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

[via cfe-commits]

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@@ -0,0 +1,44 @@
+//===--- 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_READABILITY_USESPANFIRSTLASTCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USESPANFIRSTLASTCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::readability {
+
+/// Suggests using clearer std::span member functions first()/last() instead of
+/// equivalent subspan() calls where applicable.
+///
+/// For example:
+/// \code
+///   std::span<int> s = ...;
+///   auto sub1 = s.subspan(0, n);           // ->  auto sub1 = s.first(n);
+///   auto sub2 = s.subspan(s.size() - n);   // ->  auto sub2 = s.last(n);
+///   auto sub3 = s.subspan(1, n);           // not changed
+///   auto sub4 = s.subspan(n);              // not changed
+/// \endcode
+///
+/// The check is only active in C++20 mode.
+class UseSpanFirstLastCheck : public ClangTidyCheck {
+public:
+  UseSpanFirstLastCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+  void handleSubspanCall(const ast_matchers::MatchFinder::MatchResult &Result,
+                         const CXXMemberCallExpr *Call);
+};
+
+} // namespace clang::tidy::readability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USESPANFIRSTLASTCHECK_H
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EugeneZelenko wrote:

Please add newline.

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