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| 1 | +//===--- InlayHints.cpp ------------------------------------------*- C++-*-===// |
| 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 | +#include "InlayHints.h" |
| 9 | +#include "ParsedAST.h" |
| 10 | +#include "support/Logger.h" |
| 11 | +#include "clang/AST/DeclarationName.h" |
| 12 | +#include "clang/AST/ExprCXX.h" |
| 13 | +#include "clang/AST/RecursiveASTVisitor.h" |
| 14 | +#include "clang/Basic/SourceManager.h" |
| 15 | + |
| 16 | +namespace clang { |
| 17 | +namespace clangd { |
| 18 | + |
| 19 | +class InlayHintVisitor : public RecursiveASTVisitor<InlayHintVisitor> { |
| 20 | +public: |
| 21 | + InlayHintVisitor(std::vector<InlayHint> &Results, ParsedAST &AST) |
| 22 | + : Results(Results), AST(AST.getASTContext()) {} |
| 23 | + |
| 24 | + bool VisitCXXConstructExpr(CXXConstructExpr *E) { |
| 25 | + // Weed out constructor calls that don't look like a function call with |
| 26 | + // an argument list, by checking the validity of getParenOrBraceRange(). |
| 27 | + // Also weed out std::initializer_list constructors as there are no names |
| 28 | + // for the individual arguments. |
| 29 | + if (!E->getParenOrBraceRange().isValid() || |
| 30 | + E->isStdInitListInitialization()) { |
| 31 | + return true; |
| 32 | + } |
| 33 | + |
| 34 | + processCall(E->getParenOrBraceRange().getBegin(), E->getConstructor(), |
| 35 | + {E->getArgs(), E->getNumArgs()}); |
| 36 | + return true; |
| 37 | + } |
| 38 | + |
| 39 | + bool VisitCallExpr(CallExpr *E) { |
| 40 | + // Do not show parameter hints for operator calls written using operator |
| 41 | + // syntax or user-defined literals. (Among other reasons, the resulting |
| 42 | + // hints can look awkard, e.g. the expression can itself be a function |
| 43 | + // argument and then we'd get two hints side by side). |
| 44 | + if (isa<CXXOperatorCallExpr>(E) || isa<UserDefinedLiteral>(E)) |
| 45 | + return true; |
| 46 | + |
| 47 | + processCall(E->getRParenLoc(), |
| 48 | + dyn_cast_or_null<FunctionDecl>(E->getCalleeDecl()), |
| 49 | + {E->getArgs(), E->getNumArgs()}); |
| 50 | + return true; |
| 51 | + } |
| 52 | + |
| 53 | + // FIXME: Handle RecoveryExpr to try to hint some invalid calls. |
| 54 | + |
| 55 | +private: |
| 56 | + // The purpose of Anchor is to deal with macros. It should be the call's |
| 57 | + // opening or closing parenthesis or brace. (Always using the opening would |
| 58 | + // make more sense but CallExpr only exposes the closing.) We heuristically |
| 59 | + // assume that if this location does not come from a macro definition, then |
| 60 | + // the entire argument list likely appears in the main file and can be hinted. |
| 61 | + void processCall(SourceLocation Anchor, const FunctionDecl *Callee, |
| 62 | + llvm::ArrayRef<const Expr *const> Args) { |
| 63 | + if (Args.size() == 0 || !Callee) |
| 64 | + return; |
| 65 | + |
| 66 | + // If the anchor location comes from a macro defintion, there's nowhere to |
| 67 | + // put hints. |
| 68 | + if (!AST.getSourceManager().getTopMacroCallerLoc(Anchor).isFileID()) |
| 69 | + return; |
| 70 | + |
| 71 | + // The parameter name of a move or copy constructor is not very interesting. |
| 72 | + if (auto *Ctor = dyn_cast<CXXConstructorDecl>(Callee)) |
| 73 | + if (Ctor->isCopyOrMoveConstructor()) |
| 74 | + return; |
| 75 | + |
| 76 | + // FIXME: Exclude setters (i.e. functions with one argument whose name |
| 77 | + // begins with "set"), as their parameter name is also not likely to be |
| 78 | + // interesting. |
| 79 | + |
| 80 | + // Don't show hints for variadic parameters. |
| 81 | + size_t FixedParamCount = getFixedParamCount(Callee); |
| 82 | + size_t ArgCount = std::min(FixedParamCount, Args.size()); |
| 83 | + |
| 84 | + NameVec ParameterNames = chooseParameterNames(Callee, ArgCount); |
| 85 | + |
| 86 | + for (size_t I = 0; I < ArgCount; ++I) { |
| 87 | + StringRef Name = ParameterNames[I]; |
| 88 | + if (!shouldHint(Args[I], Name)) |
| 89 | + continue; |
| 90 | + |
| 91 | + addInlayHint(Args[I]->getSourceRange(), InlayHintKind::ParameterHint, |
| 92 | + Name.str() + ": "); |
| 93 | + } |
| 94 | + } |
| 95 | + |
| 96 | + bool shouldHint(const Expr *Arg, StringRef ParamName) { |
| 97 | + if (ParamName.empty()) |
| 98 | + return false; |
| 99 | + |
| 100 | + // If the argument expression is a single name and it matches the |
| 101 | + // parameter name exactly, omit the hint. |
| 102 | + if (ParamName == getSpelledIdentifier(Arg)) |
| 103 | + return false; |
| 104 | + |
| 105 | + // FIXME: Exclude argument expressions preceded by a /*paramName=*/ comment. |
| 106 | + |
| 107 | + return true; |
| 108 | + } |
