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llvm-project/clang-tools-extra/clangd/Hover.cpp

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//===--- Hover.cpp - Information about code at the cursor location --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "Hover.h"
#include "AST.h"
#include "CodeCompletionStrings.h"
#include "FindTarget.h"
#include "ParsedAST.h"
#include "Selection.h"
#include "SourceCode.h"
#include "index/SymbolCollector.h"
#include "support/Logger.h"
#include "support/Markup.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTTypeTraits.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/OperationKinds.h"
#include "clang/AST/PrettyPrinter.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/Type.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/Specifiers.h"
#include "clang/Basic/TokenKinds.h"
#include "clang/Index/IndexSymbol.h"
#include "clang/Tooling/Syntax/Tokens.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <string>
namespace clang {
namespace clangd {
namespace {
PrintingPolicy getPrintingPolicy(PrintingPolicy Base) {
Base.AnonymousTagLocations = false;
Base.TerseOutput = true;
Base.PolishForDeclaration = true;
Base.ConstantsAsWritten = true;
Base.SuppressTemplateArgsInCXXConstructors = true;
return Base;
}
/// Given a declaration \p D, return a human-readable string representing the
/// local scope in which it is declared, i.e. class(es) and method name. Returns
/// an empty string if it is not local.
std::string getLocalScope(const Decl *D) {
std::vector<std::string> Scopes;
const DeclContext *DC = D->getDeclContext();
// ObjC scopes won't have multiple components for us to join, instead:
// - Methods: "-[Class methodParam1:methodParam2]"
// - Classes, categories, and protocols: "MyClass(Category)"
if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(DC))
return printObjCMethod(*MD);
else if (const ObjCContainerDecl *CD = dyn_cast<ObjCContainerDecl>(DC))
return printObjCContainer(*CD);
auto GetName = [](const TypeDecl *D) {
if (!D->getDeclName().isEmpty()) {
PrintingPolicy Policy = D->getASTContext().getPrintingPolicy();
Policy.SuppressScope = true;
return declaredType(D).getAsString(Policy);
}
if (auto RD = dyn_cast<RecordDecl>(D))
return ("(anonymous " + RD->getKindName() + ")").str();
return std::string("");
};
while (DC) {
if (const TypeDecl *TD = dyn_cast<TypeDecl>(DC))
Scopes.push_back(GetName(TD));
else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
Scopes.push_back(FD->getNameAsString());
DC = DC->getParent();
}
return llvm::join(llvm::reverse(Scopes), "::");
}
/// Returns the human-readable representation for namespace containing the
/// declaration \p D. Returns empty if it is contained global namespace.
std::string getNamespaceScope(const Decl *D) {
const DeclContext *DC = D->getDeclContext();
// ObjC does not have the concept of namespaces, so instead we support
// local scopes.
if (isa<ObjCMethodDecl, ObjCContainerDecl>(DC))
return "";
if (const TagDecl *TD = dyn_cast<TagDecl>(DC))
return getNamespaceScope(TD);
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
return getNamespaceScope(FD);
if (const NamespaceDecl *NSD = dyn_cast<NamespaceDecl>(DC)) {
// Skip inline/anon namespaces.
if (NSD->isInline() || NSD->isAnonymousNamespace())
return getNamespaceScope(NSD);
}
if (const NamedDecl *ND = dyn_cast<NamedDecl>(DC))
return printQualifiedName(*ND);
return "";
}
std::string printDefinition(const Decl *D, const PrintingPolicy &PP) {
std::string Definition;
llvm::raw_string_ostream OS(Definition);
D->print(OS, PP);
OS.flush();
return Definition;
}
std::string printType(QualType QT, const PrintingPolicy &PP) {
// TypePrinter doesn't resolve decltypes, so resolve them here.
// FIXME: This doesn't handle composite types that contain a decltype in them.
// We should rather have a printing policy for that.
while (!QT.isNull() && QT->isDecltypeType())
QT = QT->getAs<DecltypeType>()->getUnderlyingType();
std::string Result;
llvm::raw_string_ostream OS(Result);
// Special case: if the outer type is a tag type without qualifiers, then
// include the tag for extra clarity.
// This isn't very idiomatic, so don't attempt it for complex cases, including
// pointers/references, template specializations, etc.
if (!QT.isNull() && !QT.hasQualifiers() && PP.SuppressTagKeyword) {
if (auto *TT = llvm::dyn_cast<TagType>(QT.getTypePtr()))
OS << TT->getDecl()->getKindName() << " ";
}
OS.flush();
QT.print(OS, PP);
return Result;
}
std::string printType(const TemplateTypeParmDecl *TTP) {
std::string Res = TTP->wasDeclaredWithTypename() ? "typename" : "class";
if (TTP->isParameterPack())
Res += "...";
return Res;
}
std::string printType(const NonTypeTemplateParmDecl *NTTP,
const PrintingPolicy &PP) {
std::string Res = printType(NTTP->getType(), PP);
if (NTTP->isParameterPack())
Res += "...";
return Res;
}
std::string printType(const TemplateTemplateParmDecl *TTP,
const PrintingPolicy &PP) {
std::string Res;
llvm::raw_string_ostream OS(Res);
OS << "template <";
llvm::StringRef Sep = "";
for (const Decl *Param : *TTP->getTemplateParameters()) {
OS << Sep;
Sep = ", ";
if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
OS << printType(TTP);
else if (const auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param))
OS << printType(NTTP, PP);
else if (const auto *TTPD = dyn_cast<TemplateTemplateParmDecl>(Param))
OS << printType(TTPD, PP);
}
// FIXME: TemplateTemplateParameter doesn't store the info on whether this
// param was a "typename" or "class".
