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   uint64_t Bits = V.getZExtValue();
 412   if (V.isNegative() && V.getSignificantBits() <= 32)
 413     return llvm::format_hex(uint32_t(Bits), 0);
 414   return llvm::format_hex(Bits, 0);
 415 }
 416
 417 std::optional<std::string> printExprValue(const Expr *E,
 418                                           const ASTContext &Ctx) {
 419   // InitListExpr has two forms, syntactic and semantic. They are the same thing
 420   // (refer to a same AST node) in most cases.
 421   // When they are different, RAV returns the syntactic form, and we should feed
 422   // the semantic form to EvaluateAsRValue.
 423   if (const auto *ILE = llvm::dyn_cast<InitListExpr>(E)) {
 424     if (!ILE->isSemanticForm())
 425       E = ILE->getSemanticForm();
 426   }
 427
 428   // Evaluating [[foo]]() as "&foo" isn't useful, and prevents us walking up
 429   // to the enclosing call. Evaluating an expression of void type doesn't
 430   // produce a meaningful result.
 431   QualType T = E->getType();
 432   if (T.isNull() || T->isFunctionType() || T->isFunctionPointerType() ||
 433       T->isFunctionReferenceType() || T->isVoidType())
 434     return std::nullopt;
 435
 436   Expr::EvalResult Constant;
 437   // Attempt to evaluate. If expr is dependent, evaluation crashes!
 438   if (E->isValueDependent() || !E->EvaluateAsRValue(Constant, Ctx) ||
 439       // Disable printing for record-types, as they are usually confusing and
 440       // might make clang crash while printing the expressions.
 441       Constant.Val.isStruct() || Constant.Val.isUnion())
 442     return std::nullopt;
 443
 444   // Show enums symbolically, not numerically like APValue::printPretty().
 445   if (T->isEnumeralType() && Constant.Val.isInt() &&
 446       Constant.Val.getInt().getSignificantBits() <= 64) {
 447     // Compare to int64_t to avoid bit-width match requirements.
 448     int64_t Val = Constant.Val.getInt().getExtValue();
 449     for (const EnumConstantDecl *ECD :
 450          T->castAs<EnumType>()->getDecl()->enumerators())
 451       if (ECD->getInitVal() == Val)
 452         return llvm::formatv("{0} ({1})", ECD->getNameAsString(),
 453                              printHex(Constant.Val.getInt()))
 454             .str();
 455   }
 456   // Show hex value of integers if they're at least 10 (or negative!)
 457   if (T->isIntegralOrEnumerationType() && Constant.Val.isInt() &&
 458       Constant.Val.getInt().getSignificantBits() <= 64 &&
 459       Constant.Val.getInt().uge(10))
 460     return llvm::formatv("{0} ({1})", Constant.Val.getAsString(Ctx, T),
 461                          printHex(Constant.Val.getInt()))
 462         .str();
 463   return Constant.Val.getAsString(Ctx, T);
 464 }
 465
 466 struct PrintExprResult {
 467   /// The evaluation result on expression `Expr`.
 468   std::optional<std::string> PrintedValue;
 469   /// The Expr object that represents the closest evaluable
 470   /// expression.
 471   const clang::Expr *TheExpr;
 472   /// The node of selection tree where the traversal stops.
 473   const SelectionTree::Node *TheNode;
 474 };
 475
 476 // Seek the closest evaluable expression along the ancestors of node N
 477 // in a selection tree. If a node in the path can be converted to an evaluable
 478 // Expr, a possible evaluation would happen and the associated context
 479 // is returned.
 480 // If evaluation couldn't be done, return the node where the traversal ends.
 481 PrintExprResult printExprValue(const SelectionTree::Node *N,
 482                                const ASTContext &Ctx) {
 483   for (; N; N = N->Parent) {
 484     // Try to evaluate the first evaluatable enclosing expression.
 485     if (const Expr *E = N->ASTNode.get<Expr>()) {
 486       // Once we cross an expression of type 'cv void', the evaluated result
 487       // has nothing to do with our original cursor position.
 488       if (!E->getType().isNull() && E->getType()->isVoidType())
 489         break;
 490       if (auto Val = printExprValue(E, Ctx))
 491         return PrintExprResult{/*PrintedValue=*/std::move(Val), /*Expr=*/E,
 492                                /*Node=*/N};
 493     } else if (N->ASTNode.get<Decl>() || N->ASTNode.get<Stmt>()) {
 494       // Refuse to cross certain non-exprs. (TypeLoc are OK as part of Exprs).
 495       // This tries to ensure we're showing a value related to the cursor.
 496       break;
 497     }
 498   }
 499   return PrintExprResult{/*PrintedValue=*/std::nullopt, /*Expr=*/nullptr,
 500                          /*Node=*/N};
 501 }
 502
 503 std::optional<StringRef> fieldName(const Expr *E) {
 504   const auto *ME = llvm::dyn_cast<MemberExpr>(E->IgnoreCasts());
 505   if (!ME || !llvm::isa<CXXThisExpr>(ME->getBase()->IgnoreCasts()))
 506     return std::nullopt;
 507   const auto *Field = llvm::dyn_cast<FieldDecl>(ME->getMemberDecl());
 508   if (!Field || !Field->getDeclName().isIdentifier())
 509     return std::nullopt;
 510   return Field->getDeclName().getAsIdentifierInfo()->getName();
 511 }
 512
 513 // If CMD is of the form T foo() { return FieldName; } then returns "FieldName".
 514 std::optional<StringRef> getterVariableName(const CXXMethodDecl *CMD) {
 515   assert(CMD->hasBody());
 516   if (CMD->getNumParams() != 0 || CMD->isVariadic())
 517     return std::nullopt;
 518   const auto *Body = llvm::dyn_cast<CompoundStmt>(CMD->getBody());
 519   const auto *OnlyReturn = (Body && Body->size() == 1)
 520                                ? llvm::dyn_cast<ReturnStmt>(Body->body_front())
 521                                : nullptr;
 522   if (!OnlyReturn || !OnlyReturn->getRetValue())
 523     return std::nullopt;
 524   return fieldName(OnlyReturn->getRetValue());
 525 }
 526
 527 // If CMD is one of the forms:
 528 //   void foo(T arg) { FieldName = arg; }
 529 //   R foo(T arg) { FieldName = arg; return *this; }
 530 //   void foo(T arg) { FieldName = std::move(arg); }
 531 //   R foo(T arg) { FieldName = std::move(arg); return *this; }
 532 // then returns "FieldName"
 533 std::optional<StringRef> setterVariableName(const CXXMethodDecl *CMD) {
 534   assert(CMD->hasBody());
 535   if (CMD->isConst() || CMD->getNumParams() != 1 || CMD->isVariadic())
 536     return std::nullopt;
 537   const ParmVarDecl *Arg = CMD->getParamDecl(0);
 538   if (Arg->isParameterPack())
 539     return std::nullopt;
 540
 541   const auto *Body = llvm::dyn_cast<CompoundStmt>(CMD->getBody());
 542   if (!Body || Body->size() == 0 || Body->size() > 2)
 543     return std::nullopt;
 544   // If the second statement exists, it must be `return this` or `return *this`.
