[clang-tools-extra] [clang-tidy] Fix false positives with template in `misc-unconventional-assign-operator` check (PR #143292)

[via cfe-commits]

https://github.com/flovent updated https://github.com/llvm/llvm-project/pull/143292

>From 311bc80c0e5ab787aef8476dae51bc16805d728b Mon Sep 17 00:00:00 2001
From: flovent <144676429+flovent at users.noreply.github.com>
Date: Sun, 8 Jun 2025 10:46:48 +0800
Subject: [PATCH 1/2] [clang-tidy] Fix false positives with template in
 `misc-unconventional-assign-operator` check

---
 .../misc/UnconventionalAssignOperatorCheck.cpp      |  7 +++++--
 clang-tools-extra/docs/ReleaseNotes.rst             |  5 +++++
 .../misc/unconventional-assign-operator.cpp         | 13 +++++++++++++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp b/clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp
index afc4897eeb2ae..3fdaf9239f6af 100644
--- a/clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/UnconventionalAssignOperatorCheck.cpp
@@ -66,8 +66,11 @@ void UnconventionalAssignOperatorCheck::registerMatchers(
                                 hasArgument(0, cxxThisExpr())),
             cxxOperatorCallExpr(
                 hasOverloadedOperatorName("="),
-                hasArgument(
-                    0, unaryOperator(hasOperatorName("*"),
+                hasArgument(0, unaryOperator(hasOperatorName("*"),
+                                             hasUnaryOperand(cxxThisExpr())))),
+            binaryOperator(
+                hasOperatorName("="),
+                hasLHS(unaryOperator(hasOperatorName("*"),
                                      hasUnaryOperand(cxxThisExpr())))))))));
   const auto IsGoodAssign = cxxMethodDecl(IsAssign, HasGoodReturnType);
 
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index a275d2ccfa004..394e18cd58f84 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -208,6 +208,11 @@ Changes in existing checks
   <clang-tidy/checks/misc/unused-using-decls>` check by fixing false positives
   on ``operator""`` with template parameters.
 
+- Improved :doc:`misc-unconventional-assign-operator
+  <clang-tidy/checks/misc/misc-unconventional-assign-operator>` check by fixing
+  false positives when copy assignment operator function in a template class
+  returns the result of another assignment to ``*this``(``return *this=...``).
+
 - Improved :doc:`misc-use-internal-linkage
   <clang-tidy/checks/misc/use-internal-linkage>` check by fix false positives
   for function or variable in header file which contains macro expansion and
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/unconventional-assign-operator.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/unconventional-assign-operator.cpp
index 74a22a7c083f4..9384d88c38fd0 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/misc/unconventional-assign-operator.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/unconventional-assign-operator.cpp
@@ -163,3 +163,16 @@ struct TemplateTypeAlias {
   Alias3<TypeAlias::Alias> &operator=(double) { return *this; }
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: operator=() should return 'TemplateTypeAlias&' [misc-unconventional-assign-operator]
 };
+
+namespace issue143237 {
+template<typename T>
+struct B {
+  explicit B(int) {
+  }
+
+  B& operator=(int n) {
+    // No warning
+    return *this = B(n);
+  }
+};
+}

>From db389c1e53208213ee8b987f9bf7244df12bba4c Mon Sep 17 00:00:00 2001
From: flovent <144676429+flovent at users.noreply.github.com>
Date: Sun, 8 Jun 2025 10:59:08 +0800
Subject: [PATCH 2/2] fix release notes

---
 clang-tools-extra/docs/ReleaseNotes.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 394e18cd58f84..da502c6f40b18 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -209,7 +209,7 @@ Changes in existing checks
   on ``operator""`` with template parameters.
 
 - Improved :doc:`misc-unconventional-assign-operator
-  <clang-tidy/checks/misc/misc-unconventional-assign-operator>` check by fixing
+  <clang-tidy/checks/misc/unconventional-assign-operator>` check by fixing
   false positives when copy assignment operator function in a template class
   returns the result of another assignment to ``*this``(``return *this=...``).