[clang-tidy] new check cppcoreguidelines-pro-bounds-pointer-arithmetic

Summary:
This check flags all usage of pointer arithmetic, because it could lead
to an
invalid pointer.
Subtraction of two pointers is not flagged by this check.

Pointers should only refer to single objects, and pointer arithmetic is
fragile and easy to get wrong. array_view is a bounds-checked, safe type
for accessing arrays of data.

This rule is part of the "Bounds safety" profile of the C++ Core
Guidelines, see
https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#-bounds1-dont-use-pointer-arithmetic-use-array_view-instead

Depends on D13313

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D13311

llvm-svn: 250116

1 files changed, 53 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
new file mode 100644
index 00000000000..15ea27a4462
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
@@ -0,0 +1,53 @@
+//===--- ProBoundsPointerArithmeticCheck.cpp - clang-tidy------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ProBoundsPointerArithmeticCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+
+void ProBoundsPointerArithmeticCheck::registerMatchers(MatchFinder *Finder) {
+  if (!getLangOpts().CPlusPlus)
+    return;
+
+  // Flag all operators +, -, +=, -=, ++, -- that result in a pointer
+  Finder->addMatcher(
+      binaryOperator(anyOf(hasOperatorName("+"), hasOperatorName("-"),
+                           hasOperatorName("+="), hasOperatorName("-=")),
+                     hasType(pointerType()))
+          .bind("expr"),
+      this);
+
+  Finder->addMatcher(
+      unaryOperator(anyOf(hasOperatorName("++"), hasOperatorName("--")),
+                    hasType(pointerType()))
+          .bind("expr"),
+      this);
+
+  // Array subscript on a pointer (not an array) is also pointer arithmetic
+  Finder->addMatcher(
+      arraySubscriptExpr(hasBase(ignoringImpCasts(anyOf(hasType(pointerType()),
+                                                        hasType(decayedType(hasDecayedType(pointerType())))))))
+          .bind("expr"),
+      this);
+}
+
+void
+ProBoundsPointerArithmeticCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *MatchedExpr = Result.Nodes.getNodeAs<Expr>("expr");
+
+  diag(MatchedExpr->getExprLoc(), "do not use pointer arithmetic");
+}
+
+} // namespace tidy
+} // namespace clang