[clang-tools-extra] [clang-tidy] Add modernize-use-span-first-last check (PR #118074)

[Carlos Galvez via cfe-commits]

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@@ -0,0 +1,40 @@
+//===--- UseSpanFirstLastCheck.h - clang-tidy-------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USESPANFIRSTLASTCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USESPANFIRSTLASTCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::modernize {
+
+/// Converts std::span::subspan() calls to the more modern first()/last()
+/// methods where applicable.
+///
+/// For example:
+/// \code
+///   std::span<int> s = ...;
+///   auto sub = s.subspan(0, n);    // ->  auto sub = s.first(n);
+///   auto sub2 = s.subspan(n);      // ->  auto sub2 = s.last(s.size() - n);
+/// \endcode
+class UseSpanFirstLastCheck : public ClangTidyCheck {
+public:
+  UseSpanFirstLastCheck(StringRef Name, ClangTidyContext *Context)
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carlosgalvezp wrote:

Limit this check to C++20

https://github.com/llvm/llvm-project/pull/118074