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

   1 //===--- IncorrectRoundingsCheck.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_INCORRECTROUNDINGSCHECK_H_
  10 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_INCORRECTROUNDINGSCHECK_H_
  11
  12 #include "../ClangTidyCheck.h"
  13
  14 namespace clang::tidy::bugprone {
  15
  16 /// Checks the usage of patterns known to produce incorrect rounding.
  17 /// Programmers often use
  18 ///   (int)(double_expression + 0.5)
  19 /// to round the double expression to an integer. The problem with this
  20 ///  1. It is unnecessarily slow.
  21 ///  2. It is incorrect. The number 0.499999975 (smallest representable float
  22 ///     number below 0.5) rounds to 1.0. Even worse behavior for negative
  23 ///     numbers where both -0.5f and -1.4f both round to 0.0.
  24 class IncorrectRoundingsCheck : public ClangTidyCheck {
  25 public:
  26   IncorrectRoundingsCheck(StringRef Name, ClangTidyContext *Context)
  27       : ClangTidyCheck(Name, Context) {}
  28   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
  29   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
  30 };
  31
  32 } // namespace clang::tidy::bugprone
  33
  34 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_INCORRECTROUNDINGSCHECK_H_