clang-tools-extra/clangd/Hover.cpp

   1 //===--- Hover.cpp - Information about code at the cursor location --------===//
   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 "Hover.h"
  10
  11 #include "AST.h"
  12 #include "CodeCompletionStrings.h"
  13 #include "Config.h"
  14 #include "FindTarget.h"
  15 #include "Headers.h"
  16 #include "IncludeCleaner.h"
  17 #include "ParsedAST.h"
  18 #include "Selection.h"
  19 #include "SourceCode.h"
  20 #include "clang-include-cleaner/Analysis.h"
  21 #include "clang-include-cleaner/IncludeSpeller.h"
  22 #include "clang-include-cleaner/Types.h"
  23 #include "index/SymbolCollector.h"
  24 #include "support/Markup.h"
  25 #include "support/Trace.h"
  26 #include "clang/AST/ASTContext.h"
  27 #include "clang/AST/ASTDiagnostic.h"
  28 #include "clang/AST/ASTTypeTraits.h"
  29 #include "clang/AST/Attr.h"
  30 #include "clang/AST/Decl.h"
  31 #include "clang/AST/DeclBase.h"
  32 #include "clang/AST/DeclCXX.h"
  33 #include "clang/AST/DeclObjC.h"
  34 #include "clang/AST/DeclTemplate.h"
  35 #include "clang/AST/Expr.h"
  36 #include "clang/AST/ExprCXX.h"
  37 #include "clang/AST/OperationKinds.h"
  38 #include "clang/AST/PrettyPrinter.h"
  39 #include "clang/AST/RecordLayout.h"
  40 #include "clang/AST/Type.h"
  41 #include "clang/Basic/CharInfo.h"
  42 #include "clang/Basic/LLVM.h"
  43 #include "clang/Basic/SourceLocation.h"
  44 #include "clang/Basic/SourceManager.h"
  45 #include "clang/Basic/Specifiers.h"
  46 #include "clang/Basic/TokenKinds.h"
  47 #include "clang/Index/IndexSymbol.h"
  48 #include "clang/Tooling/Syntax/Tokens.h"
  49 #include "llvm/ADT/ArrayRef.h"
  50 #include "llvm/ADT/DenseSet.h"
  51 #include "llvm/ADT/STLExtras.h"
  52 #include "llvm/ADT/SmallVector.h"
  53 #include "llvm/ADT/StringExtras.h"
  54 #include "llvm/ADT/StringRef.h"
  55 #include "llvm/Support/Casting.h"
  56 #include "llvm/Support/Error.h"
  57 #include "llvm/Support/Format.h"
  58 #include "llvm/Support/ScopedPrinter.h"
  59 #include "llvm/Support/raw_ostream.h"
  60 #include <algorithm>
  61 #include <optional>
  62 #include <string>
  63 #include <vector>
  64
  65 namespace clang {
  66 namespace clangd {
  67 namespace {
  68
  69 PrintingPolicy getPrintingPolicy(PrintingPolicy Base) {
  70   Base.AnonymousTagLocations = false;
  71   Base.TerseOutput = true;
  72   Base.PolishForDeclaration = true;
  73   Base.ConstantsAsWritten = true;
  74   Base.SuppressTemplateArgsInCXXConstructors = true;
  75   return Base;
  76 }
  77
  78 /// Given a declaration \p D, return a human-readable string representing the
  79 /// local scope in which it is declared, i.e. class(es) and method name. Returns
  80 /// an empty string if it is not local.
  81 std::string getLocalScope(const Decl *D) {
  82   std::vector<std::string> Scopes;
  83   const DeclContext *DC = D->getDeclContext();
  84
  85   // ObjC scopes won't have multiple components for us to join, instead:
  86   // - Methods: "-[Class methodParam1:methodParam2]"
  87   // - Classes, categories, and protocols: "MyClass(Category)"
  88   if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(DC))
  89     return printObjCMethod(*MD);
  90   if (const ObjCContainerDecl *CD = dyn_cast<ObjCContainerDecl>(DC))
  91     return printObjCContainer(*CD);
  92
  93   auto GetName = [](const TypeDecl *D) {
  94     if (!D->getDeclName().isEmpty()) {
  95       PrintingPolicy Policy = D->getASTContext().getPrintingPolicy();
  96       Policy.SuppressScope = true;
  97       return declaredType(D).getAsString(Policy);
  98     }
  99     if (auto *RD = dyn_cast<RecordDecl>(D))
 100       return ("(anonymous " + RD->getKindName() + ")").str();
 101     return std::string("");
 102   };
 103   while (DC) {
 104     if (const TypeDecl *TD = dyn_cast<TypeDecl>(DC))
 105       Scopes.push_back(GetName(TD));
 106     else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
 107       Scopes.push_back(FD->getNameAsString());
 108     DC = DC->getParent();
 109   }
 110
 111   return llvm::join(llvm::reverse(Scopes), "::");
 112 }
 113
 114 /// Returns the human-readable representation for namespace containing the
 115 /// declaration \p D. Returns empty if it is contained global namespace.
 116 std::string getNamespaceScope(const Decl *D) {
 117   const DeclContext *DC = D->getDeclContext();
 118
 119   // ObjC does not have the concept of namespaces, so instead we support
 120   // local scopes.
 121   if (isa<ObjCMethodDecl, ObjCContainerDecl>(DC))
 122     return "";
 123
 124   if (const TagDecl *TD = dyn_cast<TagDecl>(DC))
 125     return getNamespaceScope(TD);
 126   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
 127     return getNamespaceScope(FD);
 128   if (const NamespaceDecl *NSD = dyn_cast<NamespaceDecl>(DC)) {
 129     // Skip inline/anon namespaces.
 130     if (NSD->isInline() || NSD->isAnonymousNamespace())
 131       return getNamespaceScope(NSD);
 132   }
 133   if (const NamedDecl *ND = dyn_cast<NamedDecl>(DC))
 134     return printQualifiedName(*ND);
 135
 136   return "";
 137 }
 138
 139 std::string printDefinition(const Decl *D, PrintingPolicy PP,
 140                             const syntax::TokenBuffer &TB) {
 141   if (auto *VD = llvm::dyn_cast<VarDecl>(D)) {
 142     if (auto *IE = VD->getInit()) {
 143       // Initializers might be huge and result in lots of memory allocations in
 144       // some catostrophic cases. Such long lists are not useful in hover cards
 145       // anyway.
 146       if (200 < TB.expandedTokens(IE->getSourceRange()).size())
 147         PP.SuppressInitializers = true;
 148     }
 149   }
 150   std::string Definition;
 151   llvm::raw_string_ostream OS(Definition);
 152   D->print(OS, PP);
 153   OS.flush();
 154   return Definition;
 155 }
 156
 157 const char *getMarkdownLanguage(const ASTContext &Ctx) {
 158   const auto &LangOpts = Ctx.getLangOpts();
 159   if (LangOpts.ObjC && LangOpts.CPlusPlus)
 160     return "objective-cpp";
 161   return LangOpts.ObjC ? "objective-c" : "cpp";
 162 }
 163
 164 HoverInfo::PrintedType printType(QualType QT, ASTContext &ASTCtx,
 165                                  const PrintingPolicy &PP) {
 166   // TypePrinter doesn't resolve decltypes, so resolve them here.
 167   // FIXME: This doesn't handle composite types that contain a decltype in them.
 168   // We should rather have a printing policy for that.
 169   while (!QT.isNull() && QT->isDecltypeType())
 170     QT = QT->castAs<DecltypeType>()->getUnderlyingType();
 171   HoverInfo::PrintedType Result;
 172   llvm::raw_string_ostream OS(Result.Type);
 173   // Special case: if the outer type is a tag type without qualifiers, then
 174   // include the tag for extra clarity.
 175   // This isn't very idiomatic, so don't attempt it for complex cases, including
 176   // pointers/references, template specializations, etc.
 177   if (!QT.isNull() && !QT.hasQualifiers() && PP.SuppressTagKeyword) {
 178     if (auto *TT = llvm::dyn_cast<TagType>(QT.getTypePtr()))
 179       OS << TT->getDecl()->getKindName() << " ";
 180   }
 181   QT.print(OS, PP);
 182   OS.flush();
 183
 184   const Config &Cfg = Config::current();
 185   if (!QT.isNull() && Cfg.Hover.ShowAKA) {
 186     bool ShouldAKA = false;
 187     QualType DesugaredTy = clang::desugarForDiagnostic(ASTCtx, QT, ShouldAKA);
 188     if (ShouldAKA)
 189       Result.AKA = DesugaredTy.getAsString(PP);
 190   }
 191   return Result;
 192 }
 193
 194 HoverInfo::PrintedType printType(const TemplateTypeParmDecl *TTP) {
 195   HoverInfo::PrintedType Result;
 196   Result.Type = TTP->wasDeclaredWithTypename() ? "typename" : "class";
 197   if (TTP->isParameterPack())
 198     Result.Type += "...";
 199   return Result;
 200 }
 201
 202 HoverInfo::PrintedType printType(const NonTypeTemplateParmDecl *NTTP,
 203                                  const PrintingPolicy &PP) {
 204   auto PrintedType = printType(NTTP->getType(), NTTP->getASTContext(), PP);
 205   if (NTTP->isParameterPack()) {
 206     PrintedType.Type += "...";
 207     if (PrintedType.AKA)
 208       *PrintedType.AKA += "...";
 209   }
 210   return PrintedType;
 211 }
 212
 213 HoverInfo::PrintedType printType(const TemplateTemplateParmDecl *TTP,
 214                                  const PrintingPolicy &PP) {
 215   HoverInfo::PrintedType Result;
 216   llvm::raw_string_ostream OS(Result.Type);
 217   OS << "template <";
 218   llvm::StringRef Sep = "";
 219   for (const Decl *Param : *TTP->getTemplateParameters()) {
 220     OS << Sep;
 221     Sep = ", ";
 222     if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
 223       OS << printType(TTP).Type;
 224     else if (const auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param))
 225       OS << printType(NTTP, PP).Type;
 226     else if (const auto *TTPD = dyn_cast<TemplateTemplateParmDecl>(Param))
 227       OS << printType(TTPD, PP).Type;
 228   }
 229   // FIXME: TemplateTemplateParameter doesn't store the info on whether this
 230   // param was a "typename" or "class".
