[clang-tidy] Add check performance-lost-std-move #139525

segoon · 2025-05-12T10:08:36Z

No description provided.

llvmbot · 2025-05-12T10:09:10Z

@llvm/pr-subscribers-clang-tools-extra

Author: Vasiliy Kulikov (segoon)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/139525.diff

8 Files Affected:

(modified) clang-tools-extra/clang-tidy/performance/CMakeLists.txt (+1)
(added) clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp (+96)
(added) clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h (+37)
(modified) clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp (+2)
(modified) clang-tools-extra/docs/ReleaseNotes.rst (+5)
(modified) clang-tools-extra/docs/clang-tidy/checks/list.rst (+1)
(added) clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst (+14)
(added) clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp (+108)

diff --git a/clang-tools-extra/clang-tidy/performance/CMakeLists.txt b/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
index 81128ff086021..333abd10a583a 100644
--- a/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
@@ -12,6 +12,7 @@ add_clang_library(clangTidyPerformanceModule
   InefficientAlgorithmCheck.cpp
   InefficientStringConcatenationCheck.cpp
   InefficientVectorOperationCheck.cpp
+  LostStdMoveCheck.cpp
   MoveConstArgCheck.cpp
   MoveConstructorInitCheck.cpp
   NoAutomaticMoveCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp b/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp
new file mode 100644
index 0000000000000..26148e1d26de9
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp
@@ -0,0 +1,96 @@
+//===--- LostStdMoveCheck.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 "LostStdMoveCheck.h"
+#include "../utils/DeclRefExprUtils.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::performance {
+
+using utils::decl_ref_expr::allDeclRefExprs;
+
+AST_MATCHER(CXXRecordDecl, hasTrivialMoveConstructor) {
+  return Node.hasDefinition() && Node.hasTrivialMoveConstructor();
+}
+
+void LostStdMoveCheck::registerMatchers(MatchFinder *Finder) {
+  auto returnParent =
+      hasParent(expr(hasParent(cxxConstructExpr(hasParent(returnStmt())))));
+
+  Finder->addMatcher(
+      declRefExpr(
+          // not "return x;"
+          unless(returnParent),
+
+          unless(hasType(namedDecl(hasName("::std::string_view")))),
+
+          // non-trivial type
+          hasType(hasCanonicalType(hasDeclaration(cxxRecordDecl()))),
+
+          // non-trivial X(X&&)
+          unless(hasType(hasCanonicalType(
+              hasDeclaration(cxxRecordDecl(hasTrivialMoveConstructor()))))),
+
+          // Not in a cycle
+          unless(hasAncestor(forStmt())), unless(hasAncestor(doStmt())),
+          unless(hasAncestor(whileStmt())),
+
+          // only non-X&
+          unless(hasDeclaration(
+              varDecl(hasType(qualType(lValueReferenceType()))))),
+
+          hasDeclaration(
+              varDecl(hasAncestor(functionDecl().bind("func"))).bind("decl")),
+
+          hasParent(expr(hasParent(cxxConstructExpr())).bind("use_parent")))
+          .bind("use"),
+      this);
+}
+
+const Expr *LostStdMoveCheck::getLastVarUsage(const VarDecl &Var,
+                                              const Decl &Func,
+                                              ASTContext &Context) {
