ccotter updated this revision to Diff 520027.
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rebase


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D146921/new/

https://reviews.llvm.org/D146921

Files:
  clang-tools-extra/clang-tidy/cppcoreguidelines/CMakeLists.txt
  clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
  clang-tools-extra/clang-tidy/cppcoreguidelines/MissingStdForwardCheck.cpp
  clang-tools-extra/clang-tidy/cppcoreguidelines/MissingStdForwardCheck.h
  clang-tools-extra/docs/ReleaseNotes.rst
  
clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/missing-std-forward.rst
  clang-tools-extra/docs/clang-tidy/checks/list.rst
  
clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/missing-std-forward.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/missing-std-forward.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/missing-std-forward.cpp
@@ -0,0 +1,150 @@
+// RUN: %check_clang_tidy %s cppcoreguidelines-missing-std-forward %t
+
+// NOLINTBEGIN
+namespace std {
+
+template <typename T> struct remove_reference      { using type = T; };
+template <typename T> struct remove_reference<T&>  { using type = T; };
+template <typename T> struct remove_reference<T&&> { using type = T; };
+
+template <typename T> using remove_reference_t = typename remove_reference<T>::type;
+
+template <typename T> constexpr T &&forward(remove_reference_t<T> &t) noexcept;
+template <typename T> constexpr T &&forward(remove_reference_t<T> &&t) noexcept;
+template <typename T> constexpr remove_reference_t<T> &&move(T &&x);
+
+} // namespace std
+// NOLINTEND
+
+struct S {
+  S();
+  S(const S&);
+  S(S&&) noexcept;
+  S& operator=(const S&);
+  S& operator=(S&&) noexcept;
+};
+
+template <class... Ts>
+void consumes_all(Ts&&...);
+
+namespace positive_cases {
+
+template <class T>
+void does_not_forward(T&& t) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: forwarding reference parameter 't' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+  T other = t;
+}
+
+template <class T>
+void does_not_forward_invoked(T&& t) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: forwarding reference parameter 't' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+  T other = t();
+}
+
+template <class T>
+void forwards_pairwise(T&& t) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: forwarding reference parameter 't' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+  auto first = std::forward<T>(t.first);
+  auto second = std::forward<T>(t.second);
+}
+
+template <class... Ts>
+void does_not_forward_pack(Ts&&... ts) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:36: warning: forwarding reference parameter 'ts' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+  consumes_all(ts...);
+}
+
+template <class T>
+class AClass {
+
+  template <class U>
+  AClass(U&& u) : data(u) {}
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: forwarding reference parameter 'u' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+
+  template <class U>
+  AClass& operator=(U&& u) { }
+  // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: forwarding reference parameter 'u' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+
+  template <class U>
+  void mixed_params(T&& t, U&& u) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: forwarding reference parameter 'u' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+    T other1 = std::move(t);
+    U other2 = std::move(u);
+  }
+
+  T data;
+};
+
+template <class T>
+void does_not_forward_in_evaluated_code(T&& t) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: forwarding reference parameter 't' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+  using result_t = decltype(std::forward<T>(t));
