clang/lib/Frontend/DiagnosticRenderer.cpp

   1 //===- DiagnosticRenderer.cpp - Diagnostic Pretty-Printing ----------------===//
   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/DiagnosticRenderer.h"
  10 #include "clang/Basic/Diagnostic.h"
  11 #include "clang/Basic/DiagnosticOptions.h"
  12 #include "clang/Basic/LLVM.h"
  13 #include "clang/Basic/SourceLocation.h"
  14 #include "clang/Basic/SourceManager.h"
  15 #include "clang/Edit/Commit.h"
  16 #include "clang/Edit/EditedSource.h"
  17 #include "clang/Edit/EditsReceiver.h"
  18 #include "clang/Lex/Lexer.h"
  19 #include "llvm/ADT/ArrayRef.h"
  20 #include "llvm/ADT/DenseMap.h"
  21 #include "llvm/ADT/None.h"
  22 #include "llvm/ADT/SmallString.h"
  23 #include "llvm/ADT/SmallVector.h"
  24 #include "llvm/ADT/StringRef.h"
  25 #include "llvm/Support/raw_ostream.h"
  26 #include <algorithm>
  27 #include <cassert>
  28 #include <iterator>
  29 #include <utility>
  30
  31 using namespace clang;
  32
  33 DiagnosticRenderer::DiagnosticRenderer(const LangOptions &LangOpts,
  34                                        DiagnosticOptions *DiagOpts)
  35     : LangOpts(LangOpts), DiagOpts(DiagOpts), LastLevel() {}
  36
  37 DiagnosticRenderer::~DiagnosticRenderer() = default;
  38
  39 namespace {
  40
  41 class FixitReceiver : public edit::EditsReceiver {
  42   SmallVectorImpl<FixItHint> &MergedFixits;
  43
  44 public:
  45   FixitReceiver(SmallVectorImpl<FixItHint> &MergedFixits)
  46       : MergedFixits(MergedFixits) {}
  47
  48   void insert(SourceLocation loc, StringRef text) override {
  49     MergedFixits.push_back(FixItHint::CreateInsertion(loc, text));
  50   }
  51
  52   void replace(CharSourceRange range, StringRef text) override {
  53     MergedFixits.push_back(FixItHint::CreateReplacement(range, text));
  54   }
  55 };
  56
  57 } // namespace
  58
  59 static void mergeFixits(ArrayRef<FixItHint> FixItHints,
  60                         const SourceManager &SM, const LangOptions &LangOpts,
  61                         SmallVectorImpl<FixItHint> &MergedFixits) {
  62   edit::Commit commit(SM, LangOpts);
  63   for (const auto &Hint : FixItHints)
  64     if (Hint.CodeToInsert.empty()) {
  65       if (Hint.InsertFromRange.isValid())
  66         commit.insertFromRange(Hint.RemoveRange.getBegin(),
  67                            Hint.InsertFromRange, /*afterToken=*/false,
  68                            Hint.BeforePreviousInsertions);
  69       else
  70         commit.remove(Hint.RemoveRange);
  71     } else {
  72       if (Hint.RemoveRange.isTokenRange() ||
  73           Hint.RemoveRange.getBegin() != Hint.RemoveRange.getEnd())
  74         commit.replace(Hint.RemoveRange, Hint.CodeToInsert);
  75       else
  76         commit.insert(Hint.RemoveRange.getBegin(), Hint.CodeToInsert,
  77                     /*afterToken=*/false, Hint.BeforePreviousInsertions);
  78     }
  79
  80   edit::EditedSource Editor(SM, LangOpts);
  81   if (Editor.commit(commit)) {
  82     FixitReceiver Rec(MergedFixits);
  83     Editor.applyRewrites(Rec);
  84   }
  85 }
  86
  87 void DiagnosticRenderer::emitDiagnostic(FullSourceLoc Loc,
  88                                         DiagnosticsEngine::Level Level,
  89                                         StringRef Message,
  90                                         ArrayRef<CharSourceRange> Ranges,
  91                                         ArrayRef<FixItHint> FixItHints,
  92                                         DiagOrStoredDiag D) {
  93   assert(Loc.hasManager() || Loc.isInvalid());
  94
  95   beginDiagnostic(D, Level);
  96
  97   if (!Loc.isValid())
  98     // If we have no source location, just emit the diagnostic message.
