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