+  unsigned len = sizeof(std::forward<T>(t));
+  T other = t;
+}
+
+template <class T>
+void lambda_value_capture(T&& t) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: forwarding reference parameter 't' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+  [=]() { T other = std::forward<T>(t); };
+}
+
+template <class T>
+void lambda_value_reference(T&& t) {
+  // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: forwarding reference parameter 't' is never forwarded inside the function body [cppcoreguidelines-missing-std-forward]
+  [&]() { T other = std::forward<T>(t); };
+}
+
+} // namespace positive_cases
+
+namespace negative_cases {
+
+template <class T>
+void just_a_decl(T&&t);
+
+template <class T>
+void does_forward(T&& t) {
+  T other = std::forward<T>(t);
+}
+
+template <class... Ts>
+void does_forward_pack(Ts&&... ts) {
+  consumes_all(std::forward<Ts>(ts)...);
+}
+
+void pass_by_value(S s) {
+  S other = std::move(s);
+}
+
+void lvalue_ref(S& s) {
+  S other = std::move(s);
+}
+
+void rvalue_ref(S&& s) {
+  S other = std::move(s);
+}
+
+template <class T>
+void templated_rvalue_ref(std::remove_reference_t<T>&& t) {
+  T other = std::move(t);
+}
+
+template <class T>
+class AClass {
+
+  template <class U>
+  AClass(U&& u) : data(std::forward<U>(u)) {}
+
+  template <class U>
+  AClass& operator=(U&& u) {
+    data = std::forward<U>(u);
+  }
+
+  void rvalue_ref(T&& t) {
+    T other = std::move(t);
+  }
+
+  T data;
+};
+
+} // namespace negative_cases
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===================================================================
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -191,6 +191,7 @@
    `cppcoreguidelines-interfaces-global-init <cppcoreguidelines/interfaces-global-init.html>`_,
    `cppcoreguidelines-macro-usage <cppcoreguidelines/macro-usage.html>`_,
    `cppcoreguidelines-misleading-capture-default-by-value <cppcoreguidelines/misleading-capture-default-by-value.html>`_, "Yes"
+   `cppcoreguidelines-missing-std-forward <cppcoreguidelines/missing-std-forward.html>`_,
    `cppcoreguidelines-narrowing-conversions <cppcoreguidelines/narrowing-conversions.html>`_,
    `cppcoreguidelines-no-malloc <cppcoreguidelines/no-malloc.html>`_,
    `cppcoreguidelines-owning-memory <cppcoreguidelines/owning-memory.html>`_,
Index: clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/missing-std-forward.rst
===================================================================
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/missing-std-forward.rst
@@ -0,0 +1,39 @@
+.. title:: clang-tidy - cppcoreguidelines-missing-std-forward
+
+cppcoreguidelines-missing-std-forward
+=====================================
+
+Warns when a forwarding reference parameter is not forwarded inside the
+function body.
+
+Example:
+
+.. code-block:: c++
+
+  template <class T>
+  void wrapper(T&& t) {
+    impl(std::forward<T>(t), 1, 2); // Correct
+  }
+
+  template <class T>
+  void wrapper2(T&& t) {
+    impl(t, 1, 2); // Oops - should use std::forward<T>(t)
+  }
+
+  template <class T>
+  void wrapper3(T&& t) {
+    impl(std::move(t), 1, 2); // Also buggy - should use std::forward<T>(t)
+  }
+
+  template <class F>
+  void wrapper_function(F&& f) {
+    std::forward<F>(f)(1, 2); // Correct
+  }
+
+  template <class F>
+  void wrapper_function2(F&& f) {
+    f(1, 2); // Incorrect - may not invoke the desired qualified function operator
+  }
+
+This check implements
+`CppCoreGuideline F.19 <http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rf-forward>`_.
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -133,6 +133,12 @@
   use-after-free errors and suggests avoiding captures or ensuring the lambda
   closure object has a guaranteed lifetime.
 
