": for the -j option: '" << S
                   << "' value invalid for uint argument!\n";
      std::exit(1);
    }
  }

  if (const llvm::opt::Arg *A = Args.getLastArg(OPT_compilation_database_EQ))
    CompilationDB = A->getValue();

  if (const llvm::opt::Arg *A = Args.getLastArg(OPT_module_name_EQ))
    ModuleName = A->getValue();

  for (const llvm::opt::Arg *A : Args.filtered(OPT_dependency_target_EQ))
    ModuleDepTargets.emplace_back(A->getValue());

  DeprecatedDriverCommand = Args.hasArg(OPT_deprecated_driver_command);

  if (const llvm::opt::Arg *A = Args.getLastArg(OPT_resource_dir_recipe_EQ)) {
    auto Kind =
        llvm::StringSwitch<std::optional<ResourceDirRecipeKind>>(A->getValue())
            .Case("modify-compiler-path", RDRK_ModifyCompilerPath)
            .Case("invoke-compiler", RDRK_InvokeCompiler)
            .Default(std::nullopt);
    if (!Kind) {
      llvm::errs() << ToolName
                   << ": for the --resource-dir-recipe option: Cannot find "
                      "option named '"
                   << A->getValue() << "'\n";
      std::exit(1);
    }
    ResourceDirRecipe = *Kind;
  }

  PrintTiming = Args.hasArg(OPT_print_timing);

  Verbose = Args.hasArg(OPT_verbose);

  RoundTripArgs = Args.hasArg(OPT_round_trip_args);

  if (const llvm::opt::Arg *A = Args.getLastArgNoClaim(OPT_DASH_DASH))
    CommandLine.assign(A->getValues().begin(), A->getValues().end());
}

class SharedStream {
public:
  SharedStream(raw_ostream &OS) : OS(OS) {}
  void applyLocked(llvm::function_ref<void(raw_ostream &OS)> Fn) {
    std::unique_lock<std::mutex> LockGuard(Lock);
    Fn(OS);
    OS.flush();
  }

private:
  std::mutex Lock;
  raw_ostream &OS;
};

class ResourceDirectoryCache {
public:
  /// findResourceDir finds the resource directory relative to the clang
  /// compiler being used in Args, by running it with "-print-resource-dir"
  /// option and cache the results for reuse. \returns resource directory path
  /// associated with the given invocation command or empty string if the
  /// compiler path is NOT an absolute path.
  StringRef findResourceDir(const tooling::CommandLineArguments &Args,
                            bool ClangCLMode) {
    if (Args.size() < 1)
      return "";

    const std::string &ClangBinaryPath = Args[0];
    if (!llvm::sys::path::is_absolute(ClangBinaryPath))
      return "";

    const std::string &ClangBinaryName =
        std::string(llvm::sys::path::filename(ClangBinaryPath));

    std::unique_lock<std::mutex> LockGuard(CacheLock);
    const auto &CachedResourceDir = Cache.find(ClangBinaryPath);
    if (CachedResourceDir != Cache.end())
      return CachedResourceDir->second;

    std::vector<StringRef> PrintResourceDirArgs{ClangBinaryName};
    if (ClangCLMode)
      PrintResourceDirArgs.push_back("/clang:-print-resource-dir");
    else
      PrintResourceDirArgs.push_back("-print-resource-dir");

    llvm::SmallString<64> OutputFile, ErrorFile;
    llvm::sys::fs::createTemporaryFile("print-resource-dir-output",
                                       "" /*no-suffix*/, OutputFile);
    llvm::sys::fs::createTemporaryFile("print-resource-dir-error",
                                       "" /*no-suffix*/, ErrorFile);
    llvm::FileRemover OutputRemover(OutputFile.c_str());
    llvm::FileRemover ErrorRemover(ErrorFile.c_str());
    std::optional<StringRef> Redirects[] = {
        {""}, // Stdin
        OutputFile.str(),
        ErrorFile.str(),
    };
    if (llvm::sys::ExecuteAndWait(ClangBinaryPath, PrintResourceDirArgs, {},
                                  Redirects)) {
      auto ErrorBuf = llvm::MemoryBuffer::getFile(ErrorFile.c_str());
      llvm::errs() << ErrorBuf.get()->getBuffer();
      return "";
    }

    auto OutputBuf = llvm::MemoryBuffer::getFile(OutputFile.c_str());
    if (!OutputBuf)
      return "";
    StringRef Output = OutputBuf.get()->getBuffer().rtrim('\n');

