clang-tools  3.8.0
ProBoundsArrayToPointerDecayCheck.cpp
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1 //===--- ProBoundsArrayToPointerDecayCheck.cpp - clang-tidy----------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 
14 using namespace clang::ast_matchers;
15 
16 namespace clang {
17 namespace tidy {
18 
19 AST_MATCHER_P(CXXForRangeStmt, hasRangeBeginEndStmt,
20  ast_matchers::internal::Matcher<DeclStmt>, InnerMatcher) {
21  const DeclStmt *const Stmt = Node.getBeginEndStmt();
22  return (Stmt != nullptr && InnerMatcher.matches(*Stmt, Finder, Builder));
23 }
24 
25 AST_MATCHER(Stmt, isInsideOfRangeBeginEndStmt) {
26  return stmt(hasAncestor(cxxForRangeStmt(
27  hasRangeBeginEndStmt(hasDescendant(equalsNode(&Node))))))
28  .matches(Node, Finder, Builder);
29 }
30 
31 AST_MATCHER_P(Expr, hasParentIgnoringImpCasts,
32  ast_matchers::internal::Matcher<Expr>, InnerMatcher) {
33  const Expr *E = &Node;
34  do {
35  ASTContext::DynTypedNodeList Parents =
36  Finder->getASTContext().getParents(*E);
37  if (Parents.size() != 1)
38  return false;
39  E = Parents[0].get<Expr>();
40  if (!E)
41  return false;
42  } while (isa<ImplicitCastExpr>(E));
43 
44  return InnerMatcher.matches(*E, Finder, Builder);
45 }
46 
47 void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder *Finder) {
48  if (!getLangOpts().CPlusPlus)
49  return;
50 
51  // The only allowed array to pointer decay
52  // 1) just before array subscription
53  // 2) inside a range-for over an array
54  // 3) if it converts a string literal to a pointer
55  Finder->addMatcher(
56  implicitCastExpr(unless(hasParent(arraySubscriptExpr())),
57  unless(hasParentIgnoringImpCasts(explicitCastExpr())),
58  unless(isInsideOfRangeBeginEndStmt()),
59  unless(hasSourceExpression(stringLiteral())))
60  .bind("cast"),
61  this);
62 }
63 
64 void ProBoundsArrayToPointerDecayCheck::check(
65  const MatchFinder::MatchResult &Result) {
66  const auto *MatchedCast = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
67  if (MatchedCast->getCastKind() != CK_ArrayToPointerDecay)
68  return;
69 
70  diag(MatchedCast->getExprLoc(), "do not implicitly decay an array into a "
71  "pointer; consider using gsl::array_view or "
72  "an explicit cast instead");
73 }
74 
75 } // namespace tidy
76 } // namespace clang
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:188
AST_MATCHER(Stmt, isInsideOfRangeBeginEndStmt)
AST_MATCHER_P(Expr, hasParentIgnoringImpCasts, ast_matchers::internal::Matcher< Expr >, InnerMatcher)
const NamedDecl * Result
Definition: USRFinder.cpp:121