[clang-tidy] Added a check for forward declaration in the potentially wrong namespace

Adds a new check "misc-forward-declaration-namespace".
In check, A forward declaration is considerred in a potentially wrong namespace
if there is any definition/declaration with the same name exists in a different
namespace.

Reviewers: akuegel, hokein, alexfh

Patch by Eric Liu!

Differential Revision: http://reviews.llvm.org/D17195

llvm-svn: 261737

1 files changed, 59 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/misc/ForwardDeclarationNamespaceCheck.h b/clang-tools-extra/clang-tidy/misc/ForwardDeclarationNamespaceCheck.h
new file mode 100644
index 00000000000..cc701daad6a
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/misc/ForwardDeclarationNamespaceCheck.h
@@ -0,0 +1,59 @@
+//===--- ForwardDeclarationNamespaceCheck.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_FORWARDDECLARATIONNAMESPACECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_FORWARDDECLARATIONNAMESPACECHECK_H
+
+#include <set>
+#include <vector>
+#include "llvm/ADT/SmallPtrSet.h"
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+/// Checks if an unused forward declaration is in a wrong namespace.
+///
+/// The check inspects all unused forward declarations and checks if there is
+/// any declaration/definition with the same name, which could indicate
+/// that the forward declaration is potentially in a wrong namespace.
+///
+/// \code
+///   namespace na { struct A; }
+///   namespace nb { struct A {} };
+///   nb::A a;
+///   // warning : no definition found for 'A', but a definition with the same
+///   name 'A' found in another namespace 'nb::'
+/// \endcode
+///
+/// This check can only generate warnings, but it can't suggest fixes at this
+/// point.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/misc-forward-declaration-namespace.html
+class ForwardDeclarationNamespaceCheck : public ClangTidyCheck {
+public:
+  ForwardDeclarationNamespaceCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  void onEndOfTranslationUnit() override;
+
+private:
+  llvm::StringMap<std::vector<const CXXRecordDecl *>> DeclNameToDefinitions;
+  llvm::StringMap<std::vector<const CXXRecordDecl *>> DeclNameToDeclarations;
+  llvm::SmallPtrSet<const Type *, 16> FriendTypes;
+};
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_FORWARDDECLARATIONNAMESPACECHECK_H