 231   OS << "> class";
 232   OS.flush();
 233   return Result;
 234 }
 235
 236 std::vector<HoverInfo::Param>
 237 fetchTemplateParameters(const TemplateParameterList *Params,
 238                         const PrintingPolicy &PP) {
 239   assert(Params);
 240   std::vector<HoverInfo::Param> TempParameters;
 241
 242   for (const Decl *Param : *Params) {
 243     HoverInfo::Param P;
 244     if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(Param)) {
 245       P.Type = printType(TTP);
 246
 247       if (!TTP->getName().empty())
 248         P.Name = TTP->getNameAsString();
 249
 250       if (TTP->hasDefaultArgument())
 251         P.Default = TTP->getDefaultArgument().getAsString(PP);
 252     } else if (const auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
 253       P.Type = printType(NTTP, PP);
 254
 255       if (IdentifierInfo *II = NTTP->getIdentifier())
 256         P.Name = II->getName().str();
 257
 258       if (NTTP->hasDefaultArgument()) {
 259         P.Default.emplace();
 260         llvm::raw_string_ostream Out(*P.Default);
 261         NTTP->getDefaultArgument()->printPretty(Out, nullptr, PP);
 262       }
 263     } else if (const auto *TTPD = dyn_cast<TemplateTemplateParmDecl>(Param)) {
 264       P.Type = printType(TTPD, PP);
 265
 266       if (!TTPD->getName().empty())
 267         P.Name = TTPD->getNameAsString();
 268
 269       if (TTPD->hasDefaultArgument()) {
 270         P.Default.emplace();
 271         llvm::raw_string_ostream Out(*P.Default);
 272         TTPD->getDefaultArgument().getArgument().print(PP, Out,
 273                                                        /*IncludeType*/ false);
 274       }
 275     }
 276     TempParameters.push_back(std::move(P));
 277   }
 278
 279   return TempParameters;
 280 }
 281
 282 const FunctionDecl *getUnderlyingFunction(const Decl *D) {
 283   // Extract lambda from variables.
 284   if (const VarDecl *VD = llvm::dyn_cast<VarDecl>(D)) {
 285     auto QT = VD->getType();
 286     if (!QT.isNull()) {
 287       while (!QT->getPointeeType().isNull())
 288         QT = QT->getPointeeType();
 289
 290       if (const auto *CD = QT->getAsCXXRecordDecl())
 291         return CD->getLambdaCallOperator();
 292     }
 293   }
 294
 295   // Non-lambda functions.
 296   return D->getAsFunction();
 297 }
 298
 299 // Returns the decl that should be used for querying comments, either from index
 300 // or AST.
 301 const NamedDecl *getDeclForComment(const NamedDecl *D) {
 302   const NamedDecl *DeclForComment = D;
 303   if (const auto *TSD = llvm::dyn_cast<ClassTemplateSpecializationDecl>(D)) {
 304     // Template may not be instantiated e.g. if the type didn't need to be
 305     // complete; fallback to primary template.
 306     if (TSD->getTemplateSpecializationKind() == TSK_Undeclared)
 307       DeclForComment = TSD->getSpecializedTemplate();
 308     else if (const auto *TIP = TSD->getTemplateInstantiationPattern())
 309       DeclForComment = TIP;
 310   } else if (const auto *TSD =
 311                  llvm::dyn_cast<VarTemplateSpecializationDecl>(D)) {
 312     if (TSD->getTemplateSpecializationKind() == TSK_Undeclared)
 313       DeclForComment = TSD->getSpecializedTemplate();
 314     else if (const auto *TIP = TSD->getTemplateInstantiationPattern())
 315       DeclForComment = TIP;
 316   } else if (const auto *FD = D->getAsFunction())
 317     if (const auto *TIP = FD->getTemplateInstantiationPattern())
 318       DeclForComment = TIP;
 319   // Ensure that getDeclForComment(getDeclForComment(X)) = getDeclForComment(X).
 320   // This is usually not needed, but in strange cases of comparision operators
 321   // being instantiated from spasceship operater, which itself is a template
 322   // instantiation the recursrive call is necessary.
 323   if (D != DeclForComment)
 324     DeclForComment = getDeclForComment(DeclForComment);
 325   return DeclForComment;
 326 }
 327
 328 // Look up information about D from the index, and add it to Hover.
 329 void enhanceFromIndex(HoverInfo &Hover, const NamedDecl &ND,
 330                       const SymbolIndex *Index) {
 331   assert(&ND == getDeclForComment(&ND));
 332   // We only add documentation, so don't bother if we already have some.
 333   if (!Hover.Documentation.empty() || !Index)
 334     return;
 335
 336   // Skip querying for non-indexable symbols, there's no point.
 337   // We're searching for symbols that might be indexed outside this main file.
 338   if (!SymbolCollector::shouldCollectSymbol(ND, ND.getASTContext(),
 339                                             SymbolCollector::Options(),
 340                                             /*IsMainFileOnly=*/false))
 341     return;
 342   auto ID = getSymbolID(&ND);
 343   if (!ID)
 344     return;
 345   LookupRequest Req;
 346   Req.IDs.insert(ID);
 347   Index->lookup(Req, [&](const Symbol &S) {
 348     Hover.Documentation = std::string(S.Documentation);
 349   });
 350 }
 351
 352 // Default argument might exist but be unavailable, in the case of unparsed
 353 // arguments for example. This function returns the default argument if it is
 354 // available.
 355 const Expr *getDefaultArg(const ParmVarDecl *PVD) {
 356   // Default argument can be unparsed or uninstantiated. For the former we
 357   // can't do much, as token information is only stored in Sema and not
 358   // attached to the AST node. For the latter though, it is safe to proceed as
 359   // the expression is still valid.
 360   if (!PVD->hasDefaultArg() || PVD->hasUnparsedDefaultArg())
 361     return nullptr;
 362   return PVD->hasUninstantiatedDefaultArg() ? PVD->getUninstantiatedDefaultArg()
 363                                             : PVD->getDefaultArg();
 364 }
 365
 366 HoverInfo::Param toHoverInfoParam(const ParmVarDecl *PVD,
 367                                   const PrintingPolicy &PP) {
 368   HoverInfo::Param Out;
 369   Out.Type = printType(PVD->getType(), PVD->getASTContext(), PP);
 370   if (!PVD->getName().empty())
 371     Out.Name = PVD->getNameAsString();
 372   if (const Expr *DefArg = getDefaultArg(PVD)) {
 373     Out.Default.emplace();
 374     llvm::raw_string_ostream OS(*Out.Default);
 375     DefArg->printPretty(OS, nullptr, PP);
 376   }
 377   return Out;
 378 }
 379
 380 // Populates Type, ReturnType, and Parameters for function-like decls.
 381 void fillFunctionTypeAndParams(HoverInfo &HI, const Decl *D,
 382                                const FunctionDecl *FD,
 383                                const PrintingPolicy &PP) {
 384   HI.Parameters.emplace();
 385   for (const ParmVarDecl *PVD : FD->parameters())
 386     HI.Parameters->emplace_back(toHoverInfoParam(PVD, PP));
 387
 388   // We don't want any type info, if name already contains it. This is true for
 389   // constructors/destructors and conversion operators.
 390   const auto NK = FD->getDeclName().getNameKind();
 391   if (NK == DeclarationName::CXXConstructorName ||
 392       NK == DeclarationName::CXXDestructorName ||
 393       NK == DeclarationName::CXXConversionFunctionName)
 394     return;
 395
 396   HI.ReturnType = printType(FD->getReturnType(), FD->getASTContext(), PP);
 397   QualType QT = FD->getType();
 398   if (const VarDecl *VD = llvm::dyn_cast<VarDecl>(D)) // Lambdas
 399     QT = VD->getType().getDesugaredType(D->getASTContext());
 400   HI.Type = printType(QT, D->getASTContext(), PP);
 401   // FIXME: handle variadics.
 402 }
 403
 404 // Non-negative numbers are printed using min digits
 405 // 0     => 0x0
 406 // 100   => 0x64
 407 // Negative numbers are sign-extended to 32/64 bits
 408 // -2    => 0xfffffffe
 409 // -2^32 => 0xffffffff00000000
 410 static llvm::FormattedNumber printHex(const llvm::APSInt &V) {
 411   assert(V.getSignificantBits() <= 64 && "Can't print more than 64 bits.");
 412   uint64_t Bits =
 413       V.getBitWidth() > 64 ? V.trunc(64).getZExtValue() : V.getZExtValue();
 414   if (V.isNegative() && V.getSignificantBits() <= 32)
 415     return llvm::format_hex(uint32_t(Bits), 0);
 416   return llvm::format_hex(Bits, 0);
 417 }
 418
 419 std::optional<std::string> printExprValue(const Expr *E,
 420                                           const ASTContext &Ctx) {
 421   // InitListExpr has two forms, syntactic and semantic. They are the same thing
 422   // (refer to a same AST node) in most cases.
 423   // When they are different, RAV returns the syntactic form, and we should feed
 424   // the semantic form to EvaluateAsRValue.