 545   if (Body->size() == 2) {
 546     auto *Ret = llvm::dyn_cast<ReturnStmt>(Body->body_back());
 547     if (!Ret || !Ret->getRetValue())
 548       return std::nullopt;
 549     const Expr *RetVal = Ret->getRetValue()->IgnoreCasts();
 550     if (const auto *UO = llvm::dyn_cast<UnaryOperator>(RetVal)) {
 551       if (UO->getOpcode() != UO_Deref)
 552         return std::nullopt;
 553       RetVal = UO->getSubExpr()->IgnoreCasts();
 554     }
 555     if (!llvm::isa<CXXThisExpr>(RetVal))
 556       return std::nullopt;
 557   }
 558   // The first statement must be an assignment of the arg to a field.
 559   const Expr *LHS, *RHS;
 560   if (const auto *BO = llvm::dyn_cast<BinaryOperator>(Body->body_front())) {
 561     if (BO->getOpcode() != BO_Assign)
 562       return std::nullopt;
 563     LHS = BO->getLHS();
 564     RHS = BO->getRHS();
 565   } else if (const auto *COCE =
 566                  llvm::dyn_cast<CXXOperatorCallExpr>(Body->body_front())) {
 567     if (COCE->getOperator() != OO_Equal || COCE->getNumArgs() != 2)
 568       return std::nullopt;
 569     LHS = COCE->getArg(0);
 570     RHS = COCE->getArg(1);
 571   } else {
 572     return std::nullopt;
 573   }
 574
 575   // Detect the case when the item is moved into the field.
 576   if (auto *CE = llvm::dyn_cast<CallExpr>(RHS->IgnoreCasts())) {
 577     if (CE->getNumArgs() != 1)
 578       return std::nullopt;
 579     auto *ND = llvm::dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl());
 580     if (!ND || !ND->getIdentifier() || ND->getName() != "move" ||
 581         !ND->isInStdNamespace())
 582       return std::nullopt;
 583     RHS = CE->getArg(0);
 584   }
 585
 586   auto *DRE = llvm::dyn_cast<DeclRefExpr>(RHS->IgnoreCasts());
 587   if (!DRE || DRE->getDecl() != Arg)
 588     return std::nullopt;
 589   return fieldName(LHS);
 590 }
 591
 592 std::string synthesizeDocumentation(const NamedDecl *ND) {
 593   if (const auto *CMD = llvm::dyn_cast<CXXMethodDecl>(ND)) {
 594     // Is this an ordinary, non-static method whose definition is visible?
 595     if (CMD->getDeclName().isIdentifier() && !CMD->isStatic() &&
 596         (CMD = llvm::dyn_cast_or_null<CXXMethodDecl>(CMD->getDefinition())) &&
 597         CMD->hasBody()) {
 598       if (const auto GetterField = getterVariableName(CMD))
 599         return llvm::formatv("Trivial accessor for `{0}`.", *GetterField);
 600       if (const auto SetterField = setterVariableName(CMD))
 601         return llvm::formatv("Trivial setter for `{0}`.", *SetterField);
 602     }
 603   }
 604   return "";
 605 }
 606
 607 /// Generate a \p Hover object given the declaration \p D.
 608 HoverInfo getHoverContents(const NamedDecl *D, const PrintingPolicy &PP,
 609                            const SymbolIndex *Index,
 610                            const syntax::TokenBuffer &TB) {
 611   HoverInfo HI;
 612   auto &Ctx = D->getASTContext();
 613
 614   HI.AccessSpecifier = getAccessSpelling(D->getAccess()).str();
 615   HI.NamespaceScope = getNamespaceScope(D);
 616   if (!HI.NamespaceScope->empty())
 617     HI.NamespaceScope->append("::");
 618   HI.LocalScope = getLocalScope(D);
 619   if (!HI.LocalScope.empty())
 620     HI.LocalScope.append("::");
 621
 622   HI.Name = printName(Ctx, *D);
 623   const auto *CommentD = getDeclForComment(D);
 624   HI.Documentation = getDeclComment(Ctx, *CommentD);
 625   enhanceFromIndex(HI, *CommentD, Index);
 626   if (HI.Documentation.empty())
 627     HI.Documentation = synthesizeDocumentation(D);
 628
 629   HI.Kind = index::getSymbolInfo(D).Kind;
 630
 631   // Fill in template params.
 632   if (const TemplateDecl *TD = D->getDescribedTemplate()) {
 633     HI.TemplateParameters =
 634         fetchTemplateParameters(TD->getTemplateParameters(), PP);
 635     D = TD;
 636   } else if (const FunctionDecl *FD = D->getAsFunction()) {
 637     if (const auto *FTD = FD->getDescribedTemplate()) {
 638       HI.TemplateParameters =
 639           fetchTemplateParameters(FTD->getTemplateParameters(), PP);
 640       D = FTD;
 641     }
 642   }
 643
 644   // Fill in types and params.
 645   if (const FunctionDecl *FD = getUnderlyingFunction(D))
 646     fillFunctionTypeAndParams(HI, D, FD, PP);
 647   else if (const auto *VD = dyn_cast<ValueDecl>(D))
 648     HI.Type = printType(VD->getType(), Ctx, PP);
 649   else if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(D))
 650     HI.Type = TTP->wasDeclaredWithTypename() ? "typename" : "class";
 651   else if (const auto *TTP = dyn_cast<TemplateTemplateParmDecl>(D))
 652     HI.Type = printType(TTP, PP);
 653   else if (const auto *VT = dyn_cast<VarTemplateDecl>(D))
 654     HI.Type = printType(VT->getTemplatedDecl()->getType(), Ctx, PP);
 655   else if (const auto *TN = dyn_cast<TypedefNameDecl>(D))
 656     HI.Type = printType(TN->getUnderlyingType().getDesugaredType(Ctx), Ctx, PP);
 657   else if (const auto *TAT = dyn_cast<TypeAliasTemplateDecl>(D))
 658     HI.Type = printType(TAT->getTemplatedDecl()->getUnderlyingType(), Ctx, PP);
 659
 660   // Fill in value with evaluated initializer if possible.
 661   if (const auto *Var = dyn_cast<VarDecl>(D); Var && !Var->isInvalidDecl()) {
 662     if (const Expr *Init = Var->getInit())
 663       HI.Value = printExprValue(Init, Ctx);
 664   } else if (const auto *ECD = dyn_cast<EnumConstantDecl>(D)) {
 665     // Dependent enums (e.g. nested in template classes) don't have values yet.
 666     if (!ECD->getType()->isDependentType())
 667       HI.Value = toString(ECD->getInitVal(), 10);
 668   }
 669
 670   HI.Definition = printDefinition(D, PP, TB);
 671   return HI;
 672 }
 673
 674 /// The standard defines __func__ as a "predefined variable".
 675 std::optional<HoverInfo>
 676 getPredefinedExprHoverContents(const PredefinedExpr &PE, ASTContext &Ctx,
 677                                const PrintingPolicy &PP) {
 678   HoverInfo HI;
 679   HI.Name = PE.getIdentKindName();
 680   HI.Kind = index::SymbolKind::Variable;
 681   HI.Documentation = "Name of the current function (predefined variable)";
 682   if (const StringLiteral *Name = PE.getFunctionName()) {
 683     HI.Value.emplace();
 684     llvm::raw_string_ostream OS(*HI.Value);
 685     Name->outputString(OS);
 686     HI.Type = printType(Name->getType(), Ctx, PP);
 687   } else {
 688     // Inside templates, the approximate type `const char[]` is still useful.