  99     emitDiagnosticMessage(Loc, PresumedLoc(), Level, Message, Ranges, D);
 100   else {
 101     // Get the ranges into a local array we can hack on.
 102     SmallVector<CharSourceRange, 20> MutableRanges(Ranges.begin(),
 103                                                    Ranges.end());
 104
 105     SmallVector<FixItHint, 8> MergedFixits;
 106     if (!FixItHints.empty()) {
 107       mergeFixits(FixItHints, Loc.getManager(), LangOpts, MergedFixits);
 108       FixItHints = MergedFixits;
 109     }
 110
 111     for (const auto &Hint : FixItHints)
 112       if (Hint.RemoveRange.isValid())
 113         MutableRanges.push_back(Hint.RemoveRange);
 114
 115     FullSourceLoc UnexpandedLoc = Loc;
 116
 117     // Find the ultimate expansion location for the diagnostic.
 118     Loc = Loc.getFileLoc();
 119
 120     PresumedLoc PLoc = Loc.getPresumedLoc(DiagOpts->ShowPresumedLoc);
 121
 122     // First, if this diagnostic is not in the main file, print out the
 123     // "included from" lines.
 124     emitIncludeStack(Loc, PLoc, Level);
 125
 126     // Next, emit the actual diagnostic message and caret.
 127     emitDiagnosticMessage(Loc, PLoc, Level, Message, Ranges, D);
 128     emitCaret(Loc, Level, MutableRanges, FixItHints);
 129
 130     // If this location is within a macro, walk from UnexpandedLoc up to Loc
 131     // and produce a macro backtrace.
 132     if (UnexpandedLoc.isValid() && UnexpandedLoc.isMacroID()) {
 133       emitMacroExpansions(UnexpandedLoc, Level, MutableRanges, FixItHints);
 134     }
 135   }
 136
 137   LastLoc = Loc;
 138   LastLevel = Level;
 139
 140   endDiagnostic(D, Level);
 141 }
 142
 143 void DiagnosticRenderer::emitStoredDiagnostic(StoredDiagnostic &Diag) {
 144   emitDiagnostic(Diag.getLocation(), Diag.getLevel(), Diag.getMessage(),
 145                  Diag.getRanges(), Diag.getFixIts(),
 146                  &Diag);
 147 }
 148
 149 void DiagnosticRenderer::emitBasicNote(StringRef Message) {
 150   emitDiagnosticMessage(FullSourceLoc(), PresumedLoc(), DiagnosticsEngine::Note,
 151                         Message, None, DiagOrStoredDiag());
 152 }
 153
 154 /// Prints an include stack when appropriate for a particular
 155 /// diagnostic level and location.
 156 ///
 157 /// This routine handles all the logic of suppressing particular include
 158 /// stacks (such as those for notes) and duplicate include stacks when
 159 /// repeated warnings occur within the same file. It also handles the logic
 160 /// of customizing the formatting and display of the include stack.
 161 ///
 162 /// \param Loc   The diagnostic location.
 163 /// \param PLoc  The presumed location of the diagnostic location.
 164 /// \param Level The diagnostic level of the message this stack pertains to.
 165 void DiagnosticRenderer::emitIncludeStack(FullSourceLoc Loc, PresumedLoc PLoc,
 166                                           DiagnosticsEngine::Level Level) {
 167   FullSourceLoc IncludeLoc =
 168       PLoc.isInvalid() ? FullSourceLoc()
 169                        : FullSourceLoc(PLoc.getIncludeLoc(), Loc.getManager());
 170
 171   // Skip redundant include stacks altogether.
 172   if (LastIncludeLoc == IncludeLoc)
 173     return;
 174
 175   LastIncludeLoc = IncludeLoc;
 176
 177   if (!DiagOpts->ShowNoteIncludeStack && Level == DiagnosticsEngine::Note)
 178     return;
 179
 180   if (IncludeLoc.isValid())
 181     emitIncludeStackRecursively(IncludeLoc);
 182   else {
 183     emitModuleBuildStack(Loc.getManager());
 184     emitImportStack(Loc);
 185   }
 186 }
 187
 188 /// Helper to recursively walk up the include stack and print each layer
 189 /// on the way back down.
 190 void DiagnosticRenderer::emitIncludeStackRecursively(FullSourceLoc Loc) {
 191   if (Loc.isInvalid()) {
 192     emitModuleBuildStack(Loc.getManager());
 193     return;
 194   }
 195
 196   PresumedLoc PLoc = Loc.getPresumedLoc(DiagOpts->ShowPresumedLoc);
 197   if (PLoc.isInvalid())
 198     return;
 199
 200   // If this source location was imported from a module, print the module
 201   // import stack rather than the
 202   // FIXME: We want submodule granularity here.
 203   std::pair<FullSourceLoc, StringRef> Imported = Loc.getModuleImportLoc();
 204   if (!Imported.second.empty()) {
 205     // This location was imported by a module. Emit the module import stack.
 206     emitImportStackRecursively(Imported.first, Imported.second);
 207     return;
 208   }
 209
 210   // Emit the other include frames first.
 211   emitIncludeStackRecursively(
 212       FullSourceLoc(PLoc.getIncludeLoc(), Loc.getManager()));
 213
 214   // Emit the inclusion text/note.
 215   emitIncludeLocation(Loc, PLoc);
 216 }
 217
 218 /// Emit the module import stack associated with the current location.
 219 void DiagnosticRenderer::emitImportStack(FullSourceLoc Loc) {
 220   if (Loc.isInvalid()) {
 221     emitModuleBuildStack(Loc.getManager());
 222     return;
 223   }
 224
 225   std::pair<FullSourceLoc, StringRef> NextImportLoc = Loc.getModuleImportLoc();
 226   emitImportStackRecursively(NextImportLoc.first, NextImportLoc.second);
 227 }
 228
 229 /// Helper to recursively walk up the import stack and print each layer
 230 /// on the way back down.
 231 void DiagnosticRenderer::emitImportStackRecursively(FullSourceLoc Loc,
 232                                                     StringRef ModuleName) {
 233   if (ModuleName.empty()) {
 234     return;
 235   }
 236
 237   PresumedLoc PLoc = Loc.getPresumedLoc(DiagOpts->ShowPresumedLoc);
 238
 239   // Emit the other import frames first.
 240   std::pair<FullSourceLoc, StringRef> NextImportLoc = Loc.getModuleImportLoc();
 241   emitImportStackRecursively(NextImportLoc.first, NextImportLoc.second);
 242
 243   // Emit the inclusion text/note.
 244   emitImportLocation(Loc, PLoc, ModuleName);
 245 }
 246
 247 /// Emit the module build stack, for cases where a module is (re-)built
 248 /// on demand.
 249 void DiagnosticRenderer::emitModuleBuildStack(const SourceManager &SM) {
 250   ModuleBuildStack Stack = SM.getModuleBuildStack();
 251   for (const auto &I : Stack) {
 252     emitBuildingModuleLocation(I.second, I.second.getPresumedLoc(
 253                                               DiagOpts->ShowPresumedLoc),
 254                                I.first);
 255   }
 256 }
 257
 258 /// A recursive function to trace all possible backtrace locations
 259 /// to match the \p CaretLocFileID.
 260 static SourceLocation
 261 retrieveMacroLocation(SourceLocation Loc, FileID MacroFileID,
 262                       FileID CaretFileID,
 263                       const SmallVectorImpl<FileID> &CommonArgExpansions,
 264                       bool IsBegin, const SourceManager *SM,
 265                       bool &IsTokenRange) {
 266   assert(SM->getFileID(Loc) == MacroFileID);
 267   if (MacroFileID == CaretFileID)
 268     return Loc;
 269   if (!Loc.isMacroID())
 270     return {};
 271
 272   CharSourceRange MacroRange, MacroArgRange;
 273
 274   if (SM->isMacroArgExpansion(Loc)) {
 275     // Only look at the immediate spelling location of this macro argument if
 276     // the other location in the source range is also present in that expansion.
