[clang-tidy] readability-misplaced-array-index: add new check that warns when array index is misplaced.
Reviewers: alexfh
Differential Revision: https://reviews.llvm.org/D21134
llvm-svn: 281206
diff --git a/clang-tools-extra/clang-tidy/readability/MisplacedArrayIndexCheck.cpp b/clang-tools-extra/clang-tidy/readability/MisplacedArrayIndexCheck.cpp
new file mode 100644
index 0000000..f5e09fa
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/MisplacedArrayIndexCheck.cpp
@@ -0,0 +1,57 @@
+//===--- MisplacedArrayIndexCheck.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 "MisplacedArrayIndexCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Tooling/FixIt.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+void MisplacedArrayIndexCheck::registerMatchers(MatchFinder *Finder) {
+ Finder->addMatcher(arraySubscriptExpr(hasLHS(hasType(isInteger())),
+ hasRHS(hasType(isAnyPointer())))
+ .bind("expr"),
+ this);
+}
+
+void MisplacedArrayIndexCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *ArraySubscriptE =
+ Result.Nodes.getNodeAs<ArraySubscriptExpr>("expr");
+
+ auto Diag = diag(ArraySubscriptE->getLocStart(), "confusing array subscript "
+ "expression, usually the "
+ "index is inside the []");
+
+ // Only try to fixit when LHS and RHS can be swapped directly without changing
+ // the logic.
+ const Expr *RHSE = ArraySubscriptE->getRHS()->IgnoreParenImpCasts();
+ if (!isa<StringLiteral>(RHSE) && !isa<DeclRefExpr>(RHSE) &&
+ !isa<MemberExpr>(RHSE))
+ return;
+
+ const StringRef LText = tooling::fixit::getText(
+ ArraySubscriptE->getLHS()->getSourceRange(), *Result.Context);
+ const StringRef RText = tooling::fixit::getText(
+ ArraySubscriptE->getRHS()->getSourceRange(), *Result.Context);
+
+ Diag << FixItHint::CreateReplacement(
+ ArraySubscriptE->getLHS()->getSourceRange(), RText);
+ Diag << FixItHint::CreateReplacement(
+ ArraySubscriptE->getRHS()->getSourceRange(), LText);
+}
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang