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

[Baranov Victor via cfe-commits]

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@@ -0,0 +1,143 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "../utils/FixItHintUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+
+using namespace clang;
+using namespace clang::ast_matchers;
+using namespace clang::tidy;
+
+namespace clang::tidy::misc {
+
+template <typename ContainerTy>
+static auto makeCannonicalTypesRange(ContainerTy &&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 std::pair<const FunctionDecl *, const NamespaceDecl *>
+findShadowedInNamespace(const NamespaceDecl *NS, const FunctionDecl *GlobalFunc,
+                        StringRef GlobalFuncName,
+                        llvm::SmallPtrSet<const FunctionDecl *, 16> &All) {
+
+  if (NS->isAnonymousNamespace())
+    return {nullptr, nullptr};
+
+  const FunctionDecl *ShadowedFunc = nullptr;
+  const NamespaceDecl *ShadowedNamespace = nullptr;
+
+  for (const auto *Decl : NS->decls()) {
+    // Check nested namespaces
+    if (const auto *NestedNS = dyn_cast<NamespaceDecl>(Decl)) {
+      auto [NestedShadowedFunc, NestedShadowedNamespace] =
+          findShadowedInNamespace(NestedNS, GlobalFunc, GlobalFuncName, All);
+      if (!ShadowedFunc)
+        std::tie(ShadowedFunc, ShadowedNamespace) =
+            std::tie(NestedShadowedFunc, NestedShadowedNamespace);
----------------
vbvictor wrote:

nit: can we make just 2 assignments? IMO this start to hurt readability a little.

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