+  auto Exprs = allDeclRefExprs(Var, Func, Context);
+
+  const Expr *LastExpr = nullptr;
+  for (const auto &Expr : Exprs) {
+    if (!LastExpr)
+      LastExpr = Expr;
+
+    if (LastExpr->getBeginLoc() < Expr->getBeginLoc())
+      LastExpr = Expr;
+  }
+
+  return LastExpr;
+}
+
+void LostStdMoveCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("decl");
+  const auto *MatchedFunc = Result.Nodes.getNodeAs<FunctionDecl>("func");
+  const auto *MatchedUse = Result.Nodes.getNodeAs<Expr>("use");
+  const auto *MatchedUseCall = Result.Nodes.getNodeAs<CallExpr>("use_parent");
+
+  if (MatchedUseCall)
+    return;
+
+  const auto *LastUsage =
+      getLastVarUsage(*MatchedDecl, *MatchedFunc, *Result.Context);
+  if (LastUsage == nullptr)
+    return;
+
+  if (LastUsage->getBeginLoc() > MatchedUse->getBeginLoc()) {
+    // "use" is not the last reference to x
+    return;
+  }
+
+  diag(LastUsage->getBeginLoc(), "Could be std::move()");
+}
+
+} // namespace clang::tidy::performance
diff --git a/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h b/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h
new file mode 100644
index 0000000000000..c62c3f6448a82
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h
@@ -0,0 +1,37 @@
+//===--- LostStdMoveCheck.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_PERFORMANCE_LOSTSTDMOVECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PERFORMANCE_LOSTSTDMOVECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::performance {
+
+/// Search for lost std::move().
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/performance/lost-std-move.html
+class LostStdMoveCheck : public ClangTidyCheck {
+public:
+  LostStdMoveCheck(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.CPlusPlus;
+  }
+
+private:
+  const Expr *getLastVarUsage(const VarDecl &Var, const Decl &Func,
+                              ASTContext &Context);
+};
+
+} // namespace clang::tidy::performance
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PERFORMANCE_LOSTSTDMOVECHECK_H
diff --git a/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp b/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
index 9e0fa6f88b36a..6c45f8678fe63 100644
--- a/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
@@ -17,6 +17,7 @@
 #include "InefficientAlgorithmCheck.h"
 #include "InefficientStringConcatenationCheck.h"
 #include "InefficientVectorOperationCheck.h"
+#include "LostStdMoveCheck.h"
 #include "MoveConstArgCheck.h"
 #include "MoveConstructorInitCheck.h"
 #include "NoAutomaticMoveCheck.h"
@@ -49,6 +50,7 @@ class PerformanceModule : public ClangTidyModule {
         "performance-inefficient-string-concatenation");
     CheckFactories.registerCheck<InefficientVectorOperationCheck>(
         "performance-inefficient-vector-operation");
+    CheckFactories.registerCheck<LostStdMoveCheck>("performance-lost-std-move");
     CheckFactories.registerCheck<MoveConstArgCheck>(
         "performance-move-const-arg");
     CheckFactories.registerCheck<MoveConstructorInitCheck>(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 6d91748e4cef1..17da163ff041c 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -212,6 +212,11 @@ New checks
   Recommends the smallest possible underlying type for an ``enum`` or ``enum``
   class based on the range of its enumerators.
 
