clang-tools-extra/clang-tidy/cppcoreguidelines/InitVariablesCheck.cpp

   1 //===--- InitVariablesCheck.cpp - clang-tidy ------------------------------===//
   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 "InitVariablesCheck.h"
  10
  11 #include "../utils/LexerUtils.h"
  12 #include "clang/AST/ASTContext.h"
  13 #include "clang/AST/Type.h"
  14 #include "clang/ASTMatchers/ASTMatchFinder.h"
  15 #include "clang/Lex/Preprocessor.h"
  16 #include <optional>
  17
  18 using namespace clang::ast_matchers;
  19
  20 namespace clang::tidy::cppcoreguidelines {
  21
  22 namespace {
  23 AST_MATCHER(VarDecl, isLocalVarDecl) { return Node.isLocalVarDecl(); }
  24 } // namespace
  25
  26 InitVariablesCheck::InitVariablesCheck(StringRef Name,
  27                                        ClangTidyContext *Context)
  28     : ClangTidyCheck(Name, Context),
  29       IncludeInserter(Options.getLocalOrGlobal("IncludeStyle",
  30                                                utils::IncludeSorter::IS_LLVM),
  31                       areDiagsSelfContained()),
  32       MathHeader(Options.get("MathHeader", "<math.h>")) {}
  33
  34 void InitVariablesCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  35   Options.store(Opts, "IncludeStyle", IncludeInserter.getStyle());
  36   Options.store(Opts, "MathHeader", MathHeader);
  37 }
  38
  39 void InitVariablesCheck::registerMatchers(MatchFinder *Finder) {
  40   std::string BadDecl = "badDecl";
  41   Finder->addMatcher(
  42       varDecl(unless(hasInitializer(anything())), unless(isInstantiated()),
  43               isLocalVarDecl(), unless(isStaticLocal()), isDefinition(),
  44               unless(hasParent(cxxCatchStmt())),
  45               optionally(hasParent(declStmt(hasParent(
  46                   cxxForRangeStmt(hasLoopVariable(varDecl().bind(BadDecl))))))),
  47               unless(equalsBoundNode(BadDecl)))
  48           .bind("vardecl"),
  49       this);
  50 }
  51
  52 void InitVariablesCheck::registerPPCallbacks(const SourceManager &SM,
  53                                              Preprocessor *PP,
  54                                              Preprocessor *ModuleExpanderPP) {
  55   IncludeInserter.registerPreprocessor(PP);
  56 }
  57
  58 void InitVariablesCheck::check(const MatchFinder::MatchResult &Result) {
  59   const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("vardecl");
  60   const ASTContext &Context = *Result.Context;
  61   const SourceManager &Source = Context.getSourceManager();
  62
  63   // Clang diagnostic error may cause the variable to be an invalid int vardecl
  64   if (MatchedDecl->isInvalidDecl())
  65     return;
  66
  67   // We want to warn about cases where the type name
  68   // comes from a macro like this:
  69   //
  70   // TYPENAME_FROM_MACRO var;
  71   //
  72   // but not if the entire declaration comes from
  73   // one:
  74   //
  75   // DEFINE_SOME_VARIABLE();
  76   //
  77   // or if the definition comes from a macro like SWAP
  78   // that uses an internal temporary variable.
  79   //
  80   // Thus check that the variable name does
  81   // not come from a macro expansion.
  82   if (MatchedDecl->getEndLoc().isMacroID())
  83     return;
  84
  85   QualType TypePtr = MatchedDecl->getType();
  86   std::optional<const char *> InitializationString;
  87   bool AddMathInclude = false;
  88
  89   if (TypePtr->isEnumeralType())
  90     InitializationString = nullptr;
  91   else if (TypePtr->isBooleanType())
  92     InitializationString = " = false";
  93   else if (TypePtr->isIntegerType())
  94     InitializationString = " = 0";
  95   else if (TypePtr->isFloatingType()) {
  96     InitializationString = " = NAN";
  97     AddMathInclude = true;
  98   } else if (TypePtr->isAnyPointerType()) {
  99     if (getLangOpts().CPlusPlus11)
 100       InitializationString = " = nullptr";
 101     else
 102       InitializationString = " = NULL";
 103   }
 104
 105   if (InitializationString) {
 106     auto Diagnostic =
 107         diag(MatchedDecl->getLocation(), "variable %0 is not initialized")
 108         << MatchedDecl;
 109     if (*InitializationString != nullptr)
 110       Diagnostic << FixItHint::CreateInsertion(
 111           utils::lexer::findNextTerminator(MatchedDecl->getLocation(),
 112                                            *Result.SourceManager,
 113                                            Result.Context->getLangOpts()),
 114           *InitializationString);
 115     if (AddMathInclude) {
 116       Diagnostic << IncludeInserter.createIncludeInsertion(
 117           Source.getFileID(MatchedDecl->getBeginLoc()), MathHeader);
 118     }
 119   }
 120 }
 121 } // namespace clang::tidy::cppcoreguidelines