[clang-tools-extra] [clang-tidy] Add new modernize-string-find-startswith check (PR #72385)

[Piotr Zegar via cfe-commits]

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@@ -0,0 +1,41 @@
+//===--- StringFindStartswithCheck.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_STRINGFINDSTARTSWITHCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_STRINGFINDSTARTSWITHCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+#include <vector>
+
+namespace clang::tidy::modernize {
+
+/// Checks whether a ``std::string::find()`` or ``std::string::rfind()`` (and
+/// corresponding ``std::string_view`` methods) result is compared with 0, and
+/// suggests replacing with ``starts_with()``. This is both a readability and a
+/// performance issue.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/modernize/string-find-startswith.html
+class StringFindStartswithCheck : public ClangTidyCheck {
+public:
+  StringFindStartswithCheck(StringRef Name, ClangTidyContext *Context);
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus20;
+  }
+
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PiotrZSL wrote:

use TK_IgnoreUnlessSpelledInSource, check other checks...

https://github.com/llvm/llvm-project/pull/72385