+- New :doc:`performance-lost-std-move
+  <clang-tidy/checks/performance/lost-std-move>` check.
+
+  Searches for lost std::move().
+
 - New :doc:`readability-reference-to-constructed-temporary
   <clang-tidy/checks/readability/reference-to-constructed-temporary>` check.
 
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 31f0e090db1d7..2eba4aacb2c33 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -321,6 +321,7 @@ Clang-Tidy Checks
    :doc:`performance-inefficient-algorithm <performance/inefficient-algorithm>`, "Yes"
    :doc:`performance-inefficient-string-concatenation <performance/inefficient-string-concatenation>`,
    :doc:`performance-inefficient-vector-operation <performance/inefficient-vector-operation>`, "Yes"
+   :doc:`performance-lost-std-move <performance/lost-std-move>`, "Yes"
    :doc:`performance-move-const-arg <performance/move-const-arg>`, "Yes"
    :doc:`performance-move-constructor-init <performance/move-constructor-init>`,
    :doc:`performance-no-automatic-move <performance/no-automatic-move>`,
diff --git a/clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst b/clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst
new file mode 100644
index 0000000000000..ded49de7b8126
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst
@@ -0,0 +1,14 @@
+.. title:: clang-tidy - performance-lost-std-move
+
+performance-lost-std-move
+=========================
+
+The check warns if copy constructor is used instead of std::move().
+
+.. code-block:: c++
+
+   void f(X);
+
+   void g(X x) {
+     f(x);  // warning: Could be std::move() [performance-lost-std-move]
+   }
diff --git a/clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp
new file mode 100644
index 0000000000000..ce2d1b972dbd5
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp
@@ -0,0 +1,108 @@
+// RUN: %check_clang_tidy %s performance-lost-std-move %t
+
+namespace std {
+
+template<typename T>
+class shared_ptr {
+public:
+  T& operator*() { return reinterpret_cast<T&>(*this); }
+  shared_ptr() {}
+  shared_ptr(const shared_ptr<T>&) {}
+};
+
+template<typename T>
+T&& move(T&)
+{
+}
+
+} // namespace std
+
+int f(std::shared_ptr<int>);
+
+void f_arg(std::shared_ptr<int> ptr)
+{
+  if (*ptr)
+    f(ptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: Could be std::move() [performance-lost-std-move]
+}
+
+void f_rvalue_ref(std::shared_ptr<int>&& ptr)
+{
+  if (*ptr)
+    f(ptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: Could be std::move() [performance-lost-std-move]
+}
+
+using SharedPtr = std::shared_ptr<int>;
+void f_using(SharedPtr ptr)
+{
+  if (*ptr)
+    f(ptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: Could be std::move() [performance-lost-std-move]
+}
+
+void f_local()
+{
+  std::shared_ptr<int> ptr;
+  if (*ptr)
+    f(ptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: Could be std::move() [performance-lost-std-move]
+}
+
+void f_move()
+{
+  std::shared_ptr<int> ptr;
+  if (*ptr)
+    f(std::move(ptr));
+}
+
+void f_ref(std::shared_ptr<int> &ptr)
+{
+  if (*ptr)
+    f(ptr);
+}
+
+std::shared_ptr<int> f_return()
+{
+  std::shared_ptr<int> ptr;
+  return ptr;
+}
+
+void f_still_used(std::shared_ptr<int> ptr)
+{
+  if (*ptr)
+    f(ptr);
+
+  *ptr = 1;
+  *ptr = *ptr;
+}
+
+void f_cycle1()
+{
+  std::shared_ptr<int> ptr;
+  for(;;)
+    f(ptr);
+}
+
+void f_cycle2()
+{
+  std::shared_ptr<int> ptr;
+  for(int i=0; i<5; i++)
+    f(ptr);
+}
+
+void f_cycle3()
+{
+  std::shared_ptr<int> ptr;
+  while (*ptr) {
+    f(ptr);
+  }
+}
+
+void f_cycle4()
+{
+  std::shared_ptr<int> ptr;
+  do {
+    f(ptr);
+  } while (*ptr);
+}

llvmbot · 2025-05-12T10:09:10Z

@llvm/pr-subscribers-clang-tidy

Author: Vasiliy Kulikov (segoon)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/139525.diff

8 Files Affected:

(modified) clang-tools-extra/clang-tidy/performance/CMakeLists.txt (+1)
(added) clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp (+96)
(added) clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h (+37)
(modified) clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp (+2)
(modified) clang-tools-extra/docs/ReleaseNotes.rst (+5)
(modified) clang-tools-extra/docs/clang-tidy/checks/list.rst (+1)
(added) clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst (+14)
(added) clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp (+108)

