1 //===--- ProBoundsPointerArithmeticCheck.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 "ProBoundsPointerArithmeticCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 
13 using namespace clang::ast_matchers;
14 
15 namespace clang {
16 namespace tidy {
17 namespace cppcoreguidelines {
18 
19 void ProBoundsPointerArithmeticCheck::registerMatchers(MatchFinder *Finder) {
20   if (!getLangOpts().CPlusPlus)
21     return;
22 
23   const auto AllPointerTypes = anyOf(
24       hasType(pointerType()), hasType(autoType(hasDeducedType(pointerType()))),
25       hasType(decltypeType(hasUnderlyingType(pointerType()))));
26 
27   // Flag all operators +, -, +=, -=, ++, -- that result in a pointer
28   Finder->addMatcher(
29       binaryOperator(
30           anyOf(hasOperatorName("+"), hasOperatorName("-"),
31                 hasOperatorName("+="), hasOperatorName("-=")),
32           AllPointerTypes,
33           unless(hasLHS(ignoringImpCasts(declRefExpr(to(isImplicit()))))))
34           .bind("expr"),
35       this);
36 
37   Finder->addMatcher(
38       unaryOperator(anyOf(hasOperatorName("++"), hasOperatorName("--")),
39                     hasType(pointerType()))
40           .bind("expr"),
41       this);
42 
43   // Array subscript on a pointer (not an array) is also pointer arithmetic
44   Finder->addMatcher(
45       arraySubscriptExpr(
46           hasBase(ignoringImpCasts(
47               anyOf(AllPointerTypes,
48                     hasType(decayedType(hasDecayedType(pointerType())))))))
49           .bind("expr"),
50       this);
51 }
52 
53 void ProBoundsPointerArithmeticCheck::check(
54     const MatchFinder::MatchResult &Result) {
55   const auto *MatchedExpr = Result.Nodes.getNodeAs<Expr>("expr");
56 
57   diag(MatchedExpr->getExprLoc(), "do not use pointer arithmetic");
58 }
59 
60 } // namespace cppcoreguidelines
61 } // namespace tidy
62 } // namespace clang
63