clang-tools-extra/clang-tidy/bugprone/MoveForwardingReferenceCheck.h

   1 //===--- MoveForwardingReferenceCheck.h - clang-tidy ----------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_MOVEFORWARDINGREFERENCECHECK_H
  10 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_MOVEFORWARDINGREFERENCECHECK_H
  11
  12 #include "../ClangTidyCheck.h"
  13
  14 namespace clang::tidy::bugprone {
  15
  16 /// The check warns if std::move is applied to a forwarding reference (i.e. an
  17 /// rvalue reference of a function template argument type).
  18 ///
  19 /// If a developer is unaware of the special rules for template argument
  20 /// deduction on forwarding references, it will seem reasonable to apply
  21 /// std::move to the forwarding reference, in the same way that this would be
  22 /// done for a "normal" rvalue reference.
  23 ///
  24 /// This has a consequence that is usually unwanted and possibly surprising: if
  25 /// the function that takes the forwarding reference as its parameter is called
  26 /// with an lvalue, that lvalue will be moved from (and hence placed into an
  27 /// indeterminate state) even though no std::move was applied to the lvalue at
  28 /// the call site.
  29 //
  30 /// The check suggests replacing the std::move with a std::forward.
  31 ///
  32 /// For the user-facing documentation see:
  33 /// http://clang.llvm.org/extra/clang-tidy/checks/bugprone/move-forwarding-reference.html
  34 class MoveForwardingReferenceCheck : public ClangTidyCheck {
  35 public:
  36   MoveForwardingReferenceCheck(StringRef Name, ClangTidyContext *Context)
  37       : ClangTidyCheck(Name, Context) {}
  38   bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
  39     return LangOpts.CPlusPlus11;
  40   }
  41   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
  42   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
  43 };
  44
  45 } // namespace clang::tidy::bugprone
  46
  47 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_MOVEFORWARDINGREFERENCECHECK_H