 425   if (const auto *ILE = llvm::dyn_cast<InitListExpr>(E)) {
 426     if (!ILE->isSemanticForm())
 427       E = ILE->getSemanticForm();
 428   }
 429
 430   // Evaluating [[foo]]() as "&foo" isn't useful, and prevents us walking up
 431   // to the enclosing call. Evaluating an expression of void type doesn't
 432   // produce a meaningful result.
 433   QualType T = E->getType();
 434   if (T.isNull() || T->isFunctionType() || T->isFunctionPointerType() ||
 435       T->isFunctionReferenceType() || T->isVoidType())
 436     return std::nullopt;
 437
 438   Expr::EvalResult Constant;
 439   // Attempt to evaluate. If expr is dependent, evaluation crashes!
 440   if (E->isValueDependent() || !E->EvaluateAsRValue(Constant, Ctx) ||
 441       // Disable printing for record-types, as they are usually confusing and
 442       // might make clang crash while printing the expressions.
 443       Constant.Val.isStruct() || Constant.Val.isUnion())
 444     return std::nullopt;
 445
 446   // Show enums symbolically, not numerically like APValue::printPretty().
 447   if (T->isEnumeralType() && Constant.Val.isInt() &&
 448       Constant.Val.getInt().getSignificantBits() <= 64) {
 449     // Compare to int64_t to avoid bit-width match requirements.
 450     int64_t Val = Constant.Val.getInt().getExtValue();
 451     for (const EnumConstantDecl *ECD :
 452          T->castAs<EnumType>()->getDecl()->enumerators())
 453       if (ECD->getInitVal() == Val)
 454         return llvm::formatv("{0} ({1})", ECD->getNameAsString(),
 455                              printHex(Constant.Val.getInt()))
 456             .str();
 457   }
 458   // Show hex value of integers if they're at least 10 (or negative!)
 459   if (T->isIntegralOrEnumerationType() && Constant.Val.isInt() &&
 460       Constant.Val.getInt().getSignificantBits() <= 64 &&
 461       Constant.Val.getInt().uge(10))
 462     return llvm::formatv("{0} ({1})", Constant.Val.getAsString(Ctx, T),
 463                          printHex(Constant.Val.getInt()))
 464         .str();
 465   return Constant.Val.getAsString(Ctx, T);
 466 }
 467
 468 struct PrintExprResult {
 469   /// The evaluation result on expression `Expr`.
 470   std::optional<std::string> PrintedValue;
 471   /// The Expr object that represents the closest evaluable
 472   /// expression.
 473   const clang::Expr *TheExpr;
 474   /// The node of selection tree where the traversal stops.
 475   const SelectionTree::Node *TheNode;
 476 };
 477
 478 // Seek the closest evaluable expression along the ancestors of node N
 479 // in a selection tree. If a node in the path can be converted to an evaluable
 480 // Expr, a possible evaluation would happen and the associated context
 481 // is returned.
 482 // If evaluation couldn't be done, return the node where the traversal ends.
 483 PrintExprResult printExprValue(const SelectionTree::Node *N,
 484                                const ASTContext &Ctx) {
 485   for (; N; N = N->Parent) {
 486     // Try to evaluate the first evaluatable enclosing expression.
 487     if (const Expr *E = N->ASTNode.get<Expr>()) {
 488       // Once we cross an expression of type 'cv void', the evaluated result
 489       // has nothing to do with our original cursor position.
 490       if (!E->getType().isNull() && E->getType()->isVoidType())
 491         break;
 492       if (auto Val = printExprValue(E, Ctx))
 493         return PrintExprResult{/*PrintedValue=*/std::move(Val), /*Expr=*/E,
 494                                /*Node=*/N};
 495     } else if (N->ASTNode.get<Decl>() || N->ASTNode.get<Stmt>()) {
 496       // Refuse to cross certain non-exprs. (TypeLoc are OK as part of Exprs).
 497       // This tries to ensure we're showing a value related to the cursor.
 498       break;
 499     }
 500   }
 501   return PrintExprResult{/*PrintedValue=*/std::nullopt, /*Expr=*/nullptr,
 502                          /*Node=*/N};
 503 }
 504
 505 std::optional<StringRef> fieldName(const Expr *E) {
 506   const auto *ME = llvm::dyn_cast<MemberExpr>(E->IgnoreCasts());
 507   if (!ME || !llvm::isa<CXXThisExpr>(ME->getBase()->IgnoreCasts()))
 508     return std::nullopt;
 509   const auto *Field = llvm::dyn_cast<FieldDecl>(ME->getMemberDecl());
 510   if (!Field || !Field->getDeclName().isIdentifier())
 511     return std::nullopt;
 512   return Field->getDeclName().getAsIdentifierInfo()->getName();
 513 }
 514
 515 // If CMD is of the form T foo() { return FieldName; } then returns "FieldName".
 516 std::optional<StringRef> getterVariableName(const CXXMethodDecl *CMD) {
 517   assert(CMD->hasBody());
 518   if (CMD->getNumParams() != 0 || CMD->isVariadic())
 519     return std::nullopt;
 520   const auto *Body = llvm::dyn_cast<CompoundStmt>(CMD->getBody());
 521   const auto *OnlyReturn = (Body && Body->size() == 1)
 522                                ? llvm::dyn_cast<ReturnStmt>(Body->body_front())
 523                                : nullptr;
 524   if (!OnlyReturn || !OnlyReturn->getRetValue())
 525     return std::nullopt;
 526   return fieldName(OnlyReturn->getRetValue());
 527 }
 528
 529 // If CMD is one of the forms:
 530 //   void foo(T arg) { FieldName = arg; }
 531 //   R foo(T arg) { FieldName = arg; return *this; }
 532 //   void foo(T arg) { FieldName = std::move(arg); }
 533 //   R foo(T arg) { FieldName = std::move(arg); return *this; }
 534 // then returns "FieldName"
 535 std::optional<StringRef> setterVariableName(const CXXMethodDecl *CMD) {
 536   assert(CMD->hasBody());
 537   if (CMD->isConst() || CMD->getNumParams() != 1 || CMD->isVariadic())
 538     return std::nullopt;
 539   const ParmVarDecl *Arg = CMD->getParamDecl(0);
 540   if (Arg->isParameterPack())
 541     return std::nullopt;
 542
 543   const auto *Body = llvm::dyn_cast<CompoundStmt>(CMD->getBody());
 544   if (!Body || Body->size() == 0 || Body->size() > 2)
 545     return std::nullopt;
 546   // If the second statement exists, it must be `return this` or `return *this`.
 547   if (Body->size() == 2) {
 548     auto *Ret = llvm::dyn_cast<ReturnStmt>(Body->body_back());
 549     if (!Ret || !Ret->getRetValue())
 550       return std::nullopt;
 551     const Expr *RetVal = Ret->getRetValue()->IgnoreCasts();
 552     if (const auto *UO = llvm::dyn_cast<UnaryOperator>(RetVal)) {
 553       if (UO->getOpcode() != UO_Deref)
 554         return std::nullopt;
 555       RetVal = UO->getSubExpr()->IgnoreCasts();
 556     }
 557     if (!llvm::isa<CXXThisExpr>(RetVal))
 558       return std::nullopt;
 559   }
 560   // The first statement must be an assignment of the arg to a field.
 561   const Expr *LHS, *RHS;
 562   if (const auto *BO = llvm::dyn_cast<BinaryOperator>(Body->body_front())) {
 563     if (BO->getOpcode() != BO_Assign)
 564       return std::nullopt;
 565     LHS = BO->getLHS();
 566     RHS = BO->getRHS();
 567   } else if (const auto *COCE =
 568                  llvm::dyn_cast<CXXOperatorCallExpr>(Body->body_front())) {
 569     if (COCE->getOperator() != OO_Equal || COCE->getNumArgs() != 2)
 570       return std::nullopt;
 571     LHS = COCE->getArg(0);
 572     RHS = COCE->getArg(1);
 573   } else {
 574     return std::nullopt;
 575   }
 576
 577   // Detect the case when the item is moved into the field.
 578   if (auto *CE = llvm::dyn_cast<CallExpr>(RHS->IgnoreCasts())) {
 579     if (CE->getNumArgs() != 1)
 580       return std::nullopt;
 581     auto *ND = llvm::dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl());
 582     if (!ND || !ND->getIdentifier() || ND->getName() != "move" ||
 583         !ND->isInStdNamespace())
 584       return std::nullopt;
 585     RHS = CE->getArg(0);
 586   }
 587
 588   auto *DRE = llvm::dyn_cast<DeclRefExpr>(RHS->IgnoreCasts());
 589   if (!DRE || DRE->getDecl() != Arg)
 590     return std::nullopt;
 591   return fieldName(LHS);
 592 }
 593
 594 std::string synthesizeDocumentation(const NamedDecl *ND) {
 595   if (const auto *CMD = llvm::dyn_cast<CXXMethodDecl>(ND)) {
 596     // Is this an ordinary, non-static method whose definition is visible?
 597     if (CMD->getDeclName().isIdentifier() && !CMD->isStatic() &&
 598         (CMD = llvm::dyn_cast_or_null<CXXMethodDecl>(CMD->getDefinition())) &&
 599         CMD->hasBody()) {
 600       if (const auto GetterField = getterVariableName(CMD))
 601         return llvm::formatv("Trivial accessor for `{0}`.", *GetterField);
 602       if (const auto SetterField = setterVariableName(CMD))
 603         return llvm::formatv("Trivial setter for `{0}`.", *SetterField);
 604     }
 605   }
 606   return "";
 607 }
 608
 609 /// Generate a \p Hover object given the declaration \p D.
