[clang-tools-extra] [clang-tidy] Add check 'bugprone-invalid-enum-default-initialization' (PR #136823)

[Balázs Kéri via cfe-commits]

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@@ -0,0 +1,114 @@
+//===--- InvalidEnumDefaultInitializationCheck.cpp - clang-tidy -----------===//
+//
+// 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 "InvalidEnumDefaultInitializationCheck.h"
+// #include "../utils/Matchers.h"
+// #include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include <algorithm>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+
+namespace {
+
+AST_MATCHER(EnumDecl, isCompleteAndHasNoZeroValue) {
+  const EnumDecl *Definition = Node.getDefinition();
+  return Definition && Node.isComplete() &&
+         std::none_of(Definition->enumerator_begin(),
+                      Definition->enumerator_end(),
+                      [](const EnumConstantDecl *Value) {
+                        return Value->getInitVal().isZero();
+                      });
+}
+
+AST_MATCHER(Expr, isEmptyInit) {
+  if (isa<CXXScalarValueInitExpr>(&Node))
+    return true;
+  if (isa<ImplicitValueInitExpr>(&Node))
+    return true;
+  if (const auto *Init = dyn_cast<InitListExpr>(&Node))
+    return Init->getNumInits() == 0;
+  return false;
+}
+
+} // namespace
+
+InvalidEnumDefaultInitializationCheck::InvalidEnumDefaultInitializationCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context) {}
+
+bool InvalidEnumDefaultInitializationCheck::isLanguageVersionSupported(
+    const LangOptions &LangOpts) const {
+  return LangOpts.CPlusPlus;
+}
+
+void InvalidEnumDefaultInitializationCheck::registerMatchers(
+    MatchFinder *Finder) {
+  Finder->addMatcher(
+      expr(isEmptyInit(),
+           hasType(hasUnqualifiedDesugaredType(enumType(hasDeclaration(
+               enumDecl(isCompleteAndHasNoZeroValue()).bind("enum"))))))
+          .bind("expr"),
+      this);
+}
+
+void InvalidEnumDefaultInitializationCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *InitExpr = Result.Nodes.getNodeAs<Expr>("expr");
+  const auto *Enum = Result.Nodes.getNodeAs<EnumDecl>("enum");
+  if (!InitExpr || !Enum)
+    return;
+
+  ASTContext &ACtx = Enum->getASTContext();
----------------
balazske wrote:

`getParents` requires it to be non-const.

https://github.com/llvm/llvm-project/pull/136823