[clang-tools-extra] r212535 - [clang-tidy] Add a little checker for Twine locals in LLVM.
Benjamin Kramer
benny.kra at googlemail.com
Tue Jul 8 07:32:18 PDT 2014
Author: d0k
Date: Tue Jul 8 09:32:17 2014
New Revision: 212535
URL: http://llvm.org/viewvc/llvm-project?rev=212535&view=rev
Log:
[clang-tidy] Add a little checker for Twine locals in LLVM.
Those often cause use after free bugs and should be generally avoided.
Technically it is safe to have a Twine with >=2 components in a variable
but I don't think it is a good pattern to follow. The almost trivial checker
comes with elaborated fix-it hints that turn the Twine into a std::string
if necessary and otherwise fall back to the original type if the Twine
is created from a single value.
Added:
clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.cpp
clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.h
clang-tools-extra/trunk/test/clang-tidy/llvm-twine-local.cpp
Modified:
clang-tools-extra/trunk/clang-tidy/llvm/CMakeLists.txt
clang-tools-extra/trunk/clang-tidy/llvm/LLVMTidyModule.cpp
Modified: clang-tools-extra/trunk/clang-tidy/llvm/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/llvm/CMakeLists.txt?rev=212535&r1=212534&r2=212535&view=diff
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/llvm/CMakeLists.txt (original)
+++ clang-tools-extra/trunk/clang-tidy/llvm/CMakeLists.txt Tue Jul 8 09:32:17 2014
@@ -4,6 +4,7 @@ add_clang_library(clangTidyLLVMModule
IncludeOrderCheck.cpp
LLVMTidyModule.cpp
NamespaceCommentCheck.cpp
+ TwineLocalCheck.cpp
LINK_LIBS
clangAST
Modified: clang-tools-extra/trunk/clang-tidy/llvm/LLVMTidyModule.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/llvm/LLVMTidyModule.cpp?rev=212535&r1=212534&r2=212535&view=diff
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/llvm/LLVMTidyModule.cpp (original)
+++ clang-tools-extra/trunk/clang-tidy/llvm/LLVMTidyModule.cpp Tue Jul 8 09:32:17 2014
@@ -12,6 +12,7 @@
#include "../ClangTidyModuleRegistry.h"
#include "IncludeOrderCheck.h"
#include "NamespaceCommentCheck.h"
+#include "TwineLocalCheck.h"
namespace clang {
namespace tidy {
@@ -24,6 +25,9 @@ public:
CheckFactories.addCheckFactory(
"llvm-namespace-comment",
new ClangTidyCheckFactory<NamespaceCommentCheck>());
+ CheckFactories.addCheckFactory(
+ "llvm-twine-local",
+ new ClangTidyCheckFactory<TwineLocalCheck>());
}
};
Added: clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.cpp?rev=212535&view=auto
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.cpp (added)
+++ clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.cpp Tue Jul 8 09:32:17 2014
@@ -0,0 +1,64 @@
+//===--- TwineLocalCheck.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 "TwineLocalCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+
+TwineLocalCheck::TwineLocalCheck() {}
+
+void TwineLocalCheck::registerMatchers(MatchFinder *Finder) {
+ auto TwineType =
+ qualType(hasDeclaration(recordDecl(hasName("::llvm::Twine"))));
+ Finder->addMatcher(varDecl(hasType(TwineType)).bind("variable"), this);
+}
+
+void TwineLocalCheck::check(const MatchFinder::MatchResult &Result) {
+ const VarDecl *VD = Result.Nodes.getNodeAs<VarDecl>("variable");
+ auto Diag = diag(VD->getLocation(),
+ "twine variables are prone to use after free bugs");
+
+ // If this VarDecl has an initializer try to fix it.
+ if (VD->hasInit()) {
+ // Peel away implicit constructors and casts so we can see the actual type
+ // of the initializer.
