clang-tools-extra/clang-tidy/bugprone/StringviewNullptrCheck.h

   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 {
  15 namespace tidy {
  16 namespace bugprone {
  17
  18 /// Checks for various ways that the `const CharT*` constructor of
  19 /// `std::basic_string_view` can be passed a null argument and replaces them
  20 /// with the default constructor in most cases. For the comparison operators,
  21 /// braced initializer list does not compile so instead a call to `.empty()` or
  22 /// the empty string literal are used, where appropriate.
  23 ///
  24 /// This prevents code from invoking behavior which is unconditionally
  25 /// undefined. The single-argument `const CharT*` constructor does not check
  26 /// for the null case before dereferencing its input. The standard is slated to
  27 /// add an explicitly-deleted overload to catch some of these cases:
  28 /// wg21.link/p2166
  29 ///
  30 /// To catch the additional cases of `NULL` (which expands to `__null`) and
  31 /// `0`, first run the ``modernize-use-nullptr`` check to convert the callers
  32 /// to `nullptr`.
  33 ///
  34 /// For the user-facing documentation see:
  35 /// http://clang.llvm.org/extra/clang-tidy/checks/bugprone/stringview-nullptr.html
  36 class StringviewNullptrCheck : public utils::TransformerClangTidyCheck {
  37 public:
  38   StringviewNullptrCheck(StringRef Name, ClangTidyContext *Context);
  39
  40   bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
  41     return LangOpts.CPlusPlus17;
  42   }
  43 };
  44
  45 } // namespace bugprone
  46 } // namespace tidy
  47 } // namespace clang
  48
  49 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_STRINGVIEWNULLPTRCHECK_H