    Cache[ClangBinaryPath] = Output.str();
    return Cache[ClangBinaryPath];
  }

private:
  std::map<std::string, std::string> Cache;
  std::mutex CacheLock;
};

} // end anonymous namespace

/// Takes the result of a dependency scan and prints error / dependency files
/// based on the result.
///
/// \returns True on error.
static bool
handleMakeDependencyToolResult(const std::string &Input,
                               llvm::Expected<std::string> &MaybeFile,
                               SharedStream &OS, SharedStream &Errs) {
  if (!MaybeFile) {
    llvm::handleAllErrors(
        MaybeFile.takeError(), [&Input, &Errs](llvm::StringError &Err) {
          Errs.applyLocked([&](raw_ostream &OS) {
            OS << "Error while scanning dependencies for " << Input << ":\n";
            OS << Err.getMessage();
          });
        });
    return true;
  }
  OS.applyLocked([&](raw_ostream &OS) { OS << *MaybeFile; });
  return false;
}

static llvm::json::Array toJSONSorted(const llvm::StringSet<> &Set) {
  std::vector<llvm::StringRef> Strings;
  for (auto &&I : Set)
    Strings.push_back(I.getKey());
  llvm::sort(Strings);
  return llvm::json::Array(Strings);
}

// Technically, we don't need to sort the dependency list to get determinism.
// Leaving these be will simply preserve the import order.
static llvm::json::Array toJSONSorted(std::vector<ModuleID> V) {
  llvm::sort(V);

  llvm::json::Array Ret;
  for (const ModuleID &MID : V)
    Ret.push_back(llvm::json::Object(
        {{"module-name", MID.ModuleName}, {"context-hash", MID.ContextHash}}));
  return Ret;
}

// Thread safe.
class FullDeps {
public:
  FullDeps(size_t NumInputs) : Inputs(NumInputs) {}

  void mergeDeps(StringRef Input, TranslationUnitDeps TUDeps,
                 size_t InputIndex) {
    mergeDeps(std::move(TUDeps.ModuleGraph), InputIndex);

    InputDeps ID;
    ID.FileName = std::string(Input);
    ID.ContextHash = std::move(TUDeps.ID.ContextHash);
    ID.FileDeps = std::move(TUDeps.FileDeps);
    ID.ModuleDeps = std::move(TUDeps.ClangModuleDeps);
    ID.DriverCommandLine = std::move(TUDeps.DriverCommandLine);
    ID.Commands = std::move(TUDeps.Commands);

    assert(InputIndex < Inputs.size() && "Input index out of bounds");
    assert(Inputs[InputIndex].FileName.empty() && "Result already populated");
    Inputs[InputIndex] = std::move(ID);
  }

  void mergeDeps(ModuleDepsGraph Graph, size_t InputIndex) {
    std::vector<ModuleDeps *> NewMDs;
    {
      std::unique_lock<std::mutex> ul(Lock);
      for (const ModuleDeps &MD : Graph) {
        auto I = Modules.find({MD.ID, 0});
        if (I != Modules.end()) {
          I->first.InputIndex = std::min(I->first.InputIndex, InputIndex);
          continue;
        }
        auto Res = Modules.insert(I, {{MD.ID, InputIndex}, std::move(MD)});
        NewMDs.push_back(&Res->second);
      }
      // First call to \c getBuildArguments is somewhat expensive. Let's call it
      // on the current thread (instead of the main one), and outside the
      // critical section.
      for (ModuleDeps *MD : NewMDs)
        (void)MD->getBuildArguments();
    }
  }

  bool roundTripCommand(ArrayRef<std::string> ArgStrs,
                        DiagnosticsEngine &Diags) {
    if (ArgStrs.empty() || ArgStrs[0] != "-cc1")
      return false;
    SmallVector<const char *> Args;
    for (const std::string &Arg : ArgStrs)
      Args.push_back(Arg.c_str());
    return !CompilerInvocation::checkCC1RoundTrip(Args, Diags);
  }