OS << "> class";
return OS.str();
}
std::vector<HoverInfo::Param>
fetchTemplateParameters(const TemplateParameterList *Params,
const PrintingPolicy &PP) {
assert(Params);
std::vector<HoverInfo::Param> TempParameters;
for (const Decl *Param : *Params) {
HoverInfo::Param P;
if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(Param)) {
P.Type = printType(TTP);
if (!TTP->getName().empty())
P.Name = TTP->getNameAsString();
if (TTP->hasDefaultArgument())
P.Default = TTP->getDefaultArgument().getAsString(PP);
} else if (const auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
P.Type = printType(NTTP, PP);
if (IdentifierInfo *II = NTTP->getIdentifier())
P.Name = II->getName().str();
if (NTTP->hasDefaultArgument()) {
P.Default.emplace();
llvm::raw_string_ostream Out(*P.Default);
NTTP->getDefaultArgument()->printPretty(Out, nullptr, PP);
}
} else if (const auto *TTPD = dyn_cast<TemplateTemplateParmDecl>(Param)) {
P.Type = printType(TTPD, PP);
if (!TTPD->getName().empty())
P.Name = TTPD->getNameAsString();
if (TTPD->hasDefaultArgument()) {
P.Default.emplace();
llvm::raw_string_ostream Out(*P.Default);
TTPD->getDefaultArgument().getArgument().print(PP, Out);
}
}
TempParameters.push_back(std::move(P));
}
return TempParameters;
}
const FunctionDecl *getUnderlyingFunction(const Decl *D) {
// Extract lambda from variables.
if (const VarDecl *VD = llvm::dyn_cast<VarDecl>(D)) {
auto QT = VD->getType();
if (!QT.isNull()) {
while (!QT->getPointeeType().isNull())
QT = QT->getPointeeType();
if (const auto *CD = QT->getAsCXXRecordDecl())
return CD->getLambdaCallOperator();
}
}
// Non-lambda functions.
return D->getAsFunction();
}
// Returns the decl that should be used for querying comments, either from index
// or AST.
const NamedDecl *getDeclForComment(const NamedDecl *D) {
if (const auto *TSD = llvm::dyn_cast<ClassTemplateSpecializationDecl>(D)) {
// Template may not be instantiated e.g. if the type didn't need to be
// complete; fallback to primary template.
if (TSD->getTemplateSpecializationKind() == TSK_Undeclared)
return TSD->getSpecializedTemplate();
if (const auto *TIP = TSD->getTemplateInstantiationPattern())
return TIP;
}
if (const auto *TSD = llvm::dyn_cast<VarTemplateSpecializationDecl>(D)) {
if (TSD->getTemplateSpecializationKind() == TSK_Undeclared)
return TSD->getSpecializedTemplate();
if (const auto *TIP = TSD->getTemplateInstantiationPattern())
return TIP;
}
if (const auto *FD = D->getAsFunction())
if (const auto *TIP = FD->getTemplateInstantiationPattern())
return TIP;
return D;
}
// Look up information about D from the index, and add it to Hover.
void enhanceFromIndex(HoverInfo &Hover, const NamedDecl &ND,
const SymbolIndex *Index) {
assert(&ND == getDeclForComment(&ND));
// We only add documentation, so don't bother if we already have some.
if (!Hover.Documentation.empty() || !Index)
return;
// Skip querying for non-indexable symbols, there's no point.
// We're searching for symbols that might be indexed outside this main file.
if (!SymbolCollector::shouldCollectSymbol(ND, ND.getASTContext(),
SymbolCollector::Options(),
/*IsMainFileOnly=*/false))
return;
auto ID = getSymbolID(&ND);
if (!ID)
return;
LookupRequest Req;
Req.IDs.insert(ID);
Index->lookup(Req, [&](const Symbol &S) {
Hover.Documentation = std::string(S.Documentation);
});
}
// Default argument might exist but be unavailable, in the case of unparsed
// arguments for example. This function returns the default argument if it is
// available.
const Expr *getDefaultArg(const ParmVarDecl *PVD) {
// Default argument can be unparsed or uninstantiated. For the former we
// can't do much, as token information is only stored in Sema and not
// attached to the AST node. For the latter though, it is safe to proceed as
// the expression is still valid.
if (!PVD->hasDefaultArg() || PVD->hasUnparsedDefaultArg())
return nullptr;
return PVD->hasUninstantiatedDefaultArg() ? PVD->getUninstantiatedDefaultArg()
: PVD->getDefaultArg();
}
HoverInfo::Param toHoverInfoParam(const ParmVarDecl *PVD,
const PrintingPolicy &PP) {
HoverInfo::Param Out;
Out.Type = printType(PVD->getType(), PP);
if (!PVD->getName().empty())
Out.Name = PVD->getNameAsString();
if (const Expr *DefArg = getDefaultArg(PVD)) {
Out.Default.emplace();
llvm::raw_string_ostream OS(*Out.Default);
DefArg->printPretty(OS, nullptr, PP);
}
return Out;
}
// Populates Type, ReturnType, and Parameters for function-like decls.
void fillFunctionTypeAndParams(HoverInfo &HI, const Decl *D,
const FunctionDecl *FD,
const PrintingPolicy &PP) {
HI.Parameters.emplace();
for (const ParmVarDecl *PVD : FD->parameters())
HI.Parameters->emplace_back(toHoverInfoParam(PVD, PP));
// We don't want any type info, if name already contains it. This is true for
// constructors/destructors and conversion operators.
const auto NK = FD->getDeclName().getNameKind();
if (NK == DeclarationName::CXXConstructorName ||
NK == DeclarationName::CXXDestructorName ||
NK == DeclarationName::CXXConversionFunctionName)
return;
HI.ReturnType = printType(FD->getReturnType(), PP);
QualType QT = FD->getType();
if (const VarDecl *VD = llvm::dyn_cast<VarDecl>(D)) // Lambdas
QT = VD->getType().getDesugaredType(D->getASTContext());
HI.Type = printType(QT, PP);
// FIXME: handle variadics.
}
// Non-negative numbers are printed using min digits
// 0 => 0x0
// 100 => 0x64
// Negative numbers are sign-extended to 32/64 bits
// -2 => 0xfffffffe
// -2^32 => 0xfffffffeffffffff
static llvm::FormattedNumber printHex(const llvm::APSInt &V) {
uint64_t Bits = V.getExtValue();
if (V.isNegative() && V.getMinSignedBits() <= 32)
return llvm::format_hex(uint32_t(Bits), 0);
return llvm::format_hex(Bits, 0);
}
llvm::Optional<std::string> printExprValue(const Expr *E,
const ASTContext &Ctx) {
// InitListExpr has two forms, syntactic and semantic. They are the same thing
// (refer to a same AST node) in most cases.
// When they are different, RAV returns the syntactic form, and we should feed
// the semantic form to EvaluateAsRValue.
if (const auto *ILE = llvm::dyn_cast<InitListExpr>(E)) {
if (!ILE->isSemanticForm())
E = ILE->getSemanticForm();
}
// Evaluating [[foo]]() as "&foo" isn't useful, and prevents us walking up
// to the enclosing call. Evaluating an expression of void type doesn't
// produce a meaningful result.
QualType T = E->getType();
if (T.isNull() || T->isFunctionType() || T->isFunctionPointerType() ||
T->isFunctionReferenceType() || T->isVoidType())
return llvm::None;
Expr::EvalResult Constant;
// Attempt to evaluate. If expr is dependent, evaluation crashes!
if (E->isValueDependent() || !E->EvaluateAsRValue(Constant, Ctx) ||
// Disable printing for record-types, as they are usually confusing and
// might make clang crash while printing the expressions.
Constant.Val.isStruct() || Constant.Val.isUnion())
return llvm::None;
// Show enums symbolically, not numerically like APValue::printPretty().
if (T->isEnumeralType() && Constant.Val.getInt().getMinSignedBits() <= 64) {
// Compare to int64_t to avoid bit-width match requirements.
int64_t Val = Constant.Val.getInt().getExtValue();
for (const EnumConstantDecl *ECD :
T->castAs<EnumType>()->getDecl()->enumerators())
if (ECD->getInitVal() == Val)
return llvm::formatv("{0} ({1})", ECD->getNameAsString(),
printHex(Constant.Val.getInt()))
.str();
}
// Show hex value of integers if they're at least 10 (or negative!)
if (T->isIntegralOrEnumerationType() &&
Constant.Val.getInt().getMinSignedBits() <= 64 &&
Constant.Val.getInt().uge(10))
return llvm::formatv("{0} ({1})", Constant.Val.getAsString(Ctx, T),
printHex(Constant.Val.getInt()))
.str();
return Constant.Val.getAsString(Ctx, T);
}
llvm::Optional<std::string> printExprValue(const SelectionTree::Node *N,
const ASTContext &Ctx) {
for (; N; N = N->Parent) {
// Try to evaluate the first evaluatable enclosing expression.
if (const Expr *E = N->ASTNode.get<Expr>()) {
// Once we cross an expression of type 'cv void', the evaluated result
// has nothing to do with our original cursor position.
if (!E->getType().isNull() && E->getType()->isVoidType())
break;
if (auto Val = printExprValue(E, Ctx))
return Val;
} else if (N->ASTNode.get<Decl>() || N->ASTNode.get<Stmt>()) {
// Refuse to cross certain non-exprs. (TypeLoc are OK as part of Exprs).
// This tries to ensure we're showing a value related to the cursor.
break;
}
}
return llvm::None;
}
llvm::Optional<StringRef> fieldName(const Expr *E) {
const auto *ME = llvm::dyn_cast<MemberExpr>(E->IgnoreCasts());
if (!ME || !llvm::isa<CXXThisExpr>(ME->getBase()->IgnoreCasts()))
return llvm::None;
const auto *Field = llvm::dyn_cast<FieldDecl>(ME->getMemberDecl());
if (!Field || !Field->getDeclName().isIdentifier())
return llvm::None;
return Field->getDeclName().getAsIdentifierInfo()->getName();
}
// If CMD is of the form T foo() { return FieldName; } then returns "FieldName".