 610 HoverInfo getHoverContents(const NamedDecl *D, const PrintingPolicy &PP,
 611                            const SymbolIndex *Index,
 612                            const syntax::TokenBuffer &TB) {
 613   HoverInfo HI;
 614   auto &Ctx = D->getASTContext();
 615
 616   HI.AccessSpecifier = getAccessSpelling(D->getAccess()).str();
 617   HI.NamespaceScope = getNamespaceScope(D);
 618   if (!HI.NamespaceScope->empty())
 619     HI.NamespaceScope->append("::");
 620   HI.LocalScope = getLocalScope(D);
 621   if (!HI.LocalScope.empty())
 622     HI.LocalScope.append("::");
 623
 624   HI.Name = printName(Ctx, *D);
 625   const auto *CommentD = getDeclForComment(D);
 626   HI.Documentation = getDeclComment(Ctx, *CommentD);
 627   enhanceFromIndex(HI, *CommentD, Index);
 628   if (HI.Documentation.empty())
 629     HI.Documentation = synthesizeDocumentation(D);
 630
 631   HI.Kind = index::getSymbolInfo(D).Kind;
 632
 633   // Fill in template params.
 634   if (const TemplateDecl *TD = D->getDescribedTemplate()) {
 635     HI.TemplateParameters =
 636         fetchTemplateParameters(TD->getTemplateParameters(), PP);
 637     D = TD;
 638   } else if (const FunctionDecl *FD = D->getAsFunction()) {
 639     if (const auto *FTD = FD->getDescribedTemplate()) {
 640       HI.TemplateParameters =
 641           fetchTemplateParameters(FTD->getTemplateParameters(), PP);
 642       D = FTD;
 643     }
 644   }
 645
 646   // Fill in types and params.
 647   if (const FunctionDecl *FD = getUnderlyingFunction(D))
 648     fillFunctionTypeAndParams(HI, D, FD, PP);
 649   else if (const auto *VD = dyn_cast<ValueDecl>(D))
 650     HI.Type = printType(VD->getType(), Ctx, PP);
 651   else if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(D))
 652     HI.Type = TTP->wasDeclaredWithTypename() ? "typename" : "class";
 653   else if (const auto *TTP = dyn_cast<TemplateTemplateParmDecl>(D))
 654     HI.Type = printType(TTP, PP);
 655   else if (const auto *VT = dyn_cast<VarTemplateDecl>(D))
 656     HI.Type = printType(VT->getTemplatedDecl()->getType(), Ctx, PP);
 657   else if (const auto *TN = dyn_cast<TypedefNameDecl>(D))
 658     HI.Type = printType(TN->getUnderlyingType().getDesugaredType(Ctx), Ctx, PP);
 659   else if (const auto *TAT = dyn_cast<TypeAliasTemplateDecl>(D))
 660     HI.Type = printType(TAT->getTemplatedDecl()->getUnderlyingType(), Ctx, PP);
 661
 662   // Fill in value with evaluated initializer if possible.
 663   if (const auto *Var = dyn_cast<VarDecl>(D); Var && !Var->isInvalidDecl()) {
 664     if (const Expr *Init = Var->getInit())
 665       HI.Value = printExprValue(Init, Ctx);
 666   } else if (const auto *ECD = dyn_cast<EnumConstantDecl>(D)) {
 667     // Dependent enums (e.g. nested in template classes) don't have values yet.
 668     if (!ECD->getType()->isDependentType())
 669       HI.Value = toString(ECD->getInitVal(), 10);
 670   }
 671
 672   HI.Definition = printDefinition(D, PP, TB);
 673   return HI;
 674 }
 675
 676 /// The standard defines __func__ as a "predefined variable".
 677 std::optional<HoverInfo>
 678 getPredefinedExprHoverContents(const PredefinedExpr &PE, ASTContext &Ctx,
 679                                const PrintingPolicy &PP) {
 680   HoverInfo HI;
 681   HI.Name = PE.getIdentKindName();
 682   HI.Kind = index::SymbolKind::Variable;
 683   HI.Documentation = "Name of the current function (predefined variable)";
 684   if (const StringLiteral *Name = PE.getFunctionName()) {
 685     HI.Value.emplace();
 686     llvm::raw_string_ostream OS(*HI.Value);
 687     Name->outputString(OS);
 688     HI.Type = printType(Name->getType(), Ctx, PP);
 689   } else {
 690     // Inside templates, the approximate type `const char[]` is still useful.
 691     QualType StringType = Ctx.getIncompleteArrayType(Ctx.CharTy.withConst(),
 692                                                      ArraySizeModifier::Normal,
 693                                                      /*IndexTypeQuals=*/0);
 694     HI.Type = printType(StringType, Ctx, PP);
 695   }
 696   return HI;
 697 }
 698
 699 HoverInfo evaluateMacroExpansion(unsigned int SpellingBeginOffset,
 700                                  unsigned int SpellingEndOffset,
 701                                  llvm::ArrayRef<syntax::Token> Expanded,
 702                                  ParsedAST &AST) {
 703   auto &Context = AST.getASTContext();
 704   auto &Tokens = AST.getTokens();
 705   auto PP = getPrintingPolicy(Context.getPrintingPolicy());
 706   auto Tree = SelectionTree::createRight(Context, Tokens, SpellingBeginOffset,
 707                                          SpellingEndOffset);
 708
 709   // If macro expands to one single token, rule out punctuator or digraph.
 710   // E.g., for the case `array L_BRACKET 42 R_BRACKET;` where L_BRACKET and
 711   // R_BRACKET expand to
 712   // '[' and ']' respectively, we don't want the type of
 713   // 'array[42]' when user hovers on L_BRACKET.
 714   if (Expanded.size() == 1)
 715     if (tok::getPunctuatorSpelling(Expanded[0].kind()))
 716       return {};
 717
 718   auto *StartNode = Tree.commonAncestor();
 719   if (!StartNode)
 720     return {};
 721   // If the common ancestor is partially selected, do evaluate if it has no
 722   // children, thus we can disallow evaluation on incomplete expression.
 723   // For example,
 724   // #define PLUS_2 +2
 725   // 40 PL^US_2
 726   // In this case we don't want to present 'value: 2' as PLUS_2 actually expands
 727   // to a non-value rather than a binary operand.
 728   if (StartNode->Selected == SelectionTree::Selection::Partial)
 729     if (!StartNode->Children.empty())
 730       return {};
 731
 732   HoverInfo HI;
 733   // Attempt to evaluate it from Expr first.
 734   auto ExprResult = printExprValue(StartNode, Context);
 735   HI.Value = std::move(ExprResult.PrintedValue);
 736   if (auto *E = ExprResult.TheExpr)
 737     HI.Type = printType(E->getType(), Context, PP);
 738
 739   // If failed, extract the type from Decl if possible.
 740   if (!HI.Value && !HI.Type && ExprResult.TheNode)
 741     if (auto *VD = ExprResult.TheNode->ASTNode.get<VarDecl>())
 742       HI.Type = printType(VD->getType(), Context, PP);
 743
 744   return HI;
 745 }
 746
 747 /// Generate a \p Hover object given the macro \p MacroDecl.
 748 HoverInfo getHoverContents(const DefinedMacro &Macro, const syntax::Token &Tok,
 749                            ParsedAST &AST) {
 750   HoverInfo HI;
 751   SourceManager &SM = AST.getSourceManager();
 752   HI.Name = std::string(Macro.Name);
 753   HI.Kind = index::SymbolKind::Macro;
 754   // FIXME: Populate documentation
 755   // FIXME: Populate parameters
 756
 757   // Try to get the full definition, not just the name
 758   SourceLocation StartLoc = Macro.Info->getDefinitionLoc();
 759   SourceLocation EndLoc = Macro.Info->getDefinitionEndLoc();
 760   // Ensure that EndLoc is a valid offset. For example it might come from
 761   // preamble, and source file might've changed, in such a scenario EndLoc still
 762   // stays valid, but getLocForEndOfToken will fail as it is no longer a valid
 763   // offset.
 764   // Note that this check is just to ensure there's text data inside the range.
 765   // It will still succeed even when the data inside the range is irrelevant to
 766   // macro definition.
 767   if (SM.getPresumedLoc(EndLoc, /*UseLineDirectives=*/false).isValid()) {
 768     EndLoc = Lexer::getLocForEndOfToken(EndLoc, 0, SM, AST.getLangOpts());
 769     bool Invalid;
 770     StringRef Buffer = SM.getBufferData(SM.getFileID(StartLoc), &Invalid);
 771     if (!Invalid) {
 772       unsigned StartOffset = SM.getFileOffset(StartLoc);
 773       unsigned EndOffset = SM.getFileOffset(EndLoc);
 774       if (EndOffset <= Buffer.size() && StartOffset < EndOffset)
 775         HI.Definition =
 776             ("#define " + Buffer.substr(StartOffset, EndOffset - StartOffset))
 777                 .str();
 778     }
 779   }
 780
 781   if (auto Expansion = AST.getTokens().expansionStartingAt(&Tok)) {
 782     // We drop expansion that's longer than the threshold.
 783     // For extremely long expansion text, it's not readable from hover card
 784     // anyway.
