[clang-tools-extra] [clang-tidy] Skip overloaded functions in modernize-use-string-view (PR #183921)

[Zinovy Nis via cfe-commits]

https://github.com/irishrover updated https://github.com/llvm/llvm-project/pull/183921

>From 5d517060b6dc37b1568b5af332e763b81ad35eba Mon Sep 17 00:00:00 2001
From: Zinovy Nis <zinovy.nis at gmail.com>
Date: Sat, 28 Feb 2026 17:33:50 +0300
Subject: [PATCH 1/2] [clang-tidy] Skip overloaded functions in
 modernize-use-string-view

---
 .../modernize/UseStringViewCheck.cpp          | 24 +++++++++++++++++++
 .../checkers/modernize/use-string-view.cpp    |  7 ++++++
 2 files changed, 31 insertions(+)

diff --git a/clang-tools-extra/clang-tidy/modernize/UseStringViewCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseStringViewCheck.cpp
index 1dc4cc9856549..f03c9c008389a 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseStringViewCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseStringViewCheck.cpp
@@ -21,6 +21,29 @@ using namespace clang::ast_matchers;
 
 namespace clang::tidy::modernize {
 
+namespace {
+AST_MATCHER(FunctionDecl, isOverloaded) {
+  const DeclarationName Name = Node.getDeclName();
+  // Skip lambda-like functions
+  if (Name.isEmpty())
+    return false;
+  const DeclContext *DC = Node.getDeclContext();
+  auto LookupResult = DC->lookup(Name);
+  size_t UniqueSignatures = 0;
+  llvm::SmallPtrSet<const FunctionDecl *, 2> SeenFunctions;
+  for (NamedDecl *ND : LookupResult) {
+    if (const auto *FD = dyn_cast<FunctionDecl>(ND)) {
+      if (SeenFunctions.insert(FD->getCanonicalDecl()).second) {
+        UniqueSignatures++;
+        if (UniqueSignatures > 1)
+          return true;
+      }
+    }
+  }
+  return false;
+}
+} // namespace
+
 static constexpr StringRef StringViewClassKey = "string";
 static constexpr StringRef WStringViewClassKey = "wstring";
 static constexpr StringRef U8StringViewClassKey = "u8string";
@@ -81,6 +104,7 @@ void UseStringViewCheck::registerMatchers(MatchFinder *Finder) {
       functionDecl(
           isDefinition(),
           unless(anyOf(VirtualOrOperator, IgnoredFunctionsMatcher,
+                       isOverloaded(),
                        ast_matchers::isExplicitTemplateSpecialization())),
           returns(IsStdString), hasDescendant(returnStmt()),
           unless(hasDescendant(returnStmt(hasReturnValue(unless(
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-string-view.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-string-view.cpp
index 2a00a7200ee76..832af0c26ef70 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-string-view.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-string-view.cpp
@@ -365,6 +365,13 @@ std::string lambda() {
   }();
 }
 
+namespace overloads {
+std::string dbl2str(double f);
+std::string overload(int) { return "int"; }
+std::string overload(double f) { return "f=" + dbl2str(f); }
+std::string overload(std::string) { return "string"; }
+}
+
 struct TemplateString {
   static constexpr char* val = "TEMPLATE";
   template<typename T>

>From c6a2182af238655f16544447f50e046e305edd8b Mon Sep 17 00:00:00 2001
From: Zinovy Nis <zinovy.nis at gmail.com>
Date: Thu, 5 Mar 2026 21:38:56 +0300
Subject: [PATCH 2/2] Extend the tests

