[PATCH] D115124: [clang-tidy] Fix `readability-container-size-empty` check for smart pointers

[Fabian Wolff via Phabricator via cfe-commits]

fwolff updated this revision to Diff 400625.
fwolff added a comment.

In D115124#3209199 <https://reviews.llvm.org/D115124#3209199>, @Sockke wrote:

> Could you please add a test case where the smart pointer object is dereferenced before calling `size()`? E.g. `return (*ptr).size() == 0;`. I think this change doesn't work on this test case.

This is not entirely true; what you're seeing is an existing, unrelated bug: https://godbolt.org/z/9zEfdrPW8

In any case, I've fixed it, added a test for it, and added a bullet point to the release notes.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115124/new/

https://reviews.llvm.org/D115124

Files:
  clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
  clang-tools-extra/docs/ReleaseNotes.rst
  clang-tools-extra/test/clang-tidy/checkers/readability-container-size-empty.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/readability-container-size-empty.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/readability-container-size-empty.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/readability-container-size-empty.cpp
@@ -696,3 +696,25 @@
   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();
+}
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -83,6 +83,9 @@
 - Generalized the `modernize-use-default-member-init` check to handle non-default
   constructors.
 
+- Fixed incorrect suggestions for `readability-container-size-empty` when
+  smart pointers are involved.
+
 New checks
 ^^^^^^^^^^
 
Index: clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
+++ clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
@@ -191,10 +191,17 @@
   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()";


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