  // Returns \c true if any command lines fail to round-trip. We expect
  // commands already be canonical when output by the scanner.
  bool roundTripCommands(raw_ostream &ErrOS) {
    IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions{};
    TextDiagnosticPrinter DiagConsumer(ErrOS, &*DiagOpts);
    IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
        CompilerInstance::createDiagnostics(&*DiagOpts, &DiagConsumer,
                                            /*ShouldOwnClient=*/false);

    for (auto &&M : Modules)
      if (roundTripCommand(M.second.getBuildArguments(), *Diags))
        return true;

    for (auto &&I : Inputs)
      for (const auto &Cmd : I.Commands)
        if (roundTripCommand(Cmd.Arguments, *Diags))
          return true;

    return false;
  }

  void printFullOutput(raw_ostream &OS) {
    // Skip sorting modules and constructing the JSON object if the output
    // cannot be observed anyway. This makes timings less noisy.
    if (&OS == &llvm::nulls())
      return;

    // Sort the modules by name to get a deterministic order.
    std::vector<IndexedModuleID> ModuleIDs;
    for (auto &&M : Modules)
      ModuleIDs.push_back(M.first);
    llvm::sort(ModuleIDs);

    using namespace llvm::json;

    Array OutModules;
    for (auto &&ModID : ModuleIDs) {
      auto &MD = Modules[ModID];
      Object O{
          {"name", MD.ID.ModuleName},
          {"context-hash", MD.ID.ContextHash},
          {"file-deps", toJSONSorted(MD.FileDeps)},
          {"clang-module-deps", toJSONSorted(MD.ClangModuleDeps)},
          {"clang-modulemap-file", MD.ClangModuleMapFile},
          {"command-line", MD.getBuildArguments()},
      };
      OutModules.push_back(std::move(O));
    }

    Array TUs;
    for (auto &&I : Inputs) {
      Array Commands;
      if (I.DriverCommandLine.empty()) {
        for (const auto &Cmd : I.Commands) {
          Object O{
              {"input-file", I.FileName},
              {"clang-context-hash", I.ContextHash},
              {"file-deps", I.FileDeps},
              {"clang-module-deps", toJSONSorted(I.ModuleDeps)},
              {"executable", Cmd.Executable},
              {"command-line", Cmd.Arguments},
          };
          Commands.push_back(std::move(O));
        }
      } else {
        Object O{
            {"input-file", I.FileName},
            {"clang-context-hash", I.ContextHash},
            {"file-deps", I.FileDeps},
            {"clang-module-deps", toJSONSorted(I.ModuleDeps)},
            {"executable", "clang"},
            {"command-line", I.DriverCommandLine},
        };
        Commands.push_back(std::move(O));
      }
      TUs.push_back(Object{
          {"commands", std::move(Commands)},
      });
    }

    Object Output{
        {"modules", std::move(OutModules)},
        {"translation-units", std::move(TUs)},
    };

    OS << llvm::formatv("{0:2}\n", Value(std::move(Output)));
  }

private:
  struct IndexedModuleID {
    ModuleID ID;

    // FIXME: This is mutable so that it can still be updated after insertion
    //  into an unordered associative container. This is "fine", since this
    //  field doesn't contribute to the hash, but it's a brittle hack.
    mutable size_t InputIndex;

    bool operator==(const IndexedModuleID &Other) const {
      return ID == Other.ID;
    }

    bool operator<(const IndexedModuleID &Other) const {
      /// We need the output of clang-scan-deps to be deterministic. However,
      /// the dependency graph may contain two modules with the same name. How
      /// do we decide which one to print first? If we made that decision based
      /// on the context hash, the ordering would be deterministic, but
      /// different across machines. This can happen for example when the inputs
      /// or the SDKs (which both contribute to the "context" hash) live in
      /// different absolute locations. We solve that by tracking the index of
      /// the first input TU that (transitively) imports the dependency, which
      /// is always the same for the same input, resulting in deterministic
      /// sorting that's also reproducible across machines.
      return std::tie(ID.ModuleName, InputIndex) <
             std::tie(Other.ID.ModuleName, Other.InputIndex);
    }

    struct Hasher {
      std::size_t operator()(const IndexedModuleID &IMID) const {
        return llvm::hash_value(IMID.ID);
      }
    };
  };

  struct InputDeps {
    std::string FileName;
    std::string ContextHash;
    std::vector<std::string> FileDeps;
    std::vector<ModuleID> ModuleDeps;
    std::vector<std::string> DriverCommandLine;
    std::vector<Command> Commands;
  };

  std::mutex Lock;
  std::unordered_map<IndexedModuleID, ModuleDeps, IndexedModuleID::Hasher>
      Modules;
  std::vector<InputDeps> Inputs;
};

static bool handleTranslationUnitResult(
    StringRef Input, llvm::Expected<TranslationUnitDeps> &MaybeTUDeps,
    FullDeps &FD, size_t InputIndex, SharedStream &OS, SharedStream &Errs) {
  if (!MaybeTUDeps) {
    llvm::handleAllErrors(
        MaybeTUDeps.takeError(), [&Input, &Errs](llvm::StringError &Err) {
          Errs.applyLocked([&](raw_ostream &OS) {
            OS << "Error while scanning dependencies for " << Input << ":\n";
            OS << Err.getMessage();
          });
        });
    return true;
  }
  FD.mergeDeps(Input, std::move(*MaybeTUDeps), InputIndex);
  return false;
}

static bool handleModuleResult(
    StringRef ModuleName, llvm::Expected<ModuleDepsGraph> &MaybeModuleGraph,
    FullDeps &FD, size_t InputIndex, SharedStream &OS, SharedStream &Errs) {
  if (!MaybeModuleGraph) {
    llvm::handleAllErrors(MaybeModuleGraph.takeError(),
                          [&ModuleName, &Errs](llvm::StringError &Err) {
                            Errs.applyLocked([&](raw_ostream &OS) {
                              OS << "Error while scanning dependencies for "
                                 << ModuleName << ":\n";
                              OS << Err.getMessage();
                            });
                          });
    return true;
  }
  FD.mergeDeps(std::move(*MaybeModuleGraph), InputIndex);
  return false;
}

class P1689Deps {
public:
  void printDependencies(raw_ostream &OS) {
    addSourcePathsToRequires();
    // Sort the modules by name to get a deterministic order.
    llvm::sort(Rules, [](const P1689Rule &A, const P1689Rule &B) {
      return A.PrimaryOutput < B.PrimaryOutput;
    });

    using namespace llvm::json;
    Array OutputRules;
    for (const P1689Rule &R : Rules) {
      Object O{{"primary-output", R.PrimaryOutput}};

      if (R.Provides) {
        Array Provides;
        Object Provided{{"logical-name", R.Provides->ModuleName},
                        {"source-path", R.Provides->SourcePath},
                        {"is-interface", R.Provides->IsStdCXXModuleInterface}};
        Provides.push_back(std::move(Provided));
        O.insert({"provides", std::move(Provides)});
      }

      Array Requires;
      for (const P1689ModuleInfo &Info : R.Requires) {
        Object RequiredInfo{{"logical-name", Info.ModuleName}};
        if (!Info.SourcePath.empty())
          RequiredInfo.insert({"source-path", Info.SourcePath});
        Requires.push_back(std::move(RequiredInfo));
      }

      if (!Requires.empty())
        O.insert({"requires", std::move(Requires)});

      OutputRules.push_back(std::move(O));
    }

    Object Output{
        {"version", 1}, {"revision", 0}, {"rules", std::move(OutputRules)}};