diff --git a/clang-tools-extra/clang-tidy/performance/CMakeLists.txt b/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
index 81128ff086021..333abd10a583a 100644
--- a/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
@@ -12,6 +12,7 @@ add_clang_library(clangTidyPerformanceModule
   InefficientAlgorithmCheck.cpp
   InefficientStringConcatenationCheck.cpp
   InefficientVectorOperationCheck.cpp
+  LostStdMoveCheck.cpp
   MoveConstArgCheck.cpp
   MoveConstructorInitCheck.cpp
   NoAutomaticMoveCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp b/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp
new file mode 100644
index 0000000000000..26148e1d26de9
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp
@@ -0,0 +1,96 @@
+//===--- LostStdMoveCheck.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 "LostStdMoveCheck.h"
+#include "../utils/DeclRefExprUtils.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::performance {
+
+using utils::decl_ref_expr::allDeclRefExprs;
+
+AST_MATCHER(CXXRecordDecl, hasTrivialMoveConstructor) {
+  return Node.hasDefinition() && Node.hasTrivialMoveConstructor();
+}
+
+void LostStdMoveCheck::registerMatchers(MatchFinder *Finder) {
+  auto returnParent =
+      hasParent(expr(hasParent(cxxConstructExpr(hasParent(returnStmt())))));
+
+  Finder->addMatcher(
+      declRefExpr(
+          // not "return x;"
+          unless(returnParent),
+
+          unless(hasType(namedDecl(hasName("::std::string_view")))),
+
+          // non-trivial type
+          hasType(hasCanonicalType(hasDeclaration(cxxRecordDecl()))),
+
+          // non-trivial X(X&&)
+          unless(hasType(hasCanonicalType(
+              hasDeclaration(cxxRecordDecl(hasTrivialMoveConstructor()))))),
+
+          // Not in a cycle
+          unless(hasAncestor(forStmt())), unless(hasAncestor(doStmt())),
+          unless(hasAncestor(whileStmt())),
+
+          // only non-X&
+          unless(hasDeclaration(
+              varDecl(hasType(qualType(lValueReferenceType()))))),
+
+          hasDeclaration(
+              varDecl(hasAncestor(functionDecl().bind("func"))).bind("decl")),
+
+          hasParent(expr(hasParent(cxxConstructExpr())).bind("use_parent")))
+          .bind("use"),
+      this);
+}
+
+const Expr *LostStdMoveCheck::getLastVarUsage(const VarDecl &Var,
+                                              const Decl &Func,
+                                              ASTContext &Context) {
+  auto Exprs = allDeclRefExprs(Var, Func, Context);
+
+  const Expr *LastExpr = nullptr;
+  for (const auto &Expr : Exprs) {
+    if (!LastExpr)
+      LastExpr = Expr;
+
+    if (LastExpr->getBeginLoc() < Expr->getBeginLoc())
+      LastExpr = Expr;
+  }
+
+  return LastExpr;
+}
+
+void LostStdMoveCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("decl");
+  const auto *MatchedFunc = Result.Nodes.getNodeAs<FunctionDecl>("func");
+  const auto *MatchedUse = Result.Nodes.getNodeAs<Expr>("use");
+  const auto *MatchedUseCall = Result.Nodes.getNodeAs<CallExpr>("use_parent");
+
+  if (MatchedUseCall)
+    return;
+
+  const auto *LastUsage =
+      getLastVarUsage(*MatchedDecl, *MatchedFunc, *Result.Context);
+  if (LastUsage == nullptr)
+    return;
+
+  if (LastUsage->getBeginLoc() > MatchedUse->getBeginLoc()) {
+    // "use" is not the last reference to x
+    return;
+  }
+
+  diag(LastUsage->getBeginLoc(), "Could be std::move()");
+}
+
+} // namespace clang::tidy::performance
diff --git a/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h b/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h
new file mode 100644
index 0000000000000..c62c3f6448a82
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h
@@ -0,0 +1,37 @@
+//===--- LostStdMoveCheck.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_PERFORMANCE_LOSTSTDMOVECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PERFORMANCE_LOSTSTDMOVECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::performance {
+
+/// Search for lost std::move().
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/performance/lost-std-move.html
+class LostStdMoveCheck : public ClangTidyCheck {
+public:
+  LostStdMoveCheck(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.CPlusPlus;
+  }
+
+private:
+  const Expr *getLastVarUsage(const VarDecl &Var, const Decl &Func,
+                              ASTContext &Context);
+};
+
+} // namespace clang::tidy::performance
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PERFORMANCE_LOSTSTDMOVECHECK_H
diff --git a/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp b/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
index 9e0fa6f88b36a..6c45f8678fe63 100644
--- a/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
@@ -17,6 +17,7 @@
 #include "InefficientAlgorithmCheck.h"
 #include "InefficientStringConcatenationCheck.h"
 #include "InefficientVectorOperationCheck.h"
+#include "LostStdMoveCheck.h"
 #include "MoveConstArgCheck.h"
 #include "MoveConstructorInitCheck.h"
 #include "NoAutomaticMoveCheck.h"
@@ -49,6 +50,7 @@ class PerformanceModule : public ClangTidyModule {
         "performance-inefficient-string-concatenation");
     CheckFactories.registerCheck<InefficientVectorOperationCheck>(
         "performance-inefficient-vector-operation");
+    CheckFactories.registerCheck<LostStdMoveCheck>("performance-lost-std-move");
     CheckFactories.registerCheck<MoveConstArgCheck>(
         "performance-move-const-arg");
     CheckFactories.registerCheck<MoveConstructorInitCheck>(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 6d91748e4cef1..17da163ff041c 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -212,6 +212,11 @@ New checks
   Recommends the smallest possible underlying type for an ``enum`` or ``enum``
   class based on the range of its enumerators.
 
+- New :doc:`performance-lost-std-move
+  <clang-tidy/checks/performance/lost-std-move>` check.
+
+  Searches for lost std::move().
+
 - New :doc:`readability-reference-to-constructed-temporary
   <clang-tidy/checks/readability/reference-to-constructed-temporary>` check.
 
