[clang-tidy]: fix false positive of cert-oop54-cpp check.

Summary:
It seems we need a different matcher for binary operator
in a template context.

Fixes this issue:
https://bugs.llvm.org/show_bug.cgi?id=44499

Reviewers: aaron.ballman, alexfh, hokein, njames93

Reviewed By: aaron.ballman

Subscribers: xazax.hun, cfe-commits

Tags: #clang, #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D76990

Author: tzolnai

clang-tools-extra/clang-tidy/bugprone/UnhandledSelfAssignmentCheck.cpp

@@ -40,9 +40,12 @@ void UnhandledSelfAssignmentCheck::registerMatchers(MatchFinder *Finder) {
 
   // Self-check: Code compares something with 'this' pointer. We don't check
   // whether it is actually the parameter what we compare.
-  const auto HasNoSelfCheck = cxxMethodDecl(unless(
+  const auto HasNoSelfCheck = cxxMethodDecl(unless(anyOf(
       hasDescendant(binaryOperator(hasAnyOperatorName("==", "!="),
-                                   has(ignoringParenCasts(cxxThisExpr()))))));
+                                   has(ignoringParenCasts(cxxThisExpr())))),
+      hasDescendant(cxxOperatorCallExpr(
+          hasAnyOverloadedOperatorName("==", "!="), argumentCountIs(2),
+          has(ignoringParenCasts(cxxThisExpr())))))));
 
   // Both copy-and-swap and copy-and-move method creates a copy first and
   // assign it to 'this' with swap or move.

clang-tools-extra/test/clang-tidy/checkers/bugprone-unhandled-self-assignment.cpp

@@ -212,6 +212,21 @@ class WrongTemplateCopyAndMove {
   T *p;
 };
 
+// https://bugs.llvm.org/show_bug.cgi?id=44499
+class Foo2;
+template <int a>
+bool operator!=(Foo2 &, Foo2 &) {
+  class Bar2 {
+    Bar2 &operator=(const Bar2 &other) {
+      // CHECK-MESSAGES: [[@LINE-1]]:11: warning: operator=() does not handle self-assignment properly [bugprone-unhandled-self-assignment]
+      p = other.p;
+      return *this;
+    }
+
+    int *p;
+  };
+}
+
 ///////////////////////////////////////////////////////////////////
 /// Test cases correctly ignored by the check.
 
@@ -283,6 +298,21 @@ class TemplateSelfCheck {
   T *p;
 };
 
+// https://bugs.llvm.org/show_bug.cgi?id=44499
+class Foo;
+template <int a>
+bool operator!=(Foo &, Foo &) {
+  class Bar {
+    Bar &operator=(const Bar &other) {
+      if (this != &other) {
+      }
+      return *this;
+    }
+
+    int *p;
+  };
+}
+
 // There is no warning if the copy assignment operator gets the object by value.
 class PassedByValue {
 public: