[clang-tidy] Fix `readability-container-size-empty` check for smart pointers

Fixes https://github.com/llvm/llvm-project/issues/51118.

Reviewed By: Sockke

Differential Revision: https://reviews.llvm.org/D115124

clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp

@@ -191,10 +191,17 @@ void ContainerSizeEmptyCheck::check(const MatchFinder::MatchResult &Result) {
   std::string ReplacementText = std::string(
       Lexer::getSourceText(CharSourceRange::getTokenRange(E->getSourceRange()),
                            *Result.SourceManager, getLangOpts()));
-  if (isBinaryOrTernary(E) || isa<UnaryOperator>(E)) {
+  const auto *OpCallExpr = dyn_cast<CXXOperatorCallExpr>(E);
+  if (isBinaryOrTernary(E) || isa<UnaryOperator>(E) ||
+      (OpCallExpr && (OpCallExpr->getOperator() == OO_Star))) {
     ReplacementText = "(" + ReplacementText + ")";
   }
-  if (E->getType()->isPointerType())
+  if (OpCallExpr &&
+      OpCallExpr->getOperator() == OverloadedOperatorKind::OO_Arrow) {
+    // This can happen if the object is a smart pointer. Don't add anything
+    // because a '->' is already there (PR#51776), just call the method.
+    ReplacementText += "empty()";
+  } else if (E->getType()->isPointerType())
     ReplacementText += "->empty()";
   else
     ReplacementText += ".empty()";

clang-tools-extra/docs/ReleaseNotes.rst

@@ -173,6 +173,9 @@ Changes in existing checks
 - Fixed nonsensical suggestion of :doc:`altera-struct-pack-align
   <clang-tidy/checks/altera-struct-pack-align>` check for empty structs.
 
+- Fixed incorrect suggestions for :doc:`readability-container-size-empty
+  <clang-tidy/checks/readability-container-size-empty>` when smart pointers are involved.
+
 Removed checks
 ^^^^^^^^^^^^^^
 

clang-tools-extra/test/clang-tidy/checkers/readability-container-size-empty.cpp

@@ -696,3 +696,25 @@ void instantiator() {
   instantiatedTemplateWithSizeCall<TypeWithSize>();
   instantiatedTemplateWithSizeCall<std::vector<int>>();
 }
+
+namespace std {
+template <typename T>
+struct unique_ptr {
+  T *operator->() const;
+  T &operator*() const;
+};
+} // namespace std
+
+bool call_through_unique_ptr(const std::unique_ptr<std::vector<int>> &ptr) {
+  return ptr->size() > 0;
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: the 'empty' method should be used
+  // CHECK-MESSAGES: :9:8: note: method 'vector'::empty() defined here
+  // CHECK-FIXES: {{^  }}return !ptr->empty();
+}
+
+bool call_through_unique_ptr_deref(const std::unique_ptr<std::vector<int>> &ptr) {
+  return (*ptr).size() > 0;
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: the 'empty' method should be used
+  // CHECK-MESSAGES: :9:8: note: method 'vector'::empty() defined here
+  // CHECK-FIXES: {{^  }}return !(*ptr).empty();
+}