 277     if (std::binary_search(CommonArgExpansions.begin(),
 278                            CommonArgExpansions.end(), MacroFileID))
 279       MacroRange =
 280           CharSourceRange(SM->getImmediateSpellingLoc(Loc), IsTokenRange);
 281     MacroArgRange = SM->getImmediateExpansionRange(Loc);
 282   } else {
 283     MacroRange = SM->getImmediateExpansionRange(Loc);
 284     MacroArgRange =
 285         CharSourceRange(SM->getImmediateSpellingLoc(Loc), IsTokenRange);
 286   }
 287
 288   SourceLocation MacroLocation =
 289       IsBegin ? MacroRange.getBegin() : MacroRange.getEnd();
 290   if (MacroLocation.isValid()) {
 291     MacroFileID = SM->getFileID(MacroLocation);
 292     bool TokenRange = IsBegin ? IsTokenRange : MacroRange.isTokenRange();
 293     MacroLocation =
 294         retrieveMacroLocation(MacroLocation, MacroFileID, CaretFileID,
 295                               CommonArgExpansions, IsBegin, SM, TokenRange);
 296     if (MacroLocation.isValid()) {
 297       IsTokenRange = TokenRange;
 298       return MacroLocation;
 299     }
 300   }
 301
 302   // If we moved the end of the range to an expansion location, we now have
 303   // a range of the same kind as the expansion range.
 304   if (!IsBegin)
 305     IsTokenRange = MacroArgRange.isTokenRange();
 306
 307   SourceLocation MacroArgLocation =
 308       IsBegin ? MacroArgRange.getBegin() : MacroArgRange.getEnd();
 309   MacroFileID = SM->getFileID(MacroArgLocation);
 310   return retrieveMacroLocation(MacroArgLocation, MacroFileID, CaretFileID,
 311                                CommonArgExpansions, IsBegin, SM, IsTokenRange);
 312 }
 313
 314 /// Walk up the chain of macro expansions and collect the FileIDs identifying the
 315 /// expansions.
 316 static void getMacroArgExpansionFileIDs(SourceLocation Loc,
 317                                         SmallVectorImpl<FileID> &IDs,
 318                                         bool IsBegin, const SourceManager *SM) {
 319   while (Loc.isMacroID()) {
 320     if (SM->isMacroArgExpansion(Loc)) {
 321       IDs.push_back(SM->getFileID(Loc));
 322       Loc = SM->getImmediateSpellingLoc(Loc);
 323     } else {
 324       auto ExpRange = SM->getImmediateExpansionRange(Loc);
 325       Loc = IsBegin ? ExpRange.getBegin() : ExpRange.getEnd();
 326     }
 327   }
 328 }
 329
 330 /// Collect the expansions of the begin and end locations and compute the set
 331 /// intersection. Produces a sorted vector of FileIDs in CommonArgExpansions.
 332 static void computeCommonMacroArgExpansionFileIDs(
 333     SourceLocation Begin, SourceLocation End, const SourceManager *SM,
 334     SmallVectorImpl<FileID> &CommonArgExpansions) {
 335   SmallVector<FileID, 4> BeginArgExpansions;
 336   SmallVector<FileID, 4> EndArgExpansions;
 337   getMacroArgExpansionFileIDs(Begin, BeginArgExpansions, /*IsBegin=*/true, SM);
 338   getMacroArgExpansionFileIDs(End, EndArgExpansions, /*IsBegin=*/false, SM);
 339   llvm::sort(BeginArgExpansions);
 340   llvm::sort(EndArgExpansions);
 341   std::set_intersection(BeginArgExpansions.begin(), BeginArgExpansions.end(),
 342                         EndArgExpansions.begin(), EndArgExpansions.end(),
 343                         std::back_inserter(CommonArgExpansions));
 344 }
 345
 346 // Helper function to fix up source ranges.  It takes in an array of ranges,
 347 // and outputs an array of ranges where we want to draw the range highlighting
 348 // around the location specified by CaretLoc.
 349 //
 350 // To find locations which correspond to the caret, we crawl the macro caller
 351 // chain for the beginning and end of each range.  If the caret location
 352 // is in a macro expansion, we search each chain for a location
 353 // in the same expansion as the caret; otherwise, we crawl to the top of
 354 // each chain. Two locations are part of the same macro expansion
 355 // iff the FileID is the same.
 356 static void
 357 mapDiagnosticRanges(FullSourceLoc CaretLoc, ArrayRef<CharSourceRange> Ranges,
 358                     SmallVectorImpl<CharSourceRange> &SpellingRanges) {
 359   FileID CaretLocFileID = CaretLoc.getFileID();
 360
 361   const SourceManager *SM = &CaretLoc.getManager();
 362
 363   for (const auto &Range : Ranges) {
 364     if (Range.isInvalid())
 365       continue;
 366
 367     SourceLocation Begin = Range.getBegin(), End = Range.getEnd();
 368     bool IsTokenRange = Range.isTokenRange();
 369
 370     FileID BeginFileID = SM->getFileID(Begin);
 371     FileID EndFileID = SM->getFileID(End);
 372
 373     // Find the common parent for the beginning and end of the range.