llvm::Optional<StringRef> getterVariableName(const CXXMethodDecl *CMD) {
assert(CMD->hasBody());
if (CMD->getNumParams() != 0 || CMD->isVariadic())
return llvm::None;
const auto *Body = llvm::dyn_cast<CompoundStmt>(CMD->getBody());
const auto *OnlyReturn = (Body && Body->size() == 1)
? llvm::dyn_cast<ReturnStmt>(Body->body_front())
: nullptr;
if (!OnlyReturn || !OnlyReturn->getRetValue())
return llvm::None;
return fieldName(OnlyReturn->getRetValue());
}
// If CMD is one of the forms:
// void foo(T arg) { FieldName = arg; }
// R foo(T arg) { FieldName = arg; return *this; }
// void foo(T arg) { FieldName = std::move(arg); }
// R foo(T arg) { FieldName = std::move(arg); return *this; }
// then returns "FieldName"
llvm::Optional<StringRef> setterVariableName(const CXXMethodDecl *CMD) {
assert(CMD->hasBody());
if (CMD->isConst() || CMD->getNumParams() != 1 || CMD->isVariadic())
return llvm::None;
const ParmVarDecl *Arg = CMD->getParamDecl(0);
if (Arg->isParameterPack())
return llvm::None;
const auto *Body = llvm::dyn_cast<CompoundStmt>(CMD->getBody());
if (!Body || Body->size() == 0 || Body->size() > 2)
return llvm::None;
// If the second statement exists, it must be `return this` or `return *this`.
if (Body->size() == 2) {
auto *Ret = llvm::dyn_cast<ReturnStmt>(Body->body_back());
if (!Ret || !Ret->getRetValue())
return llvm::None;
const Expr *RetVal = Ret->getRetValue()->IgnoreCasts();
if (const auto *UO = llvm::dyn_cast<UnaryOperator>(RetVal)) {
if (UO->getOpcode() != UO_Deref)
return llvm::None;
RetVal = UO->getSubExpr()->IgnoreCasts();
}
if (!llvm::isa<CXXThisExpr>(RetVal))
return llvm::None;
}
// The first statement must be an assignment of the arg to a field.
const Expr *LHS, *RHS;
if (const auto *BO = llvm::dyn_cast<BinaryOperator>(Body->body_front())) {
if (BO->getOpcode() != BO_Assign)
return llvm::None;
LHS = BO->getLHS();
RHS = BO->getRHS();
} else if (const auto *COCE =
llvm::dyn_cast<CXXOperatorCallExpr>(Body->body_front())) {
if (COCE->getOperator() != OO_Equal || COCE->getNumArgs() != 2)
return llvm::None;
LHS = COCE->getArg(0);
RHS = COCE->getArg(1);
} else {
return llvm::None;
}
// Detect the case when the item is moved into the field.
if (auto *CE = llvm::dyn_cast<CallExpr>(RHS->IgnoreCasts())) {
if (CE->getNumArgs() != 1)
return llvm::None;
auto *ND = llvm::dyn_cast<NamedDecl>(CE->getCalleeDecl());
if (!ND || !ND->getIdentifier() || ND->getName() != "move" ||
!ND->isInStdNamespace())
return llvm::None;
RHS = CE->getArg(0);
}
auto *DRE = llvm::dyn_cast<DeclRefExpr>(RHS->IgnoreCasts());
if (!DRE || DRE->getDecl() != Arg)
return llvm::None;
return fieldName(LHS);
}
std::string synthesizeDocumentation(const NamedDecl *ND) {
if (const auto *CMD = llvm::dyn_cast<CXXMethodDecl>(ND)) {
// Is this an ordinary, non-static method whose definition is visible?
if (CMD->getDeclName().isIdentifier() && !CMD->isStatic() &&
(CMD = llvm::dyn_cast_or_null<CXXMethodDecl>(CMD->getDefinition())) &&
CMD->hasBody()) {
if (const auto GetterField = getterVariableName(CMD))
return llvm::formatv("Trivial accessor for `{0}`.", *GetterField);
if (const auto SetterField = setterVariableName(CMD))
return llvm::formatv("Trivial setter for `{0}`.", *SetterField);
}
}
return "";
}
/// Generate a \p Hover object given the declaration \p D.
HoverInfo getHoverContents(const NamedDecl *D, const PrintingPolicy &PP,
const SymbolIndex *Index) {
HoverInfo HI;
const ASTContext &Ctx = D->getASTContext();
HI.AccessSpecifier = getAccessSpelling(D->getAccess()).str();
HI.NamespaceScope = getNamespaceScope(D);
if (!HI.NamespaceScope->empty())
HI.NamespaceScope->append("::");
HI.LocalScope = getLocalScope(D);
if (!HI.LocalScope.empty())
HI.LocalScope.append("::");
HI.Name = printName(Ctx, *D);
const auto *CommentD = getDeclForComment(D);
HI.Documentation = getDeclComment(Ctx, *CommentD);
enhanceFromIndex(HI, *CommentD, Index);
if (HI.Documentation.empty())
HI.Documentation = synthesizeDocumentation(D);
HI.Kind = index::getSymbolInfo(D).Kind;
// Fill in template params.
if (const TemplateDecl *TD = D->getDescribedTemplate()) {
HI.TemplateParameters =
fetchTemplateParameters(TD->getTemplateParameters(), PP);
D = TD;
} else if (const FunctionDecl *FD = D->getAsFunction()) {
if (const auto *FTD = FD->getDescribedTemplate()) {
HI.TemplateParameters =
fetchTemplateParameters(FTD->getTemplateParameters(), PP);
D = FTD;
}
}
// Fill in types and params.
if (const FunctionDecl *FD = getUnderlyingFunction(D))
fillFunctionTypeAndParams(HI, D, FD, PP);
else if (const auto *VD = dyn_cast<ValueDecl>(D))
HI.Type = printType(VD->getType(), PP);
else if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(D))
HI.Type = TTP->wasDeclaredWithTypename() ? "typename" : "class";
else if (const auto *TTP = dyn_cast<TemplateTemplateParmDecl>(D))
HI.Type = printType(TTP, PP);
// Fill in value with evaluated initializer if possible.
if (const auto *Var = dyn_cast<VarDecl>(D)) {
if (const Expr *Init = Var->getInit())
HI.Value = printExprValue(Init, Ctx);
} else if (const auto *ECD = dyn_cast<EnumConstantDecl>(D)) {
// Dependent enums (e.g. nested in template classes) don't have values yet.
if (!ECD->getType()->isDependentType())
HI.Value = ECD->getInitVal().toString(10);
}
HI.Definition = printDefinition(D, PP);
return HI;
}
/// Generate a \p Hover object given the macro \p MacroDecl.
