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

[via cfe-commits]

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@@ -0,0 +1,192 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "StringviewSubstrCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+void StringViewSubstrCheck::registerMatchers(MatchFinder *Finder) {
+  // Match string_view type
+  const auto StringViewDecl = recordDecl(hasName("::std::basic_string_view"));
+  const auto IsStringView = qualType(
+      hasUnqualifiedDesugaredType(recordType(hasDeclaration(StringViewDecl))));
+
+  // Length/size matcher reused in multiple places
+  const auto LengthMatcher = cxxMemberCallExpr(callee(memberExpr(hasDeclaration(
+      cxxMethodDecl(anyOf(hasName("length"), hasName("size")))))));
+
+  // Match various forms of zero
+  const auto IsZero =
+      expr(anyOf(ignoringParenImpCasts(integerLiteral(equals(0))),
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zeyi2 wrote:

I'm not sure about `ignoringParenImpCasts`, IMHO it may fail to match expressions like `(size_t)0`?

Would like to hear the opinions from other reviewers :)

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