[clang-tools-extra] [clang-tidy] Add new check bugprone-tagged-union-member-count (PR #89925)

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=?utf-8?b?R8OhYm9yIFTDs3RodsOhcmk=?= <tigbrcode at protonmail.com>
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In-Reply-To: <llvm.org/llvm/llvm-project/pull/89925 at github.com>


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@@ -0,0 +1,145 @@
+//===--- TaggedUnionMemberCountCheck.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 "TaggedUnionMemberCountCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Expr.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/AST/PrettyPrinter.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/Casting.h"
+#include <limits>
+#include <iostream>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+
+TaggedUnionMemberCountCheck::TaggedUnionMemberCountCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context),
+        EnumCounterHeuristicIsEnabled(Options.get("EnumCounterHeuristicIsEnabled", true)),
+        EnumCounterSuffix(Options.get("EnumCounterSuffix", "count")),
+        StrictMode(Options.get("StrictMode", true)) { }
+
+void TaggedUnionMemberCountCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "StrictMode", StrictMode);
+  Options.store(Opts, "EnumCounterHeuristicIsEnabled", EnumCounterHeuristicIsEnabled);
+  Options.store(Opts, "EnumCounterSuffix", EnumCounterSuffix);
+}
+
+void TaggedUnionMemberCountCheck::registerMatchers(MatchFinder *Finder) {
+Finder->addMatcher(
+      recordDecl(
+          allOf(isStruct(),
+				has(fieldDecl(hasType(qualType(hasCanonicalType(recordType())))).bind("union")),
+				has(fieldDecl(hasType(qualType(hasCanonicalType(enumType())))).bind("tags"))))
+          .bind("root"),
+      this);
+}
+
+static bool isUnion(const FieldDecl *R) {
+	return R->getType().getCanonicalType().getTypePtr()->isUnionType();
+}
+
+static bool isEnum(const FieldDecl *R) {
+	return R->getType().getCanonicalType().getTypePtr()->isEnumeralType();
+}
+
+static bool hasMultipleUnionsOrEnums(const RecordDecl *rec) {
+  return llvm::count_if(rec->fields(), isUnion) > 1 ||
+         llvm::count_if(rec->fields(), isEnum) > 1;
+}
+
+static size_t getNumberOfValidEnumValues(const EnumDecl *ed, bool EnumCounterHeuristicIsEnabled, StringRef EnumCounterSuffix) {
+  int64_t maxTagValue = std::numeric_limits<int64_t>::min();
+  int64_t minTagValue = std::numeric_limits<int64_t>::max();
+
+  // Heuristic for counter enum constants.
+  //
+  //   enum tag_with_counter {
+  //     tag1,
+  //     tag2,
+  //     tag_count, <-- Searching for these enum constants
+  //   };
+  //
+  // The 'ce' prefix is used to abbreviate counterEnum.
+  // The final tag count is decreased by 1 if and only if:
+  // 1. The number of counting enum constants = 1,
+  int ceCount = 0;
+  // 2. The counting enum constant is the last enum constant that is defined,
+  int ceFirstIndex = 0;
+  // 3. The value of the counting enum constant is the largest out of every enum constant.
+  int64_t ceValue = 0;
+
+  int64_t enumConstantsCount = 0;
+  for (auto En : llvm::enumerate(ed->enumerators())) {
+    enumConstantsCount += 1;
+
+    int64_t enumValue = En.value()->getInitVal().getExtValue();
+    StringRef enumName = En.value()->getName();
+
+    if (enumValue > maxTagValue)
+      maxTagValue = enumValue;
+    if (enumValue < minTagValue)
+      minTagValue = enumValue;
+
+    if (enumName.ends_with_insensitive(EnumCounterSuffix)) {
+      if (ceCount == 0) {
+        ceFirstIndex = En.index();
+      }
+      ceValue = enumValue;
+      ceCount += 1;
+    }
+  }
+
+  int64_t validValuesCount = maxTagValue - minTagValue + 1;
+  if (EnumCounterHeuristicIsEnabled &&
+      ceCount == 1 &&
+      ceFirstIndex == enumConstantsCount - 1 &&
+      ceValue == maxTagValue) {
+    validValuesCount -= 1;
+  }
+  return validValuesCount;
+}
+
+// Feladatok:
+// - typedef tesztelés
+// - template tesztelés
+// - névtelen union tesztelés
+// - "count" paraméterezése
----------------
whisperity wrote:

In-development comments remained in the patch.

https://github.com/llvm/llvm-project/pull/89925