131 lines · cpp
1//===----------------------------------------------------------------------===//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-exception6//7//===----------------------------------------------------------------------===//8 9#include "ProBoundsConstantArrayIndexCheck.h"10#include "clang/AST/ASTContext.h"11#include "clang/ASTMatchers/ASTMatchFinder.h"12#include "clang/Frontend/CompilerInstance.h"13#include "clang/Lex/Preprocessor.h"14#include <optional>15 16using namespace clang::ast_matchers;17 18namespace clang::tidy::cppcoreguidelines {19 20ProBoundsConstantArrayIndexCheck::ProBoundsConstantArrayIndexCheck(21 StringRef Name, ClangTidyContext *Context)22 : ClangTidyCheck(Name, Context), GslHeader(Options.get("GslHeader", "")),23 Inserter(Options.getLocalOrGlobal("IncludeStyle",24 utils::IncludeSorter::IS_LLVM),25 areDiagsSelfContained()) {}26 27void ProBoundsConstantArrayIndexCheck::storeOptions(28 ClangTidyOptions::OptionMap &Opts) {29 Options.store(Opts, "GslHeader", GslHeader);30 Options.store(Opts, "IncludeStyle", Inserter.getStyle());31}32 33void ProBoundsConstantArrayIndexCheck::registerPPCallbacks(34 const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {35 Inserter.registerPreprocessor(PP);36}37 38void ProBoundsConstantArrayIndexCheck::registerMatchers(MatchFinder *Finder) {39 // Note: if a struct contains an array member, the compiler-generated40 // constructor has an arraySubscriptExpr.41 Finder->addMatcher(arraySubscriptExpr(hasBase(ignoringImpCasts(hasType(42 constantArrayType().bind("type")))),43 hasIndex(expr().bind("index")),44 unless(hasAncestor(decl(isImplicit()))))45 .bind("expr"),46 this);47 48 Finder->addMatcher(49 cxxOperatorCallExpr(50 hasOverloadedOperatorName("[]"),51 callee(cxxMethodDecl(52 ofClass(cxxRecordDecl(hasName("::std::array")).bind("type")))),53 hasArgument(1, expr().bind("index")))54 .bind("expr"),55 this);56}57 58void ProBoundsConstantArrayIndexCheck::check(59 const MatchFinder::MatchResult &Result) {60 const auto *Matched = Result.Nodes.getNodeAs<Expr>("expr");61 const auto *IndexExpr = Result.Nodes.getNodeAs<Expr>("index");62 63 // This expression can only appear inside ArrayInitLoopExpr, which64 // is always implicitly generated. ArrayInitIndexExpr is not a65 // constant, but we shouldn't report a warning for it.66 if (isa<ArrayInitIndexExpr>(IndexExpr))67 return;68 69 if (IndexExpr->isValueDependent())70 return; // We check in the specialization.71 72 std::optional<llvm::APSInt> Index =73 IndexExpr->getIntegerConstantExpr(*Result.Context);74 if (!Index) {75 SourceRange BaseRange;76 if (const auto *ArraySubscriptE = dyn_cast<ArraySubscriptExpr>(Matched))77 BaseRange = ArraySubscriptE->getBase()->getSourceRange();78 else79 BaseRange =80 cast<CXXOperatorCallExpr>(Matched)->getArg(0)->getSourceRange();81 const SourceRange IndexRange = IndexExpr->getSourceRange();82 83 auto Diag = diag(Matched->getExprLoc(),84 "do not use array subscript when the index is "85 "not an integer constant expression");86 if (!GslHeader.empty()) {87 Diag << FixItHint::CreateInsertion(BaseRange.getBegin(), "gsl::at(")88 << FixItHint::CreateReplacement(89 SourceRange(BaseRange.getEnd().getLocWithOffset(1),90 IndexRange.getBegin().getLocWithOffset(-1)),91 ", ")92 << FixItHint::CreateReplacement(Matched->getEndLoc(), ")")93 << Inserter.createMainFileIncludeInsertion(GslHeader);94 }95 return;96 }97 98 const auto *StdArrayDecl =99 Result.Nodes.getNodeAs<ClassTemplateSpecializationDecl>("type");100 101 // For static arrays, this is handled in clang-diagnostic-array-bounds.102 if (!StdArrayDecl)103 return;104 105 if (Index->isSigned() && Index->isNegative()) {106 diag(Matched->getExprLoc(), "std::array<> index %0 is negative")107 << toString(*Index, 10);108 return;109 }110 111 const TemplateArgumentList &TemplateArgs = StdArrayDecl->getTemplateArgs();112 if (TemplateArgs.size() < 2)113 return;114 // First template arg of std::array is the type, second arg is the size.115 const auto &SizeArg = TemplateArgs[1];116 if (SizeArg.getKind() != TemplateArgument::Integral)117 return;118 const llvm::APInt ArraySize = SizeArg.getAsIntegral();119 120 // Get uint64_t values, because different bitwidths would lead to an assertion121 // in APInt::uge.122 if (Index->getZExtValue() >= ArraySize.getZExtValue()) {123 diag(Matched->getExprLoc(),124 "std::array<> index %0 is past the end of the array "125 "(which contains %1 elements)")126 << toString(*Index, 10) << toString(ArraySize, 10, false);127 }128}129 130} // namespace clang::tidy::cppcoreguidelines131