HoverInfo getHoverContents(const DefinedMacro &Macro, ParsedAST &AST) {
HoverInfo HI;
SourceManager &SM = AST.getSourceManager();
HI.Name = std::string(Macro.Name);
HI.Kind = index::SymbolKind::Macro;
// FIXME: Populate documentation
// FIXME: Populate parameters
// Try to get the full definition, not just the name
SourceLocation StartLoc = Macro.Info->getDefinitionLoc();
SourceLocation EndLoc = Macro.Info->getDefinitionEndLoc();
// Ensure that EndLoc is a valid offset. For example it might come from
// preamble, and source file might've changed, in such a scenario EndLoc still
// stays valid, but getLocForEndOfToken will fail as it is no longer a valid
// offset.
// Note that this check is just to ensure there's text data inside the range.
// It will still succeed even when the data inside the range is irrelevant to
// macro definition.
if (SM.getPresumedLoc(EndLoc, /*UseLineDirectives=*/false).isValid()) {
EndLoc = Lexer::getLocForEndOfToken(EndLoc, 0, SM, AST.getLangOpts());
bool Invalid;
StringRef Buffer = SM.getBufferData(SM.getFileID(StartLoc), &Invalid);
if (!Invalid) {
unsigned StartOffset = SM.getFileOffset(StartLoc);
unsigned EndOffset = SM.getFileOffset(EndLoc);
if (EndOffset <= Buffer.size() && StartOffset < EndOffset)
HI.Definition =
("#define " + Buffer.substr(StartOffset, EndOffset - StartOffset))
.str();
}
}
return HI;
}
llvm::Optional<HoverInfo> getThisExprHoverContents(const CXXThisExpr *CTE,
ASTContext &ASTCtx,
const PrintingPolicy &PP) {
QualType OriginThisType = CTE->getType()->getPointeeType();
QualType ClassType = declaredType(OriginThisType->getAsTagDecl());
// For partial specialization class, origin `this` pointee type will be
// parsed as `InjectedClassNameType`, which will ouput template arguments
// like "type-parameter-0-0". So we retrieve user written class type in this
// case.
QualType PrettyThisType = ASTCtx.getPointerType(
QualType(ClassType.getTypePtr(), OriginThisType.getCVRQualifiers()));
HoverInfo HI;
HI.Name = "this";
HI.Definition = printType(PrettyThisType, PP);
return HI;
}
/// Generate a HoverInfo object given the deduced type \p QT
HoverInfo getDeducedTypeHoverContents(QualType QT, const syntax::Token &Tok,
ASTContext &ASTCtx,
const PrintingPolicy &PP,
const SymbolIndex *Index) {
HoverInfo HI;
// FIXME: distinguish decltype(auto) vs decltype(expr)
HI.Name = tok::getTokenName(Tok.kind());
HI.Kind = index::SymbolKind::TypeAlias;
if (QT->isUndeducedAutoType()) {
HI.Definition = "/* not deduced */";
} else {
HI.Definition = printType(QT, PP);
if (const auto *D = QT->getAsTagDecl()) {
const auto *CommentD = getDeclForComment(D);
HI.Documentation = getDeclComment(ASTCtx, *CommentD);
enhanceFromIndex(HI, *CommentD, Index);
}
}
return HI;
}
bool isLiteral(const Expr *E) {
// Unfortunately there's no common base Literal classes inherits from
// (apart from Expr), therefore these exclusions.
return llvm::isa<CharacterLiteral>(E) || llvm::isa<CompoundLiteralExpr>(E) ||
llvm::isa<CXXBoolLiteralExpr>(E) ||
llvm::isa<CXXNullPtrLiteralExpr>(E) ||
llvm::isa<FixedPointLiteral>(E) || llvm::isa<FloatingLiteral>(E) ||
llvm::isa<ImaginaryLiteral>(E) || llvm::isa<IntegerLiteral>(E) ||
llvm::isa<StringLiteral>(E) || llvm::isa<UserDefinedLiteral>(E);
}
llvm::StringLiteral getNameForExpr(const Expr *E) {
// FIXME: Come up with names for `special` expressions.
//
// It's an known issue for GCC5, https://godbolt.org/z/Z_tbgi. Work around
// that by using explicit conversion constructor.
//
// TODO: Once GCC5 is fully retired and not the minimal requirement as stated
// in `GettingStarted`, please remove the explicit conversion constructor.
return llvm::StringLiteral("expression");
}
// Generates hover info for `this` and evaluatable expressions.