 689     QualType StringType = Ctx.getIncompleteArrayType(Ctx.CharTy.withConst(),
 690                                                      ArraySizeModifier::Normal,
 691                                                      /*IndexTypeQuals=*/0);
 692     HI.Type = printType(StringType, Ctx, PP);
 693   }
 694   return HI;
 695 }
 696
 697 HoverInfo evaluateMacroExpansion(unsigned int SpellingBeginOffset,
 698                                  unsigned int SpellingEndOffset,
 699                                  llvm::ArrayRef<syntax::Token> Expanded,
 700                                  ParsedAST &AST) {
 701   auto &Context = AST.getASTContext();
 702   auto &Tokens = AST.getTokens();
 703   auto PP = getPrintingPolicy(Context.getPrintingPolicy());
 704   auto Tree = SelectionTree::createRight(Context, Tokens, SpellingBeginOffset,
 705                                          SpellingEndOffset);
 706
 707   // If macro expands to one single token, rule out punctuator or digraph.
 708   // E.g., for the case `array L_BRACKET 42 R_BRACKET;` where L_BRACKET and
 709   // R_BRACKET expand to
 710   // '[' and ']' respectively, we don't want the type of
 711   // 'array[42]' when user hovers on L_BRACKET.
 712   if (Expanded.size() == 1)
 713     if (tok::getPunctuatorSpelling(Expanded[0].kind()))
 714       return {};
 715
 716   auto *StartNode = Tree.commonAncestor();
 717   if (!StartNode)
 718     return {};
 719   // If the common ancestor is partially selected, do evaluate if it has no
 720   // children, thus we can disallow evaluation on incomplete expression.
 721   // For example,
 722   // #define PLUS_2 +2
 723   // 40 PL^US_2
 724   // In this case we don't want to present 'value: 2' as PLUS_2 actually expands
 725   // to a non-value rather than a binary operand.
 726   if (StartNode->Selected == SelectionTree::Selection::Partial)
 727     if (!StartNode->Children.empty())
 728       return {};
 729
 730   HoverInfo HI;
 731   // Attempt to evaluate it from Expr first.
 732   auto ExprResult = printExprValue(StartNode, Context);
 733   HI.Value = std::move(ExprResult.PrintedValue);
 734   if (auto *E = ExprResult.TheExpr)
 735     HI.Type = printType(E->getType(), Context, PP);
 736
 737   // If failed, extract the type from Decl if possible.
 738   if (!HI.Value && !HI.Type && ExprResult.TheNode)
 739     if (auto *VD = ExprResult.TheNode->ASTNode.get<VarDecl>())
 740       HI.Type = printType(VD->getType(), Context, PP);
 741
 742   return HI;
 743 }
 744
 745 /// Generate a \p Hover object given the macro \p MacroDecl.
 746 HoverInfo getHoverContents(const DefinedMacro &Macro, const syntax::Token &Tok,
 747                            ParsedAST &AST) {
 748   HoverInfo HI;
 749   SourceManager &SM = AST.getSourceManager();
 750   HI.Name = std::string(Macro.Name);
 751   HI.Kind = index::SymbolKind::Macro;
 752   // FIXME: Populate documentation
 753   // FIXME: Populate parameters
 754
 755   // Try to get the full definition, not just the name
 756   SourceLocation StartLoc = Macro.Info->getDefinitionLoc();
 757   SourceLocation EndLoc = Macro.Info->getDefinitionEndLoc();
 758   // Ensure that EndLoc is a valid offset. For example it might come from
 759   // preamble, and source file might've changed, in such a scenario EndLoc still
 760   // stays valid, but getLocForEndOfToken will fail as it is no longer a valid
 761   // offset.
 762   // Note that this check is just to ensure there's text data inside the range.
 763   // It will still succeed even when the data inside the range is irrelevant to
 764   // macro definition.
 765   if (SM.getPresumedLoc(EndLoc, /*UseLineDirectives=*/false).isValid()) {
 766     EndLoc = Lexer::getLocForEndOfToken(EndLoc, 0, SM, AST.getLangOpts());
 767     bool Invalid;
 768     StringRef Buffer = SM.getBufferData(SM.getFileID(StartLoc), &Invalid);
 769     if (!Invalid) {
 770       unsigned StartOffset = SM.getFileOffset(StartLoc);
 771       unsigned EndOffset = SM.getFileOffset(EndLoc);
 772       if (EndOffset <= Buffer.size() && StartOffset < EndOffset)
 773         HI.Definition =
 774             ("#define " + Buffer.substr(StartOffset, EndOffset - StartOffset))
 775                 .str();
 776     }
 777   }
 778
 779   if (auto Expansion = AST.getTokens().expansionStartingAt(&Tok)) {
 780     // We drop expansion that's longer than the threshold.
 781     // For extremely long expansion text, it's not readable from hover card
 782     // anyway.
 783     std::string ExpansionText;
 784     for (const auto &ExpandedTok : Expansion->Expanded) {
 785       ExpansionText += ExpandedTok.text(SM);
 786       ExpansionText += " ";
 787       if (ExpansionText.size() > 2048) {
 788         ExpansionText.clear();
 789         break;
 790       }
 791     }
 792
 793     if (!ExpansionText.empty()) {
 794       if (!HI.Definition.empty()) {
 795         HI.Definition += "\n\n";
 796       }
 797       HI.Definition += "// Expands to\n";
 798       HI.Definition += ExpansionText;
 799     }
 800
 801     auto Evaluated = evaluateMacroExpansion(
 802         /*SpellingBeginOffset=*/SM.getFileOffset(Tok.location()),
 803         /*SpellingEndOffset=*/SM.getFileOffset(Tok.endLocation()),
 804         /*Expanded=*/Expansion->Expanded, AST);
 805     HI.Value = std::move(Evaluated.Value);
 806     HI.Type = std::move(Evaluated.Type);
 807   }
 808   return HI;
 809 }
 810
 811 std::string typeAsDefinition(const HoverInfo::PrintedType &PType) {
 812   std::string Result;
 813   llvm::raw_string_ostream OS(Result);
 814   OS << PType.Type;
 815   if (PType.AKA)
 816     OS << " // aka: " << *PType.AKA;
 817   OS.flush();
 818   return Result;
 819 }
 820
 821 std::optional<HoverInfo> getThisExprHoverContents(const CXXThisExpr *CTE,
 822                                                   ASTContext &ASTCtx,
 823                                                   const PrintingPolicy &PP) {
 824   QualType OriginThisType = CTE->getType()->getPointeeType();
 825   QualType ClassType = declaredType(OriginThisType->getAsTagDecl());
 826   // For partial specialization class, origin `this` pointee type will be
 827   // parsed as `InjectedClassNameType`, which will ouput template arguments
 828   // like "type-parameter-0-0". So we retrieve user written class type in this
 829   // case.
