[clang-tools-extra] [clang-tidy] Add readability-string-view-substr check (PR #120055)

[Julian Schmidt via cfe-commits]

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@@ -0,0 +1,39 @@
+//===--- StringViewSubstrCheck.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_STRINGVIEWSUBSTRCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_STRINGVIEWSUBSTRCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::readability {
+
+/// Finds string_view substr() calls that can be replaced with remove_prefix()
+/// or remove_suffix().
+///
+/// For the user-facing documentation see:
+/// https://clang.llvm.org/extra/clang-tidy/checks/readability/string-view-substr.html
+///
+/// The check matches two patterns:
+///   sv = sv.substr(N) -> sv.remove_prefix(N)
+///   sv = sv.substr(0, sv.length() - N) -> sv.remove_suffix(N)
+///
+/// These replacements make the intent clearer and are more efficient as they
+/// modify the string_view in place rather than creating a new one.
+class StringViewSubstrCheck : public ClangTidyCheck {
+public:
+  StringViewSubstrCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
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5chmidti wrote:

`std::string_view` was only added in C++17, please add `isLanguageVersionSupported`

https://github.com/llvm/llvm-project/pull/120055