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