[clang-tidy] Add flag to specify an alternative to std::move in cppcoreguidelines-rvalue-reference-param-not-moved (#138757)

Since std::move is nothing more than a cast, part of STL and not the
language itself, it's easy to provide a custom implementation if one
wishes not to include the entirety of <utility>.

Added flag (MoveFunction) provides a way to continue using this
essential check even with the custom implementation of moving.

---------

Co-authored-by: EugeneZelenko <eugene.zelenko@gmail.com>

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

@@ -42,9 +42,9 @@ void RvalueReferenceParamNotMovedCheck::registerMatchers(MatchFinder *Finder) {
   StatementMatcher MoveCallMatcher =
       callExpr(
           argumentCountIs(1),
-          anyOf(callee(functionDecl(hasName("::std::move"))),
+          anyOf(callee(functionDecl(hasName(MoveFunction))),
                 callee(unresolvedLookupExpr(hasAnyDeclaration(
-                    namedDecl(hasUnderlyingDecl(hasName("::std::move"))))))),
+                    namedDecl(hasUnderlyingDecl(hasName(MoveFunction))))))),
           hasArgument(
               0, argumentOf(
                      AllowPartialMove,
@@ -122,7 +122,8 @@ RvalueReferenceParamNotMovedCheck::RvalueReferenceParamNotMovedCheck(
       AllowPartialMove(Options.get("AllowPartialMove", false)),
       IgnoreUnnamedParams(Options.get("IgnoreUnnamedParams", false)),
       IgnoreNonDeducedTemplateTypes(
-          Options.get("IgnoreNonDeducedTemplateTypes", false)) {}
+          Options.get("IgnoreNonDeducedTemplateTypes", false)),
+      MoveFunction(Options.get("MoveFunction", "::std::move")) {}
 
 void RvalueReferenceParamNotMovedCheck::storeOptions(
     ClangTidyOptions::OptionMap &Opts) {
@@ -130,6 +131,7 @@ void RvalueReferenceParamNotMovedCheck::storeOptions(
   Options.store(Opts, "IgnoreUnnamedParams", IgnoreUnnamedParams);
   Options.store(Opts, "IgnoreNonDeducedTemplateTypes",
                 IgnoreNonDeducedTemplateTypes);
+  Options.store(Opts, "MoveFunction", MoveFunction);
 }
 
 } // namespace clang::tidy::cppcoreguidelines

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

@@ -32,6 +32,7 @@ private:
   const bool AllowPartialMove;
   const bool IgnoreUnnamedParams;
   const bool IgnoreNonDeducedTemplateTypes;
+  const StringRef MoveFunction;
 };
 
 } // namespace clang::tidy::cppcoreguidelines

clang-tools-extra/docs/ReleaseNotes.rst

@@ -215,6 +215,11 @@ Changes in existing checks
 - Improved :doc:`cppcoreguidelines-missing-std-forward
   <clang-tidy/checks/cppcoreguidelines/missing-std-forward>` check by adding a
   flag to specify the function used for forwarding instead of ``std::forward``.
+   
+- Improved :doc:`cppcoreguidelines-rvalue-reference-param-not-moved
+  <clang-tidy/checks/cppcoreguidelines/rvalue-reference-param-not-moved>` check
+  by adding a flag to specify the function used for moving instead of
+  ``std::move``.
 
 - Improved :doc:`cppcoreguidelines-special-member-functions
   <clang-tidy/checks/cppcoreguidelines/special-member-functions>` check by

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/rvalue-reference-param-not-moved.rst

@@ -79,6 +79,10 @@ Options
       T other = std::forward<T>(t);
     }
 
+.. option:: MoveFunction
+
+   Specify the function used for moving. Default is `::std::move`.
+
 This check implements `F.18
 <http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#f18-for-will-move-from-parameters-pass-by-x-and-stdmove-the-parameter>`_
 from the C++ Core Guidelines.

clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/rvalue-reference-param-not-moved-custom-function.cpp

@@ -0,0 +1,47 @@
+// RUN: %check_clang_tidy -std=c++11 %s cppcoreguidelines-rvalue-reference-param-not-moved %t -- \
+// RUN: -config="{CheckOptions: {cppcoreguidelines-rvalue-reference-param-not-moved.AllowPartialMove: true, cppcoreguidelines-rvalue-reference-param-not-moved.IgnoreUnnamedParams: true, cppcoreguidelines-rvalue-reference-param-not-moved.IgnoreNonDeducedTemplateTypes: true, cppcoreguidelines-rvalue-reference-param-not-moved.MoveFunction: custom_move}}" -- -fno-delayed-template-parsing
+
+// NOLINTBEGIN
+namespace std {
+template <typename>
+struct remove_reference;
+
+template <typename _Tp> struct remove_reference { typedef _Tp type; };
+template <typename _Tp> struct remove_reference<_Tp&> { typedef _Tp type; };
+template <typename _Tp> struct remove_reference<_Tp&&> { typedef _Tp type; };
+
+template <typename _Tp>
+constexpr typename std::remove_reference<_Tp>::type &&move(_Tp &&__t) noexcept;
+
+template <typename _Tp>
+constexpr _Tp &&
+forward(typename remove_reference<_Tp>::type &__t) noexcept;
+
+}
+// NOLINTEND
+
+
+struct Obj {
+  Obj();
+  Obj(const Obj&);
+  Obj& operator=(const Obj&);
+  Obj(Obj&&);
+  Obj& operator=(Obj&&);
+  void member() const;
+};
+
+template<class T>
+constexpr typename std::remove_reference<T>::type&& custom_move(T&& x) noexcept
+{
+    return static_cast<typename std::remove_reference<T>::type&&>(x);
+}
+
+void move_with_std(Obj&& o) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: rvalue reference parameter 'o' is never moved from inside the function body [cppcoreguidelines-rvalue-reference-param-not-moved]
+  Obj other{std::move(o)};
+}
+
+void move_with_custom(Obj&& o) {
+  Obj other{custom_move(o)};
+}
+