 785     std::string ExpansionText;
 786     for (const auto &ExpandedTok : Expansion->Expanded) {
 787       ExpansionText += ExpandedTok.text(SM);
 788       ExpansionText += " ";
 789       if (ExpansionText.size() > 2048) {
 790         ExpansionText.clear();
 791         break;
 792       }
 793     }
 794
 795     if (!ExpansionText.empty()) {
 796       if (!HI.Definition.empty()) {
 797         HI.Definition += "\n\n";
 798       }
 799       HI.Definition += "// Expands to\n";
 800       HI.Definition += ExpansionText;
 801     }
 802
 803     auto Evaluated = evaluateMacroExpansion(
 804         /*SpellingBeginOffset=*/SM.getFileOffset(Tok.location()),
 805         /*SpellingEndOffset=*/SM.getFileOffset(Tok.endLocation()),
 806         /*Expanded=*/Expansion->Expanded, AST);
 807     HI.Value = std::move(Evaluated.Value);
 808     HI.Type = std::move(Evaluated.Type);
 809   }
 810   return HI;
 811 }
 812
 813 std::string typeAsDefinition(const HoverInfo::PrintedType &PType) {
 814   std::string Result;
 815   llvm::raw_string_ostream OS(Result);
 816   OS << PType.Type;
 817   if (PType.AKA)
 818     OS << " // aka: " << *PType.AKA;
 819   OS.flush();
 820   return Result;
 821 }
 822
 823 std::optional<HoverInfo> getThisExprHoverContents(const CXXThisExpr *CTE,
 824                                                   ASTContext &ASTCtx,
 825                                                   const PrintingPolicy &PP) {
 826   QualType OriginThisType = CTE->getType()->getPointeeType();
 827   QualType ClassType = declaredType(OriginThisType->getAsTagDecl());
 828   // For partial specialization class, origin `this` pointee type will be
 829   // parsed as `InjectedClassNameType`, which will ouput template arguments
 830   // like "type-parameter-0-0". So we retrieve user written class type in this
 831   // case.
 832   QualType PrettyThisType = ASTCtx.getPointerType(
 833       QualType(ClassType.getTypePtr(), OriginThisType.getCVRQualifiers()));
 834
 835   HoverInfo HI;
 836   HI.Name = "this";
 837   HI.Definition = typeAsDefinition(printType(PrettyThisType, ASTCtx, PP));
 838   return HI;
 839 }
 840
 841 /// Generate a HoverInfo object given the deduced type \p QT
 842 HoverInfo getDeducedTypeHoverContents(QualType QT, const syntax::Token &Tok,
 843                                       ASTContext &ASTCtx,
 844                                       const PrintingPolicy &PP,
 845                                       const SymbolIndex *Index) {
 846   HoverInfo HI;
 847   // FIXME: distinguish decltype(auto) vs decltype(expr)
 848   HI.Name = tok::getTokenName(Tok.kind());
 849   HI.Kind = index::SymbolKind::TypeAlias;
 850
 851   if (QT->isUndeducedAutoType()) {
 852     HI.Definition = "/* not deduced */";
 853   } else {
 854     HI.Definition = typeAsDefinition(printType(QT, ASTCtx, PP));
 855
 856     if (const auto *D = QT->getAsTagDecl()) {
 857       const auto *CommentD = getDeclForComment(D);
 858       HI.Documentation = getDeclComment(ASTCtx, *CommentD);
 859       enhanceFromIndex(HI, *CommentD, Index);
 860     }
 861   }
 862
 863   return HI;
 864 }
 865
 866 HoverInfo getStringLiteralContents(const StringLiteral *SL,
 867                                    const PrintingPolicy &PP) {
 868   HoverInfo HI;
 869
 870   HI.Name = "string-literal";
 871   HI.Size = (SL->getLength() + 1) * SL->getCharByteWidth() * 8;
 872   HI.Type = SL->getType().getAsString(PP).c_str();
 873
 874   return HI;
 875 }
 876
 877 bool isLiteral(const Expr *E) {
 878   // Unfortunately there's no common base Literal classes inherits from
 879   // (apart from Expr), therefore these exclusions.
 880   return llvm::isa<CompoundLiteralExpr>(E) ||
 881          llvm::isa<CXXBoolLiteralExpr>(E) ||
 882          llvm::isa<CXXNullPtrLiteralExpr>(E) ||
 883          llvm::isa<FixedPointLiteral>(E) || llvm::isa<FloatingLiteral>(E) ||
 884          llvm::isa<ImaginaryLiteral>(E) || llvm::isa<IntegerLiteral>(E) ||
 885          llvm::isa<StringLiteral>(E) || llvm::isa<UserDefinedLiteral>(E);
 886 }
 887
 888 llvm::StringLiteral getNameForExpr(const Expr *E) {
 889   // FIXME: Come up with names for `special` expressions.
 890   //
 891   // It's an known issue for GCC5, https://godbolt.org/z/Z_tbgi. Work around
 892   // that by using explicit conversion constructor.
 893   //
 894   // TODO: Once GCC5 is fully retired and not the minimal requirement as stated
 895   // in `GettingStarted`, please remove the explicit conversion constructor.
 896   return llvm::StringLiteral("expression");
 897 }
 898
 899 void maybeAddCalleeArgInfo(const SelectionTree::Node *N, HoverInfo &HI,
 900                            const PrintingPolicy &PP);
 901
 902 // Generates hover info for `this` and evaluatable expressions.
 903 // FIXME: Support hover for literals (esp user-defined)
 904 std::optional<HoverInfo> getHoverContents(const SelectionTree::Node *N,
 905                                           const Expr *E, ParsedAST &AST,
 906                                           const PrintingPolicy &PP,
 907                                           const SymbolIndex *Index) {
 908   std::optional<HoverInfo> HI;
 909
 910   if (const StringLiteral *SL = dyn_cast<StringLiteral>(E)) {
 911     // Print the type and the size for string literals
 912     HI = getStringLiteralContents(SL, PP);
 913   } else if (isLiteral(E)) {
 914     // There's not much value in hovering over "42" and getting a hover card
 915     // saying "42 is an int", similar for most other literals.
 916     // However, if we have CalleeArgInfo, it's still useful to show it.
 917     maybeAddCalleeArgInfo(N, HI.emplace(), PP);
 918     if (HI->CalleeArgInfo) {
 919       // FIXME Might want to show the expression's value here instead?
 920       // E.g. if the literal is in hex it might be useful to show the decimal
 921       // value here.
 922       HI->Name = "literal";
 923       return HI;
 924     }
 925     return std::nullopt;
 926   }
 927
 928   // For `this` expr we currently generate hover with pointee type.
 929   if (const CXXThisExpr *CTE = dyn_cast<CXXThisExpr>(E))
 930     HI = getThisExprHoverContents(CTE, AST.getASTContext(), PP);
 931   if (const PredefinedExpr *PE = dyn_cast<PredefinedExpr>(E))
 932     HI = getPredefinedExprHoverContents(*PE, AST.getASTContext(), PP);
 933   // For expressions we currently print the type and the value, iff it is
 934   // evaluatable.
 935   if (auto Val = printExprValue(E, AST.getASTContext())) {
 936     HI.emplace();
 937     HI->Type = printType(E->getType(), AST.getASTContext(), PP);
 938     HI->Value = *Val;
 939     HI->Name = std::string(getNameForExpr(E));
 940   }
 941
 942   if (HI)
 943     maybeAddCalleeArgInfo(N, *HI, PP);
 944
 945   return HI;
 946 }
 947
 948 // Generates hover info for attributes.
 949 std::optional<HoverInfo> getHoverContents(const Attr *A, ParsedAST &AST) {
 950   HoverInfo HI;
 951   HI.Name = A->getSpelling();
 952   if (A->hasScope())
 953     HI.LocalScope = A->getScopeName()->getName().str();
 954   {
 955     llvm::raw_string_ostream OS(HI.Definition);
 956     A->printPretty(OS, AST.getASTContext().getPrintingPolicy());
 957   }
 958   HI.Documentation = Attr::getDocumentation(A->getKind()).str();
 959   return HI;
 960 }
 961
 962 bool isParagraphBreak(llvm::StringRef Rest) {
 963   return Rest.ltrim(" \t").starts_with("\n");
 964 }
 965
 966 bool punctuationIndicatesLineBreak(llvm::StringRef Line) {
 967   constexpr llvm::StringLiteral Punctuation = R"txt(.:,;!?)txt";
 968
 969   Line = Line.rtrim();
 970   return !Line.empty() && Punctuation.contains(Line.back());
 971 }
 972
 973 bool isHardLineBreakIndicator(llvm::StringRef Rest) {
 974   // '-'/'*' md list, '@'/'\' documentation command, '>' md blockquote,
 975   // '#' headings, '`' code blocks
 976   constexpr llvm::StringLiteral LinebreakIndicators = R"txt(-*@\>#`)txt";
 977
 978   Rest = Rest.ltrim(" \t");
 979   if (Rest.empty())
 980     return false;
 981
 982   if (LinebreakIndicators.contains(Rest.front()))
 983     return true;
 984
 985   if (llvm::isDigit(Rest.front())) {
 986     llvm::StringRef AfterDigit = Rest.drop_while(llvm::isDigit);
 987     if (AfterDigit.starts_with(".") || AfterDigit.starts_with(")"))
 988       return true;
 989   }
 990   return false;
 991 }
 992
 993 bool isHardLineBreakAfter(llvm::StringRef Line, llvm::StringRef Rest) {
 994   // Should we also consider whether Line is short?
 995   return punctuationIndicatesLineBreak(Line) || isHardLineBreakIndicator(Rest);
 996 }
 997
 998 void addLayoutInfo(const NamedDecl &ND, HoverInfo &HI) {
 999   if (ND.isInvalidDecl())
1000     return;
1001
1002   const auto &Ctx = ND.getASTContext();
1003   if (auto *RD = llvm::dyn_cast<RecordDecl>(&ND)) {
1004     if (auto Size = Ctx.getTypeSizeInCharsIfKnown(RD->getTypeForDecl()))
1005       HI.Size = Size->getQuantity() * 8;
1006     if (!RD->isDependentType() && RD->isCompleteDefinition())
1007       HI.Align = Ctx.getTypeAlign(RD->getTypeForDecl());
1008     return;
1009   }
1010
1011   if (const auto *FD = llvm::dyn_cast<FieldDecl>(&ND)) {
1012     const auto *Record = FD->getParent();
1013     if (Record)
1014       Record = Record->getDefinition();
1015     if (Record && !Record->isInvalidDecl() && !Record->isDependentType()) {
1016       HI.Align = Ctx.getTypeAlign(FD->getType());
1017       const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Record);
1018       HI.Offset = Layout.getFieldOffset(FD->getFieldIndex());
1019       if (FD->isBitField())
1020         HI.Size = FD->getBitWidthValue(Ctx);
1021       else if (auto Size = Ctx.getTypeSizeInCharsIfKnown(FD->getType()))
1022         HI.Size = FD->isZeroSize(Ctx) ? 0 : Size->getQuantity() * 8;
1023       if (HI.Size) {
1024         unsigned EndOfField = *HI.Offset + *HI.Size;
1025
1026         // Calculate padding following the field.