 830   QualType PrettyThisType = ASTCtx.getPointerType(
 831       QualType(ClassType.getTypePtr(), OriginThisType.getCVRQualifiers()));
 832
 833   HoverInfo HI;
 834   HI.Name = "this";
 835   HI.Definition = typeAsDefinition(printType(PrettyThisType, ASTCtx, PP));
 836   return HI;
 837 }
 838
 839 /// Generate a HoverInfo object given the deduced type \p QT
 840 HoverInfo getDeducedTypeHoverContents(QualType QT, const syntax::Token &Tok,
 841                                       ASTContext &ASTCtx,
 842                                       const PrintingPolicy &PP,
 843                                       const SymbolIndex *Index) {
 844   HoverInfo HI;
 845   // FIXME: distinguish decltype(auto) vs decltype(expr)
 846   HI.Name = tok::getTokenName(Tok.kind());
 847   HI.Kind = index::SymbolKind::TypeAlias;
 848
 849   if (QT->isUndeducedAutoType()) {
 850     HI.Definition = "/* not deduced */";
 851   } else {
 852     HI.Definition = typeAsDefinition(printType(QT, ASTCtx, PP));
 853
 854     if (const auto *D = QT->getAsTagDecl()) {
 855       const auto *CommentD = getDeclForComment(D);
 856       HI.Documentation = getDeclComment(ASTCtx, *CommentD);
 857       enhanceFromIndex(HI, *CommentD, Index);
 858     }
 859   }
 860
 861   return HI;
 862 }
 863
 864 HoverInfo getStringLiteralContents(const StringLiteral *SL,
 865                                    const PrintingPolicy &PP) {
 866   HoverInfo HI;
 867
 868   HI.Name = "string-literal";
 869   HI.Size = (SL->getLength() + 1) * SL->getCharByteWidth() * 8;
 870   HI.Type = SL->getType().getAsString(PP).c_str();
 871
 872   return HI;
 873 }
 874
 875 bool isLiteral(const Expr *E) {
 876   // Unfortunately there's no common base Literal classes inherits from
 877   // (apart from Expr), therefore these exclusions.
 878   return llvm::isa<CompoundLiteralExpr>(E) ||
 879          llvm::isa<CXXBoolLiteralExpr>(E) ||
 880          llvm::isa<CXXNullPtrLiteralExpr>(E) ||
 881          llvm::isa<FixedPointLiteral>(E) || llvm::isa<FloatingLiteral>(E) ||
 882          llvm::isa<ImaginaryLiteral>(E) || llvm::isa<IntegerLiteral>(E) ||
 883          llvm::isa<StringLiteral>(E) || llvm::isa<UserDefinedLiteral>(E);
 884 }
 885
 886 llvm::StringLiteral getNameForExpr(const Expr *E) {
 887   // FIXME: Come up with names for `special` expressions.
 888   //
 889   // It's an known issue for GCC5, https://godbolt.org/z/Z_tbgi. Work around
 890   // that by using explicit conversion constructor.
 891   //
 892   // TODO: Once GCC5 is fully retired and not the minimal requirement as stated
 893   // in `GettingStarted`, please remove the explicit conversion constructor.
 894   return llvm::StringLiteral("expression");
 895 }
 896
 897 void maybeAddCalleeArgInfo(const SelectionTree::Node *N, HoverInfo &HI,
 898                            const PrintingPolicy &PP);
 899
 900 // Generates hover info for `this` and evaluatable expressions.
 901 // FIXME: Support hover for literals (esp user-defined)
 902 std::optional<HoverInfo> getHoverContents(const SelectionTree::Node *N,
 903                                           const Expr *E, ParsedAST &AST,
 904                                           const PrintingPolicy &PP,
 905                                           const SymbolIndex *Index) {
 906   std::optional<HoverInfo> HI;
 907
 908   if (const StringLiteral *SL = dyn_cast<StringLiteral>(E)) {
 909     // Print the type and the size for string literals
 910     HI = getStringLiteralContents(SL, PP);
 911   } else if (isLiteral(E)) {
 912     // There's not much value in hovering over "42" and getting a hover card
 913     // saying "42 is an int", similar for most other literals.
 914     // However, if we have CalleeArgInfo, it's still useful to show it.
 915     maybeAddCalleeArgInfo(N, HI.emplace(), PP);
 916     if (HI->CalleeArgInfo) {
 917       // FIXME Might want to show the expression's value here instead?
 918       // E.g. if the literal is in hex it might be useful to show the decimal
 919       // value here.
 920       HI->Name = "literal";
 921       return HI;
 922     }
 923     return std::nullopt;
 924   }
 925
 926   // For `this` expr we currently generate hover with pointee type.
 927   if (const CXXThisExpr *CTE = dyn_cast<CXXThisExpr>(E))
 928     HI = getThisExprHoverContents(CTE, AST.getASTContext(), PP);
 929   if (const PredefinedExpr *PE = dyn_cast<PredefinedExpr>(E))
 930     HI = getPredefinedExprHoverContents(*PE, AST.getASTContext(), PP);
 931   // For expressions we currently print the type and the value, iff it is
 932   // evaluatable.
 933   if (auto Val = printExprValue(E, AST.getASTContext())) {
 934     HI.emplace();
 935     HI->Type = printType(E->getType(), AST.getASTContext(), PP);
 936     HI->Value = *Val;
 937     HI->Name = std::string(getNameForExpr(E));
 938   }
 939
 940   if (HI)
 941     maybeAddCalleeArgInfo(N, *HI, PP);
 942
 943   return HI;
 944 }
 945
 946 // Generates hover info for attributes.
 947 std::optional<HoverInfo> getHoverContents(const Attr *A, ParsedAST &AST) {
 948   HoverInfo HI;
 949   HI.Name = A->getSpelling();
 950   if (A->hasScope())
 951     HI.LocalScope = A->getScopeName()->getName().str();
 952   {
 953     llvm::raw_string_ostream OS(HI.Definition);
 954     A->printPretty(OS, AST.getASTContext().getPrintingPolicy());
 955   }
 956   HI.Documentation = Attr::getDocumentation(A->getKind()).str();
 957   return HI;
 958 }
 959
 960 bool isParagraphBreak(llvm::StringRef Rest) {
 961   return Rest.ltrim(" \t").startswith("\n");
 962 }
 963
 964 bool punctuationIndicatesLineBreak(llvm::StringRef Line) {
 965   constexpr llvm::StringLiteral Punctuation = R"txt(.:,;!?)txt";
 966
 967   Line = Line.rtrim();
 968   return !Line.empty() && Punctuation.contains(Line.back());
 969 }
 970
 971 bool isHardLineBreakIndicator(llvm::StringRef Rest) {
 972   // '-'/'*' md list, '@'/'\' documentation command, '>' md blockquote,
 973   // '#' headings, '`' code blocks
 974   constexpr llvm::StringLiteral LinebreakIndicators = R"txt(-*@\>#`)txt";
 975
 976   Rest = Rest.ltrim(" \t");
 977   if (Rest.empty())
 978     return false;
 979
 980   if (LinebreakIndicators.contains(Rest.front()))
 981     return true;
 982
 983   if (llvm::isDigit(Rest.front())) {
 984     llvm::StringRef AfterDigit = Rest.drop_while(llvm::isDigit);
 985     if (AfterDigit.startswith(".") || AfterDigit.startswith(")"))
 986       return true;
 987   }
 988   return false;
 989 }
 990
 991 bool isHardLineBreakAfter(llvm::StringRef Line, llvm::StringRef Rest) {
 992   // Should we also consider whether Line is short?
