[clang-tools-extra] [clang-tidy] New bugprone-derived-method-shadowing-base-method (PR #154746)

[Baranov Victor via cfe-commits]

================
@@ -0,0 +1,127 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "DerivedMethodShadowingBaseMethodCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+
+namespace {
+
+bool sameBasicType(const ParmVarDecl *Lhs, const ParmVarDecl *Rhs) {
+  return Lhs && Rhs &&
+         Lhs->getType()
+                 .getCanonicalType()
+                 .getNonReferenceType()
+                 .getUnqualifiedType() == Rhs->getType()
+                                              .getCanonicalType()
+                                              .getNonReferenceType()
+                                              .getUnqualifiedType();
+}
+
+bool namesCollide(const CXXMethodDecl &Lhs, const CXXMethodDecl &Rhs) {
+  if (Lhs.getNameAsString() != Rhs.getNameAsString())
+    return false;
+  if (Lhs.isConst() != Rhs.isConst())
+    return false;
+  if (Lhs.getNumParams() != Rhs.getNumParams())
+    return false;
+  for (unsigned int It = 0; It < Lhs.getNumParams(); ++It)
+    if (!sameBasicType(Lhs.getParamDecl(It), Rhs.getParamDecl(It)))
+      return false;
+  return true;
+}
+
+AST_MATCHER(CXXMethodDecl, nameCollidesWithMethodInBase) {
+  const CXXRecordDecl *DerivedClass = Node.getParent();
+  for (const auto &Base : DerivedClass->bases()) {
+    llvm::SmallVector<const CXXBaseSpecifier *, 8> Stack;
+    Stack.push_back(&Base);
+    while (!Stack.empty()) {
+      const CXXBaseSpecifier *CurrentBaseSpec = Stack.back();
+      Stack.pop_back();
+
+      if (CurrentBaseSpec->getAccessSpecifier() ==
+          clang::AccessSpecifier::AS_private)
+        continue;
+
+      const auto *CurrentRecord =
+          CurrentBaseSpec->getType()->getAsCXXRecordDecl();
+      if (!CurrentRecord)
+        continue;
+
+      // For multiple inheritance, we ignore only the bases that come from the
+      // std:: namespace
+      if (CurrentRecord->isInStdNamespace())
+        continue;
+
+      for (const auto &BaseMethod : CurrentRecord->methods()) {
+        if (namesCollide(*BaseMethod, Node)) {
+          ast_matchers::internal::BoundNodesTreeBuilder Result(*Builder);
+          Builder->setBinding("base_method",
+                              clang::DynTypedNode::create(*BaseMethod));
+          return true;
+        }
+      }
+
+      for (const auto &SubBase : CurrentRecord->bases())
+        Stack.push_back(&SubBase);
+    }
+  }
+  return false;
+}
+
+// Same as clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp,
+// similar matchers are used elsewhere in LLVM
+AST_MATCHER(CXXMethodDecl, isOutOfLine) { return Node.isOutOfLine(); }
+
+} // namespace
+
+DerivedMethodShadowingBaseMethodCheck::DerivedMethodShadowingBaseMethodCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context) {}
+
+void DerivedMethodShadowingBaseMethodCheck::registerMatchers(
+    MatchFinder *Finder) {
+  Finder->addMatcher(
+      cxxMethodDecl(
+          unless(anyOf(isOutOfLine(), isStaticStorageClass(), isImplicit(),
+                       cxxConstructorDecl(), isOverride(), isPrivate(),
+                       // isFinal(), //included with isOverride,
+                       // Templates are not handled yet
+                       ast_matchers::isTemplateInstantiation(),
+                       ast_matchers::isExplicitTemplateSpecialization())),
+          ofClass(cxxRecordDecl(isDerivedFrom(cxxRecordDecl()))
+                      .bind("derived_class")),
+          nameCollidesWithMethodInBase())
+          .bind("shadowing_method"),
+      this);
+}
+
+void DerivedMethodShadowingBaseMethodCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *ShadowingMethod =
+      Result.Nodes.getNodeAs<CXXMethodDecl>("shadowing_method");
+  const auto *DerivedClass =
+      Result.Nodes.getNodeAs<CXXRecordDecl>("derived_class");
+  const auto *BaseMethod = Result.Nodes.getNodeAs<CXXMethodDecl>("base_method");
+
+  if (!ShadowingMethod || !DerivedClass || !BaseMethod)
+    llvm_unreachable("Required binding not found");
+
+  diag(ShadowingMethod->getBeginLoc(), "'%0' hides same method in %1")
----------------
vbvictor wrote:

```suggestion
  diag(ShadowingMethod->getBeginLoc(), "'%0' shadows method with the same name in class %1")
```

https://github.com/llvm/llvm-project/pull/154746