[clang-tools-extra] [clang-tidy] New bugprone-method-hiding check (PR #154746)

[via cfe-commits]

================
@@ -0,0 +1,146 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "MethodHidingCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <stack>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+
+namespace {
+
+bool sameBasicType(ParmVarDecl const *Lhs, ParmVarDecl const *Rhs) {
+  if (Lhs && Rhs) {
+    return Lhs->getType()
+               .getCanonicalType()
+               .getNonReferenceType()
+               .getUnqualifiedType() == Rhs->getType()
+                                            .getCanonicalType()
+                                            .getNonReferenceType()
+                                            .getUnqualifiedType();
+  }
+  return false;
+}
+
+bool namesCollide(CXXMethodDecl const &Lhs, CXXMethodDecl const &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;
+    }
+  }
+  // Templates are not handled yet
+  if (Lhs.isTemplated() || Rhs.isTemplated()) {
+    return false;
+  }
+  if (Lhs.isTemplateInstantiation() || Rhs.isTemplateInstantiation()) {
+    return false;
+  }
+  if (Lhs.isFunctionTemplateSpecialization() ||
+      Rhs.isFunctionTemplateSpecialization()) {
+    return false;
+  }
+  return true;
+}
+
+AST_MATCHER(CXXMethodDecl, nameCollidesWithMethodInBase) {
+  CXXRecordDecl const *DerivedClass = Node.getParent();
+  for (auto const &Base : DerivedClass->bases()) {
+    std::stack<CXXBaseSpecifier const *> Stack;
+    Stack.push(&Base);
+    while (!Stack.empty()) {
+      CXXBaseSpecifier const *CurrentBaseSpec = Stack.top();
+      Stack.pop();
+
+      if (CurrentBaseSpec->getAccessSpecifier() ==
+          clang::AccessSpecifier::AS_private) {
+        continue;
+      }
+
+      const auto *CurrentRecord =
+          CurrentBaseSpec->getType()->getAsCXXRecordDecl();
+      if (!CurrentRecord) {
+        continue;
+      }
+
+      for (auto const &BaseMethod : CurrentRecord->methods()) {
+        if (namesCollide(*BaseMethod, Node)) {
+          ast_matchers::internal::BoundNodesTreeBuilder Result(*Builder);
+          Builder->setBinding("base_method",
+                              clang::DynTypedNode::create(*BaseMethod));
+          return true;
+        }
+      }
+
+      for (auto const &SubBase : CurrentRecord->bases()) {
+        Stack.push(&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
+
+MethodHidingCheck::MethodHidingCheck(StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context) {}
+
+void MethodHidingCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      cxxMethodDecl(
+          unless(anyOf(isOutOfLine(), isStaticStorageClass(), isImplicit(),
+                       cxxConstructorDecl(), isOverride(),
+                       // isFinal(), //included with isOverride,
+                       isPrivate())),
+          ofClass(cxxRecordDecl(
+                      isDerivedFrom(cxxRecordDecl(unless(isInStdNamespace()))))
+                      .bind("derived_class")),
+          nameCollidesWithMethodInBase())
+          .bind("shadowing_method"),
+      this);
+}
+
+void MethodHidingCheck::check(const MatchFinder::MatchResult &Result) {
+  auto const *ShadowingMethod =
+      Result.Nodes.getNodeAs<CXXMethodDecl>("shadowing_method");
+  auto const *DerivedClass =
+      Result.Nodes.getNodeAs<CXXRecordDecl>("derived_class");
+  auto const *BaseMethod = Result.Nodes.getNodeAs<CXXMethodDecl>("base_method");
+
+  if (!ShadowingMethod || !DerivedClass || !BaseMethod) {
+    llvm_unreachable("Required binding not found");
+  }
+
+  auto const MethodName = ShadowingMethod->getNameInfo().getAsString();
----------------
t-a-james wrote:

I actually just removed these intermediate variables, I don't think they add much

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