 374
 375     // First, crawl the expansion chain for the beginning of the range.
 376     llvm::SmallDenseMap<FileID, SourceLocation> BeginLocsMap;
 377     while (Begin.isMacroID() && BeginFileID != EndFileID) {
 378       BeginLocsMap[BeginFileID] = Begin;
 379       Begin = SM->getImmediateExpansionRange(Begin).getBegin();
 380       BeginFileID = SM->getFileID(Begin);
 381     }
 382
 383     // Then, crawl the expansion chain for the end of the range.
 384     if (BeginFileID != EndFileID) {
 385       while (End.isMacroID() && !BeginLocsMap.count(EndFileID)) {
 386         auto Exp = SM->getImmediateExpansionRange(End);
 387         IsTokenRange = Exp.isTokenRange();
 388         End = Exp.getEnd();
 389         EndFileID = SM->getFileID(End);
 390       }
 391       if (End.isMacroID()) {
 392         Begin = BeginLocsMap[EndFileID];
 393         BeginFileID = EndFileID;
 394       }
 395     }
 396
 397     // There is a chance that begin or end is invalid here, for example if
 398     // specific compile error is reported.
 399     // It is possible that the FileID's do not match, if one comes from an
 400     // included file. In this case we can not produce a meaningful source range.
 401     if (Begin.isInvalid() || End.isInvalid() || BeginFileID != EndFileID)
 402       continue;
 403
 404     // Do the backtracking.
 405     SmallVector<FileID, 4> CommonArgExpansions;
 406     computeCommonMacroArgExpansionFileIDs(Begin, End, SM, CommonArgExpansions);
 407     Begin = retrieveMacroLocation(Begin, BeginFileID, CaretLocFileID,
 408                                   CommonArgExpansions, /*IsBegin=*/true, SM,
 409                                   IsTokenRange);
 410     End = retrieveMacroLocation(End, BeginFileID, CaretLocFileID,
 411                                 CommonArgExpansions, /*IsBegin=*/false, SM,
 412                                 IsTokenRange);
 413     if (Begin.isInvalid() || End.isInvalid()) continue;
 414
 415     // Return the spelling location of the beginning and end of the range.
 416     Begin = SM->getSpellingLoc(Begin);
 417     End = SM->getSpellingLoc(End);
 418
 419     SpellingRanges.push_back(CharSourceRange(SourceRange(Begin, End),
 420                                              IsTokenRange));
 421   }
 422 }
 423
 424 void DiagnosticRenderer::emitCaret(FullSourceLoc Loc,
 425                                    DiagnosticsEngine::Level Level,
 426                                    ArrayRef<CharSourceRange> Ranges,
 427                                    ArrayRef<FixItHint> Hints) {
 428   SmallVector<CharSourceRange, 4> SpellingRanges;
 429   mapDiagnosticRanges(Loc, Ranges, SpellingRanges);
 430   emitCodeContext(Loc, Level, SpellingRanges, Hints);
 431 }
 432
 433 /// A helper function for emitMacroExpansion to print the
 434 /// macro expansion message
 435 void DiagnosticRenderer::emitSingleMacroExpansion(
 436     FullSourceLoc Loc, DiagnosticsEngine::Level Level,
 437     ArrayRef<CharSourceRange> Ranges) {
 438   // Find the spelling location for the macro definition. We must use the
 439   // spelling location here to avoid emitting a macro backtrace for the note.
 440   FullSourceLoc SpellingLoc = Loc.getSpellingLoc();
 441
 442   // Map the ranges into the FileID of the diagnostic location.
 443   SmallVector<CharSourceRange, 4> SpellingRanges;
 444   mapDiagnosticRanges(Loc, Ranges, SpellingRanges);
 445
 446   SmallString<100> MessageStorage;
 447   llvm::raw_svector_ostream Message(MessageStorage);
 448   StringRef MacroName = Lexer::getImmediateMacroNameForDiagnostics(
 449       Loc, Loc.getManager(), LangOpts);
 450   if (MacroName.empty())
 451     Message << "expanded from here";
 452   else
 453     Message << "expanded from macro '" << MacroName << "'";
 454
 455   emitDiagnostic(SpellingLoc, DiagnosticsEngine::Note, Message.str(),
 456                  SpellingRanges, None);
 457 }
 458
 459 /// Check that the macro argument location of Loc starts with ArgumentLoc.