1027         if (!Record->isUnion() &&
1028             FD->getFieldIndex() + 1 < Layout.getFieldCount()) {
1029           // Measure padding up to the next class field.
1030           unsigned NextOffset = Layout.getFieldOffset(FD->getFieldIndex() + 1);
1031           if (NextOffset >= EndOfField) // next field could be a bitfield!
1032             HI.Padding = NextOffset - EndOfField;
1033         } else {
1034           // Measure padding up to the end of the object.
1035           HI.Padding = Layout.getSize().getQuantity() * 8 - EndOfField;
1036         }
1037       }
1038       // Offset in a union is always zero, so not really useful to report.
1039       if (Record->isUnion())
1040         HI.Offset.reset();
1041     }
1042     return;
1043   }
1044 }
1045
1046 HoverInfo::PassType::PassMode getPassMode(QualType ParmType) {
1047   if (ParmType->isReferenceType()) {
1048     if (ParmType->getPointeeType().isConstQualified())
1049       return HoverInfo::PassType::ConstRef;
1050     return HoverInfo::PassType::Ref;
1051   }
1052   return HoverInfo::PassType::Value;
1053 }
1054
1055 // If N is passed as argument to a function, fill HI.CalleeArgInfo with
1056 // information about that argument.
1057 void maybeAddCalleeArgInfo(const SelectionTree::Node *N, HoverInfo &HI,
1058                            const PrintingPolicy &PP) {
1059   const auto &OuterNode = N->outerImplicit();
1060   if (!OuterNode.Parent)
1061     return;
1062
1063   const FunctionDecl *FD = nullptr;
1064   llvm::ArrayRef<const Expr *> Args;
1065
1066   if (const auto *CE = OuterNode.Parent->ASTNode.get<CallExpr>()) {
1067     FD = CE->getDirectCallee();
1068     Args = {CE->getArgs(), CE->getNumArgs()};
1069   } else if (const auto *CE =
1070                  OuterNode.Parent->ASTNode.get<CXXConstructExpr>()) {
1071     FD = CE->getConstructor();
1072     Args = {CE->getArgs(), CE->getNumArgs()};
1073   }
1074   if (!FD)
1075     return;
1076
1077   // For non-function-call-like operators (e.g. operator+, operator<<) it's
1078   // not immediately obvious what the "passed as" would refer to and, given
1079   // fixed function signature, the value would be very low anyway, so we choose
1080   // to not support that.
1081   // Both variadic functions and operator() (especially relevant for lambdas)
1082   // should be supported in the future.
1083   if (!FD || FD->isOverloadedOperator() || FD->isVariadic())
1084     return;
1085
1086   HoverInfo::PassType PassType;
1087
1088   auto Parameters = resolveForwardingParameters(FD);
1089
1090   // Find argument index for N.
1091   for (unsigned I = 0; I < Args.size() && I < Parameters.size(); ++I) {
1092     if (Args[I] != OuterNode.ASTNode.get<Expr>())
1093       continue;
1094
1095     // Extract matching argument from function declaration.
1096     if (const ParmVarDecl *PVD = Parameters[I]) {
1097       HI.CalleeArgInfo.emplace(toHoverInfoParam(PVD, PP));
1098       if (N == &OuterNode)
1099         PassType.PassBy = getPassMode(PVD->getType());
1100     }
1101     break;
1102   }
1103   if (!HI.CalleeArgInfo)
1104     return;
1105
1106   // If we found a matching argument, also figure out if it's a
1107   // [const-]reference. For this we need to walk up the AST from the arg itself
1108   // to CallExpr and check all implicit casts, constructor calls, etc.
1109   if (const auto *E = N->ASTNode.get<Expr>()) {
1110     if (E->getType().isConstQualified())
1111       PassType.PassBy = HoverInfo::PassType::ConstRef;
1112   }
1113
1114   for (auto *CastNode = N->Parent;
1115        CastNode != OuterNode.Parent && !PassType.Converted;
1116        CastNode = CastNode->Parent) {
1117     if (const auto *ImplicitCast = CastNode->ASTNode.get<ImplicitCastExpr>()) {
1118       switch (ImplicitCast->getCastKind()) {
1119       case CK_NoOp:
1120       case CK_DerivedToBase:
1121       case CK_UncheckedDerivedToBase:
1122         // If it was a reference before, it's still a reference.
1123         if (PassType.PassBy != HoverInfo::PassType::Value)
1124           PassType.PassBy = ImplicitCast->getType().isConstQualified()
1125                                 ? HoverInfo::PassType::ConstRef
1126                                 : HoverInfo::PassType::Ref;
1127         break;
1128       case CK_LValueToRValue:
1129       case CK_ArrayToPointerDecay:
1130       case CK_FunctionToPointerDecay:
1131       case CK_NullToPointer:
1132       case CK_NullToMemberPointer:
1133         // No longer a reference, but we do not show this as type conversion.
1134         PassType.PassBy = HoverInfo::PassType::Value;
1135         break;
1136       default:
1137         PassType.PassBy = HoverInfo::PassType::Value;
1138         PassType.Converted = true;
1139         break;
1140       }
1141     } else if (const auto *CtorCall =
1142                    CastNode->ASTNode.get<CXXConstructExpr>()) {
1143       // We want to be smart about copy constructors. They should not show up as
1144       // type conversion, but instead as passing by value.
1145       if (CtorCall->getConstructor()->isCopyConstructor())
1146         PassType.PassBy = HoverInfo::PassType::Value;
1147       else
1148         PassType.Converted = true;
1149     } else if (CastNode->ASTNode.get<MaterializeTemporaryExpr>()) {
1150       // Can't bind a non-const-ref to a temporary, so has to be const-ref
1151       PassType.PassBy = HoverInfo::PassType::ConstRef;
1152     } else { // Unknown implicit node, assume type conversion.
1153       PassType.PassBy = HoverInfo::PassType::Value;
1154       PassType.Converted = true;
1155     }
1156   }
1157
1158   HI.CallPassType.emplace(PassType);
1159 }
1160
1161 const NamedDecl *pickDeclToUse(llvm::ArrayRef<const NamedDecl *> Candidates) {
1162   if (Candidates.empty())
1163     return nullptr;
1164
1165   // This is e.g the case for
1166   //     namespace ns { void foo(); }
1167   //     void bar() { using ns::foo; f^oo(); }
1168   // One declaration in Candidates will refer to the using declaration,
1169   // which isn't really useful for Hover. So use the other one,
1170   // which in this example would be the actual declaration of foo.
1171   if (Candidates.size() <= 2) {
1172     if (llvm::isa<UsingDecl>(Candidates.front()))
1173       return Candidates.back();
1174     return Candidates.front();
1175   }
1176
1177   // For something like
1178   //     namespace ns { void foo(int); void foo(char); }
1179   //     using ns::foo;
1180   //     template <typename T> void bar() { fo^o(T{}); }
1181   // we actually want to show the using declaration,
1182   // it's not clear which declaration to pick otherwise.
1183   auto BaseDecls = llvm::make_filter_range(
1184       Candidates, [](const NamedDecl *D) { return llvm::isa<UsingDecl>(D); });
1185   if (std::distance(BaseDecls.begin(), BaseDecls.end()) == 1)
1186     return *BaseDecls.begin();
1187
1188   return Candidates.front();
1189 }
1190
1191 void maybeAddSymbolProviders(ParsedAST &AST, HoverInfo &HI,
1192                              include_cleaner::Symbol Sym) {
1193   trace::Span Tracer("Hover::maybeAddSymbolProviders");
1194
1195   const SourceManager &SM = AST.getSourceManager();
1196   llvm::SmallVector<include_cleaner::Header> RankedProviders =
1197       include_cleaner::headersForSymbol(Sym, SM, AST.getPragmaIncludes().get());
1198   if (RankedProviders.empty())
1199     return;
1200
1201   std::string Result;
1202   include_cleaner::Includes ConvertedIncludes = convertIncludes(AST);
1203   for (const auto &P : RankedProviders) {
1204     if (P.kind() == include_cleaner::Header::Physical &&
1205         P.physical() == SM.getFileEntryForID(SM.getMainFileID()))
1206       // Main file ranked higher than any #include'd file
1207       break;
1208
1209     // Pick the best-ranked #include'd provider
1210     auto Matches = ConvertedIncludes.match(P);
1211     if (!Matches.empty()) {
1212       Result = Matches[0]->quote();
1213       break;
1214     }
1215   }
1216
1217   if (!Result.empty()) {
1218     HI.Provider = std::move(Result);
1219     return;
1220   }
1221
1222   // Pick the best-ranked non-#include'd provider
1223   const auto &H = RankedProviders.front();
1224   if (H.kind() == include_cleaner::Header::Physical &&
1225       H.physical() == SM.getFileEntryForID(SM.getMainFileID()))
1226     // Do not show main file as provider, otherwise we'll show provider info
1227     // on local variables, etc.
