Hi alexfh, djasper,
This tries to find code similar that immediately destroys
an object that looks like it's trying to follow RAII.
{
scoped_lock(&global_mutex);
critical_section();
}
This checker will have false positives if someone uses this pattern
to legitimately invoke a destructor immediately (or the statement is
at the end of a scope anyway). To reduce the number we ignore this
pattern in macros (this is heavily used by gtest) and ignore objects
with no user-defined destructor.
http://reviews.llvm.org/D4615
Files:
clang-tidy/misc/CMakeLists.txt
clang-tidy/misc/MiscTidyModule.cpp
clang-tidy/misc/UnusedRAII.cpp
clang-tidy/misc/UnusedRAII.h
test/clang-tidy/misc-unused-raii.cpp
Index: clang-tidy/misc/CMakeLists.txt
===================================================================
--- clang-tidy/misc/CMakeLists.txt
+++ clang-tidy/misc/CMakeLists.txt
@@ -6,6 +6,7 @@
MiscTidyModule.cpp
RedundantSmartptrGet.cpp
SwappedArgumentsCheck.cpp
+ UnusedRAII.cpp
UseOverride.cpp
LINK_LIBS
Index: clang-tidy/misc/MiscTidyModule.cpp
===================================================================
--- clang-tidy/misc/MiscTidyModule.cpp
+++ clang-tidy/misc/MiscTidyModule.cpp
@@ -14,6 +14,7 @@
#include "BoolPointerImplicitConversion.h"
#include "RedundantSmartptrGet.h"
#include "SwappedArgumentsCheck.h"
+#include "UnusedRAII.h"
#include "UseOverride.h"
namespace clang {
@@ -35,6 +36,9 @@
"misc-swapped-arguments",
new ClangTidyCheckFactory<SwappedArgumentsCheck>());
CheckFactories.addCheckFactory(
+ "misc-unused-raii",
+ new ClangTidyCheckFactory<UnusedRAIICheck>());
+ CheckFactories.addCheckFactory(
"misc-use-override",
new ClangTidyCheckFactory<UseOverride>());
}
Index: clang-tidy/misc/UnusedRAII.cpp
===================================================================
--- /dev/null
+++ clang-tidy/misc/UnusedRAII.cpp
@@ -0,0 +1,56 @@
+//===--- UnusedRAII.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 "UnusedRAII.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/SmallPtrSet.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace ast_matchers {
+AST_MATCHER(CXXRecordDecl, hasUserDeclaredDestructor) {
+ return Node.hasUserDeclaredDestructor();
+}
+} // namespace ast_matchers
+
+namespace tidy {
+
+void UnusedRAIICheck::registerMatchers(MatchFinder *Finder) {
+ // Look for temporaries that are constructed in-place and immediately
+ // destroyed. Look for temporaries created by a functional cast but not for
+ // those returned from a call.
+ auto BindTemp = bindTemporaryExpr(unless(has(callExpr())));
+ Finder->addMatcher(
+ exprWithCleanups(
+ unless(hasAncestor(decl(
+ anyOf(recordDecl(ast_matchers::isTemplateInstantiation()),
+ functionDecl(ast_matchers::isTemplateInstantiation()))))),
+ hasParent(compoundStmt()),
+ hasType(recordDecl(hasUserDeclaredDestructor())),
+ anyOf(has(BindTemp), has(functionalCastExpr(has(BindTemp)))))
+ .bind("expr"),
+ this);
+}
+
+void UnusedRAIICheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *E = Result.Nodes.getStmtAs<Expr>("expr");
+
+ // We ignore code expanded from macros to reduce the number of false
+ // positives.
+ if (E->getLocStart().isMacroID())
+ return;
+
+ diag(E->getLocStart(), "object created and destroyed immediately; did you "
+ "mean to name the object?");
+}
+
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/misc/UnusedRAII.h
===================================================================
--- /dev/null
+++ clang-tidy/misc/UnusedRAII.h
@@ -0,0 +1,46 @@
+//===--- UnusedRAII.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_UNUSED_RAII_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_UNUSED_RAII_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+
+/// \brief Finds temporaries that look like RAII objects.
+///
+/// The canonical example for this is a scoped lock.
+/// \code
+/// {
+/// scoped_lock(&global_mutex);
+/// critical_section();
+/// }
+/// \endcode
+/// The destructor of the scoped_lock is called before the critical_section is
+/// entered, leaving it unprotected.
+///
+/// We apply a number of heuristics to reduce the false positive count of this
+/// check:
+/// - Ignore code expanded from macros. Testing frameworks make heavy use of
+/// this.
+/// - Ignore types with no user-declared constructor. Those are very unlikely
+/// to be RAII objects.
+/// - Ignore objects returned from a call.
+class UnusedRAIICheck : public ClangTidyCheck {
+public:
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_UNUSED_RAII_H
Index: test/clang-tidy/misc-unused-raii.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/misc-unused-raii.cpp
@@ -0,0 +1,33 @@
+// RUN: clang-tidy %s -checks='-*,misc-unused-raii' -header-filter='.*' -- | FileCheck %s -implicit-check-not="{{warning|error}}:"
+
+struct Foo {
+ Foo();
+ Foo(int);
+ ~Foo();
+};
+
+struct Bar {
+ Bar();
+ Foo f;
+};
+
+template <typename T>
+void qux() {
+ T(42);
+}
+
+Foo f();
+
+int main() {
+ Foo(42);
+// CHECK: :[[@LINE-1]]:3: warning: object created and destroyed immediately; did you mean to name the object?
+ Foo();
+// CHECK: :[[@LINE-1]]:3: warning: object created and destroyed immediately; did you mean to name the object?
+
+ Bar();
+ f();
+ qux<Foo>();
+
+#define M Foo();
+ M
+}
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