    OS << llvm::formatv("{0:2}\n", Value(std::move(Output)));
  }

  void addRules(P1689Rule &Rule) {
    std::unique_lock<std::mutex> LockGuard(Lock);
    Rules.push_back(Rule);
  }

private:
  void addSourcePathsToRequires() {
    llvm::DenseMap<StringRef, StringRef> ModuleSourceMapper;
    for (const P1689Rule &R : Rules)
      if (R.Provides && !R.Provides->SourcePath.empty())
        ModuleSourceMapper[R.Provides->ModuleName] = R.Provides->SourcePath;

    for (P1689Rule &R : Rules) {
      for (P1689ModuleInfo &Info : R.Requires) {
        auto Iter = ModuleSourceMapper.find(Info.ModuleName);
        if (Iter != ModuleSourceMapper.end())
          Info.SourcePath = Iter->second;
      }
    }
  }

  std::mutex Lock;
  std::vector<P1689Rule> Rules;
};

static bool
handleP1689DependencyToolResult(const std::string &Input,
                                llvm::Expected<P1689Rule> &MaybeRule,
                                P1689Deps &PD, SharedStream &Errs) {
  if (!MaybeRule) {
    llvm::handleAllErrors(
        MaybeRule.takeError(), [&Input, &Errs](llvm::StringError &Err) {
          Errs.applyLocked([&](raw_ostream &OS) {
            OS << "Error while scanning dependencies for " << Input << ":\n";
            OS << Err.getMessage();
          });
        });
    return true;
  }
  PD.addRules(*MaybeRule);
  return false;
}

/// Construct a path for the explicitly built PCM.
static std::string constructPCMPath(ModuleID MID, StringRef OutputDir) {
  SmallString<256> ExplicitPCMPath(OutputDir);
  llvm::sys::path::append(ExplicitPCMPath, MID.ContextHash,
                          MID.ModuleName + "-" + MID.ContextHash + ".pcm");
  return std::string(ExplicitPCMPath);
}

static std::string lookupModuleOutput(const ModuleID &MID, ModuleOutputKind MOK,
                                      StringRef OutputDir) {
  std::string PCMPath = constructPCMPath(MID, OutputDir);
  switch (MOK) {
  case ModuleOutputKind::ModuleFile:
    return PCMPath;
  case ModuleOutputKind::DependencyFile:
    return PCMPath + ".d";
  case ModuleOutputKind::DependencyTargets:
    // Null-separate the list of targets.
    return join(ModuleDepTargets, StringRef("\0", 1));
  case ModuleOutputKind::DiagnosticSerializationFile:
    return PCMPath + ".diag";
  }
  llvm_unreachable("Fully covered switch above!");
}

static std::string getModuleCachePath(ArrayRef<std::string> Args) {
  for (StringRef Arg : llvm::reverse(Args)) {
    Arg.consume_front("/clang:");
    if (Arg.consume_front("-fmodules-cache-path="))
      return std::string(Arg);
  }
  SmallString<128> Path;
  driver::Driver::getDefaultModuleCachePath(Path);
  return std::string(Path);
}

/// Attempts to construct the compilation database from '-compilation-database'
/// or from the arguments following the positional '--'.
static std::unique_ptr<tooling::CompilationDatabase>
getCompilationDatabase(int argc, char **argv, std::string &ErrorMessage) {
  ParseArgs(argc, argv);

  if (!(CommandLine.empty() ^ CompilationDB.empty())) {
    llvm::errs() << "The compilation command line must be provided either via "
                    "'-compilation-database' or after '--'.";
    return nullptr;
  }

  if (!CompilationDB.empty())
    return tooling::JSONCompilationDatabase::loadFromFile(
        CompilationDB, ErrorMessage,
        tooling::JSONCommandLineSyntax::AutoDetect);

  llvm::IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
      CompilerInstance::createDiagnostics(new DiagnosticOptions);
  driver::Driver TheDriver(CommandLine[0], llvm::sys::getDefaultTargetTriple(),
                           *Diags);
  TheDriver.setCheckInputsExist(false);
  std::unique_ptr<driver::Compilation> C(
      TheDriver.BuildCompilation(CommandLine));
  if (!C || C->getJobs().empty())
    return nullptr;

  auto Cmd = C->getJobs().begin();
  auto CI = std::make_unique<CompilerInvocation>();
  CompilerInvocation::CreateFromArgs(*CI, Cmd->getArguments(), *Diags,
                                     CommandLine[0]);
  if (!CI)
    return nullptr;

