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

[via cfe-commits]

https://github.com/flovent updated https://github.com/llvm/llvm-project/pull/152486

>From d5b8bebfb79ac67ecf144c9668081469c843e16f Mon Sep 17 00:00:00 2001
From: flovent <flbven at protonmail.com>
Date: Thu, 7 Aug 2025 19:25:15 +0800
Subject: [PATCH 1/3] [clang-tidy] `readability-container-size-empty`:
 Correctly generate fixit when `size` method's base is `this`

---
 .../readability/ContainerSizeEmptyCheck.cpp         | 11 ++++++++---
 clang-tools-extra/docs/ReleaseNotes.rst             |  4 ++++
 .../checkers/readability/container-size-empty.cpp   | 13 +++++++++++++
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp b/clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
index ce736a8d16023..c4dc319f23c38 100644
--- a/clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
+++ b/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
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 2dc5c73073cf8..a0c03754e8fbf 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -182,6 +182,10 @@ 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/portability/container-size-empty>` check by correctly
+  generating fix hints when size method is inherited from parent class.
+
 - Improved :doc:`readability-identifier-naming
   <clang-tidy/checks/readability/identifier-naming>` check by ignoring
   declarations in system headers.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/container-size-empty.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/container-size-empty.cpp
index 2fd0b2224cb1c..462db5acbaade 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/readability/container-size-empty.cpp
+++ b/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 PR152387 {
+
+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()) {
+    }
+  }
+};
+
+}

>From 019ca4ba07ff8b23d22c9da5758201e53bb39f67 Mon Sep 17 00:00:00 2001
From: flovent <flbven at protonmail.com>
Date: Thu, 7 Aug 2025 20:27:39 +0800
Subject: [PATCH 2/3] [NFC] fix release note

---
 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 a0c03754e8fbf..de3e4062081c6 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -183,7 +183,7 @@ Changes in existing checks
   avoid false positives on pure virtual member functions.
 
 - Improved :doc:`readability-container-size-empty
-  <clang-tidy/checks/portability/container-size-empty>` check by correctly
+  <clang-tidy/checks/readability/container-size-empty>` check by correctly
   generating fix hints when size method is inherited from parent class.
 
 - Improved :doc:`readability-identifier-naming

>From 3d90d15dae1c9c62046674509ba18432d9d09910 Mon Sep 17 00:00:00 2001
From: flovent <flbven at protonmail.com>
Date: Thu, 7 Aug 2025 20:47:16 +0800
Subject: [PATCH 3/3] [NFC] improve doc

---
 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 de3e4062081c6..2e021ebca1daf 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -184,7 +184,7 @@ Changes in existing checks
 
 - Improved :doc:`readability-container-size-empty
   <clang-tidy/checks/readability/container-size-empty>` check by correctly
-  generating fix hints when size method is inherited from parent class.
+  generating fix hints when size method is called from implicit this.
 
 - Improved :doc:`readability-identifier-naming
   <clang-tidy/checks/readability/identifier-naming>` check by ignoring