+- New :doc:`cppcoreguidelines-missing-std-forward
+  <clang-tidy/checks/cppcoreguidelines/missing-std-forward>` check.
+
+  Warns when a forwarding reference parameter is not forwarded within the
+  function body.
+
 - New :doc:`cppcoreguidelines-misleading-capture-default-by-value
   <clang-tidy/checks/cppcoreguidelines/misleading-capture-default-by-value>` check.
 
Index: clang-tools-extra/clang-tidy/cppcoreguidelines/MissingStdForwardCheck.h
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/cppcoreguidelines/MissingStdForwardCheck.h
@@ -0,0 +1,38 @@
+//===--- MissingStdForwardCheck.h - clang-tidy ------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_MISSINGSTDFORWARDCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_MISSINGSTDFORWARDCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::cppcoreguidelines {
+
+/// Warns when a function accepting a forwarding reference does anything besides
+/// forwarding (with std::forward) the parameter in the body of the function.
+/// This check implement CppCoreGuideline F.19.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines/missing-std-forward.html
+class MissingStdForwardCheck : public ClangTidyCheck {
+public:
+  MissingStdForwardCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus11;
+  }
+  std::optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
+};
+
+} // namespace clang::tidy::cppcoreguidelines
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_MISSINGSTDFORWARDCHECK_H
Index: clang-tools-extra/clang-tidy/cppcoreguidelines/MissingStdForwardCheck.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/cppcoreguidelines/MissingStdForwardCheck.cpp
@@ -0,0 +1,90 @@
+//===--- MissingStdForwardCheck.cpp - clang-tidy --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "MissingStdForwardCheck.h"
+#include "../utils/Matchers.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ExprConcepts.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::cppcoreguidelines {
+
+namespace {
+
+using matchers::hasUnevaluatedContext;
+
+AST_MATCHER_P(QualType, possiblyPackExpansionOf,
+              ast_matchers::internal::Matcher<QualType>, InnerMatcher) {
+  return InnerMatcher.matches(Node.getNonPackExpansionType(), Finder, Builder);
+}
+
+AST_MATCHER(ParmVarDecl, isTemplateTypeParameter) {
+  ast_matchers::internal::Matcher<QualType> Inner = possiblyPackExpansionOf(
+      qualType(rValueReferenceType(),
+               references(templateTypeParmType(
+                   hasDeclaration(templateTypeParmDecl()))),
+               unless(references(qualType(isConstQualified())))));
+  if (!Inner.matches(Node.getType(), Finder, Builder))
+    return false;
+
+  const auto *Function = dyn_cast<FunctionDecl>(Node.getDeclContext());
+  if (!Function)
+    return false;
+
+  const FunctionTemplateDecl *FuncTemplate =
+      Function->getDescribedFunctionTemplate();
+  if (!FuncTemplate)
+    return false;
+
+  QualType ParamType =
+      Node.getType().getNonPackExpansionType()->getPointeeType();
+  const auto *TemplateType = ParamType->getAs<TemplateTypeParmType>();
+  if (!TemplateType)
+    return false;
+
+  return TemplateType->getDepth() ==
+         FuncTemplate->getTemplateParameters()->getDepth();
+}
+
+} // namespace
+
+void MissingStdForwardCheck::registerMatchers(MatchFinder *Finder) {
+  auto ToParam = hasAnyParameter(parmVarDecl(equalsBoundNode("param")));
+
+  auto ForwardCallMatcher = callExpr(
+      forCallable(equalsBoundNode("func")), argumentCountIs(1),
+      callee(unresolvedLookupExpr(hasAnyDeclaration(
+          namedDecl(hasUnderlyingDecl(hasName("::std::forward")))))),
+      hasArgument(0, declRefExpr(to(equalsBoundNode("param"))).bind("ref")),
+      unless(anyOf(hasAncestor(typeLoc()),
+                   hasAncestor(expr(hasUnevaluatedContext())))));
+
+  Finder->addMatcher(
+      parmVarDecl(parmVarDecl().bind("param"), isTemplateTypeParameter(),
+                  hasAncestor(functionDecl().bind("func")),
+                  hasAncestor(functionDecl(
+                      isDefinition(), equalsBoundNode("func"), ToParam,
+                      unless(hasDescendant(std::move(ForwardCallMatcher)))))),
+      this);
+}
+
+void MissingStdForwardCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *Param = Result.Nodes.getNodeAs<ParmVarDecl>("param");
+
+  if (!Param)
+    return;
+
+  diag(Param->getLocation(),
+       "forwarding reference parameter %0 is never forwarded "
+       "inside the function body")
+      << Param;
+}
+
+} // namespace clang::tidy::cppcoreguidelines
Index: clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
===================================================================
--- clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
+++ clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
@@ -24,7 +24,11 @@
 #include "InitVariablesCheck.h"
 #include "InterfacesGlobalInitCheck.h"
 #include "MacroUsageCheck.h"
+<<<<<<< HEAD
 #include "MisleadingCaptureDefaultByValueCheck.h"
+=======
+#include "MissingStdForwardCheck.h"
+>>>>>>> 9bb204a22dc6 (Rename)
 #include "NarrowingConversionsCheck.h"
 #include "NoMallocCheck.h"
 #include "OwningMemoryCheck.h"
@@ -77,6 +81,8 @@
         "cppcoreguidelines-macro-usage");
     CheckFactories.registerCheck<MisleadingCaptureDefaultByValueCheck>(
         "cppcoreguidelines-misleading-capture-default-by-value");
+    CheckFactories.registerCheck<MissingStdForwardCheck>(
+        "cppcoreguidelines-missing-std-forward");
     CheckFactories.registerCheck<NarrowingConversionsCheck>(
         "cppcoreguidelines-narrowing-conversions");
     CheckFactories.registerCheck<NoMallocCheck>("cppcoreguidelines-no-malloc");
Index: clang-tools-extra/clang-tidy/cppcoreguidelines/CMakeLists.txt
===================================================================
--- clang-tools-extra/clang-tidy/cppcoreguidelines/CMakeLists.txt
+++ clang-tools-extra/clang-tidy/cppcoreguidelines/CMakeLists.txt
@@ -15,6 +15,7 @@
   InterfacesGlobalInitCheck.cpp
   MacroUsageCheck.cpp
   MisleadingCaptureDefaultByValueCheck.cpp
+  MissingStdForwardCheck.cpp
   NarrowingConversionsCheck.cpp
   NoMallocCheck.cpp
   OwningMemoryCheck.cpp
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