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 31f0e090db1d7..2eba4aacb2c33 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -321,6 +321,7 @@ Clang-Tidy Checks
    :doc:`performance-inefficient-algorithm <performance/inefficient-algorithm>`, "Yes"
    :doc:`performance-inefficient-string-concatenation <performance/inefficient-string-concatenation>`,
    :doc:`performance-inefficient-vector-operation <performance/inefficient-vector-operation>`, "Yes"
+   :doc:`performance-lost-std-move <performance/lost-std-move>`, "Yes"
    :doc:`performance-move-const-arg <performance/move-const-arg>`, "Yes"
    :doc:`performance-move-constructor-init <performance/move-constructor-init>`,
    :doc:`performance-no-automatic-move <performance/no-automatic-move>`,
diff --git a/clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst b/clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst
new file mode 100644
index 0000000000000..ded49de7b8126
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst
@@ -0,0 +1,14 @@
+.. title:: clang-tidy - performance-lost-std-move
+
+performance-lost-std-move
+=========================
+
+The check warns if copy constructor is used instead of std::move().
+
+.. code-block:: c++
+
+   void f(X);
+
+   void g(X x) {
+     f(x);  // warning: Could be std::move() [performance-lost-std-move]
+   }
diff --git a/clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp
new file mode 100644
index 0000000000000..ce2d1b972dbd5
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp
@@ -0,0 +1,108 @@
+// RUN: %check_clang_tidy %s performance-lost-std-move %t
+
+namespace std {
+
+template<typename T>
+class shared_ptr {
+public:
+  T& operator*() { return reinterpret_cast<T&>(*this); }
+  shared_ptr() {}
+  shared_ptr(const shared_ptr<T>&) {}
+};
+
+template<typename T>
+T&& move(T&)
+{
+}
+
+} // namespace std
+
+int f(std::shared_ptr<int>);
+
+void f_arg(std::shared_ptr<int> ptr)
+{
+  if (*ptr)
+    f(ptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: Could be std::move() [performance-lost-std-move]
+}
+
+void f_rvalue_ref(std::shared_ptr<int>&& ptr)
+{
+  if (*ptr)
+    f(ptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: Could be std::move() [performance-lost-std-move]
+}
+
+using SharedPtr = std::shared_ptr<int>;
+void f_using(SharedPtr ptr)
+{
+  if (*ptr)
+    f(ptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: Could be std::move() [performance-lost-std-move]
+}
+
+void f_local()
+{
+  std::shared_ptr<int> ptr;
+  if (*ptr)
+    f(ptr);
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: Could be std::move() [performance-lost-std-move]
+}
+
+void f_move()
+{
+  std::shared_ptr<int> ptr;
+  if (*ptr)
+    f(std::move(ptr));
+}
+
+void f_ref(std::shared_ptr<int> &ptr)
+{
+  if (*ptr)
+    f(ptr);
+}
+
+std::shared_ptr<int> f_return()
+{
+  std::shared_ptr<int> ptr;
+  return ptr;
+}
+
+void f_still_used(std::shared_ptr<int> ptr)
+{
+  if (*ptr)
+    f(ptr);
+
+  *ptr = 1;
+  *ptr = *ptr;
+}
+
+void f_cycle1()
+{
+  std::shared_ptr<int> ptr;
+  for(;;)
+    f(ptr);
+}
+
+void f_cycle2()
+{
+  std::shared_ptr<int> ptr;
+  for(int i=0; i<5; i++)
+    f(ptr);
+}
+
+void f_cycle3()
+{
+  std::shared_ptr<int> ptr;
+  while (*ptr) {
+    f(ptr);
+  }
+}
+
+void f_cycle4()
+{
+  std::shared_ptr<int> ptr;
+  do {
+    f(ptr);
+  } while (*ptr);
+}

firewave · 2025-05-12T10:34:46Z

See also #53489 and #57908.

CC @Febbe

github-actions · 2025-05-12T12:23:12Z

✅ With the latest revision this PR passed the C/C++ code formatter.

EugeneZelenko · 2025-05-12T14:18:42Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

Please do not use auto unless type is explicitly states in same statement or iterator.

EugeneZelenko · 2025-05-12T14:19:04Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

EugeneZelenko · 2025-05-12T14:19:38Z

clang-tools-extra/docs/ReleaseNotes.rst

Suggested change

Searches for lost std::move().

