[clang-tidy] readability-container-size-empty: Correctly generating fix hints when size method is called from implicit this (#152486)

Correctly generating fix hints when size method is called from implicit
this.

Closes #152387.

---------

Co-authored-by: Baranov Victor <[email protected]>
Co-authored-by: EugeneZelenko <[email protected]>

Author: 3 people

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

@@ -238,9 +238,12 @@ void ContainerSizeEmptyCheck::check(const MatchFinder::MatchResult &Result) {
           ? MemberCallObject
           : (Pointee ? Pointee : Result.Nodes.getNodeAs<Expr>("STLObject"));
   FixItHint Hint;
-  std::string ReplacementText = std::string(
-      Lexer::getSourceText(CharSourceRange::getTokenRange(E->getSourceRange()),
-                           *Result.SourceManager, getLangOpts()));
+  std::string ReplacementText =
+      E->isImplicitCXXThis()
+          ? ""
+          : std::string(Lexer::getSourceText(
+                CharSourceRange::getTokenRange(E->getSourceRange()),
+                *Result.SourceManager, getLangOpts()));
   const auto *OpCallExpr = dyn_cast<CXXOperatorCallExpr>(E);
   if (isBinaryOrTernary(E) || isa<UnaryOperator>(E) ||
       (OpCallExpr && (OpCallExpr->getOperator() == OO_Star))) {
@@ -251,6 +254,8 @@ void ContainerSizeEmptyCheck::check(const MatchFinder::MatchResult &Result) {
     // 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->isImplicitCXXThis()) {
+    ReplacementText += "empty()";
   } else if (E->getType()->isPointerType())
     ReplacementText += "->empty()";
   else

clang-tools-extra/docs/ReleaseNotes.rst

@@ -186,6 +186,10 @@ Changes in existing checks
   <clang-tidy/checks/portability/template-virtual-member-function>` check to
   avoid false positives on pure virtual member functions.
 
+- Improved :doc:`readability-container-size-empty
+  <clang-tidy/checks/readability/container-size-empty>` check by correctly
+  generating fix-it hints when size method is called from implicit ``this``.
+
 - Improved :doc:`readability-identifier-naming
   <clang-tidy/checks/readability/identifier-naming>` check by ignoring
   declarations in system headers.

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

@@ -895,3 +895,16 @@ namespace PR94454 {
   int operator""_ci() { return 0; }
   auto eq = 0_ci == 0;
 }
+
+namespace GH152387 {
+
+class foo : public std::string{
+  void doit() {
+    if (!size()) {
+      // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: the 'empty' method should be used to check for emptiness instead of 'size'
+      // CHECK-FIXES: if (empty()) {
+    }
+  }
+};
+
+}