================
@@ -0,0 +1,149 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "StringViewConversionsCheck.h"
+#include "clang/AST/Expr.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::performance {
+
+static auto getStringTypeMatcher(StringRef CharType) {
+ return hasCanonicalType(hasDeclaration(cxxRecordDecl(hasName(CharType))));
+}
+
+void StringViewConversionsCheck::registerMatchers(MatchFinder *Finder) {
+ // Matchers for std::basic_[w|u8|u16|u32]string and
+ // std::basic_[w|u8|u16|u32]string_view families.
+ const auto IsStdString = getStringTypeMatcher("::std::basic_string");
+ const auto IsStdStringView =
getStringTypeMatcher("::std::basic_string_view");
+
+ // Matches pointer to any character type (char*, const char*, wchar_t*, etc.)
+ // or array of any character type (char[], char[N], const char[N], etc.).
+ const auto IsCharPointerOrArray =
+ anyOf(hasType(pointerType(pointee(isAnyCharacter()))),
+ hasType(arrayType(hasElementType(isAnyCharacter()))));
+
+ // Matches expressions that can be implicitly converted to string_view
+ // without going through std::string:
+ // - string_view itself (no conversion needed)
+ // - string literals ("hello", L"wide", u8"utf8", etc.)
+ // - character pointers (const char*, char*)
+ // - character arrays (char arr[], char arr[N])
+ // - std::string (has implicit conversion to string_view)
+ // These are the expressions we want to preserve after removing
+ // the redundant std::string conversion.
+ const auto ImplicitlyConvertibleToStringView =
+ expr(anyOf(hasType(IsStdStringView), stringLiteral(),
+ IsCharPointerOrArray, hasType(IsStdString)))
----------------
localspook wrote:
String literals have type "array of char", so it seems like they would be
matched by `IsCharPointerOrArray` already:
```suggestion
expr(anyOf(hasType(IsStdStringView),
IsCharPointerOrArray, hasType(IsStdString)))
```
https://github.com/llvm/llvm-project/pull/174288
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