[clang-tidy] Let bugprone-use-after-move also handle calls to std::forward

[AMS21]

Fixes #82023

[llvmbot]

@llvm/pr-subscribers-clang-tidy

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

Author: None (AMS21)

Changes

Fixes #82023

---

Full diff: https://github.com/llvm/llvm-project/pull/82673.diff

3 Files Affected:

• (modified) clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp (+2-2)
• (modified) clang-tools-extra/docs/ReleaseNotes.rst (+4)
• (modified) clang-tools-extra/test/clang-tidy/checkers/bugprone/use-after-move.cpp (+37)

diff --git a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
index c5b6b541096ca9..f2eaebb7e57833 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UseAfterMoveCheck.cpp
@@ -330,7 +330,7 @@ void UseAfterMoveFinder::getReinits(
                             traverse(TK_AsIs, DeclRefMatcher),
                             unless(parmVarDecl(hasType(
                                 references(qualType(isConstQualified())))))),
-                        unless(callee(functionDecl(hasName("::std::move")))))))
+                        unless(callee(functionDecl(hasAnyName("::std::move", "::std::forward")))))))
           .bind("reinit");
 
   Stmts->clear();
@@ -388,7 +388,7 @@ void UseAfterMoveCheck::registerMatchers(MatchFinder *Finder) {
   auto TryEmplaceMatcher =
       cxxMemberCallExpr(callee(cxxMethodDecl(hasName("try_emplace"))));
   auto CallMoveMatcher =
-      callExpr(argumentCountIs(1), callee(functionDecl(hasName("::std::move"))),
+      callExpr(argumentCountIs(1), callee(functionDecl(hasAnyName("::std::move", "::std::forward"))),
                hasArgument(0, declRefExpr().bind("arg")),
                unless(inDecltypeOrTemplateArg()),
                unless(hasParent(TryEmplaceMatcher)), expr().bind("call-move"),
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index a0b9fcfe0d7774..55c47c7617ce2a 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -130,6 +130,10 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/unused-local-non-trivial-variable>` check by
   ignoring local variable with ``[maybe_unused]`` attribute.
 
+- Improved :doc:`bugprone-use-after-move
+  <clang-tidy/checks/bugprone/use-after-move>` check to also handle
+  calls to ``std::forward``.
+
 - Cleaned up :doc:`cppcoreguidelines-prefer-member-initializer
   <clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>`
   by removing enforcement of rule `C.48
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/use-after-move.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/use-after-move.cpp
index 00b1da1e727e4f..0138064ed811b5 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/use-after-move.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/use-after-move.cpp
@@ -111,6 +111,18 @@ constexpr typename std::remove_reference<_Tp>::type &&move(_Tp &&__t) noexcept {
   return static_cast<typename remove_reference<_Tp>::type &&>(__t);
 }
 
+template <class _Tp>
+constexpr _Tp&&
+forward(typename std::remove_reference<_Tp>::type& __t) noexcept {
+  return static_cast<_Tp&&>(__t);
+}
+
+template <class _Tp>
+constexpr _Tp&&
+forward(typename std::remove_reference<_Tp>::type&& __t) noexcept {
+  return static_cast<_Tp&&>(__t);
+}
+
 } // namespace std
 
 class A {
@@ -1525,3 +1537,28 @@ class PR38187 {
 private:
   std::string val_;
 };
+
+namespace issue82023
+{
+
+struct S {
+  S();
+  S(S&&);
+};
+
+void consume(S s);
+
+template <typename T>
+void forward(T&& t) {
+  consume(std::forward<T>(t));
+  consume(std::forward<T>(t));
+  // CHECK-NOTES: [[@LINE-1]]:27: warning: 't' used after it was moved
+  // CHECK-NOTES: [[@LINE-3]]:11: note: move occurred here
+}
+
+void create() {
+  S s;
+  forward(std::move(s));
+}
+
+} // namespace issue82023

[github-actions]

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

[5chmidti]

I'd like to see the diagnostics say forwarded instead of moved when diagnosing forwarding calls (for all 4 possible diagnostics). after it was potentially moved by forwarding could work as well. Otherwise, the changes themselves look good

[AMS21]

Rebased and address review comment

[5chmidti]

Please add a short explanation that forward is also checked in the check's docs here https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/docs/clang-tidy/checks/bugprone/use-after-move.rst.

[AMS21]

Rebased and implemented review suggestions

[AMS21]

Rebased to fix merge conflict

[PiotrZSL]

Overall, LGTM

[HerrCai0907]

LGTM