Searches for lost ``std::move()``.

EugeneZelenko · 2025-05-12T14:20:01Z

clang-tools-extra/docs/ReleaseNotes.rst

Unintended change?

EugeneZelenko · 2025-05-12T14:20:47Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

Please synchronize with statement in Release Notes. This check should be omitted.

vbvictor

Commented general suggestions/improvements for the check without deep dive into matchers/tests.

Please look at tests in previous attempt in creating such check https://reviews.llvm.org/D137205.
Check that all test cases from that PR are covered in your tests.
If some cases are not covered and you can't address them, please add them to Limitations in docs and leave a fixme.

vbvictor · 2025-05-21T15:05:05Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h

Suggested change

return LangOpts.CPlusPlus;

return LangOpts.CPlusPlus11;

vbvictor · 2025-05-21T15:06:27Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h

this should be converted to static function and move to .cpp file if no fields of check class are needed

vbvictor · 2025-05-21T15:07:45Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

Use explicit type instead of auto if it isn't written explicitly in code line.

vbvictor · 2025-05-21T15:07:51Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

vbvictor · 2025-05-21T15:10:00Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

vbvictor · 2025-05-21T15:13:10Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

Try to provide fixits with the insertion of std::move

vbvictor · 2025-05-21T15:13:38Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h

This should be synced with release notes and check docs

vbvictor · 2025-05-21T15:19:15Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

This need a little more description when the check will warn, e.g when this will fire, with what types?
Look for reference at https://reviews.llvm.org/D137205

vbvictor · 2025-05-21T15:20:55Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

Nit suggestion: try make the description similar to already existing new checks in ReleaseNotes.rst.
Description should start with "Finds ..."

vbvictor · 2025-05-21T15:21:47Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

Give examples when check will not warn

EugeneZelenko · 2025-06-01T05:03:45Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

+  const auto* MatchedLeafStatement =
+      Result.Nodes.getNodeAs<Stmt>("leaf_statement");
+
+  if (!MatchedDecl->hasLocalStorage()) return;


Should be two lines as next statement.

EugeneZelenko · 2025-06-01T05:04:16Z

clang-tools-extra/docs/ReleaseNotes.rst

 - New :doc:`readability-ambiguous-smartptr-reset-call
  <clang-tidy/checks/readability/ambiguous-smartptr-reset-call>` check.

+<<<<<<< HEAD


Rebase artifact.

EugeneZelenko · 2025-09-16T14:39:27Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

+
+.. option:: StrictMode
+
+   A variable ``X`` can be referenced by another variable ``R``. In this case the last


Please follow 80 characters limit.

EugeneZelenko · 2025-09-16T14:40:17Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

+      declRefExpr(
+          // not "return x;"
+          unless(ReturnParent),
+


I don't think that such newlines improve code readability. Same in other places.

EugeneZelenko · 2025-09-16T16:04:56Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

+
+  SmallVector<BoundNodes, 1> Matches = match(
+      findAll(declRefExpr(
+


Suggested change

Same below.

HerrCai0907 · 2025-09-17T03:29:01Z

clang-tools-extra/test/clang-tidy/checkers/performance/lost-std-move.cpp

+
+} // namespace std
+
+int f(std::shared_ptr<int>);


test this check will not fix for

int f(std::shared_ptr<int> &); int f(std::shared_ptr<int> const &);

HerrCai0907 · 2025-09-17T03:40:07Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

+          anyOf(
+              // f(x)
+              hasParent(expr(hasParent(cxxConstructExpr())).bind("use_parent")),
+              // f((x))
+              hasParent(parenExpr(hasParent(
+                  expr(hasParent(cxxConstructExpr())).bind("use_parent"))))))
+          .bind("use"),


I am worry about the performance of this matcher because it will check all DeclRefExpr. Could we check the child of CXXConstructExpr instead.

Then for parenExpr, we can simply use ignoreParen

github-actions · 2025-09-24T13:07:32Z

✅ With the latest revision this PR passed the C/C++ code linter.