 460 /// The starting location of the macro expansions is used to differeniate
 461 /// different macro expansions.
 462 static bool checkLocForMacroArgExpansion(SourceLocation Loc,
 463                                          const SourceManager &SM,
 464                                          SourceLocation ArgumentLoc) {
 465   SourceLocation MacroLoc;
 466   if (SM.isMacroArgExpansion(Loc, &MacroLoc)) {
 467     if (ArgumentLoc == MacroLoc) return true;
 468   }
 469
 470   return false;
 471 }
 472
 473 /// Check if all the locations in the range have the same macro argument
 474 /// expansion, and that the expansion starts with ArgumentLoc.
 475 static bool checkRangeForMacroArgExpansion(CharSourceRange Range,
 476                                            const SourceManager &SM,
 477                                            SourceLocation ArgumentLoc) {
 478   SourceLocation BegLoc = Range.getBegin(), EndLoc = Range.getEnd();
 479   while (BegLoc != EndLoc) {
 480     if (!checkLocForMacroArgExpansion(BegLoc, SM, ArgumentLoc))
 481       return false;
 482     BegLoc.getLocWithOffset(1);
 483   }
 484
 485   return checkLocForMacroArgExpansion(BegLoc, SM, ArgumentLoc);
 486 }
 487
 488 /// A helper function to check if the current ranges are all inside the same
 489 /// macro argument expansion as Loc.
 490 static bool checkRangesForMacroArgExpansion(FullSourceLoc Loc,
 491                                             ArrayRef<CharSourceRange> Ranges) {
 492   assert(Loc.isMacroID() && "Must be a macro expansion!");
 493
 494   SmallVector<CharSourceRange, 4> SpellingRanges;
 495   mapDiagnosticRanges(Loc, Ranges, SpellingRanges);
 496
 497   /// Count all valid ranges.
 498   unsigned ValidCount = 0;
 499   for (const auto &Range : Ranges)
 500     if (Range.isValid())
 501       ValidCount++;
 502
 503   if (ValidCount > SpellingRanges.size())
 504     return false;
 505
 506   /// To store the source location of the argument location.
 507   FullSourceLoc ArgumentLoc;
 508
 509   /// Set the ArgumentLoc to the beginning location of the expansion of Loc
 510   /// so to check if the ranges expands to the same beginning location.
 511   if (!Loc.isMacroArgExpansion(&ArgumentLoc))
 512     return false;
 513
 514   for (const auto &Range : SpellingRanges)
 515     if (!checkRangeForMacroArgExpansion(Range, Loc.getManager(), ArgumentLoc))
 516       return false;
 517
 518   return true;
 519 }
 520
 521 /// Recursively emit notes for each macro expansion and caret
 522 /// diagnostics where appropriate.
 523 ///
 524 /// Walks up the macro expansion stack printing expansion notes, the code
 525 /// snippet, caret, underlines and FixItHint display as appropriate at each
 526 /// level.
 527 ///
 528 /// \param Loc The location for this caret.
 529 /// \param Level The diagnostic level currently being emitted.
 530 /// \param Ranges The underlined ranges for this code snippet.
 531 /// \param Hints The FixIt hints active for this diagnostic.
 532 void DiagnosticRenderer::emitMacroExpansions(FullSourceLoc Loc,
 533                                              DiagnosticsEngine::Level Level,
 534                                              ArrayRef<CharSourceRange> Ranges,
 535                                              ArrayRef<FixItHint> Hints) {
 536   assert(Loc.isValid() && "must have a valid source location here");
 537   const SourceManager &SM = Loc.getManager();
 538   SourceLocation L = Loc;
 539
 540   // Produce a stack of macro backtraces.
 541   SmallVector<SourceLocation, 8> LocationStack;
 542   unsigned IgnoredEnd = 0;
 543   while (L.isMacroID()) {
 544     // If this is the expansion of a macro argument, point the caret at the
 545     // use of the argument in the definition of the macro, not the expansion.
