Add checker for the C++ Core Guidelines: cppcoreguidelines-pro-type-const-cast.

Patch by Matthias Gehre!

llvm-svn: 249540

clang-tools-extra/clang-tidy/cppcoreguidelines/CMakeLists.txt

@@ -2,6 +2,7 @@ set(LLVM_LINK_COMPONENTS support)
 
 add_clang_library(clangTidyCppCoreGuidelinesModule
   CppCoreGuidelinesTidyModule.cpp
+  ProTypeConstCastCheck.cpp
   ProTypeReinterpretCastCheck.cpp
 
   LINK_LIBS

clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp

@@ -10,6 +10,7 @@
 #include "../ClangTidy.h"
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
+#include "ProTypeConstCastCheck.h"
 #include "ProTypeReinterpretCastCheck.h"
 
 namespace clang {
@@ -19,6 +20,8 @@ namespace cppcoreguidelines {
 class CppCoreGuidelinesModule : public ClangTidyModule {
 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
+    CheckFactories.registerCheck<ProTypeConstCastCheck>(
+        "cppcoreguidelines-pro-type-const-cast");
     CheckFactories.registerCheck<ProTypeReinterpretCastCheck>(
         "cppcoreguidelines-pro-type-reinterpret-cast");
   }

clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeConstCastCheck.cpp

@@ -0,0 +1,33 @@
+//===--- ProTypeConstCastCheck.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 "ProTypeConstCastCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+
+void ProTypeConstCastCheck::registerMatchers(MatchFinder *Finder) {
+  if(!getLangOpts().CPlusPlus)
+    return;
+
+  Finder->addMatcher(cxxConstCastExpr().bind("cast"), this);
+}
+
+void ProTypeConstCastCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *MatchedCast = Result.Nodes.getNodeAs<CXXConstCastExpr>("cast");
+  diag(MatchedCast->getOperatorLoc(), "do not use const_cast");
+}
+
+} // namespace tidy
+} // namespace clang
+

clang-tools-extra/clang-tidy/cppcoreguidelines/ProTypeConstCastCheck.h

@@ -0,0 +1,34 @@
+//===--- ProTypeConstCastCheck.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_CPPCOREGUIDELINES_PRO_TYPE_CONST_CAST_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_PRO_TYPE_CONST_CAST_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+
+/// This check flags all instances of const_cast
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines-pro-type-const-cast.html
+class ProTypeConstCastCheck : public ClangTidyCheck {
+public:
+  ProTypeConstCastCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  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_CPPCOREGUIDELINES_PRO_TYPE_CONST_CAST_H
+

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines-pro-type-const-cast.rst

@@ -0,0 +1,9 @@
+cppcoreguidelines-pro-type-const-cast
+=====================================
+
+This check flags all uses of const_cast in C++ code.
+
+Modifying a variable that was declared const is undefined behavior, even with const_cast.
+
+This rule is part of the "Type safety" profile of the C++ Core Guidelines, see
+https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#-type3-dont-use-const_cast-to-cast-away-const-ie-at-all.

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -3,6 +3,7 @@ List of clang-tidy Checks
 
 .. toctree::
    cert-variadic-function-def
+   cppcoreguidelines-pro-type-const-cast
    cppcoreguidelines-pro-type-reinterpret-cast
    google-build-explicit-make-pair
    google-build-namespaces

clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-type-const-cast.cpp

@@ -0,0 +1,6 @@
+// RUN: %python %S/check_clang_tidy.py %s cppcoreguidelines-pro-type-const-cast %t
+
+const int* i;
+int* j;
+void f() { j = const_cast<int*>(i); }
+// CHECK-MESSAGES: :[[@LINE-1]]:16: warning: do not use const_cast [cppcoreguidelines-pro-type-const-cast]