1 /* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
5 #include "NaNExprChecker.h"
6 #include "CustomMatchers.h"
8 void NaNExprChecker::registerMatchers(MatchFinder
*AstMatcher
) {
9 AstMatcher
->addMatcher(
11 allOf(binaryEqualityOperator(),
12 hasLHS(has(ignoringParenImpCasts(
13 declRefExpr(hasType(qualType((isFloat())))).bind("lhs")))),
14 hasRHS(has(ignoringParenImpCasts(
15 declRefExpr(hasType(qualType((isFloat())))).bind("rhs")))),
16 unless(anyOf(isInSystemHeader(), isInWhitelistForNaNExpr()))))
21 void NaNExprChecker::check(const MatchFinder::MatchResult
&Result
) {
22 if (!Result
.Context
->getLangOpts().CPlusPlus
) {
26 const BinaryOperator
*Expression
=
27 Result
.Nodes
.getNodeAs
<BinaryOperator
>("node");
28 const DeclRefExpr
*LHS
= Result
.Nodes
.getNodeAs
<DeclRefExpr
>("lhs");
29 const DeclRefExpr
*RHS
= Result
.Nodes
.getNodeAs
<DeclRefExpr
>("rhs");
30 const ImplicitCastExpr
*LHSExpr
=
31 dyn_cast
<ImplicitCastExpr
>(Expression
->getLHS());
32 const ImplicitCastExpr
*RHSExpr
=
33 dyn_cast
<ImplicitCastExpr
>(Expression
->getRHS());
34 // The AST subtree that we are looking for will look like this:
35 // -BinaryOperator ==/!=
36 // |-ImplicitCastExpr LValueToRValue
38 // |-ImplicitCastExpr LValueToRValue
40 // The check below ensures that we are dealing with the correct AST subtree
42 // also that both of the found DeclRefExpr's point to the same declaration.
43 if (LHS
->getFoundDecl() == RHS
->getFoundDecl() && LHSExpr
&& RHSExpr
&&
44 std::distance(LHSExpr
->child_begin(), LHSExpr
->child_end()) == 1 &&
45 std::distance(RHSExpr
->child_begin(), RHSExpr
->child_end()) == 1 &&
46 *LHSExpr
->child_begin() == LHS
&& *RHSExpr
->child_begin() == RHS
) {
47 diag(Expression
->getBeginLoc(),
48 "comparing a floating point value to itself for "
49 "NaN checking can lead to incorrect results",
50 DiagnosticIDs::Error
);
51 diag(Expression
->getBeginLoc(), "consider using std::isnan instead",