// FIXME: Support hover for literals (esp user-defined)
llvm::Optional<HoverInfo> getHoverContents(const Expr *E, ParsedAST &AST,
const PrintingPolicy &PP,
const SymbolIndex *Index) {
// There's not much value in hovering over "42" and getting a hover card
// saying "42 is an int", similar for other literals.
if (isLiteral(E))
return llvm::None;
HoverInfo HI;
// For `this` expr we currently generate hover with pointee type.
if (const CXXThisExpr *CTE = dyn_cast<CXXThisExpr>(E))
return getThisExprHoverContents(CTE, AST.getASTContext(), PP);
// For expressions we currently print the type and the value, iff it is
// evaluatable.
if (auto Val = printExprValue(E, AST.getASTContext())) {
HI.Type = printType(E->getType(), PP);
HI.Value = *Val;
HI.Name = std::string(getNameForExpr(E));
return HI;
}
return llvm::None;
}
bool isParagraphBreak(llvm::StringRef Rest) {
return Rest.ltrim(" \t").startswith("\n");
}
bool punctuationIndicatesLineBreak(llvm::StringRef Line) {
constexpr llvm::StringLiteral Punctuation = R"txt(.:,;!?)txt";
Line = Line.rtrim();
return !Line.empty() && Punctuation.contains(Line.back());
}
bool isHardLineBreakIndicator(llvm::StringRef Rest) {
// '-'/'*' md list, '@'/'\' documentation command, '>' md blockquote,
// '#' headings, '`' code blocks
constexpr llvm::StringLiteral LinebreakIndicators = R"txt(-*@\>#`)txt";
Rest = Rest.ltrim(" \t");
if (Rest.empty())
return false;
if (LinebreakIndicators.contains(Rest.front()))
return true;
if (llvm::isDigit(Rest.front())) {
llvm::StringRef AfterDigit = Rest.drop_while(llvm::isDigit);
if (AfterDigit.startswith(".") || AfterDigit.startswith(")"))
return true;
}
return false;
}
bool isHardLineBreakAfter(llvm::StringRef Line, llvm::StringRef Rest) {
// Should we also consider whether Line is short?
return punctuationIndicatesLineBreak(Line) || isHardLineBreakIndicator(Rest);
}
void addLayoutInfo(const NamedDecl &ND, HoverInfo &HI) {
if (ND.isInvalidDecl())
return;
const auto &Ctx = ND.getASTContext();
if (auto *RD = llvm::dyn_cast<RecordDecl>(&ND)) {
if (auto Size = Ctx.getTypeSizeInCharsIfKnown(RD->getTypeForDecl()))
HI.Size = Size->getQuantity();
return;
}
if (const auto *FD = llvm::dyn_cast<FieldDecl>(&ND)) {
const auto *Record = FD->getParent();
if (Record)
Record = Record->getDefinition();
if (Record && !Record->isInvalidDecl() && !Record->isDependentType()) {
HI.Offset = Ctx.getFieldOffset(FD) / 8;
if (auto Size = Ctx.getTypeSizeInCharsIfKnown(FD->getType()))
HI.Size = Size->getQuantity();
}
return;
}
}
// If N is passed as argument to a function, fill HI.CalleeArgInfo with
// information about that argument.
void maybeAddCalleeArgInfo(const SelectionTree::Node *N, HoverInfo &HI,
const PrintingPolicy &PP) {
const auto &OuterNode = N->outerImplicit();
if (!OuterNode.Parent)
return;
const auto *CE = OuterNode.Parent->ASTNode.get<CallExpr>();
if (!CE)
return;
const FunctionDecl *FD = CE->getDirectCallee();
// For non-function-call-like operatators (e.g. operator+, operator<<) it's
// not immediattely obvious what the "passed as" would refer to and, given
// fixed function signature, the value would be very low anyway, so we choose
// to not support that.
// Both variadic functions and operator() (especially relevant for lambdas)
// should be supported in the future.
if (!FD || FD->isOverloadedOperator() || FD->isVariadic())
return;
// Find argument index for N.
for (unsigned I = 0; I < CE->getNumArgs() && I < FD->getNumParams(); ++I) {
if (CE->getArg(I) != OuterNode.ASTNode.get<Expr>())
continue;
// Extract matching argument from function declaration.
if (const ParmVarDecl *PVD = FD->getParamDecl(I))
HI.CalleeArgInfo.emplace(toHoverInfoParam(PVD, PP));
break;
}
if (!HI.CalleeArgInfo)
return;
// If we found a matching argument, also figure out if it's a
// [const-]reference. For this we need to walk up the AST from the arg itself
// to CallExpr and check all implicit casts, constructor calls, etc.
HoverInfo::PassType PassType;
if (const auto *E = N->ASTNode.get<Expr>()) {
if (E->getType().isConstQualified())
PassType.PassBy = HoverInfo::PassType::ConstRef;
}
for (auto *CastNode = N->Parent;
CastNode != OuterNode.Parent && !PassType.Converted;
CastNode = CastNode->Parent) {
if (const auto *ImplicitCast = CastNode->ASTNode.get<ImplicitCastExpr>()) {
switch (ImplicitCast->getCastKind()) {
case CK_NoOp:
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
// If it was a reference before, it's still a reference.
if (PassType.PassBy != HoverInfo::PassType::Value)
PassType.PassBy = ImplicitCast->getType().isConstQualified()
? HoverInfo::PassType::ConstRef
: HoverInfo::PassType::Ref;
break;
case CK_LValueToRValue:
case CK_ArrayToPointerDecay:
case CK_FunctionToPointerDecay:
case CK_NullToPointer:
case CK_NullToMemberPointer:
// No longer a reference, but we do not show this as type conversion.
