clang-tools  14.0.0git
IncorrectRoundingsCheck.cpp
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1 //===--- IncorrectRoundingsCheck.cpp - clang-tidy ------------------------------===//
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 
10 #include "clang/AST/DeclBase.h"
11 #include "clang/AST/Type.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/ASTMatchers/ASTMatchers.h"
14 #include "clang/Lex/Lexer.h"
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace bugprone {
21 
22 namespace {
23 AST_MATCHER(FloatingLiteral, floatHalf) {
24  const auto &Literal = Node.getValue();
25  if ((&Node.getSemantics()) == &llvm::APFloat::IEEEsingle())
26  return Literal.convertToFloat() == 0.5f;
27  if ((&Node.getSemantics()) == &llvm::APFloat::IEEEdouble())
28  return Literal.convertToDouble() == 0.5;
29  return false;
30 }
31 } // namespace
32 
33 void IncorrectRoundingsCheck::registerMatchers(MatchFinder *MatchFinder) {
34  // Match a floating literal with value 0.5.
35  auto FloatHalf = floatLiteral(floatHalf());
36 
37  // Match a floating point expression.
38  auto FloatType = expr(hasType(realFloatingPointType()));
39 
40  // Match a floating literal of 0.5 or a floating literal of 0.5 implicitly.
41  // cast to floating type.
42  auto FloatOrCastHalf =
43  anyOf(FloatHalf,
44  implicitCastExpr(FloatType, has(ignoringParenImpCasts(FloatHalf))));
45 
46  // Match if either the LHS or RHS is a floating literal of 0.5 or a floating
47  // literal of 0.5 and the other is of type double or vice versa.
48  auto OneSideHalf = anyOf(allOf(hasLHS(FloatOrCastHalf), hasRHS(FloatType)),
49  allOf(hasRHS(FloatOrCastHalf), hasLHS(FloatType)));
50 
51  // Find expressions of cast to int of the sum of a floating point expression
52  // and 0.5.
53  MatchFinder->addMatcher(
54  traverse(TK_AsIs,
55  implicitCastExpr(hasImplicitDestinationType(isInteger()),
56  ignoringParenCasts(binaryOperator(
57  hasOperatorName("+"), OneSideHalf)))
58  .bind("CastExpr")),
59  this);
60 }
61 
62 void IncorrectRoundingsCheck::check(const MatchFinder::MatchResult &Result) {
63  const auto *CastExpr = Result.Nodes.getNodeAs<ImplicitCastExpr>("CastExpr");
64  diag(CastExpr->getBeginLoc(),
65  "casting (double + 0.5) to integer leads to incorrect rounding; "
66  "consider using lround (#include <cmath>) instead");
67 }
68 
69 } // namespace bugprone
70 } // namespace tidy
71 } // namespace clang
IncorrectRoundingsCheck.h
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::ast_matchers::AST_MATCHER
AST_MATCHER(Expr, isMacroID)
Definition: PreferIsaOrDynCastInConditionalsCheck.cpp:19
clang::clangd::check
bool check(llvm::StringRef File, llvm::function_ref< bool(const Position &)> ShouldCheckLine, const ThreadsafeFS &TFS, const ClangdLSPServer::Options &Opts, bool EnableCodeCompletion)
Definition: Check.cpp:259
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27