  FrontendOptions &FEOpts = CI->getFrontendOpts();
  if (FEOpts.Inputs.size() != 1) {
    llvm::errs()
        << "Exactly one input file is required in the per-file mode ('--').\n";
    return nullptr;
  }

  // There might be multiple jobs for a compilation. Extract the specified
  // output filename from the last job.
  auto LastCmd = C->getJobs().end();
  LastCmd--;
  if (LastCmd->getOutputFilenames().size() != 1) {
    llvm::errs()
        << "Exactly one output file is required in the per-file mode ('--').\n";
    return nullptr;
  }
  StringRef OutputFile = LastCmd->getOutputFilenames().front();

  class InplaceCompilationDatabase : public tooling::CompilationDatabase {
  public:
    InplaceCompilationDatabase(StringRef InputFile, StringRef OutputFile,
                               ArrayRef<const char *> CommandLine)
        : Command(".", InputFile, {}, OutputFile) {
      for (auto *C : CommandLine)
        Command.CommandLine.push_back(C);
    }

    std::vector<tooling::CompileCommand>
    getCompileCommands(StringRef FilePath) const override {
      if (FilePath != Command.Filename)
        return {};
      return {Command};
    }

    std::vector<std::string> getAllFiles() const override {
      return {Command.Filename};
    }

    std::vector<tooling::CompileCommand>
    getAllCompileCommands() const override {
      return {Command};
    }

  private:
    tooling::CompileCommand Command;
  };

  return std::make_unique<InplaceCompilationDatabase>(
      FEOpts.Inputs[0].getFile(), OutputFile, CommandLine);
}

int clang_scan_deps_main(int argc, char **argv, const llvm::ToolContext &) {
  std::string ErrorMessage;
  std::unique_ptr<tooling::CompilationDatabase> Compilations =
      getCompilationDatabase(argc, argv, ErrorMessage);
  if (!Compilations) {
    llvm::errs() << ErrorMessage << "\n";
    return 1;
  }

  llvm::cl::PrintOptionValues();

  // Expand response files in advance, so that we can "see" all the arguments
  // when adjusting below.
  Compilations = expandResponseFiles(std::move(Compilations),
                                     llvm::vfs::getRealFileSystem());

  // The command options are rewritten to run Clang in preprocessor only mode.
  auto AdjustingCompilations =
      std::make_unique<tooling::ArgumentsAdjustingCompilations>(
          std::move(Compilations));
  ResourceDirectoryCache ResourceDirCache;

  AdjustingCompilations->appendArgumentsAdjuster(
      [&ResourceDirCache](const tooling::CommandLineArguments &Args,
                          StringRef FileName) {
        std::string LastO;
        bool HasResourceDir = false;
        bool ClangCLMode = false;
        auto FlagsEnd = llvm::find(Args, "--");
        if (FlagsEnd != Args.begin()) {
          ClangCLMode =
              llvm::sys::path::stem(Args[0]).contains_insensitive("clang-cl") ||
              llvm::is_contained(Args, "--driver-mode=cl");

          // Reverse scan, starting at the end or at the element before "--".
          auto R = std::make_reverse_iterator(FlagsEnd);
          for (auto I = R, E = Args.rend(); I != E; ++I) {
            StringRef Arg = *I;
            if (ClangCLMode) {
              // Ignore arguments that are preceded by "-Xclang".
              if ((I + 1) != E && I[1] == "-Xclang")
                continue;
              if (LastO.empty()) {
                // With clang-cl, the output obj file can be specified with
                // "/opath", "/o path", "/Fopath", and the dash counterparts.
                // Also, clang-cl adds ".obj" extension if none is found.
                if ((Arg == "-o" || Arg == "/o") && I != R)
                  LastO = I[-1]; // Next argument (reverse iterator)
                else if (Arg.starts_with("/Fo") || Arg.starts_with("-Fo"))
                  LastO = Arg.drop_front(3).str();
                else if (Arg.starts_with("/o") || Arg.starts_with("-o"))
                  LastO = Arg.drop_front(2).str();

