[clang-tools-extra] [clang-tidy] Add misc-shadowed-namespace-function check (PR #168406)

[Denis Mikhailov via cfe-commits]

================
@@ -0,0 +1,171 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM 
Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "ShadowedNamespaceFunctionCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DynamicRecursiveASTVisitor.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::misc {
+
+template <template <typename> typename ContainerTy>
+static auto makeCannonicalTypesRange(const ContainerTy<ParmVarDecl *> &C) {
+  return llvm::map_range(C, [](const ParmVarDecl *Param) {
+    return Param->getType().getCanonicalType();
+  });
+}
+
+static bool hasSameSignature(const FunctionDecl *Func1,
+                             const FunctionDecl *Func2) {
+  if (Func1->param_size() != Func2->param_size())
+    return false;
+
+  if (Func1->getReturnType().getCanonicalType() !=
+      Func2->getReturnType().getCanonicalType())
+    return false;
+
+  return llvm::equal(makeCannonicalTypesRange(Func1->parameters()),
+                     makeCannonicalTypesRange(Func2->parameters()));
+}
+
+static bool sholdBeIgnored(const FunctionDecl *Func, bool IgnoreTemplated) {
+  if (Func->isVariadic())
+    return true;
+  if (IgnoreTemplated && Func->isTemplated())
+    return true;
+  return false;
+}
+
+namespace {
+class ShadowedFunctionFinder : public DynamicRecursiveASTVisitor {
+public:
+  ShadowedFunctionFinder(const FunctionDecl *GlobalFunc,
+                         StringRef GlobalFuncName, bool IgnoreTemplated)
+      : GlobalFunc(GlobalFunc), GlobalFuncName(GlobalFuncName),
+        IgnoreTemplated(IgnoreTemplated) {}
+
+  bool VisitFunctionDecl(FunctionDecl *Func) override {
+    // Only process functions that are inside a namespace (not in global scope)
+    if (CurrentNamespaceStack.empty())
+      return true;
+
+    if (Func->getDefinition() || sholdBeIgnored(Func, IgnoreTemplated))
+      return true;
+
+    const NamespaceDecl *CurrentNS = CurrentNamespaceStack.back();
+
+    if (Func != GlobalFunc && Func->getName() == GlobalFuncName &&
+        hasSameSignature(Func, GlobalFunc)) {
+      AllShadowedFuncs.insert(Func);
+      if (!ShadowedFunc) {
+        if (Func->isInIdentifierNamespace(Decl::IDNS_OrdinaryFriend) ||
+            Func->isInIdentifierNamespace(Decl::IDNS_TagFriend))
+          IsShadowedFuncFriend = true;
+        ShadowedFunc = Func;
+        ShadowedNamespace = CurrentNS;
+      }
+    }
+    return true;
+  }
+
+  bool TraverseNamespaceDecl(NamespaceDecl *NS) override {
+    // Skip anonymous namespaces
+    if (NS->isAnonymousNamespace())
+      return true;
+
+    // Push this namespace onto the stack
+    CurrentNamespaceStack.push_back(NS);
+
+    // Traverse children (which will call VisitFunctionDecl for functions
+    // inside)
+    const bool Result = DynamicRecursiveASTVisitor::TraverseNamespaceDecl(NS);
+
+    // Pop the namespace from the stack
+    CurrentNamespaceStack.pop_back();
+
+    return Result;
+  }
+
+  const FunctionDecl *getShadowedFunc() const { return ShadowedFunc; }
+  const NamespaceDecl *getShadowedNamespace() const {
+    return ShadowedNamespace;
+  }
+  const llvm::SmallPtrSet<const FunctionDecl *, 16> &
+  getAllShadowedFuncs() const {
+    return AllShadowedFuncs;
+  }
+  bool isShadowedFuncFriend() const { return IsShadowedFuncFriend; }
+
+private:
+  const FunctionDecl *const GlobalFunc;
+  const StringRef GlobalFuncName;
+  const bool IgnoreTemplated;
+  const FunctionDecl *ShadowedFunc = nullptr;
+  const NamespaceDecl *ShadowedNamespace = nullptr;
+  bool IsShadowedFuncFriend = false;
+  llvm::SmallPtrSet<const FunctionDecl *, 16> AllShadowedFuncs;
+  llvm::SmallVector<const NamespaceDecl *, 4> CurrentNamespaceStack;
+};
+} // anonymous namespace
+
+void ShadowedNamespaceFunctionCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      functionDecl(
+          isDefinition(), hasDeclContext(translationUnitDecl()),
+          unless(anyOf(isImplicit(), isMain(), isStaticStorageClass())))
----------------
denzor200 wrote:

Negative, it was intentionally moved from the matcher to separate function to 
be reused in `ShadowedFunctionFinder`

https://github.com/llvm/llvm-project/pull/168406
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