EugeneZelenko · 2025-09-24T14:36:33Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.cpp

@@ -0,0 +1,196 @@
+//===--- LostStdMoveCheck.cpp - clang-tidy --------------------------------===//


Suggested change

//===--- LostStdMoveCheck.cpp - clang-tidy --------------------------------===//

//===----------------------------------------------------------------------===//```

EugeneZelenko · 2025-09-24T14:37:08Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h

@@ -0,0 +1,38 @@
+//===--- LostStdMoveCheck.h - clang-tidy ------------------------*- C++ -*-===//


Suggested change

//===--- LostStdMoveCheck.h - clang-tidy ------------------------*- C++ -*-===//

//===----------------------------------------------------------------------===//

EugeneZelenko · 2025-09-24T14:37:20Z

clang-tools-extra/clang-tidy/performance/LostStdMoveCheck.h

+/// expressions.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/performance/lost-std-move.html


Suggested change

/// http://clang.llvm.org/extra/clang-tidy/checks/performance/lost-std-move.html

/// https://clang.llvm.org/extra/clang-tidy/checks/performance/lost-std-move.html

EugeneZelenko · 2025-09-29T19:08:30Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

+If you want to ignore assigns to reference variables, set ``StrictMode``
+to ``false``.


Suggested change

If you want to ignore assigns to reference variables, set ``StrictMode``

to ``false``.

If you want to ignore assigns to reference variables, set :option:`StrictMode`

to `false`.

EugeneZelenko · 2025-09-30T15:36:35Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

+If you want to ignore assigns to reference variables, set ::option::
+`StrictMode` to `true`.


Suggested change

If you want to ignore assigns to reference variables, set ::option::

`StrictMode` to `true`.

If you want to ignore assigns to reference variables, set :option:`StrictMode`

to `true`.

EugeneZelenko · 2025-09-30T15:40:45Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

+     y.f();  // because x is still used via y
+   }
+
+If you want to ignore assigns to reference variables, set :option: `StrictMode`


Suggested change

If you want to ignore assigns to reference variables, set :option: `StrictMode`

If you want to ignore assigns to reference variables, set :option:`StrictMode`

This is statement. See :program: in clang-tools-extra/docs/ReleaseNotes.rst as example.

thanks! sorry for so many small typos :(

EugeneZelenko · 2025-10-07T14:45:47Z

clang-tools-extra/docs/clang-tidy/checks/performance/lost-std-move.rst

+   references ``X``, then it will not emit a warning for ``X`` not to provoke
+   false positive. If you're sure that such references don't extend ``X``
+   lifetime and ready to handle possible false positives, then set `StrictMode`
+   to `true`. Defaults to `false`.


Suggested change

to `true`. Defaults to `false`.

to `true`. Default is `false`.

[clang-tidy] Add check performance-lost-std-move

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llvmbot added clang-tools-extra clang-tidy labels May 12, 2025

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f(x, x)

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auto -> Expr

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FixIt

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w

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Merge remote-tracking branch 'origin/main' into feature/lost-std-move

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docs

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format

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format

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``

b212770

fix UB

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format

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line 80

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rm \n

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rm \n

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Merge remote-tracking branch 'origin/main' into feature/lost-std-move

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fix

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segoon requested review from Febbe, HerrCai0907, vbvictor and EugeneZelenko October 7, 2025 08:45

EugeneZelenko reviewed Oct 7, 2025

View reviewed changes

	Searches for lost std::move().
	Searches for lost ``std::move()``.


		.. option:: StrictMode

		A variable ``X`` can be referenced by another variable ``R``. In this case the last


		SmallVector<BoundNodes, 1> Matches = match(
		findAll(declRefExpr(

		@@ -0,0 +1,196 @@
		//===--- LostStdMoveCheck.cpp - clang-tidy --------------------------------===//

	//===--- LostStdMoveCheck.cpp - clang-tidy --------------------------------===//
	//===----------------------------------------------------------------------===//```

		@@ -0,0 +1,38 @@
		//===--- LostStdMoveCheck.h - clang-tidy ------------------------- C++ --===//

	/// http://clang.llvm.org/extra/clang-tidy/checks/performance/lost-std-move.html
	/// https://clang.llvm.org/extra/clang-tidy/checks/performance/lost-std-move.html

		If you want to ignore assigns to reference variables, set ``StrictMode``
		to ``false``.

		If you want to ignore assigns to reference variables, set ::option::
		`StrictMode` to `true`.

	to `true`. Defaults to `false`.
	to `true`. Default is `false`.

[clang-tidy] Add check performance-lost-std-move #139525

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[clang-tidy] Add check performance-lost-std-move #139525

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