                if (!LastO.empty() && !llvm::sys::path::has_extension(LastO))
                  LastO.append(".obj");
              }
            }
            if (Arg == "-resource-dir")
              HasResourceDir = true;
          }
        }
        tooling::CommandLineArguments AdjustedArgs(Args.begin(), FlagsEnd);
        // The clang-cl driver passes "-o -" to the frontend. Inject the real
        // file here to ensure "-MT" can be deduced if need be.
        if (ClangCLMode && !LastO.empty()) {
          AdjustedArgs.push_back("/clang:-o");
          AdjustedArgs.push_back("/clang:" + LastO);
        }

        if (!HasResourceDir && ResourceDirRecipe == RDRK_InvokeCompiler) {
          StringRef ResourceDir =
              ResourceDirCache.findResourceDir(Args, ClangCLMode);
          if (!ResourceDir.empty()) {
            AdjustedArgs.push_back("-resource-dir");
            AdjustedArgs.push_back(std::string(ResourceDir));
          }
        }
        AdjustedArgs.insert(AdjustedArgs.end(), FlagsEnd, Args.end());
        return AdjustedArgs;
      });

  SharedStream Errs(llvm::errs());

  std::optional<llvm::raw_fd_ostream> FileOS;
  llvm::raw_ostream &ThreadUnsafeDependencyOS = [&]() -> llvm::raw_ostream & {
    if (OutputFileName == "-")
      return llvm::outs();

    if (OutputFileName == "/dev/null")
      return llvm::nulls();

    std::error_code EC;
    FileOS.emplace(OutputFileName, EC);
    if (EC) {
      llvm::errs() << "Failed to open output file '" << OutputFileName
                   << "': " << llvm::errorCodeToError(EC) << '\n';
      std::exit(1);
    }
    return *FileOS;
  }();
  SharedStream DependencyOS(ThreadUnsafeDependencyOS);

  std::vector<tooling::CompileCommand> Inputs =
      AdjustingCompilations->getAllCompileCommands();

  std::atomic<bool> HadErrors(false);
  std::optional<FullDeps> FD;
  P1689Deps PD;

  std::mutex Lock;
  size_t Index = 0;
  auto GetNextInputIndex = [&]() -> std::optional<size_t> {
    std::unique_lock<std::mutex> LockGuard(Lock);
    if (Index < Inputs.size())
      return Index++;
    return {};
  };

  if (Format == ScanningOutputFormat::Full)
    FD.emplace(ModuleName.empty() ? Inputs.size() : 0);

  auto ScanningTask = [&](DependencyScanningService &Service) {
    DependencyScanningTool WorkerTool(Service);

    llvm::DenseSet<ModuleID> AlreadySeenModules;
    while (auto MaybeInputIndex = GetNextInputIndex()) {
      size_t LocalIndex = *MaybeInputIndex;
      const tooling::CompileCommand *Input = &Inputs[LocalIndex];
      std::string Filename = std::move(Input->Filename);
      std::string CWD = std::move(Input->Directory);

      std::optional<StringRef> MaybeModuleName;
      if (!ModuleName.empty())
        MaybeModuleName = ModuleName;

      std::string OutputDir(ModuleFilesDir);
      if (OutputDir.empty())
        OutputDir = getModuleCachePath(Input->CommandLine);
      auto LookupOutput = [&](const ModuleID &MID, ModuleOutputKind MOK) {
        return ::lookupModuleOutput(MID, MOK, OutputDir);
      };

