SilverGeri created this revision.
SilverGeri added a reviewer: xazax.hun.
SilverGeri added a subscriber: cfe-commits.
removes the unnecessary if statements, if it was used to check a pointer's
validity just to call delete on that pointer
http://reviews.llvm.org/D21298
Files:
clang-tidy/misc/CMakeLists.txt
clang-tidy/misc/DeleteNullCheck.cpp
clang-tidy/misc/DeleteNullCheck.h
clang-tidy/misc/MiscTidyModule.cpp
docs/clang-tidy/checks/list.rst
docs/clang-tidy/checks/misc-delete-null.rst
test/clang-tidy/misc-delete-null.cpp
Index: test/clang-tidy/misc-delete-null.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/misc-delete-null.cpp
@@ -0,0 +1,30 @@
+// RUN: %check_clang_tidy %s misc-delete-null %t
+
+void f() {
+ int *p = 0;
+ if (p) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: if statement is unnecessary (deleting null pointer has no effect) [misc-delete_null]
+ delete p;
+ }
+ // CHECK-FIXES: delete p;
+
+ int *p3 = new int[3];
+ if (p3)
+ // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: if statement is unnecessary (deleting null pointer has no effect) [misc-delete_null]
+ delete[] p3;
+ // CHECK-FIXES: delete[] p3;
+}
+
+void g() {
+ int *p, *p2;
+ if (p)
+ delete p2;
+
+ if (p && p2)
+ delete p;
+
+ if (p2) {
+ int x = 5;
+ delete p2;
+ }
+}
Index: docs/clang-tidy/checks/misc-delete-null.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/misc-delete-null.rst
@@ -0,0 +1,12 @@
+.. title:: clang-tidy - misc-delete-null
+
+misc-delete-null
+================
+
+Checks the if statements where a pointer's existence is checked and then deletes the pointer.
+The check is unnecessary as deleting a nullpointer has no effect.
+
+.. code:: c++
+ int *p;
+ if (p)
+ delete p;
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -53,6 +53,7 @@
misc-bool-pointer-implicit-conversion
misc-dangling-handle
misc-definitions-in-headers
+ misc-delete-null
misc-fold-init-type
misc-forward-declaration-namespace
misc-inaccurate-erase
Index: clang-tidy/misc/MiscTidyModule.cpp
===================================================================
--- clang-tidy/misc/MiscTidyModule.cpp
+++ clang-tidy/misc/MiscTidyModule.cpp
@@ -16,6 +16,7 @@
#include "BoolPointerImplicitConversionCheck.h"
#include "DanglingHandleCheck.h"
#include "DefinitionsInHeadersCheck.h"
+#include "DeleteNullCheck.h"
#include "FoldInitTypeCheck.h"
#include "ForwardDeclarationNamespaceCheck.h"
#include "InaccurateEraseCheck.h"
@@ -69,6 +70,8 @@
"misc-dangling-handle");
CheckFactories.registerCheck<DefinitionsInHeadersCheck>(
"misc-definitions-in-headers");
+ CheckFactories.registerCheck<DeleteNullCheck>(
+ "misc-delete-null");
CheckFactories.registerCheck<FoldInitTypeCheck>(
"misc-fold-init-type");
CheckFactories.registerCheck<ForwardDeclarationNamespaceCheck>(
Index: clang-tidy/misc/DeleteNullCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/misc/DeleteNullCheck.h
@@ -0,0 +1,36 @@
+//===--- DeleteNullCheck.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_MISC_DELETE_NULL_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_DELETE_NULL_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+/// This checker finds if statements which check a pointer's validity
+/// and wants to free the pointer's data in the body
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/misc-delete-null.html
+class DeleteNullCheck : public ClangTidyCheck {
+public:
+ DeleteNullCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_DELETE_NULL_H
Index: clang-tidy/misc/DeleteNullCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/misc/DeleteNullCheck.cpp
@@ -0,0 +1,65 @@
+//===--- DeleteNullCheck.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 "DeleteNullCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+void DeleteNullCheck::registerMatchers(MatchFinder *Finder) {
+ const auto HasDeleteExpr =
+ cxxDeleteExpr(hasDescendant(declRefExpr().bind("pointerToDelete")))
+ .bind("deleteExpr");
+
+ Finder->addMatcher(
+ ifStmt(
+ allOf(hasCondition(implicitCastExpr(
+ hasDescendant(declRefExpr().bind("condition")))
+ .bind("castExpr")),
+ hasThen(
+ anyOf(HasDeleteExpr,
+ compoundStmt(has(HasDeleteExpr)).bind("compound")))))
+ .bind("ifWithDelete"),
+ this);
+}
+
+void DeleteNullCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *IfWithDelete = Result.Nodes.getNodeAs<IfStmt>("ifWithDelete");
+ const auto *CastExpr = Result.Nodes.getNodeAs<ImplicitCastExpr>("castExpr");
+ const auto *PointerToDelete =
+ Result.Nodes.getNodeAs<DeclRefExpr>("pointerToDelete");
+ const auto *Cond = Result.Nodes.getNodeAs<DeclRefExpr>("condition");
+ const auto *Compound = Result.Nodes.getNodeAs<CompoundStmt>("compound");
+ const auto *Delete = Result.Nodes.getNodeAs<CXXDeleteExpr>("deleteExpr");
+
+ if ((CastExpr->getCastKind() == CastKind::CK_PointerToBoolean) &&
+ (PointerToDelete->getDecl() == Cond->getDecl()) &&
+ (!Compound || Compound->size() == 1)) {
+ auto D = diag(
+ IfWithDelete->getLocStart(),
+ "if statement is unnecessary (deleting null pointer has no effect)");
+ std::string ReplacementText = Lexer::getSourceText(
+ CharSourceRange::getTokenRange(Delete->getSourceRange()),
+ *Result.SourceManager, Result.Context->getLangOpts());
+ ReplacementText += ';';
+
+ D << FixItHint::CreateReplacement(IfWithDelete->getSourceRange(),
+ ReplacementText);
+ }
+}
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/misc/CMakeLists.txt
===================================================================
--- clang-tidy/misc/CMakeLists.txt
+++ clang-tidy/misc/CMakeLists.txt
@@ -7,6 +7,7 @@
BoolPointerImplicitConversionCheck.cpp
DanglingHandleCheck.cpp
DefinitionsInHeadersCheck.cpp
+ DeleteNullCheck.cpp
FoldInitTypeCheck.cpp
ForwardDeclarationNamespaceCheck.cpp
InaccurateEraseCheck.cpp
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