clang-tools  5.0.0
ProBoundsArrayToPointerDecayCheck.cpp
Go to the documentation of this file.
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 namespace cppcoreguidelines {
19 
20 AST_MATCHER_P(CXXForRangeStmt, hasRangeBeginEndStmt,
21  ast_matchers::internal::Matcher<DeclStmt>, InnerMatcher) {
22  for (const DeclStmt *Stmt : {Node.getBeginStmt(), Node.getEndStmt()})
23  if (Stmt != nullptr && InnerMatcher.matches(*Stmt, Finder, Builder))
24  return true;
25  return false;
26 }
27 
28 AST_MATCHER(Stmt, isInsideOfRangeBeginEndStmt) {
29  return stmt(hasAncestor(cxxForRangeStmt(
30  hasRangeBeginEndStmt(hasDescendant(equalsNode(&Node))))))
31  .matches(Node, Finder, Builder);
32 }
33 
34 AST_MATCHER_P(Expr, hasParentIgnoringImpCasts,
35  ast_matchers::internal::Matcher<Expr>, InnerMatcher) {
36  const Expr *E = &Node;
37  do {
38  ASTContext::DynTypedNodeList Parents =
39  Finder->getASTContext().getParents(*E);
40  if (Parents.size() != 1)
41  return false;
42  E = Parents[0].get<Expr>();
43  if (!E)
44  return false;
45  } while (isa<ImplicitCastExpr>(E));
46 
47  return InnerMatcher.matches(*E, Finder, Builder);
48 }
49 
50 void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder *Finder) {
51  if (!getLangOpts().CPlusPlus)
52  return;
53 
54  // The only allowed array to pointer decay
55  // 1) just before array subscription
56  // 2) inside a range-for over an array
57  // 3) if it converts a string literal to a pointer
58  Finder->addMatcher(
59  implicitCastExpr(unless(hasParent(arraySubscriptExpr())),
60  unless(hasParentIgnoringImpCasts(explicitCastExpr())),
61  unless(isInsideOfRangeBeginEndStmt()),
62  unless(hasSourceExpression(stringLiteral())))
63  .bind("cast"),
64  this);
65 }
66 
67 void ProBoundsArrayToPointerDecayCheck::check(
68  const MatchFinder::MatchResult &Result) {
69  const auto *MatchedCast = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
70  if (MatchedCast->getCastKind() != CK_ArrayToPointerDecay)
71  return;
72 
73  diag(MatchedCast->getExprLoc(), "do not implicitly decay an array into a "
74  "pointer; consider using gsl::array_view or "
75  "an explicit cast instead");
76 }
77 
78 } // namespace cppcoreguidelines
79 } // namespace tidy
80 } // namespace clang
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:275
AST_MATCHER_P(Expr, hasParentIgnoringImpCasts, ast_matchers::internal::Matcher< Expr >, InnerMatcher)
AST_MATCHER(VarDecl, isAsm)