[clang-tools-extra] [clang-tidy] cppcoreguidelines-owning-memory: support new expressions through implicit casts (PR #189544)

[Yukari Kaname via cfe-commits]

https://github.com/yukarikaname updated https://github.com/llvm/llvm-project/pull/189544

>From 4299595400641a1f7101b8749e629d47e6ddc2ba Mon Sep 17 00:00:00 2001
From: Yukari Kaname <yukari at aliciaworks.com>
Date: Tue, 31 Mar 2026 14:01:17 +0800
Subject: [PATCH] [clang-tidy] cppcoreguidelines-owning-memory: handle new
 expressions wrapped in implicit casts and add regression tests for
 derived-to-base new returns/assignments

---
 .../cppcoreguidelines/OwningMemoryCheck.cpp    | 18 ++++++++++--------
 clang-tools-extra/docs/ReleaseNotes.rst        |  4 ++++
 .../cppcoreguidelines/owning-memory.cpp        | 18 ++++++++++++++++++
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
index f4e89470a80da..5a52605fa6d6a 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
@@ -63,7 +63,8 @@ void OwningMemoryCheck::registerMatchers(MatchFinder *Finder) {
                 functionDecl(returns(qualType(hasDeclaration(OwnerDecl)))))),
             CreatesLegacyOwner, LegacyOwnerCast);
 
-  const auto ConsideredOwner = eachOf(IsOwnerType, CreatesOwner);
+  const auto CreatesOwnerWithCasts = ignoringImpCasts(CreatesOwner);
+  const auto ConsideredOwner = eachOf(IsOwnerType, CreatesOwnerWithCasts);
   const auto ScopeDeclaration = anyOf(translationUnitDecl(), namespaceDecl(),
                                       recordDecl(), functionDecl());
 
@@ -127,14 +128,14 @@ void OwningMemoryCheck::registerMatchers(MatchFinder *Finder) {
   // but the LHS is not an owner.
   Finder->addMatcher(binaryOperator(isAssignmentOperator(),
                                     hasLHS(unless(IsOwnerType)),
-                                    hasRHS(CreatesOwner))
+                                    hasRHS(CreatesOwnerWithCasts))
                          .bind("bad_owner_creation_assignment"),
                      this);
 
   // Matching on initialization operations where the initial value is a newly
   // created owner, but the LHS is not an owner.
   Finder->addMatcher(
-      traverse(TK_AsIs, namedDecl(varDecl(hasInitializer(CreatesOwner),
+      traverse(TK_AsIs, namedDecl(varDecl(hasInitializer(CreatesOwnerWithCasts),
                                           unless(IsOwnerType))
                                       .bind("bad_owner_creation_variable"))),
       this);
@@ -149,11 +150,12 @@ void OwningMemoryCheck::registerMatchers(MatchFinder *Finder) {
 
   // Matching for function calls where one argument is a created owner, but the
   // parameter type is not an owner.
-  Finder->addMatcher(callExpr(forEachArgumentWithParam(
-                         expr(CreatesOwner).bind("bad_owner_creation_argument"),
-                         parmVarDecl(unless(IsOwnerType))
-                             .bind("bad_owner_creation_parameter"))),
-                     this);
+  Finder->addMatcher(
+      callExpr(forEachArgumentWithParam(
+          expr(CreatesOwnerWithCasts).bind("bad_owner_creation_argument"),
+          parmVarDecl(unless(IsOwnerType))
+              .bind("bad_owner_creation_parameter"))),
+      this);
 
   auto IsNotInSubLambda = stmt(
       hasAncestor(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 69dc5b9633398..1c1233d8164e5 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -283,6 +283,10 @@ Changes in existing checks
   <clang-tidy/checks/cppcoreguidelines/missing-std-forward>` check by fixing
   a false positive for constrained template parameters.
 
+- Improved :doc:`cppcoreguidelines-owning-memory
+  <clang-tidy/checks/cppcoreguidelines/owning-memory>` check to detect `new`
+  expressions through implicit casts (e.g., `C* x = new D`).
+
 - Improved :doc:`cppcoreguidelines-pro-type-vararg
   <clang-tidy/checks/cppcoreguidelines/pro-type-vararg>` check by no longer
   warning on builtins with custom type checking (e.g., type-generic builtins
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp
index ae61b17ca14d2..2ba8d5ce23749 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp
@@ -398,6 +398,24 @@ namespace PR63994 {
   }
 }
 
+namespace PR64361 {
+  struct C {
+    virtual ~C() {}
+  };
+
+  struct D : public C {};
+
+  void testDerivedAssignment() {
+    C* x = new D;
+    // CHECK-NOTES: [[@LINE-1]]:5: warning: initializing non-owner 'C *' with a newly created 'gsl::owner<>'
+  }
+
+  C* testDerivedReturn() {
+    return new D;
+    // CHECK-NOTES: [[@LINE-1]]:5: warning: returning a newly created resource of type 'C *' or 'gsl::owner<>' from a function whose return type is not 'gsl::owner<>'
+  }
+}
+
 namespace PR59389 {
   struct S {
     S();