[clang-tools-extra] [clang-tidy] Add new check `modernize-use-structured-binding` (PR #158462)

[via cfe-commits]

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@@ -0,0 +1,409 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "UseStructuredBindingCheck.h"
+#include "../utils/DeclRefExprUtils.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+static constexpr llvm::StringLiteral PairDeclName = "PairVarD";
+static constexpr llvm::StringLiteral PairVarTypeName = "PairVarType";
+static constexpr llvm::StringLiteral FirstVarDeclName = "FirstVarDecl";
+static constexpr llvm::StringLiteral SecondVarDeclName = "SecondVarDecl";
+static constexpr llvm::StringLiteral BeginDeclStmtName = "BeginDeclStmt";
+static constexpr llvm::StringLiteral EndDeclStmtName = "EndDeclStmt";
+static constexpr llvm::StringLiteral FirstTypeName = "FirstType";
+static constexpr llvm::StringLiteral SecondTypeName = "SecondType";
+static constexpr llvm::StringLiteral ScopeBlockName = "ScopeBlock";
+static constexpr llvm::StringLiteral StdTieAssignStmtName = "StdTieAssign";
+static constexpr llvm::StringLiteral StdTieExprName = "StdTieExpr";
+static constexpr llvm::StringLiteral ForRangeStmtName = "ForRangeStmt";
+static constexpr llvm::StringLiteral InitExprName = "init_expr";
+
+/// Matches a sequence of VarDecls matching the inner matchers, starting from
+/// the \p Iter to \p EndIter and set bindings for the first DeclStmt and the
+/// last DeclStmt if matched.
+///
+/// \p Backwards indicates whether to match the VarDecls in reverse order.
+template <typename Iterator>
+static bool matchNVarDeclStartingWith(
+    Iterator Iter, Iterator EndIter,
+    ArrayRef<ast_matchers::internal::Matcher<VarDecl>> InnerMatchers,
+    ast_matchers::internal::ASTMatchFinder *Finder,
+    ast_matchers::internal::BoundNodesTreeBuilder *Builder,
+    bool Backwards = false) {
+  const DeclStmt *BeginDS = nullptr;
+  const DeclStmt *EndDS = nullptr;
+  size_t N = InnerMatchers.size();
+  size_t Count = 0;
+  for (; Iter != EndIter; ++Iter) {
+    EndDS = dyn_cast<DeclStmt>(*Iter);
+    if (!EndDS)
+      break;
+
+    if (!BeginDS)
+      BeginDS = EndDS;
+
+    auto Matches = [&](const Decl *VD) {
+      // We don't want redundant decls in DeclStmt.
+      if (Count == N)
+        return false;
+
+      if (const auto *Var = dyn_cast<VarDecl>(VD);
+          Var && InnerMatchers[Backwards ? N - Count - 1 : Count].matches(
+                     *Var, Finder, Builder)) {
+        ++Count;
+        return true;
+      }
+
+      return false;
+    };
+
+    if (Backwards) {
+      for (const auto *VD : llvm::reverse(EndDS->decls())) {
+        if (!Matches(VD))
+          return false;
+      }
+    } else {
+      for (const auto *VD : EndDS->decls()) {
+        if (!Matches(VD))
+          return false;
+      }
+    }
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flovent wrote:

No, reverse iterator and normal iterator has different type, it will causes compile error.

https://github.com/llvm/llvm-project/pull/158462