danielmarjamaki updated this revision to Diff 67337.
danielmarjamaki added a comment.
More generic diagnostic. Diagnose all integerType[pointerType] expressions.
https://reviews.llvm.org/D21134
Files:
clang-tidy/readability/CMakeLists.txt
clang-tidy/readability/MisplacedArrayIndexCheck.cpp
clang-tidy/readability/MisplacedArrayIndexCheck.h
clang-tidy/readability/ReadabilityTidyModule.cpp
docs/ReleaseNotes.rst
docs/clang-tidy/checks/list.rst
docs/clang-tidy/checks/readability-misplaced-array-index.rst
test/clang-tidy/readability-misplaced-array-index.cpp
Index: test/clang-tidy/readability-misplaced-array-index.cpp
===================================================================
--- test/clang-tidy/readability-misplaced-array-index.cpp
+++ test/clang-tidy/readability-misplaced-array-index.cpp
@@ -0,0 +1,35 @@
+// RUN: %check_clang_tidy %s readability-misplaced-array-index %t
+
+#define ABC "abc"
+
+struct XY { int *x; int *y; };
+
+void dostuff(int);
+
+void unusualSyntax(int *x, struct XY *xy)
+{
+ 10[x] = 0;
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: confusing array subscript expression, usually the index is inside the []
+ // CHECK-FIXES: x[10] = 0;
+
+ 10[xy->x] = 0;
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: confusing array subscript expression, usually the index is inside the []
+ // CHECK-FIXES: xy->x[10] = 0;
+
+ dostuff(1["abc"]);
+ // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: confusing array subscript expression, usually the index is inside the []
+ // CHECK-FIXES: dostuff("abc"[1]);
+
+ dostuff(1[ABC]);
+ // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: confusing array subscript expression, usually the index is inside the []
+ // No fixit, we don't want to replace with "abc"[1]
+
+ dostuff(0[0 + ABC]);
+ // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: confusing array subscript expression, usually the index is inside the []
+ // No fixit. Probably the code should be ABC[0]
+}
+
+void normalSyntax(int *x)
+{
+ x[10] = 0;
+}
Index: docs/clang-tidy/checks/readability-misplaced-array-index.rst
===================================================================
--- docs/clang-tidy/checks/readability-misplaced-array-index.rst
+++ docs/clang-tidy/checks/readability-misplaced-array-index.rst
@@ -0,0 +1,29 @@
+.. title:: clang-tidy - readability-misplaced-array-index
+
+readability-misplaced-array-index
+=================================
+
+This check warns for unusual array index syntax.
+
+The following code has unusual array index syntax:
+
+.. code:: c++
+
+ void f(int *x, int y)
+ {
+ y[x] = 0;
+ }
+
+becomes
+
+.. code:: c++
+
+ void f(int *x, int y)
+ {
+ x[y] = 0;
+ }
+
+The check warns about such unusual syntax for readability reasons:
+ * There are programmers that are not familiar with this unusual syntax.
+ * It is possible that variables are mixed up.
+
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -126,6 +126,7 @@
readability-identifier-naming
readability-implicit-bool-cast
readability-inconsistent-declaration-parameter-name
+ readability-misplaced-array-index
readability-named-parameter
readability-redundant-control-flow
readability-redundant-smartptr-get
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -75,6 +75,10 @@
This check warns about the performance overhead arising from concatenating
strings using the ``operator+``, instead of ``operator+=``.
+- New `readability-misplaced-array-index
+ <http://clang.llvm.org/extra/clang-tidy/checks/readability-misplaced-array-index.html>`_ check
+
+ Warns when there is array index before the [] instead of inside it.
Improvements to include-fixer
-----------------------------
Index: clang-tidy/readability/ReadabilityTidyModule.cpp
===================================================================
--- clang-tidy/readability/ReadabilityTidyModule.cpp
+++ clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -19,6 +19,7 @@
#include "IdentifierNamingCheck.h"
#include "ImplicitBoolCastCheck.h"
#include "InconsistentDeclarationParameterNameCheck.h"
+#include "MisplacedArrayIndexCheck.h"
#include "NamedParameterCheck.h"
#include "RedundantControlFlowCheck.h"
#include "RedundantSmartptrGetCheck.h"
@@ -53,6 +54,8 @@
"readability-implicit-bool-cast");
CheckFactories.registerCheck<InconsistentDeclarationParameterNameCheck>(
"readability-inconsistent-declaration-parameter-name");
+ CheckFactories.registerCheck<MisplacedArrayIndexCheck>(
+ "readability-misplaced-array-index");
CheckFactories.registerCheck<StaticDefinitionInAnonymousNamespaceCheck>(
"readability-static-definition-in-anonymous-namespace");
CheckFactories.registerCheck<readability::NamedParameterCheck>(
Index: clang-tidy/readability/MisplacedArrayIndexCheck.h
===================================================================
--- clang-tidy/readability/MisplacedArrayIndexCheck.h
+++ clang-tidy/readability/MisplacedArrayIndexCheck.h
@@ -0,0 +1,36 @@
+//===--- MisplacedArrayIndexCheck.h - clang-tidy-----------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MISPLACED_ARRAY_INDEX_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MISPLACED_ARRAY_INDEX_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+/// Warn about unusual array index syntax (index[array] instead of
+/// array[index]).
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability-misplaced-array-index.html
+class MisplacedArrayIndexCheck : public ClangTidyCheck {
+public:
+ MisplacedArrayIndexCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MISPLACED_ARRAY_INDEX_H
Index: clang-tidy/readability/MisplacedArrayIndexCheck.cpp
===================================================================
--- clang-tidy/readability/MisplacedArrayIndexCheck.cpp
+++ clang-tidy/readability/MisplacedArrayIndexCheck.cpp
@@ -0,0 +1,67 @@
+//===--- 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);
+}
+
+static bool hasMacroID(const Expr *E) {
+ if (E->getExprLoc().isMacroID())
+ return true;
+ for (const Stmt *Child : E->children()) {
+ const Expr *ChildExpr = dyn_cast<Expr>(Child);
+ if (ChildExpr && hasMacroID(ChildExpr))
+ return true;
+ }
+ return false;
+}
+
+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;
+
+ if (hasMacroID(ArraySubscriptE) ||
+ !Result.SourceManager->isWrittenInSameFile(ArraySubscriptE->getLocStart(),
+ ArraySubscriptE->getLocEnd()))
+ return;
+
+ const Expr *LHS = ArraySubscriptE->getLHS();
+ const Expr *RHS = ArraySubscriptE->getRHS();
+
+ Diag << tooling::fixit::createReplacement(*LHS, *RHS, *Result.Context)
+ << tooling::fixit::createReplacement(*RHS, *LHS, *Result.Context);
+}
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/readability/CMakeLists.txt
===================================================================
--- clang-tidy/readability/CMakeLists.txt
+++ clang-tidy/readability/CMakeLists.txt
@@ -10,6 +10,7 @@
IdentifierNamingCheck.cpp
ImplicitBoolCastCheck.cpp
InconsistentDeclarationParameterNameCheck.cpp
+ MisplacedArrayIndexCheck.cpp
NamedParameterCheck.cpp
NamespaceCommentCheck.cpp
ReadabilityTidyModule.cpp
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