[clang-tools-extra] 2553e24 - [clang-tidy] Fix false-positives in performanc-noexcept-swap

[Piotr Zegar via cfe-commits]

Author: Piotr Zegar
Date: 2023-08-06T09:23:21Z
New Revision: 2553e2403a33824bea7ca280c9328b0b0acf2836

URL: https://github.com/llvm/llvm-project/commit/2553e2403a33824bea7ca280c9328b0b0acf2836
DIFF: https://github.com/llvm/llvm-project/commit/2553e2403a33824bea7ca280c9328b0b0acf2836.diff

LOG: [clang-tidy] Fix false-positives in performanc-noexcept-swap

Enforce a stricter match with the swap function signature, eliminating false-positives.

Fixes: #64303

Reviewed By: carlosgalvezp

Differential Revision: https://reviews.llvm.org/D157185

Added: 
    

Modified: 
    clang-tools-extra/clang-tidy/performance/NoexceptSwapCheck.cpp
    clang-tools-extra/docs/ReleaseNotes.rst
    clang-tools-extra/test/clang-tidy/checkers/performance/noexcept-swap.cpp

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clang-tidy/performance/NoexceptSwapCheck.cpp b/clang-tools-extra/clang-tidy/performance/NoexceptSwapCheck.cpp
index 65baebd808f6cf..25a58af74f7ee8 100644
--- a/clang-tools-extra/clang-tidy/performance/NoexceptSwapCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/NoexceptSwapCheck.cpp
@@ -17,9 +17,32 @@ using namespace clang::ast_matchers;
 namespace clang::tidy::performance {
 
 void NoexceptSwapCheck::registerMatchers(MatchFinder *Finder) {
-  Finder->addMatcher(
-      functionDecl(unless(isDeleted()), hasName("swap")).bind(BindFuncDeclName),
-      this);
+
+  // Match non-const method with single argument that is non-const reference to
+  // a class type that owns method and return void.
+  // Matches: void Class::swap(Class&)
+  auto MethodMatcher = cxxMethodDecl(
+      parameterCountIs(1U), unless(isConst()), returns(voidType()),
+      hasParameter(0, hasType(qualType(hasCanonicalType(
+                          qualType(unless(isConstQualified()),
+                                   references(namedDecl().bind("class"))))))),
+      ofClass(equalsBoundNode("class")));
+
+  // Match function with 2 arguments, both are non-const references to same type
+  // and return void.
+  // Matches: void swap(Type&, Type&)
+  auto FunctionMatcher = allOf(
+      unless(cxxMethodDecl()), parameterCountIs(2U), returns(voidType()),
+      hasParameter(
+          0, hasType(qualType(hasCanonicalType(
+                 qualType(unless(isConstQualified()), references(qualType()))
+                     .bind("type"))))),
+      hasParameter(1, hasType(qualType(hasCanonicalType(
+                          qualType(equalsBoundNode("type")))))));
+  Finder->addMatcher(functionDecl(unless(isDeleted()), hasName("swap"),
+                                  anyOf(MethodMatcher, FunctionMatcher))
+                         .bind(BindFuncDeclName),
+                     this);
 }
 
 DiagnosticBuilder

diff  --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 1d006ae3fa16f5..284399afc11352 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -180,6 +180,10 @@ Changes in existing checks
   <clang-tidy/checks/modernize/loop-convert>` to support for-loops with
   iterators initialized by free functions like ``begin``, ``end``, or ``size``.
 
+- Improved :doc:`performanc-noexcept-swap
+  <clang-tidy/checks/performance/noexcept-swap>` check to enforce a stricter
+  match with the swap function signature, eliminating false-positives.
+
 - Improved the :doc:`readability-identifier-naming
   <clang-tidy/checks/readability/identifier-naming>` check to emit proper
   warnings when a type forward declaration precedes its definition.

diff  --git a/clang-tools-extra/test/clang-tidy/checkers/performance/noexcept-swap.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance/noexcept-swap.cpp
index 11c65906e89682..392b5d17d456e7 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/performance/noexcept-swap.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/performance/noexcept-swap.cpp
@@ -201,3 +201,20 @@ struct OK21 {
 template <typename T>
 void swap(OK21<T> &, OK21<T> &) noexcept(noexcept(TemplateNoexceptWithInt<int>::f()));
 void swap(OK21<int> &, OK21<int> &) noexcept(noexcept(TemplateNoexceptWithInt<int>::f()));
+
+namespace PR64303 {
+  void swap();
+  void swap(int&, bool&);
+  void swap(int&, int&, int&);
+  void swap(int&);
+
+  struct Test {
+    void swap();
+    void swap(Test&, Test&);
+    void swap(int&);
+    static void swap(int&, int&);
+
+    friend void swap(Test&, Test&);
+    // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: swap functions should be marked noexcept [performance-noexcept-swap]
+  };
+}