clang-tidy/bugprone/IncorrectRoundingsCheck.h

0001 //===--- IncorrectRoundingsCheck.h - clang-tidy -----------------*- C++ -*-===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_INCORRECTROUNDINGSCHECK_H_
0010 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_INCORRECTROUNDINGSCHECK_H_
0011
0012 #include "../ClangTidyCheck.h"
0013
0014 namespace clang::tidy::bugprone {
0015
0016 /// Checks the usage of patterns known to produce incorrect rounding.
0017 /// Programmers often use
0018 ///   (int)(double_expression + 0.5)
0019 /// to round the double expression to an integer. The problem with this
0020 ///  1. It is unnecessarily slow.
0021 ///  2. It is incorrect. The number 0.499999975 (smallest representable float
0022 ///     number below 0.5) rounds to 1.0. Even worse behavior for negative
0023 ///     numbers where both -0.5f and -1.4f both round to 0.0.
0024 class IncorrectRoundingsCheck : public ClangTidyCheck {
0025 public:
0026   IncorrectRoundingsCheck(StringRef Name, ClangTidyContext *Context)
0027       : ClangTidyCheck(Name, Context) {}
0028   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
0029   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
0030 };
0031
0032 } // namespace clang::tidy::bugprone
0033
0034 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_INCORRECTROUNDINGSCHECK_H_