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 =
24       anyOf(hasType(pointerType()),
25             hasType(autoType(
26                 hasDeducedType(hasUnqualifiedDesugaredType(pointerType())))),
27             hasType(decltypeType(hasUnderlyingType(pointerType()))));
28 
29   // Flag all operators +, -, +=, -=, ++, -- that result in a pointer
30   Finder->addMatcher(
31       binaryOperator(
32           hasAnyOperatorName("+", "-", "+=", "-="), AllPointerTypes,
33           unless(hasLHS(ignoringImpCasts(declRefExpr(to(isImplicit()))))))
34           .bind("expr"),
35       this);
36 
37   Finder->addMatcher(
38       unaryOperator(hasAnyOperatorName("++", "--"), hasType(pointerType()))
39           .bind("expr"),
40       this);
41 
42   // Array subscript on a pointer (not an array) is also pointer arithmetic
43   Finder->addMatcher(
44       arraySubscriptExpr(
45           hasBase(ignoringImpCasts(
46               anyOf(AllPointerTypes,
47                     hasType(decayedType(hasDecayedType(pointerType())))))))
48           .bind("expr"),
49       this);
50 }
51 
52 void ProBoundsPointerArithmeticCheck::check(
53     const MatchFinder::MatchResult &Result) {
54   const auto *MatchedExpr = Result.Nodes.getNodeAs<Expr>("expr");
55 
56   diag(MatchedExpr->getExprLoc(), "do not use pointer arithmetic");
57 }
58 
59 } // namespace cppcoreguidelines
60 } // namespace tidy
61 } // namespace clang
62