1228     return;
1229
1230   HI.Provider = include_cleaner::spellHeader(
1231       {H, AST.getPreprocessor().getHeaderSearchInfo(),
1232        SM.getFileEntryForID(SM.getMainFileID())});
1233 }
1234
1235 // FIXME: similar functions are present in FindHeaders.cpp (symbolName)
1236 // and IncludeCleaner.cpp (getSymbolName). Introduce a name() method into
1237 // include_cleaner::Symbol instead.
1238 std::string getSymbolName(include_cleaner::Symbol Sym) {
1239   std::string Name;
1240   switch (Sym.kind()) {
1241   case include_cleaner::Symbol::Declaration:
1242     if (const auto *ND = llvm::dyn_cast<NamedDecl>(&Sym.declaration()))
1243       Name = ND->getDeclName().getAsString();
1244     break;
1245   case include_cleaner::Symbol::Macro:
1246     Name = Sym.macro().Name->getName();
1247     break;
1248   }
1249   return Name;
1250 }
1251
1252 void maybeAddUsedSymbols(ParsedAST &AST, HoverInfo &HI, const Inclusion &Inc) {
1253   auto Converted = convertIncludes(AST);
1254   llvm::DenseSet<include_cleaner::Symbol> UsedSymbols;
1255   include_cleaner::walkUsed(
1256       AST.getLocalTopLevelDecls(), collectMacroReferences(AST),
1257       AST.getPragmaIncludes().get(), AST.getPreprocessor(),
1258       [&](const include_cleaner::SymbolReference &Ref,
1259           llvm::ArrayRef<include_cleaner::Header> Providers) {
1260         if (Ref.RT != include_cleaner::RefType::Explicit ||
1261             UsedSymbols.contains(Ref.Target))
1262           return;
1263
1264         if (isPreferredProvider(Inc, Converted, Providers))
1265           UsedSymbols.insert(Ref.Target);
1266       });
1267
1268   for (const auto &UsedSymbolDecl : UsedSymbols)
1269     HI.UsedSymbolNames.push_back(getSymbolName(UsedSymbolDecl));
1270   llvm::sort(HI.UsedSymbolNames);
1271   HI.UsedSymbolNames.erase(
1272       std::unique(HI.UsedSymbolNames.begin(), HI.UsedSymbolNames.end()),
1273       HI.UsedSymbolNames.end());
1274 }
1275
1276 } // namespace
1277
1278 std::optional<HoverInfo> getHover(ParsedAST &AST, Position Pos,
1279                                   const format::FormatStyle &Style,
1280                                   const SymbolIndex *Index) {
1281   static constexpr trace::Metric HoverCountMetric(
1282       "hover", trace::Metric::Counter, "case");
1283   PrintingPolicy PP =
1284       getPrintingPolicy(AST.getASTContext().getPrintingPolicy());
1285   const SourceManager &SM = AST.getSourceManager();
1286   auto CurLoc = sourceLocationInMainFile(SM, Pos);
1287   if (!CurLoc) {
1288     llvm::consumeError(CurLoc.takeError());
1289     return std::nullopt;
1290   }
1291   const auto &TB = AST.getTokens();
1292   auto TokensTouchingCursor = syntax::spelledTokensTouching(*CurLoc, TB);
1293   // Early exit if there were no tokens around the cursor.
1294   if (TokensTouchingCursor.empty())
1295     return std::nullopt;
1296
1297   // Show full header file path if cursor is on include directive.
1298   for (const auto &Inc : AST.getIncludeStructure().MainFileIncludes) {
1299     if (Inc.Resolved.empty() || Inc.HashLine != Pos.line)
1300       continue;
1301     HoverCountMetric.record(1, "include");
1302     HoverInfo HI;
1303     HI.Name = std::string(llvm::sys::path::filename(Inc.Resolved));
1304     // FIXME: We don't have a fitting value for Kind.
1305     HI.Definition =
1306         URIForFile::canonicalize(Inc.Resolved, AST.tuPath()).file().str();
1307     HI.DefinitionLanguage = "";
1308     maybeAddUsedSymbols(AST, HI, Inc);
1309     return HI;
1310   }
1311
1312   // To be used as a backup for highlighting the selected token, we use back as
1313   // it aligns better with biases elsewhere (editors tend to send the position
1314   // for the left of the hovered token).
1315   CharSourceRange HighlightRange =
1316       TokensTouchingCursor.back().range(SM).toCharRange(SM);
1317   std::optional<HoverInfo> HI;
1318   // Macros and deducedtype only works on identifiers and auto/decltype keywords
1319   // respectively. Therefore they are only trggered on whichever works for them,
1320   // similar to SelectionTree::create().
1321   for (const auto &Tok : TokensTouchingCursor) {
1322     if (Tok.kind() == tok::identifier) {
1323       // Prefer the identifier token as a fallback highlighting range.
1324       HighlightRange = Tok.range(SM).toCharRange(SM);
1325       if (auto M = locateMacroAt(Tok, AST.getPreprocessor())) {
1326         HoverCountMetric.record(1, "macro");
1327         HI = getHoverContents(*M, Tok, AST);
1328         if (auto DefLoc = M->Info->getDefinitionLoc(); DefLoc.isValid()) {
1329           include_cleaner::Macro IncludeCleanerMacro{
1330               AST.getPreprocessor().getIdentifierInfo(Tok.text(SM)), DefLoc};
1331           maybeAddSymbolProviders(AST, *HI,
1332                                   include_cleaner::Symbol{IncludeCleanerMacro});
1333         }
1334         break;
1335       }
1336     } else if (Tok.kind() == tok::kw_auto || Tok.kind() == tok::kw_decltype) {
1337       HoverCountMetric.record(1, "keyword");
1338       if (auto Deduced = getDeducedType(AST.getASTContext(), Tok.location())) {
1339         HI = getDeducedTypeHoverContents(*Deduced, Tok, AST.getASTContext(), PP,
1340                                          Index);
1341         HighlightRange = Tok.range(SM).toCharRange(SM);
1342         break;
1343       }
1344
1345       // If we can't find interesting hover information for this
1346       // auto/decltype keyword, return nothing to avoid showing
1347       // irrelevant or incorrect informations.
1348       return std::nullopt;
1349     }
1350   }
1351
1352   // If it wasn't auto/decltype or macro, look for decls and expressions.
1353   if (!HI) {
1354     auto Offset = SM.getFileOffset(*CurLoc);
1355     // Editors send the position on the left of the hovered character.
1356     // So our selection tree should be biased right. (Tested with VSCode).
1357     SelectionTree ST =
1358         SelectionTree::createRight(AST.getASTContext(), TB, Offset, Offset);
1359     if (const SelectionTree::Node *N = ST.commonAncestor()) {
1360       // FIXME: Fill in HighlightRange with range coming from N->ASTNode.
1361       auto Decls = explicitReferenceTargets(N->ASTNode, DeclRelation::Alias,
1362                                             AST.getHeuristicResolver());
1363       if (const auto *DeclToUse = pickDeclToUse(Decls)) {
1364         HoverCountMetric.record(1, "decl");
1365         HI = getHoverContents(DeclToUse, PP, Index, TB);
1366         // Layout info only shown when hovering on the field/class itself.
1367         if (DeclToUse == N->ASTNode.get<Decl>())
1368           addLayoutInfo(*DeclToUse, *HI);
1369         // Look for a close enclosing expression to show the value of.
1370         if (!HI->Value)
1371           HI->Value = printExprValue(N, AST.getASTContext()).PrintedValue;
1372         maybeAddCalleeArgInfo(N, *HI, PP);
1373
1374         if (!isa<NamespaceDecl>(DeclToUse))
1375           maybeAddSymbolProviders(AST, *HI,
1376                                   include_cleaner::Symbol{*DeclToUse});
1377       } else if (const Expr *E = N->ASTNode.get<Expr>()) {
1378         HoverCountMetric.record(1, "expr");
1379         HI = getHoverContents(N, E, AST, PP, Index);
1380       } else if (const Attr *A = N->ASTNode.get<Attr>()) {
1381         HoverCountMetric.record(1, "attribute");
1382         HI = getHoverContents(A, AST);
1383       }
1384       // FIXME: support hovers for other nodes?
1385       //  - built-in types
1386     }
1387   }
1388
1389   if (!HI)
1390     return std::nullopt;
1391
1392   // Reformat Definition
1393   if (!HI->Definition.empty()) {
1394     auto Replacements = format::reformat(
1395         Style, HI->Definition, tooling::Range(0, HI->Definition.size()));
1396     if (auto Formatted =
1397             tooling::applyAllReplacements(HI->Definition, Replacements))
1398       HI->Definition = *Formatted;
1399   }
1400
1401   HI->DefinitionLanguage = getMarkdownLanguage(AST.getASTContext());
1402   HI->SymRange = halfOpenToRange(SM, HighlightRange);
1403
1404   return HI;
1405 }
1406
1407 // Sizes (and padding) are shown in bytes if possible, otherwise in bits.
1408 static std::string formatSize(uint64_t SizeInBits) {
1409   uint64_t Value = SizeInBits % 8 == 0 ? SizeInBits / 8 : SizeInBits;
1410   const char *Unit = Value != 0 && Value == SizeInBits ? "bit" : "byte";
1411   return llvm::formatv("{0} {1}{2}", Value, Unit, Value == 1 ? "" : "s").str();
1412 }
1413
1414 // Offsets are shown in bytes + bits, so offsets of different fields
1415 // can always be easily compared.
1416 static std::string formatOffset(uint64_t OffsetInBits) {
1417   const auto Bytes = OffsetInBits / 8;
1418   const auto Bits = OffsetInBits % 8;
1419   auto Offset = formatSize(Bytes * 8);
1420   if (Bits != 0)
1421     Offset += " and " + formatSize(Bits);
1422   return Offset;
1423 }
1424
1425 markup::Document HoverInfo::present() const {
1426   markup::Document Output;
1427
1428   // Header contains a text of the form:
1429   // variable `var`
1430   //
1431   // class `X`
1432   //
1433   // function `foo`
1434   //
1435   // expression
1436   //
1437   // Note that we are making use of a level-3 heading because VSCode renders
1438   // level 1 and 2 headers in a huge font, see
1439   // https://github.com/microsoft/vscode/issues/88417 for details.
