[clang-tools-extra] [clang-tidy] add new check readability-enum-initial-value (PR #86129)

[Julian Schmidt via cfe-commits]

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@@ -0,0 +1,199 @@
+//===--- EnumInitialValueCheck.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 "EnumInitialValueCheck.h"
+#include "../utils/LexerUtils.h"
+#include "clang/AST/Decl.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/SourceLocation.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallString.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+static bool isNoneEnumeratorsInitialized(const EnumDecl &Node) {
+  return llvm::all_of(Node.enumerators(), [](const EnumConstantDecl *ECD) {
+    return ECD->getInitExpr() == nullptr;
+  });
+}
+
+static bool isOnlyFirstEnumeratorInitialized(const EnumDecl &Node) {
+  bool IsFirst = true;
+  for (const EnumConstantDecl *ECD : Node.enumerators()) {
+    if ((IsFirst && ECD->getInitExpr() == nullptr) ||
+        (!IsFirst && ECD->getInitExpr() != nullptr))
+      return false;
+    IsFirst = false;
+  }
+  return !IsFirst;
+}
+
+static bool areAllEnumeratorsInitialized(const EnumDecl &Node) {
+  return llvm::all_of(Node.enumerators(), [](const EnumConstantDecl *ECD) {
+    return ECD->getInitExpr() != nullptr;
+  });
+}
+
+/// Check if \p Enumerator is initialized with a (potentially negated) \c
+/// IntegerLiteral.
+static bool isInitializedByLiteral(const EnumConstantDecl *Enumerator) {
+  const Expr *const Init = Enumerator->getInitExpr();
+  if (!Init)
+    return false;
+  return Init->isIntegerConstantExpr(Enumerator->getASTContext());
+}
+
+static void cleanInitialValue(DiagnosticBuilder &Diag,
+                              const EnumConstantDecl *ECD,
+                              const SourceManager &SM,
+                              const LangOptions &LangOpts) {
+  std::optional<Token> EqualToken = utils::lexer::findNextTokenSkippingComments(
+      ECD->getLocation(), SM, LangOpts);
+  if (!EqualToken.has_value())
+    return;
+  SourceLocation EqualLoc{EqualToken->getLocation()};
+  if (EqualLoc.isInvalid() || EqualLoc.isMacroID())
+    return;
+  SourceRange InitExprRange = ECD->getInitExpr()->getSourceRange();
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5chmidti wrote:

2x `const SourceRange`

https://github.com/llvm/llvm-project/pull/86129