      // Run the tool on it.
      if (Format == ScanningOutputFormat::Make) {
        auto MaybeFile = WorkerTool.getDependencyFile(Input->CommandLine, CWD);
        if (handleMakeDependencyToolResult(Filename, MaybeFile, DependencyOS,
                                           Errs))
          HadErrors = true;
      } else if (Format == ScanningOutputFormat::P1689) {
        // It is useful to generate the make-format dependency output during
        // the scanning for P1689. Otherwise the users need to scan again for
        // it. We will generate the make-format dependency output if we find
        // `-MF` in the command lines.
        std::string MakeformatOutputPath;
        std::string MakeformatOutput;

        auto MaybeRule = WorkerTool.getP1689ModuleDependencyFile(
            *Input, CWD, MakeformatOutput, MakeformatOutputPath);

        if (handleP1689DependencyToolResult(Filename, MaybeRule, PD, Errs))
          HadErrors = true;

        if (!MakeformatOutputPath.empty() && !MakeformatOutput.empty() &&
            !HadErrors) {
          static std::mutex Lock;
          // With compilation database, we may open different files
          // concurrently or we may write the same file concurrently. So we
          // use a map here to allow multiple compile commands to write to the
          // same file. Also we need a lock here to avoid data race.
          static llvm::StringMap<llvm::raw_fd_ostream> OSs;
          std::unique_lock<std::mutex> LockGuard(Lock);

          auto OSIter = OSs.find(MakeformatOutputPath);
          if (OSIter == OSs.end()) {
            std::error_code EC;
            OSIter =
                OSs.try_emplace(MakeformatOutputPath, MakeformatOutputPath, EC)
                    .first;
            if (EC)
              llvm::errs() << "Failed to open P1689 make format output file \""
                           << MakeformatOutputPath << "\" for " << EC.message()
                           << "\n";
          }

          SharedStream MakeformatOS(OSIter->second);
          llvm::Expected<std::string> MaybeOutput(MakeformatOutput);
          if (handleMakeDependencyToolResult(Filename, MaybeOutput,
                                             MakeformatOS, Errs))
            HadErrors = true;
        }
      } else if (MaybeModuleName) {
        auto MaybeModuleDepsGraph = WorkerTool.getModuleDependencies(
            *MaybeModuleName, Input->CommandLine, CWD, AlreadySeenModules,
            LookupOutput);
        if (handleModuleResult(*MaybeModuleName, MaybeModuleDepsGraph, *FD,
                               LocalIndex, DependencyOS, Errs))
          HadErrors = true;
      } else {
        auto MaybeTUDeps = WorkerTool.getTranslationUnitDependencies(
            Input->CommandLine, CWD, AlreadySeenModules, LookupOutput);
        if (handleTranslationUnitResult(Filename, MaybeTUDeps, *FD, LocalIndex,
                                        DependencyOS, Errs))
          HadErrors = true;
      }
    }
  };

  DependencyScanningService Service(ScanMode, Format, OptimizeArgs,
                                    EagerLoadModules);

  llvm::Timer T;
  T.startTimer();

  if (Inputs.size() == 1) {
    ScanningTask(Service);
  } else {
    llvm::DefaultThreadPool Pool(llvm::hardware_concurrency(NumThreads));

    if (Verbose) {
      llvm::outs() << "Running clang-scan-deps on " << Inputs.size()
                   << " files using " << Pool.getMaxConcurrency()
                   << " workers\n";
    }

    for (unsigned I = 0; I < Pool.getMaxConcurrency(); ++I)
      Pool.async([ScanningTask, &Service]() { ScanningTask(Service); });

    Pool.wait();
  }

  T.stopTimer();
  if (PrintTiming)
    llvm::errs() << llvm::format(
        "clang-scan-deps timing: %0.2fs wall, %0.2fs process\n",
        T.getTotalTime().getWallTime(), T.getTotalTime().getProcessTime());

  if (RoundTripArgs)
    if (FD && FD->roundTripCommands(llvm::errs()))
      HadErrors = true;

  if (Format == ScanningOutputFormat::Full)
    FD->printFullOutput(ThreadUnsafeDependencyOS);
  else if (Format == ScanningOutputFormat::P1689)
    PD.printDependencies(ThreadUnsafeDependencyOS);

  return HadErrors;
}