 993   return punctuationIndicatesLineBreak(Line) || isHardLineBreakIndicator(Rest);
 994 }
 995
 996 void addLayoutInfo(const NamedDecl &ND, HoverInfo &HI) {
 997   if (ND.isInvalidDecl())
 998     return;
 999
1000   const auto &Ctx = ND.getASTContext();
1001   if (auto *RD = llvm::dyn_cast<RecordDecl>(&ND)) {
1002     if (auto Size = Ctx.getTypeSizeInCharsIfKnown(RD->getTypeForDecl()))
1003       HI.Size = Size->getQuantity() * 8;
1004     if (!RD->isDependentType() && RD->isCompleteDefinition())
1005       HI.Align = Ctx.getTypeAlign(RD->getTypeForDecl());
1006     return;
1007   }
1008
1009   if (const auto *FD = llvm::dyn_cast<FieldDecl>(&ND)) {
1010     const auto *Record = FD->getParent();
1011     if (Record)
1012       Record = Record->getDefinition();
1013     if (Record && !Record->isInvalidDecl() && !Record->isDependentType()) {
1014       HI.Align = Ctx.getTypeAlign(FD->getType());
1015       const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Record);
1016       HI.Offset = Layout.getFieldOffset(FD->getFieldIndex());
1017       if (FD->isBitField())
1018         HI.Size = FD->getBitWidthValue(Ctx);
1019       else if (auto Size = Ctx.getTypeSizeInCharsIfKnown(FD->getType()))
1020         HI.Size = FD->isZeroSize(Ctx) ? 0 : Size->getQuantity() * 8;
1021       if (HI.Size) {
1022         unsigned EndOfField = *HI.Offset + *HI.Size;
1023
1024         // Calculate padding following the field.
1025         if (!Record->isUnion() &&
1026             FD->getFieldIndex() + 1 < Layout.getFieldCount()) {
1027           // Measure padding up to the next class field.
1028           unsigned NextOffset = Layout.getFieldOffset(FD->getFieldIndex() + 1);
1029           if (NextOffset >= EndOfField) // next field could be a bitfield!
1030             HI.Padding = NextOffset - EndOfField;
1031         } else {
1032           // Measure padding up to the end of the object.
1033           HI.Padding = Layout.getSize().getQuantity() * 8 - EndOfField;
1034         }
1035       }
1036       // Offset in a union is always zero, so not really useful to report.
1037       if (Record->isUnion())
1038         HI.Offset.reset();
1039     }
1040     return;
1041   }
1042 }
1043
1044 HoverInfo::PassType::PassMode getPassMode(QualType ParmType) {
1045   if (ParmType->isReferenceType()) {
1046     if (ParmType->getPointeeType().isConstQualified())
1047       return HoverInfo::PassType::ConstRef;
1048     return HoverInfo::PassType::Ref;
1049   }
1050   return HoverInfo::PassType::Value;
1051 }
1052
1053 // If N is passed as argument to a function, fill HI.CalleeArgInfo with
1054 // information about that argument.
1055 void maybeAddCalleeArgInfo(const SelectionTree::Node *N, HoverInfo &HI,
1056                            const PrintingPolicy &PP) {
1057   const auto &OuterNode = N->outerImplicit();
1058   if (!OuterNode.Parent)
1059     return;
1060
1061   const FunctionDecl *FD = nullptr;
1062   llvm::ArrayRef<const Expr *> Args;
1063
1064   if (const auto *CE = OuterNode.Parent->ASTNode.get<CallExpr>()) {
1065     FD = CE->getDirectCallee();
1066     Args = {CE->getArgs(), CE->getNumArgs()};
1067   } else if (const auto *CE =
1068                  OuterNode.Parent->ASTNode.get<CXXConstructExpr>()) {
1069     FD = CE->getConstructor();
1070     Args = {CE->getArgs(), CE->getNumArgs()};
1071   }
1072   if (!FD)
1073     return;
1074
1075   // For non-function-call-like operators (e.g. operator+, operator<<) it's
1076   // not immediately obvious what the "passed as" would refer to and, given
1077   // fixed function signature, the value would be very low anyway, so we choose
1078   // to not support that.
1079   // Both variadic functions and operator() (especially relevant for lambdas)
1080   // should be supported in the future.
1081   if (!FD || FD->isOverloadedOperator() || FD->isVariadic())
1082     return;
1083
1084   HoverInfo::PassType PassType;
1085
1086   auto Parameters = resolveForwardingParameters(FD);
1087
1088   // Find argument index for N.
1089   for (unsigned I = 0; I < Args.size() && I < Parameters.size(); ++I) {
1090     if (Args[I] != OuterNode.ASTNode.get<Expr>())
1091       continue;
1092
1093     // Extract matching argument from function declaration.
1094     if (const ParmVarDecl *PVD = Parameters[I]) {
1095       HI.CalleeArgInfo.emplace(toHoverInfoParam(PVD, PP));
1096       if (N == &OuterNode)
1097         PassType.PassBy = getPassMode(PVD->getType());
1098     }
1099     break;
1100   }
1101   if (!HI.CalleeArgInfo)
1102     return;
1103
1104   // If we found a matching argument, also figure out if it's a
1105   // [const-]reference. For this we need to walk up the AST from the arg itself
1106   // to CallExpr and check all implicit casts, constructor calls, etc.
1107   if (const auto *E = N->ASTNode.get<Expr>()) {
1108     if (E->getType().isConstQualified())
1109       PassType.PassBy = HoverInfo::PassType::ConstRef;
1110   }
1111
1112   for (auto *CastNode = N->Parent;
1113        CastNode != OuterNode.Parent && !PassType.Converted;
1114        CastNode = CastNode->Parent) {
1115     if (const auto *ImplicitCast = CastNode->ASTNode.get<ImplicitCastExpr>()) {
1116       switch (ImplicitCast->getCastKind()) {
1117       case CK_NoOp:
1118       case CK_DerivedToBase:
1119       case CK_UncheckedDerivedToBase:
1120         // If it was a reference before, it's still a reference.
1121         if (PassType.PassBy != HoverInfo::PassType::Value)
1122           PassType.PassBy = ImplicitCast->getType().isConstQualified()
1123                                 ? HoverInfo::PassType::ConstRef
1124                                 : HoverInfo::PassType::Ref;
1125         break;
1126       case CK_LValueToRValue:
1127       case CK_ArrayToPointerDecay:
1128       case CK_FunctionToPointerDecay:
1129       case CK_NullToPointer:
1130       case CK_NullToMemberPointer:
1131         // No longer a reference, but we do not show this as type conversion.
1132         PassType.PassBy = HoverInfo::PassType::Value;
1133         break;
1134       default:
1135         PassType.PassBy = HoverInfo::PassType::Value;
1136         PassType.Converted = true;
1137         break;
1138       }
1139     } else if (const auto *CtorCall =
1140                    CastNode->ASTNode.get<CXXConstructExpr>()) {
1141       // We want to be smart about copy constructors. They should not show up as
1142       // type conversion, but instead as passing by value.
1143       if (CtorCall->getConstructor()->isCopyConstructor())
1144         PassType.PassBy = HoverInfo::PassType::Value;
1145       else
1146         PassType.Converted = true;
1147     } else if (CastNode->ASTNode.get<MaterializeTemporaryExpr>()) {
1148       // Can't bind a non-const-ref to a temporary, so has to be const-ref
1149       PassType.PassBy = HoverInfo::PassType::ConstRef;
1150     } else { // Unknown implicit node, assume type conversion.
1151       PassType.PassBy = HoverInfo::PassType::Value;
1152       PassType.Converted = true;
1153     }
1154   }
1155
1156   HI.CallPassType.emplace(PassType);
1157 }
1158
1159 const NamedDecl *pickDeclToUse(llvm::ArrayRef<const NamedDecl *> Candidates) {
1160   if (Candidates.empty())
1161     return nullptr;
1162
1163   // This is e.g the case for
1164   //     namespace ns { void foo(); }
1165   //     void bar() { using ns::foo; f^oo(); }
1166   // One declaration in Candidates will refer to the using declaration,
1167   // which isn't really useful for Hover. So use the other one,
1168   // which in this example would be the actual declaration of foo.
1169   if (Candidates.size() <= 2) {
1170     if (llvm::isa<UsingDecl>(Candidates.front()))
1171       return Candidates.back();
1172     return Candidates.front();
1173   }
1174
1175   // For something like
1176   //     namespace ns { void foo(int); void foo(char); }
1177   //     using ns::foo;
1178   //     template <typename T> void bar() { fo^o(T{}); }
1179   // we actually want to show the using declaration,
1180   // it's not clear which declaration to pick otherwise.
1181   auto BaseDecls = llvm::make_filter_range(
1182       Candidates, [](const NamedDecl *D) { return llvm::isa<UsingDecl>(D); });
1183   if (std::distance(BaseDecls.begin(), BaseDecls.end()) == 1)
1184     return *BaseDecls.begin();
1185
1186   return Candidates.front();
1187 }
1188
1189 void maybeAddSymbolProviders(ParsedAST &AST, HoverInfo &HI,
1190                              include_cleaner::Symbol Sym) {
1191   trace::Span Tracer("Hover::maybeAddSymbolProviders");
1192
1193   const SourceManager &SM = AST.getSourceManager();
1194   llvm::SmallVector<include_cleaner::Header> RankedProviders =
1195       include_cleaner::headersForSymbol(Sym, SM, AST.getPragmaIncludes().get());
1196   if (RankedProviders.empty())
1197     return;
1198
1199   std::string Result;
1200   include_cleaner::Includes ConvertedIncludes = convertIncludes(AST);
1201   for (const auto &P : RankedProviders) {
1202     if (P.kind() == include_cleaner::Header::Physical &&
1203         P.physical() == SM.getFileEntryForID(SM.getMainFileID()))
1204       // Main file ranked higher than any #include'd file
1205       break;
1206
1207     // Pick the best-ranked #include'd provider
1208     auto Matches = ConvertedIncludes.match(P);
1209     if (!Matches.empty()) {
1210       Result = Matches[0]->quote();
1211       break;
1212     }
1213   }
1214
1215   if (!Result.empty()) {
1216     HI.Provider = std::move(Result);
1217     return;
1218   }
1219
1220   // Pick the best-ranked non-#include'd provider
1221   const auto &H = RankedProviders.front();
1222   if (H.kind() == include_cleaner::Header::Physical &&
1223       H.physical() == SM.getFileEntryForID(SM.getMainFileID()))
1224     // Do not show main file as provider, otherwise we'll show provider info
1225     // on local variables, etc.
1226     return;
1227
1228   HI.Provider = include_cleaner::spellHeader(
1229       {H, AST.getPreprocessor().getHeaderSearchInfo(),
1230        SM.getFileEntryForID(SM.getMainFileID())});
1231 }
1232
1233 // FIXME: similar functions are present in FindHeaders.cpp (symbolName)
1234 // and IncludeCleaner.cpp (getSymbolName). Introduce a name() method into
1235 // include_cleaner::Symbol instead.
1236 std::string getSymbolName(include_cleaner::Symbol Sym) {
1237   std::string Name;
1238   switch (Sym.kind()) {
1239   case include_cleaner::Symbol::Declaration:
1240     if (const auto *ND = llvm::dyn_cast<NamedDecl>(&Sym.declaration()))
1241       Name = ND->getDeclName().getAsString();
1242     break;
1243   case include_cleaner::Symbol::Macro:
1244     Name = Sym.macro().Name->getName();
1245     break;
1246   }
1247   return Name;
1248 }
1249
1250 void maybeAddUsedSymbols(ParsedAST &AST, HoverInfo &HI, const Inclusion &Inc) {
1251   auto Converted = convertIncludes(AST);
1252   llvm::DenseSet<include_cleaner::Symbol> UsedSymbols;
1253   include_cleaner::walkUsed(
1254       AST.getLocalTopLevelDecls(), collectMacroReferences(AST),
1255       AST.getPragmaIncludes().get(), AST.getPreprocessor(),
1256       [&](const include_cleaner::SymbolReference &Ref,
1257           llvm::ArrayRef<include_cleaner::Header> Providers) {
1258         if (Ref.RT != include_cleaner::RefType::Explicit ||
1259             UsedSymbols.contains(Ref.Target))
1260           return;
1261
1262         if (isPreferredProvider(Inc, Converted, Providers))
1263           UsedSymbols.insert(Ref.Target);
1264       });
1265
1266   for (const auto &UsedSymbolDecl : UsedSymbols)
1267     HI.UsedSymbolNames.push_back(getSymbolName(UsedSymbolDecl));
1268   llvm::sort(HI.UsedSymbolNames);
1269   HI.UsedSymbolNames.erase(
1270       std::unique(HI.UsedSymbolNames.begin(), HI.UsedSymbolNames.end()),
1271       HI.UsedSymbolNames.end());
1272 }
1273
1274 } // namespace
1275
1276 std::optional<HoverInfo> getHover(ParsedAST &AST, Position Pos,
1277                                   const format::FormatStyle &Style,
1278                                   const SymbolIndex *Index) {
1279   static constexpr trace::Metric HoverCountMetric(
1280       "hover", trace::Metric::Counter, "case");
1281   PrintingPolicy PP =
1282       getPrintingPolicy(AST.getASTContext().getPrintingPolicy());
1283   const SourceManager &SM = AST.getSourceManager();
1284   auto CurLoc = sourceLocationInMainFile(SM, Pos);
1285   if (!CurLoc) {
1286     llvm::consumeError(CurLoc.takeError());
1287     return std::nullopt;
1288   }
1289   const auto &TB = AST.getTokens();
1290   auto TokensTouchingCursor = syntax::spelledTokensTouching(*CurLoc, TB);
1291   // Early exit if there were no tokens around the cursor.
1292   if (TokensTouchingCursor.empty())
1293     return std::nullopt;
1294
1295   // Show full header file path if cursor is on include directive.
1296   for (const auto &Inc : AST.getIncludeStructure().MainFileIncludes) {
1297     if (Inc.Resolved.empty() || Inc.HashLine != Pos.line)
1298       continue;
1299     HoverCountMetric.record(1, "include");
1300     HoverInfo HI;
1301     HI.Name = std::string(llvm::sys::path::filename(Inc.Resolved));
1302     // FIXME: We don't have a fitting value for Kind.
1303     HI.Definition =
1304         URIForFile::canonicalize(Inc.Resolved, AST.tuPath()).file().str();
1305     HI.DefinitionLanguage = "";
1306     maybeAddUsedSymbols(AST, HI, Inc);
1307     return HI;
1308   }
1309
1310   // To be used as a backup for highlighting the selected token, we use back as
1311   // it aligns better with biases elsewhere (editors tend to send the position
1312   // for the left of the hovered token).
1313   CharSourceRange HighlightRange =
1314       TokensTouchingCursor.back().range(SM).toCharRange(SM);
1315   std::optional<HoverInfo> HI;
1316   // Macros and deducedtype only works on identifiers and auto/decltype keywords
1317   // respectively. Therefore they are only trggered on whichever works for them,
1318   // similar to SelectionTree::create().
1319   for (const auto &Tok : TokensTouchingCursor) {
1320     if (Tok.kind() == tok::identifier) {
1321       // Prefer the identifier token as a fallback highlighting range.
