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1 //===--- ProBoundsArrayToPointerDecayCheck.cpp - clang-tidy----------------===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8
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9 #include "ProBoundsArrayToPointerDecayCheck.h"
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10 #include "clang/AST/ASTContext.h"
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11 #include "clang/AST/ParentMapContext.h"
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12 #include "clang/ASTMatchers/ASTMatchFinder.h"
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13
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14 using namespace clang::ast_matchers;
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15
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16 namespace clang {
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17 namespace tidy {
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18 namespace cppcoreguidelines {
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19
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20 namespace {
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21 AST_MATCHER_P(CXXForRangeStmt, hasRangeBeginEndStmt,
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22 ast_matchers::internal::Matcher<DeclStmt>, InnerMatcher) {
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23 for (const DeclStmt *Stmt : {Node.getBeginStmt(), Node.getEndStmt()})
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24 if (Stmt != nullptr && InnerMatcher.matches(*Stmt, Finder, Builder))
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25 return true;
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26 return false;
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27 }
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28
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29 AST_MATCHER(Stmt, isInsideOfRangeBeginEndStmt) {
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30 return stmt(hasAncestor(cxxForRangeStmt(
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31 hasRangeBeginEndStmt(hasDescendant(equalsNode(&Node))))))
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32 .matches(Node, Finder, Builder);
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33 }
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34
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35 AST_MATCHER_P(Expr, hasParentIgnoringImpCasts,
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36 ast_matchers::internal::Matcher<Expr>, InnerMatcher) {
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37 const Expr *E = &Node;
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38 do {
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39 DynTypedNodeList Parents = Finder->getASTContext().getParents(*E);
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40 if (Parents.size() != 1)
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41 return false;
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42 E = Parents[0].get<Expr>();
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43 if (!E)
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44 return false;
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45 } while (isa<ImplicitCastExpr>(E));
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46
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47 return InnerMatcher.matches(*E, Finder, Builder);
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48 }
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49 } // namespace
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50
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51 void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder *Finder) {
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52 // The only allowed array to pointer decay
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53 // 1) just before array subscription
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54 // 2) inside a range-for over an array
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55 // 3) if it converts a string literal to a pointer
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56 Finder->addMatcher(
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173
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57 traverse(ast_type_traits::TK_AsIs,
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58 implicitCastExpr(
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59 unless(hasParent(arraySubscriptExpr())),
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60 unless(hasParentIgnoringImpCasts(explicitCastExpr())),
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61 unless(isInsideOfRangeBeginEndStmt()),
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62 unless(hasSourceExpression(ignoringParens(stringLiteral()))))
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63 .bind("cast")),
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150
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64 this);
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65 }
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66
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67 void ProBoundsArrayToPointerDecayCheck::check(
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68 const MatchFinder::MatchResult &Result) {
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69 const auto *MatchedCast = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
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70 if (MatchedCast->getCastKind() != CK_ArrayToPointerDecay)
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71 return;
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72
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73 diag(MatchedCast->getExprLoc(), "do not implicitly decay an array into a "
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74 "pointer; consider using gsl::array_view or "
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75 "an explicit cast instead");
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76 }
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77
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78 } // namespace cppcoreguidelines
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79 } // namespace tidy
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80 } // namespace clang
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