+ const Expr *C = VD->getInit();
+ while (isa<CXXConstructExpr>(C))
+ C = cast<CXXConstructExpr>(C)->getArg(0)->IgnoreParenImpCasts();
+
+ SourceRange TypeRange =
+ VD->getTypeSourceInfo()->getTypeLoc().getSourceRange();
+
+ // A real Twine, turn it into a std::string.
+ if (VD->getType()->getCanonicalTypeUnqualified() ==
+ C->getType()->getCanonicalTypeUnqualified()) {
+ SourceLocation EndLoc = Lexer::getLocForEndOfToken(
+ VD->getInit()->getLocEnd(), 0, *Result.SourceManager,
+ Result.Context->getLangOpts());
+ Diag << FixItHint::CreateReplacement(TypeRange, "std::string")
+ << FixItHint::CreateInsertion(VD->getInit()->getLocStart(), "(")
+ << FixItHint::CreateInsertion(EndLoc, ").str()");
+ } else {
+ // Just an implicit conversion. Insert the real type.
+ Diag << FixItHint::CreateReplacement(
+ TypeRange,
+ C->getType().getAsString(Result.Context->getPrintingPolicy()));
+ }
+ }
+}
+
+} // namespace tidy
+} // namespace clang
Added: clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.h
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.h?rev=212535&view=auto
==============================================================================
--- clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.h (added)
+++ clang-tools-extra/trunk/clang-tidy/llvm/TwineLocalCheck.h Tue Jul 8 09:32:17 2014
@@ -0,0 +1,31 @@
+//===--- TwineLocalCheck.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_LLVM_TWINE_LOCAL_CHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LLVM_TWINE_LOCAL_CHECK_H
+
+#include "../ClangTidy.h"
+#include "llvm/Support/Regex.h"
+
+namespace clang {
+namespace tidy {
+
+/// \brief Looks for local Twine variables which are prone to use after frees
+/// and should be generally avoided.
+class TwineLocalCheck : public ClangTidyCheck {
+public:
+ TwineLocalCheck();
+ 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_LLVM_TWINE_LOCAL_CHECK_H
Added: clang-tools-extra/trunk/test/clang-tidy/llvm-twine-local.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/llvm-twine-local.cpp?rev=212535&view=auto
==============================================================================
--- clang-tools-extra/trunk/test/clang-tidy/llvm-twine-local.cpp (added)
+++ clang-tools-extra/trunk/test/clang-tidy/llvm-twine-local.cpp Tue Jul 8 09:32:17 2014
@@ -0,0 +1,35 @@
+// RUN: grep -Ev "// *[A-Z-]+:" %s > %t.cpp
+// RUN: clang-tidy %t.cpp -checks='-*,llvm-twine-local' -fix -- > %t.msg 2>&1
+// RUN: FileCheck -input-file=%t.cpp %s
+// RUN: FileCheck -input-file=%t.msg -check-prefix=CHECK-MESSAGES %s
+
+namespace llvm {
+class Twine {
+public:
+ Twine(const char *);
+ Twine(int);
+ Twine &operator+(const Twine &);
+};
+}
+
+using namespace llvm;
+
+void foo(const Twine &x);
+
+static Twine Moo = Twine("bark") + "bah";
+// CHECK-MASSAGES: twine variables are prone to use after free bugs
+// CHECK-MESSAGES: note: FIX-IT applied suggested code changes
+// CHECK: static std::string Moo = (Twine("bark") + "bah").str();
+
+int main() {
+ const Twine t = Twine("a") + "b" + Twine(42);
+// CHECK-MASSAGES: twine variables are prone to use after free bugs
+// CHECK-MESSAGES: note: FIX-IT applied suggested code changes
+// CHECK: std::string t = (Twine("a") + "b" + Twine(42)).str();
+ foo(Twine("a") + "b");
+
+ Twine Prefix = false ? "__INT_FAST" : "__UINT_FAST";
+// CHECK-MASSAGES: twine variables are prone to use after free bugs
+// CHECK-MESSAGES: note: FIX-IT applied suggested code changes
+// CHECK: const char * Prefix = false ? "__INT_FAST" : "__UINT_FAST";
+}
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