1322       HighlightRange = Tok.range(SM).toCharRange(SM);
1323       if (auto M = locateMacroAt(Tok, AST.getPreprocessor())) {
1324         HoverCountMetric.record(1, "macro");
1325         HI = getHoverContents(*M, Tok, AST);
1326         if (auto DefLoc = M->Info->getDefinitionLoc(); DefLoc.isValid()) {
1327           include_cleaner::Macro IncludeCleanerMacro{
1328               AST.getPreprocessor().getIdentifierInfo(Tok.text(SM)), DefLoc};
1329           maybeAddSymbolProviders(AST, *HI,
1330                                   include_cleaner::Symbol{IncludeCleanerMacro});
1331         }
1332         break;
1333       }
1334     } else if (Tok.kind() == tok::kw_auto || Tok.kind() == tok::kw_decltype) {
1335       HoverCountMetric.record(1, "keyword");
1336       if (auto Deduced = getDeducedType(AST.getASTContext(), Tok.location())) {
1337         HI = getDeducedTypeHoverContents(*Deduced, Tok, AST.getASTContext(), PP,
1338                                          Index);
1339         HighlightRange = Tok.range(SM).toCharRange(SM);
1340         break;
1341       }
1342
1343       // If we can't find interesting hover information for this
1344       // auto/decltype keyword, return nothing to avoid showing
1345       // irrelevant or incorrect informations.
1346       return std::nullopt;
1347     }
1348   }
1349
1350   // If it wasn't auto/decltype or macro, look for decls and expressions.
1351   if (!HI) {
1352     auto Offset = SM.getFileOffset(*CurLoc);
1353     // Editors send the position on the left of the hovered character.
1354     // So our selection tree should be biased right. (Tested with VSCode).
1355     SelectionTree ST =
1356         SelectionTree::createRight(AST.getASTContext(), TB, Offset, Offset);
1357     if (const SelectionTree::Node *N = ST.commonAncestor()) {
1358       // FIXME: Fill in HighlightRange with range coming from N->ASTNode.
1359       auto Decls = explicitReferenceTargets(N->ASTNode, DeclRelation::Alias,
1360                                             AST.getHeuristicResolver());
1361       if (const auto *DeclToUse = pickDeclToUse(Decls)) {
1362         HoverCountMetric.record(1, "decl");
1363         HI = getHoverContents(DeclToUse, PP, Index, TB);
1364         // Layout info only shown when hovering on the field/class itself.
1365         if (DeclToUse == N->ASTNode.get<Decl>())
1366           addLayoutInfo(*DeclToUse, *HI);
1367         // Look for a close enclosing expression to show the value of.
1368         if (!HI->Value)
1369           HI->Value = printExprValue(N, AST.getASTContext()).PrintedValue;
1370         maybeAddCalleeArgInfo(N, *HI, PP);
1371
1372         if (!isa<NamespaceDecl>(DeclToUse))
1373           maybeAddSymbolProviders(AST, *HI,
1374                                   include_cleaner::Symbol{*DeclToUse});
1375       } else if (const Expr *E = N->ASTNode.get<Expr>()) {
1376         HoverCountMetric.record(1, "expr");
1377         HI = getHoverContents(N, E, AST, PP, Index);
1378       } else if (const Attr *A = N->ASTNode.get<Attr>()) {
1379         HoverCountMetric.record(1, "attribute");
1380         HI = getHoverContents(A, AST);
1381       }
1382       // FIXME: support hovers for other nodes?
1383       //  - built-in types
1384     }
1385   }
1386
1387   if (!HI)
1388     return std::nullopt;
1389
1390   // Reformat Definition
1391   if (!HI->Definition.empty()) {
1392     auto Replacements = format::reformat(
1393         Style, HI->Definition, tooling::Range(0, HI->Definition.size()));
1394     if (auto Formatted =
1395             tooling::applyAllReplacements(HI->Definition, Replacements))
1396       HI->Definition = *Formatted;
1397   }
1398
1399   HI->DefinitionLanguage = getMarkdownLanguage(AST.getASTContext());
1400   HI->SymRange = halfOpenToRange(SM, HighlightRange);
1401
1402   return HI;
1403 }
1404
1405 // Sizes (and padding) are shown in bytes if possible, otherwise in bits.
1406 static std::string formatSize(uint64_t SizeInBits) {
1407   uint64_t Value = SizeInBits % 8 == 0 ? SizeInBits / 8 : SizeInBits;
1408   const char *Unit = Value != 0 && Value == SizeInBits ? "bit" : "byte";
1409   return llvm::formatv("{0} {1}{2}", Value, Unit, Value == 1 ? "" : "s").str();
1410 }
1411
1412 // Offsets are shown in bytes + bits, so offsets of different fields
1413 // can always be easily compared.
1414 static std::string formatOffset(uint64_t OffsetInBits) {
1415   const auto Bytes = OffsetInBits / 8;
1416   const auto Bits = OffsetInBits % 8;
1417   auto Offset = formatSize(Bytes * 8);
1418   if (Bits != 0)
1419     Offset += " and " + formatSize(Bits);
1420   return Offset;
1421 }
1422
1423 markup::Document HoverInfo::present() const {
1424   markup::Document Output;
1425
1426   // Header contains a text of the form:
1427   // variable `var`
1428   //
1429   // class `X`
1430   //
1431   // function `foo`
1432   //
1433   // expression
1434   //
1435   // Note that we are making use of a level-3 heading because VSCode renders
1436   // level 1 and 2 headers in a huge font, see
1437   // https://github.com/microsoft/vscode/issues/88417 for details.
1438   markup::Paragraph &Header = Output.addHeading(3);
1439   if (Kind != index::SymbolKind::Unknown)
1440     Header.appendText(index::getSymbolKindString(Kind)).appendSpace();
1441   assert(!Name.empty() && "hover triggered on a nameless symbol");
1442   Header.appendCode(Name);
1443
1444   if (!Provider.empty()) {
1445     markup::Paragraph &DI = Output.addParagraph();
1446     DI.appendText("provided by");
1447     DI.appendSpace();
1448     DI.appendCode(Provider);
1449     Output.addRuler();
1450   }
1451
1452   // Put a linebreak after header to increase readability.
1453   Output.addRuler();
1454   // Print Types on their own lines to reduce chances of getting line-wrapped by
1455   // editor, as they might be long.