PassType.PassBy = HoverInfo::PassType::Value;
break;
default:
PassType.PassBy = HoverInfo::PassType::Value;
PassType.Converted = true;
break;
}
} else if (const auto *CtorCall =
CastNode->ASTNode.get<CXXConstructExpr>()) {
// We want to be smart about copy constructors. They should not show up as
// type conversion, but instead as passing by value.
if (CtorCall->getConstructor()->isCopyConstructor())
PassType.PassBy = HoverInfo::PassType::Value;
else
PassType.Converted = true;
} else { // Unknown implicit node, assume type conversion.
PassType.PassBy = HoverInfo::PassType::Value;
PassType.Converted = true;
}
}
HI.CallPassType.emplace(PassType);
}
} // namespace
llvm::Optional<HoverInfo> getHover(ParsedAST &AST, Position Pos,
format::FormatStyle Style,
const SymbolIndex *Index) {
PrintingPolicy PP =
getPrintingPolicy(AST.getASTContext().getPrintingPolicy());
const SourceManager &SM = AST.getSourceManager();
auto CurLoc = sourceLocationInMainFile(SM, Pos);
if (!CurLoc) {
llvm::consumeError(CurLoc.takeError());
return llvm::None;
}
const auto &TB = AST.getTokens();
auto TokensTouchingCursor = syntax::spelledTokensTouching(*CurLoc, TB);
// Early exit if there were no tokens around the cursor.
if (TokensTouchingCursor.empty())
return llvm::None;
// To be used as a backup for highlighting the selected token, we use back as
// it aligns better with biases elsewhere (editors tend to send the position
// for the left of the hovered token).
CharSourceRange HighlightRange =
TokensTouchingCursor.back().range(SM).toCharRange(SM);
llvm::Optional<HoverInfo> HI;
// Macros and deducedtype only works on identifiers and auto/decltype keywords
// respectively. Therefore they are only trggered on whichever works for them,
// similar to SelectionTree::create().
for (const auto &Tok : TokensTouchingCursor) {
if (Tok.kind() == tok::identifier) {
// Prefer the identifier token as a fallback highlighting range.
HighlightRange = Tok.range(SM).toCharRange(SM);
if (auto M = locateMacroAt(Tok, AST.getPreprocessor())) {
HI = getHoverContents(*M, AST);
break;
}
} else if (Tok.kind() == tok::kw_auto || Tok.kind() == tok::kw_decltype) {
if (auto Deduced = getDeducedType(AST.getASTContext(), Tok.location())) {
HI = getDeducedTypeHoverContents(*Deduced, Tok, AST.getASTContext(), PP,
Index);
HighlightRange = Tok.range(SM).toCharRange(SM);
break;
}
// If we can't find interesting hover information for this
// auto/decltype keyword, return nothing to avoid showing
// irrelevant or incorrect informations.
return llvm::None;
}
}
// If it wasn't auto/decltype or macro, look for decls and expressions.
if (!HI) {
auto Offset = SM.getFileOffset(*CurLoc);
// Editors send the position on the left of the hovered character.
// So our selection tree should be biased right. (Tested with VSCode).
SelectionTree ST =
SelectionTree::createRight(AST.getASTContext(), TB, Offset, Offset);
std::vector<const Decl *> Result;
if (const SelectionTree::Node *N = ST.commonAncestor()) {
// FIXME: Fill in HighlightRange with range coming from N->ASTNode.
auto Decls = explicitReferenceTargets(N->ASTNode, DeclRelation::Alias,
AST.getHeuristicResolver());
if (!Decls.empty()) {
HI = getHoverContents(Decls.front(), PP, Index);
// Layout info only shown when hovering on the field/class itself.
if (Decls.front() == N->ASTNode.get<Decl>())
addLayoutInfo(*Decls.front(), *HI);
// Look for a close enclosing expression to show the value of.
if (!HI->Value)
HI->Value = printExprValue(N, AST.getASTContext());
maybeAddCalleeArgInfo(N, *HI, PP);
} else if (const Expr *E = N->ASTNode.get<Expr>()) {
HI = getHoverContents(E, AST, PP, Index);
}
// FIXME: support hovers for other nodes?
// - built-in types
}
}
if (!HI)
return llvm::None;
auto Replacements = format::reformat(
Style, HI->Definition, tooling::Range(0, HI->Definition.size()));
if (auto Formatted =
tooling::applyAllReplacements(HI->Definition, Replacements))
HI->Definition = *Formatted;
HI->SymRange = halfOpenToRange(SM, HighlightRange);
return HI;
}
markup::Document HoverInfo::present() const {
markup::Document Output;
// Header contains a text of the form:
// variable `var`
//
// class `X`
//
// function `foo`
//
// expression
//
// Note that we are making use of a level-3 heading because VSCode renders
// level 1 and 2 headers in a huge font, see
// https://github.com/microsoft/vscode/issues/88417 for details.
markup::Paragraph &Header = Output.addHeading(3);
if (Kind != index::SymbolKind::Unknown)
Header.appendText(index::getSymbolKindString(Kind)).appendSpace();
assert(!Name.empty() && "hover triggered on a nameless symbol");
Header.appendCode(Name);
// Put a linebreak after header to increase readability.