1440   markup::Paragraph &Header = Output.addHeading(3);
1441   if (Kind != index::SymbolKind::Unknown)
1442     Header.appendText(index::getSymbolKindString(Kind)).appendSpace();
1443   assert(!Name.empty() && "hover triggered on a nameless symbol");
1444   Header.appendCode(Name);
1445
1446   if (!Provider.empty()) {
1447     markup::Paragraph &DI = Output.addParagraph();
1448     DI.appendText("provided by");
1449     DI.appendSpace();
1450     DI.appendCode(Provider);
1451     Output.addRuler();
1452   }
1453
1454   // Put a linebreak after header to increase readability.
1455   Output.addRuler();
1456   // Print Types on their own lines to reduce chances of getting line-wrapped by
1457   // editor, as they might be long.
1458   if (ReturnType) {
1459     // For functions we display signature in a list form, e.g.:
1460     // → `x`
1461     // Parameters:
1462     // - `bool param1`
1463     // - `int param2 = 5`
1464     Output.addParagraph().appendText("→ ").appendCode(
1465         llvm::to_string(*ReturnType));
1466   }
1467
1468   if (Parameters && !Parameters->empty()) {
1469     Output.addParagraph().appendText("Parameters: ");
1470     markup::BulletList &L = Output.addBulletList();
1471     for (const auto &Param : *Parameters)
1472       L.addItem().addParagraph().appendCode(llvm::to_string(Param));
1473   }
1474
1475   // Don't print Type after Parameters or ReturnType as this will just duplicate
1476   // the information
1477   if (Type && !ReturnType && !Parameters)
1478     Output.addParagraph().appendText("Type: ").appendCode(
1479         llvm::to_string(*Type));
1480
1481   if (Value) {
1482     markup::Paragraph &P = Output.addParagraph();
1483     P.appendText("Value = ");
1484     P.appendCode(*Value);
1485   }
1486
1487   if (Offset)
1488     Output.addParagraph().appendText("Offset: " + formatOffset(*Offset));
1489   if (Size) {
1490     auto &P = Output.addParagraph().appendText("Size: " + formatSize(*Size));
1491     if (Padding && *Padding != 0) {
1492       P.appendText(
1493           llvm::formatv(" (+{0} padding)", formatSize(*Padding)).str());
1494     }
1495     if (Align)
1496       P.appendText(", alignment " + formatSize(*Align));
1497   }
1498
1499   if (CalleeArgInfo) {
1500     assert(CallPassType);
1501     std::string Buffer;
1502     llvm::raw_string_ostream OS(Buffer);
1503     OS << "Passed ";
1504     if (CallPassType->PassBy != HoverInfo::PassType::Value) {
1505       OS << "by ";
1506       if (CallPassType->PassBy == HoverInfo::PassType::ConstRef)
1507         OS << "const ";
1508       OS << "reference ";
1509     }
1510     if (CalleeArgInfo->Name)
1511       OS << "as " << CalleeArgInfo->Name;
1512     else if (CallPassType->PassBy == HoverInfo::PassType::Value)
1513       OS << "by value";
1514     if (CallPassType->Converted && CalleeArgInfo->Type)
1515       OS << " (converted to " << CalleeArgInfo->Type->Type << ")";
1516     Output.addParagraph().appendText(OS.str());
1517   }
1518
1519   if (!Documentation.empty())
1520     parseDocumentation(Documentation, Output);
1521
1522   if (!Definition.empty()) {
1523     Output.addRuler();
1524     std::string Buffer;
1525
1526     if (!Definition.empty()) {
1527       // Append scope comment, dropping trailing "::".
1528       // Note that we don't print anything for global namespace, to not annoy
1529       // non-c++ projects or projects that are not making use of namespaces.
1530       if (!LocalScope.empty()) {
1531         // Container name, e.g. class, method, function.
1532         // We might want to propagate some info about container type to print
1533         // function foo, class X, method X::bar, etc.
1534         Buffer +=
1535             "// In " + llvm::StringRef(LocalScope).rtrim(':').str() + '\n';
1536       } else if (NamespaceScope && !NamespaceScope->empty()) {
1537         Buffer += "// In namespace " +
1538                   llvm::StringRef(*NamespaceScope).rtrim(':').str() + '\n';
1539       }
1540
1541       if (!AccessSpecifier.empty()) {
1542         Buffer += AccessSpecifier + ": ";
1543       }
1544
1545       Buffer += Definition;
1546     }
1547
1548     Output.addCodeBlock(Buffer, DefinitionLanguage);
1549   }
1550
1551   if (!UsedSymbolNames.empty()) {
1552     Output.addRuler();
1553     markup::Paragraph &P = Output.addParagraph();
1554     P.appendText("provides ");
1555
1556     const std::vector<std::string>::size_type SymbolNamesLimit = 5;
1557     auto Front = llvm::ArrayRef(UsedSymbolNames).take_front(SymbolNamesLimit);
1558
1559     llvm::interleave(
1560         Front, [&](llvm::StringRef Sym) { P.appendCode(Sym); },
1561         [&] { P.appendText(", "); });
1562     if (UsedSymbolNames.size() > Front.size()) {
1563       P.appendText(" and ");
1564       P.appendText(std::to_string(UsedSymbolNames.size() - Front.size()));
1565       P.appendText(" more");
1566     }
1567   }
1568
1569   return Output;
1570 }
1571
1572 // If the backtick at `Offset` starts a probable quoted range, return the range
1573 // (including the quotes).
1574 std::optional<llvm::StringRef> getBacktickQuoteRange(llvm::StringRef Line,
1575                                                      unsigned Offset) {
1576   assert(Line[Offset] == '`');
1577
1578   // The open-quote is usually preceded by whitespace.
1579   llvm::StringRef Prefix = Line.substr(0, Offset);
1580   constexpr llvm::StringLiteral BeforeStartChars = " \t(=";
1581   if (!Prefix.empty() && !BeforeStartChars.contains(Prefix.back()))
1582     return std::nullopt;
1583
1584   // The quoted string must be nonempty and usually has no leading/trailing ws.
1585   auto Next = Line.find('`', Offset + 1);
1586   if (Next == llvm::StringRef::npos)
1587     return std::nullopt;
1588   llvm::StringRef Contents = Line.slice(Offset + 1, Next);
1589   if (Contents.empty() || isWhitespace(Contents.front()) ||
1590       isWhitespace(Contents.back()))
1591     return std::nullopt;
1592
1593   // The close-quote is usually followed by whitespace or punctuation.
1594   llvm::StringRef Suffix = Line.substr(Next + 1);
1595   constexpr llvm::StringLiteral AfterEndChars = " \t)=.,;:";
1596   if (!Suffix.empty() && !AfterEndChars.contains(Suffix.front()))
1597     return std::nullopt;
1598
1599   return Line.slice(Offset, Next + 1);
1600 }
1601
1602 void parseDocumentationLine(llvm::StringRef Line, markup::Paragraph &Out) {
1603   // Probably this is appendText(Line), but scan for something interesting.
1604   for (unsigned I = 0; I < Line.size(); ++I) {
1605     switch (Line[I]) {
1606     case '`':
1607       if (auto Range = getBacktickQuoteRange(Line, I)) {
1608         Out.appendText(Line.substr(0, I));
1609         Out.appendCode(Range->trim("`"), /*Preserve=*/true);
1610         return parseDocumentationLine(Line.substr(I + Range->size()), Out);
1611       }
1612       break;
1613     }
1614   }
1615   Out.appendText(Line).appendSpace();
1616 }
1617
1618 void parseDocumentation(llvm::StringRef Input, markup::Document &Output) {
1619   std::vector<llvm::StringRef> ParagraphLines;
1620   auto FlushParagraph = [&] {
1621     if (ParagraphLines.empty())
1622       return;
1623     auto &P = Output.addParagraph();
1624     for (llvm::StringRef Line : ParagraphLines)
1625       parseDocumentationLine(Line, P);
1626     ParagraphLines.clear();
1627   };
1628
1629   llvm::StringRef Line, Rest;
1630   for (std::tie(Line, Rest) = Input.split('\n');
1631        !(Line.empty() && Rest.empty());
1632        std::tie(Line, Rest) = Rest.split('\n')) {
1633
1634     // After a linebreak remove spaces to avoid 4 space markdown code blocks.
1635     // FIXME: make FlushParagraph handle this.
1636     Line = Line.ltrim();
1637     if (!Line.empty())
1638       ParagraphLines.push_back(Line);
1639
1640     if (isParagraphBreak(Rest) || isHardLineBreakAfter(Line, Rest)) {
1641       FlushParagraph();
1642     }
1643   }
1644   FlushParagraph();
1645 }
1646
1647 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
1648                               const HoverInfo::PrintedType &T) {
1649   OS << T.Type;
1650   if (T.AKA)
1651     OS << " (aka " << *T.AKA << ")";
1652   return OS;
1653 }
1654
1655 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
1656                               const HoverInfo::Param &P) {
1657   if (P.Type)
1658     OS << P.Type->Type;
1659   if (P.Name)
1660     OS << " " << *P.Name;
1661   if (P.Default)
1662     OS << " = " << *P.Default;
1663   if (P.Type && P.Type->AKA)
1664     OS << " (aka " << *P.Type->AKA << ")";
1665   return OS;
1666 }
1667
1668 } // namespace clangd
1669 } // namespace clang