 546     if (SM.isMacroArgExpansion(L))
 547       LocationStack.push_back(SM.getImmediateExpansionRange(L).getBegin());
 548     else
 549       LocationStack.push_back(L);
 550
 551     if (checkRangesForMacroArgExpansion(FullSourceLoc(L, SM), Ranges))
 552       IgnoredEnd = LocationStack.size();
 553
 554     L = SM.getImmediateMacroCallerLoc(L);
 555
 556     // Once the location no longer points into a macro, try stepping through
 557     // the last found location.  This sometimes produces additional useful
 558     // backtraces.
 559     if (L.isFileID())
 560       L = SM.getImmediateMacroCallerLoc(LocationStack.back());
 561     assert(L.isValid() && "must have a valid source location here");
 562   }
 563
 564   LocationStack.erase(LocationStack.begin(),
 565                       LocationStack.begin() + IgnoredEnd);
 566
 567   unsigned MacroDepth = LocationStack.size();
 568   unsigned MacroLimit = DiagOpts->MacroBacktraceLimit;
 569   if (MacroDepth <= MacroLimit || MacroLimit == 0) {
 570     for (auto I = LocationStack.rbegin(), E = LocationStack.rend();
 571          I != E; ++I)
 572       emitSingleMacroExpansion(FullSourceLoc(*I, SM), Level, Ranges);
 573     return;
 574   }
 575
 576   unsigned MacroStartMessages = MacroLimit / 2;
 577   unsigned MacroEndMessages = MacroLimit / 2 + MacroLimit % 2;
 578
 579   for (auto I = LocationStack.rbegin(),
 580             E = LocationStack.rbegin() + MacroStartMessages;
 581        I != E; ++I)
 582     emitSingleMacroExpansion(FullSourceLoc(*I, SM), Level, Ranges);
 583
 584   SmallString<200> MessageStorage;
 585   llvm::raw_svector_ostream Message(MessageStorage);
 586   Message << "(skipping " << (MacroDepth - MacroLimit)
 587           << " expansions in backtrace; use -fmacro-backtrace-limit=0 to "
 588              "see all)";
 589   emitBasicNote(Message.str());
 590
 591   for (auto I = LocationStack.rend() - MacroEndMessages,
 592             E = LocationStack.rend();
 593        I != E; ++I)
 594     emitSingleMacroExpansion(FullSourceLoc(*I, SM), Level, Ranges);
 595 }
 596
 597 DiagnosticNoteRenderer::~DiagnosticNoteRenderer() = default;
 598
 599 void DiagnosticNoteRenderer::emitIncludeLocation(FullSourceLoc Loc,
 600                                                  PresumedLoc PLoc) {
 601   // Generate a note indicating the include location.
 602   SmallString<200> MessageStorage;
 603   llvm::raw_svector_ostream Message(MessageStorage);
 604   Message << "in file included from " << PLoc.getFilename() << ':'
 605           << PLoc.getLine() << ":";
 606   emitNote(Loc, Message.str());
 607 }
 608
 609 void DiagnosticNoteRenderer::emitImportLocation(FullSourceLoc Loc,
 610                                                 PresumedLoc PLoc,
 611                                                 StringRef ModuleName) {
 612   // Generate a note indicating the include location.
 613   SmallString<200> MessageStorage;
 614   llvm::raw_svector_ostream Message(MessageStorage);
 615   Message << "in module '" << ModuleName;
 616   if (PLoc.isValid())
 617     Message << "' imported from " << PLoc.getFilename() << ':'
 618             << PLoc.getLine();
 619   Message << ":";
 620   emitNote(Loc, Message.str());
 621 }
 622
 623 void DiagnosticNoteRenderer::emitBuildingModuleLocation(FullSourceLoc Loc,
 624                                                         PresumedLoc PLoc,
 625                                                         StringRef ModuleName) {
 626   // Generate a note indicating the include location.
 627   SmallString<200> MessageStorage;
 628   llvm::raw_svector_ostream Message(MessageStorage);
 629   if (PLoc.isValid())
 630     Message << "while building module '" << ModuleName << "' imported from "
 631             << PLoc.getFilename() << ':' << PLoc.getLine() << ":";
 632   else
 633     Message << "while building module '" << ModuleName << "':";
 634   emitNote(Loc, Message.str());
 635 }