Output.addRuler();
// Print Types on their own lines to reduce chances of getting line-wrapped by
// editor, as they might be long.
if (ReturnType) {
// For functions we display signature in a list form, e.g.:
// → `x`
// Parameters:
// - `bool param1`
// - `int param2 = 5`
Output.addParagraph().appendText("→ ").appendCode(*ReturnType);
if (Parameters && !Parameters->empty()) {
Output.addParagraph().appendText("Parameters: ");
markup::BulletList &L = Output.addBulletList();
for (const auto &Param : *Parameters) {
std::string Buffer;
llvm::raw_string_ostream OS(Buffer);
OS << Param;
L.addItem().addParagraph().appendCode(std::move(OS.str()));
}
}
} else if (Type) {
Output.addParagraph().appendText("Type: ").appendCode(*Type);
}
if (Value) {
markup::Paragraph &P = Output.addParagraph();
P.appendText("Value = ");
P.appendCode(*Value);
}
if (Offset)
Output.addParagraph().appendText(
llvm::formatv("Offset: {0} byte{1}", *Offset, *Offset == 1 ? "" : "s")
.str());
if (Size)
Output.addParagraph().appendText(
llvm::formatv("Size: {0} byte{1}", *Size, *Size == 1 ? "" : "s").str());
if (CalleeArgInfo) {
assert(CallPassType);
std::string Buffer;
llvm::raw_string_ostream OS(Buffer);
OS << "Passed ";
if (CallPassType->PassBy != HoverInfo::PassType::Value) {
OS << "by ";
if (CallPassType->PassBy == HoverInfo::PassType::ConstRef)
OS << "const ";
OS << "reference ";
}
if (CalleeArgInfo->Name)
OS << "as " << CalleeArgInfo->Name;
if (CallPassType->Converted && CalleeArgInfo->Type)
OS << " (converted to " << CalleeArgInfo->Type << ")";
Output.addParagraph().appendText(OS.str());
}
if (!Documentation.empty())
parseDocumentation(Documentation, Output);
if (!Definition.empty()) {
Output.addRuler();
std::string ScopeComment;
// Drop trailing "::".
if (!LocalScope.empty()) {
// Container name, e.g. class, method, function.
// We might want to propagate some info about container type to print
// function foo, class X, method X::bar, etc.
ScopeComment =
"// In " + llvm::StringRef(LocalScope).rtrim(':').str() + '\n';
} else if (NamespaceScope && !NamespaceScope->empty()) {
ScopeComment = "// In namespace " +
llvm::StringRef(*NamespaceScope).rtrim(':').str() + '\n';
}
std::string DefinitionWithAccess = !AccessSpecifier.empty()
? AccessSpecifier + ": " + Definition
: Definition;
// Note that we don't print anything for global namespace, to not annoy
// non-c++ projects or projects that are not making use of namespaces.
Output.addCodeBlock(ScopeComment + DefinitionWithAccess);
}
return Output;
}
// If the backtick at `Offset` starts a probable quoted range, return the range
// (including the quotes).
llvm::Optional<llvm::StringRef> getBacktickQuoteRange(llvm::StringRef Line,
unsigned Offset) {
assert(Line[Offset] == '`');
// The open-quote is usually preceded by whitespace.
llvm::StringRef Prefix = Line.substr(0, Offset);
constexpr llvm::StringLiteral BeforeStartChars = " \t(=";
if (!Prefix.empty() && !BeforeStartChars.contains(Prefix.back()))
return llvm::None;
// The quoted string must be nonempty and usually has no leading/trailing ws.
auto Next = Line.find('`', Offset + 1);
if (Next == llvm::StringRef::npos)
return llvm::None;
llvm::StringRef Contents = Line.slice(Offset + 1, Next);
if (Contents.empty() || isWhitespace(Contents.front()) ||
isWhitespace(Contents.back()))
return llvm::None;
// The close-quote is usually followed by whitespace or punctuation.
llvm::StringRef Suffix = Line.substr(Next + 1);
constexpr llvm::StringLiteral AfterEndChars = " \t)=.,;:";
if (!Suffix.empty() && !AfterEndChars.contains(Suffix.front()))
return llvm::None;
return Line.slice(Offset, Next + 1);
}
void parseDocumentationLine(llvm::StringRef Line, markup::Paragraph &Out) {
// Probably this is appendText(Line), but scan for something interesting.
for (unsigned I = 0; I < Line.size(); ++I) {
switch (Line[I]) {
case '`':
if (auto Range = getBacktickQuoteRange(Line, I)) {
Out.appendText(Line.substr(0, I));
Out.appendCode(Range->trim("`"), /*Preserve=*/true);
return parseDocumentationLine(Line.substr(I + Range->size()), Out);
}
break;
}
}
Out.appendText(Line).appendSpace();
}
void parseDocumentation(llvm::StringRef Input, markup::Document &Output) {
std::vector<llvm::StringRef> ParagraphLines;
auto FlushParagraph = [&] {
if (ParagraphLines.empty())
return;
auto &P = Output.addParagraph();
for (llvm::StringRef Line : ParagraphLines)
parseDocumentationLine(Line, P);
ParagraphLines.clear();
};
llvm::StringRef Line, Rest;
for (std::tie(Line, Rest) = Input.split('\n');
!(Line.empty() && Rest.empty());
std::tie(Line, Rest) = Rest.split('\n')) {
// After a linebreak remove spaces to avoid 4 space markdown code blocks.
// FIXME: make FlushParagraph handle this.
Line = Line.ltrim();
if (!Line.empty())
ParagraphLines.push_back(Line);
if (isParagraphBreak(Rest) || isHardLineBreakAfter(Line, Rest)) {
FlushParagraph();
}
}
FlushParagraph();
}
llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
const HoverInfo::Param &P) {
std::vector<llvm::StringRef> Output;
if (P.Type)
Output.push_back(*P.Type);
if (P.Name)
Output.push_back(*P.Name);
OS << llvm::join(Output, " ");
if (P.Default)
OS << " = " << *P.Default;
return OS;
}
} // namespace clangd
} // namespace clang
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