---
 .../modernize/UseStringViewCheck.cpp          | 15 ++++-
 .../checkers/modernize/use-string-view.cpp    | 55 ++++++++++++++++++-
 2 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/modernize/UseStringViewCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseStringViewCheck.cpp
index f03c9c008389a..638b02c175576 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseStringViewCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseStringViewCheck.cpp
@@ -24,7 +24,7 @@ namespace clang::tidy::modernize {
 namespace {
 AST_MATCHER(FunctionDecl, isOverloaded) {
   const DeclarationName Name = Node.getDeclName();
-  // Skip lambda-like functions
+  // Sanity check
   if (Name.isEmpty())
     return false;
   const DeclContext *DC = Node.getDeclContext();
@@ -32,7 +32,18 @@ AST_MATCHER(FunctionDecl, isOverloaded) {
   size_t UniqueSignatures = 0;
   llvm::SmallPtrSet<const FunctionDecl *, 2> SeenFunctions;
   for (NamedDecl *ND : LookupResult) {
-    if (const auto *FD = dyn_cast<FunctionDecl>(ND)) {
+    const FunctionDecl *FD = nullptr;
+    if (const auto *Func = dyn_cast<FunctionDecl>(ND)) {
+      // Regular functions
+      FD = Func;
+    } else if (const auto *USD = dyn_cast<UsingShadowDecl>(ND)) {
+      // Overloads via "using ns::func_name"
+      FD = dyn_cast<FunctionDecl>(USD->getTargetDecl());
+    } else if (const auto *FTD = dyn_cast<FunctionTemplateDecl>(ND)) {
+      // Templated functions
+      FD = FTD->getTemplatedDecl();
+    }
+    if (FD) {
       if (SeenFunctions.insert(FD->getCanonicalDecl()).second) {
         UniqueSignatures++;
         if (UniqueSignatures > 1)
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-string-view.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-string-view.cpp
index 832af0c26ef70..a43e846eea40d 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-string-view.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-string-view.cpp
@@ -211,6 +211,21 @@ MyString<wchar_t> aliasedWChar() {
   return L"aliasedWChar";
 }
 
+namespace overload_funcs_redeclared {
+std::basic_string<char> overload(int);
+std::string overload(int);
+std::string overload(int) { return "int"; }
+// CHECK-MESSAGES:[[@LINE-1]]:1: warning: consider using 'std::string_view' to avoid unnecessary copying and allocations [modernize-use-string-view]
+// CHECK-FIXES: std::string_view overload(int) { return "int"; }
+}
+
+namespace overload_non_func {
+struct overload {};
+std::string overload(int) { return "int"; }
+// CHECK-MESSAGES:[[@LINE-1]]:1: warning: consider using 'std::string_view' to avoid unnecessary copying and allocations [modernize-use-string-view]
+// CHECK-FIXES: std::string_view overload(int) { return "int"; }
+}
+
 // ==========================================================
 // Negative tests
 // ==========================================================
@@ -365,13 +380,51 @@ std::string lambda() {
   }();
 }
 
-namespace overloads {
+namespace overload_funcs {
 std::string dbl2str(double f);
+// Skip overloaded functions
 std::string overload(int) { return "int"; }
+// Because of this overload (non-literal return) the fix should not be applied
 std::string overload(double f) { return "f=" + dbl2str(f); }
 std::string overload(std::string) { return "string"; }
 }
 
+namespace overload_methods {
+struct Foo {
+  // Skip overloaded methods
+  std::string overload(int) { return "int"; }
+  std::string overload(double f) { return "double"; }
+  std::string overload(std::string) { return "string"; }
+};
+}
+
+namespace overload_methods_nested_classes {
+struct Bar {
+  std::string overload(int) { return "int"; }
+  std::string overload(std::string) { return "string"; }
+
+  struct FooBar {
+    std::string overload(char*) { return "char*"; }
+    std::string overload(double f) { return "double"; }
+  };
+};
+}
+
+namespace overload_methods_nested_namespaces {
+namespace foo {
+  std::string overload(int) { return "int"; }
+  std::string overload(std::string) { return "string"; }
+}
+using foo::overload;
+std::string overload(char*) { return "char*"; }
+}
+
+namespace overload_methods_templated {
+    template <typename T>
+    std::string overload(T value) { return "T";}
+    std::string overload(int value) { return "int"; }
+}
+
 struct TemplateString {
   static constexpr char* val = "TEMPLATE";
   template<typename T>