| 109 | + |
| 110 | + // If "E" spells a single unqualified identifier, return that name. |
| 111 | + // Otherwise, return an empty string. |
| 112 | + static StringRef getSpelledIdentifier(const Expr *E) { |
| 113 | + E = E->IgnoreUnlessSpelledInSource(); |
| 114 | + |
| 115 | + if (auto *DRE = dyn_cast<DeclRefExpr>(E)) |
| 116 | + if (!DRE->getQualifier()) |
| 117 | + return getSimpleName(*DRE->getDecl()); |
| 118 | + |
| 119 | + if (auto *ME = dyn_cast<MemberExpr>(E)) |
| 120 | + if (!ME->getQualifier() && ME->isImplicitAccess()) |
| 121 | + return getSimpleName(*ME->getMemberDecl()); |
| 122 | + |
| 123 | + return {}; |
| 124 | + } |
| 125 | + |
| 126 | + using NameVec = SmallVector<StringRef, 8>; |
| 127 | + |
| 128 | + NameVec chooseParameterNames(const FunctionDecl *Callee, size_t ArgCount) { |
| 129 | + // The current strategy here is to use all the parameter names from the |
| 130 | + // canonical declaration, unless they're all empty, in which case we |
| 131 | + // use all the parameter names from the definition (in present in the |
| 132 | + // translation unit). |
| 133 | + // We could try a bit harder, e.g.: |
| 134 | + // - try all re-declarations, not just canonical + definition |
| 135 | + // - fall back arg-by-arg rather than wholesale |
| 136 | + |
| 137 | + NameVec ParameterNames = getParameterNamesForDecl(Callee, ArgCount); |
| 138 | + |
| 139 | + if (llvm::all_of(ParameterNames, std::mem_fn(&StringRef::empty))) { |
| 140 | + if (const FunctionDecl *Def = Callee->getDefinition()) { |
| 141 | + ParameterNames = getParameterNamesForDecl(Def, ArgCount); |
| 142 | + } |
| 143 | + } |
| 144 | + assert(ParameterNames.size() == ArgCount); |
| 145 | + |
| 146 | + // Standard library functions often have parameter names that start |
| 147 | + // with underscores, which makes the hints noisy, so strip them out. |
| 148 | + for (auto &Name : ParameterNames) |
| 149 | + stripLeadingUnderscores(Name); |
| 150 | + |
| 151 | + return ParameterNames; |
| 152 | + } |
| 153 | + |
| 154 | + static void stripLeadingUnderscores(StringRef &Name) { |
| 155 | + Name = Name.ltrim('_'); |
| 156 | + } |
| 157 | + |
| 158 | + // Return the number of fixed parameters Function has, that is, not counting |
| 159 | + // parameters that are variadic (instantiated from a parameter pack) or |
| 160 | + // C-style varargs. |
| 161 | + static size_t getFixedParamCount(const FunctionDecl *Function) { |
| 162 | + if (FunctionTemplateDecl *Template = Function->getPrimaryTemplate()) { |
| 163 | + FunctionDecl *F = Template->getTemplatedDecl(); |
| 164 | + size_t Result = 0; |
| 165 | + for (ParmVarDecl *Parm : F->parameters()) { |
| 166 | + if (Parm->isParameterPack()) { |
| 167 | + break; |
| 168 | + } |
| 169 | + ++Result; |
| 170 | + } |
| 171 | + return Result; |
| 172 | + } |
| 173 | + // C-style varargs don't need special handling, they're already |
| 174 | + // not included in getNumParams(). |
| 175 | + return Function->getNumParams(); |
| 176 | + } |
| 177 | + |
| 178 | + static StringRef getSimpleName(const NamedDecl &D) { |
| 179 | + if (IdentifierInfo *Ident = D.getDeclName().getAsIdentifierInfo()) { |
| 180 | + return Ident->getName(); |
| 181 | + } |
| 182 | + |
| 183 | + return StringRef(); |
| 184 | + } |
| 185 | + |
| 186 | + NameVec getParameterNamesForDecl(const FunctionDecl *Function, |
| 187 | + size_t ArgCount) { |
| 188 | + NameVec Result; |
| 189 | + for (size_t I = 0; I < ArgCount; ++I) { |
| 190 | + const ParmVarDecl *Parm = Function->getParamDecl(I); |
| 191 | + assert(Parm); |
| 192 | + Result.emplace_back(getSimpleName(*Parm)); |
| 193 | + } |
| 194 | + return Result; |
| 195 | + } |
| 196 | + |
| 197 | + void addInlayHint(SourceRange R, InlayHintKind Kind, llvm::StringRef Label) { |
| 198 | + auto FileRange = |
| 199 | + toHalfOpenFileRange(AST.getSourceManager(), AST.getLangOpts(), R); |
| 200 | + if (!FileRange) |
| 201 | + return; |
| 202 | + Results.push_back(InlayHint{ |
| 203 | + Range{ |
| 204 | + sourceLocToPosition(AST.getSourceManager(), FileRange->getBegin()), |
| 205 | + sourceLocToPosition(AST.getSourceManager(), FileRange->getEnd())}, |
| 206 | + Kind, Label.str()}); |
| 207 | + } |
| 208 | + |
| 209 | + std::vector<InlayHint> &Results; |
| 210 | + ASTContext &AST; |
| 211 | +}; |
| 212 | + |
| 213 | +std::vector<InlayHint> inlayHints(ParsedAST &AST) { |
| 214 | + std::vector<InlayHint> Results; |
| 215 | + InlayHintVisitor Visitor(Results, AST); |
| 216 | + Visitor.TraverseAST(AST.getASTContext()); |
| 217 | + return Results; |
| 218 | +} |
| 219 | + |
| 220 | +} // namespace clangd |
| 221 | +} // namespace clang |
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