1 //===--- StringviewNullptrCheck.h - clang-tidy ------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_STRINGVIEWNULLPTRCHECK_H
10 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_STRINGVIEWNULLPTRCHECK_H
11 
12 #include "../utils/TransformerClangTidyCheck.h"
13 
14 namespace clang::tidy::bugprone {
15 
16 /// Checks for various ways that the `const CharT*` constructor of
17 /// `std::basic_string_view` can be passed a null argument and replaces them
18 /// with the default constructor in most cases. For the comparison operators,
19 /// braced initializer list does not compile so instead a call to `.empty()` or
20 /// the empty string literal are used, where appropriate.
21 ///
22 /// This prevents code from invoking behavior which is unconditionally
23 /// undefined. The single-argument `const CharT*` constructor does not check
24 /// for the null case before dereferencing its input. The standard is slated to
25 /// add an explicitly-deleted overload to catch some of these cases:
26 /// wg21.link/p2166
27 ///
28 /// To catch the additional cases of `NULL` (which expands to `__null`) and
29 /// `0`, first run the ``modernize-use-nullptr`` check to convert the callers
30 /// to `nullptr`.
31 ///
32 /// For the user-facing documentation see:
33 /// http://clang.llvm.org/extra/clang-tidy/checks/bugprone/stringview-nullptr.html
34 class StringviewNullptrCheck : public utils::TransformerClangTidyCheck {
35 public:
36   StringviewNullptrCheck(StringRef Name, ClangTidyContext *Context);
37 
isLanguageVersionSupported(const LangOptions & LangOpts)38   bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
39     return LangOpts.CPlusPlus17;
40   }
41 };
42 
43 } // namespace clang::tidy::bugprone
44 
45 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_STRINGVIEWNULLPTRCHECK_H
46