[clang-tools-extra] [clang-tidy] Add `modernize-use-bit-cast` check (PR #189962)

[Daniil Dudkin via cfe-commits]

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@@ -0,0 +1,293 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "UseBitCastCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/Type.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/TypeSwitch.h"
+#include "llvm/Support/FormatVariadic.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+static bool isSupportedMemcpyObjectExpr(const Expr *ExprNode) {
+  ExprNode = ExprNode->IgnoreParenImpCasts();
+
+  if (isa<DeclRefExpr>(ExprNode))
+    return true;
+
+  if (const auto *MemberPointer = dyn_cast<BinaryOperator>(ExprNode))
+    return MemberPointer->isPtrMemOp() &&
+           isSupportedMemcpyObjectExpr(MemberPointer->getLHS());
+
+  if (const auto *Member = dyn_cast<MemberExpr>(ExprNode))
+    return isa<FieldDecl>(Member->getMemberDecl()) &&
+           isSupportedMemcpyObjectExpr(Member->getBase());
+
+  return false;
+}
+
+static const Expr *extractMemcpyObjectExpr(const Expr *ExprNode) {
+  ExprNode = ExprNode->IgnoreParenCasts();
+  const auto *AddressOf = dyn_cast<UnaryOperator>(ExprNode);
+  if (!AddressOf || AddressOf->getOpcode() != UO_AddrOf)
+    return nullptr;
+
+  const Expr *ObjectExpr = AddressOf->getSubExpr()->IgnoreParenImpCasts();
+  return isSupportedMemcpyObjectExpr(ObjectExpr) ? ObjectExpr : nullptr;
+}
+
+static bool isBitCastableMemcpyObjectType(QualType Type,
+                                          const ASTContext &Context) {
+  Type = Type.getCanonicalType().getNonReferenceType();
+  return !Type.isNull() && !Type.isVolatileQualified() &&
+         !Type->isAnyPointerType() && Type.isTriviallyCopyableType(Context) &&
+         Type.isBitwiseCloneableType(Context);
+}
+
+static bool canAssignBitCastResult(QualType Type) {
+  Type = Type.getCanonicalType().getNonReferenceType();
+  if (Type.isNull() || Type.isConstQualified() || Type->isArrayType())
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unterumarmung wrote:

Removed.

https://github.com/llvm/llvm-project/pull/189962