1456   if (ReturnType) {
1457     // For functions we display signature in a list form, e.g.:
1458     // → `x`
1459     // Parameters:
1460     // - `bool param1`
1461     // - `int param2 = 5`
1462     Output.addParagraph().appendText("→ ").appendCode(
1463         llvm::to_string(*ReturnType));
1464   }
1465
1466   if (Parameters && !Parameters->empty()) {
1467     Output.addParagraph().appendText("Parameters: ");
1468     markup::BulletList &L = Output.addBulletList();
1469     for (const auto &Param : *Parameters)
1470       L.addItem().addParagraph().appendCode(llvm::to_string(Param));
1471   }
1472
1473   // Don't print Type after Parameters or ReturnType as this will just duplicate
1474   // the information
1475   if (Type && !ReturnType && !Parameters)
1476     Output.addParagraph().appendText("Type: ").appendCode(
1477         llvm::to_string(*Type));
1478
1479   if (Value) {
1480     markup::Paragraph &P = Output.addParagraph();
1481     P.appendText("Value = ");
1482     P.appendCode(*Value);
1483   }
1484
1485   if (Offset)
1486     Output.addParagraph().appendText("Offset: " + formatOffset(*Offset));
1487   if (Size) {
1488     auto &P = Output.addParagraph().appendText("Size: " + formatSize(*Size));
1489     if (Padding && *Padding != 0) {
1490       P.appendText(
1491           llvm::formatv(" (+{0} padding)", formatSize(*Padding)).str());
1492     }
1493     if (Align)
1494       P.appendText(", alignment " + formatSize(*Align));
1495   }
1496
1497   if (CalleeArgInfo) {
1498     assert(CallPassType);
1499     std::string Buffer;
1500     llvm::raw_string_ostream OS(Buffer);
1501     OS << "Passed ";
1502     if (CallPassType->PassBy != HoverInfo::PassType::Value) {
1503       OS << "by ";
1504       if (CallPassType->PassBy == HoverInfo::PassType::ConstRef)
1505         OS << "const ";
1506       OS << "reference ";
1507     }
1508     if (CalleeArgInfo->Name)
1509       OS << "as " << CalleeArgInfo->Name;
1510     else if (CallPassType->PassBy == HoverInfo::PassType::Value)
1511       OS << "by value";
1512     if (CallPassType->Converted && CalleeArgInfo->Type)
1513       OS << " (converted to " << CalleeArgInfo->Type->Type << ")";
1514     Output.addParagraph().appendText(OS.str());
1515   }
1516
1517   if (!Documentation.empty())
1518     parseDocumentation(Documentation, Output);
1519
1520   if (!Definition.empty()) {
1521     Output.addRuler();
1522     std::string Buffer;
1523
1524     if (!Definition.empty()) {
1525       // Append scope comment, dropping trailing "::".
1526       // Note that we don't print anything for global namespace, to not annoy
1527       // non-c++ projects or projects that are not making use of namespaces.
1528       if (!LocalScope.empty()) {
1529         // Container name, e.g. class, method, function.
1530         // We might want to propagate some info about container type to print
1531         // function foo, class X, method X::bar, etc.
1532         Buffer +=
1533             "// In " + llvm::StringRef(LocalScope).rtrim(':').str() + '\n';
1534       } else if (NamespaceScope && !NamespaceScope->empty()) {
1535         Buffer += "// In namespace " +
1536                   llvm::StringRef(*NamespaceScope).rtrim(':').str() + '\n';
1537       }
1538
1539       if (!AccessSpecifier.empty()) {
1540         Buffer += AccessSpecifier + ": ";
1541       }
1542
1543       Buffer += Definition;
1544     }
1545
1546     Output.addCodeBlock(Buffer, DefinitionLanguage);
1547   }
1548
1549   if (!UsedSymbolNames.empty()) {
1550     Output.addRuler();
1551     markup::Paragraph &P = Output.addParagraph();
1552     P.appendText("provides ");
1553
1554     const std::vector<std::string>::size_type SymbolNamesLimit = 5;
1555     auto Front = llvm::ArrayRef(UsedSymbolNames).take_front(SymbolNamesLimit);
1556
1557     llvm::interleave(
1558         Front, [&](llvm::StringRef Sym) { P.appendCode(Sym); },
1559         [&] { P.appendText(", "); });
1560     if (UsedSymbolNames.size() > Front.size()) {
1561       P.appendText(" and ");
1562       P.appendText(std::to_string(UsedSymbolNames.size() - Front.size()));
1563       P.appendText(" more");
1564     }
1565   }
1566
1567   return Output;
1568 }
1569
1570 // If the backtick at `Offset` starts a probable quoted range, return the range
1571 // (including the quotes).
1572 std::optional<llvm::StringRef> getBacktickQuoteRange(llvm::StringRef Line,
1573                                                      unsigned Offset) {
1574   assert(Line[Offset] == '`');
1575
1576   // The open-quote is usually preceded by whitespace.
1577   llvm::StringRef Prefix = Line.substr(0, Offset);
1578   constexpr llvm::StringLiteral BeforeStartChars = " \t(=";
1579   if (!Prefix.empty() && !BeforeStartChars.contains(Prefix.back()))
1580     return std::nullopt;
1581
1582   // The quoted string must be nonempty and usually has no leading/trailing ws.
1583   auto Next = Line.find('`', Offset + 1);
1584   if (Next == llvm::StringRef::npos)
1585     return std::nullopt;
1586   llvm::StringRef Contents = Line.slice(Offset + 1, Next);
1587   if (Contents.empty() || isWhitespace(Contents.front()) ||
1588       isWhitespace(Contents.back()))
1589     return std::nullopt;
1590
1591   // The close-quote is usually followed by whitespace or punctuation.
1592   llvm::StringRef Suffix = Line.substr(Next + 1);
1593   constexpr llvm::StringLiteral AfterEndChars = " \t)=.,;:";
1594   if (!Suffix.empty() && !AfterEndChars.contains(Suffix.front()))
1595     return std::nullopt;
1596
1597   return Line.slice(Offset, Next + 1);
1598 }
1599
1600 void parseDocumentationLine(llvm::StringRef Line, markup::Paragraph &Out) {
1601   // Probably this is appendText(Line), but scan for something interesting.
1602   for (unsigned I = 0; I < Line.size(); ++I) {
1603     switch (Line[I]) {
1604     case '`':
1605       if (auto Range = getBacktickQuoteRange(Line, I)) {
1606         Out.appendText(Line.substr(0, I));
1607         Out.appendCode(Range->trim("`"), /*Preserve=*/true);
1608         return parseDocumentationLine(Line.substr(I + Range->size()), Out);
1609       }
1610       break;
1611     }
1612   }
1613   Out.appendText(Line).appendSpace();
1614 }
1615
1616 void parseDocumentation(llvm::StringRef Input, markup::Document &Output) {
1617   std::vector<llvm::StringRef> ParagraphLines;
1618   auto FlushParagraph = [&] {
1619     if (ParagraphLines.empty())
1620       return;
1621     auto &P = Output.addParagraph();
1622     for (llvm::StringRef Line : ParagraphLines)
1623       parseDocumentationLine(Line, P);
1624     ParagraphLines.clear();
1625   };
1626
1627   llvm::StringRef Line, Rest;
1628   for (std::tie(Line, Rest) = Input.split('\n');
1629        !(Line.empty() && Rest.empty());
1630        std::tie(Line, Rest) = Rest.split('\n')) {
1631
1632     // After a linebreak remove spaces to avoid 4 space markdown code blocks.
1633     // FIXME: make FlushParagraph handle this.
1634     Line = Line.ltrim();
1635     if (!Line.empty())
1636       ParagraphLines.push_back(Line);
1637
1638     if (isParagraphBreak(Rest) || isHardLineBreakAfter(Line, Rest)) {
1639       FlushParagraph();
1640     }
1641   }
1642   FlushParagraph();
1643 }
1644
1645 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
1646                               const HoverInfo::PrintedType &T) {
1647   OS << T.Type;
1648   if (T.AKA)
1649     OS << " (aka " << *T.AKA << ")";
1650   return OS;
1651 }
1652
1653 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
1654                               const HoverInfo::Param &P) {
1655   if (P.Type)
1656     OS << P.Type->Type;
1657   if (P.Name)
1658     OS << " " << *P.Name;
1659   if (P.Default)
1660     OS << " = " << *P.Default;
1661   if (P.Type && P.Type->AKA)
1662     OS << " (aka " << *P.Type->AKA << ")";
1663   return OS;
1664 }
1665
1666 } // namespace clangd
1667 } // namespace clang