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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "NaNExprChecker.h"
#include "CustomMatchers.h"
void NaNExprChecker::registerMatchers(MatchFinder *AstMatcher) {
AstMatcher->addMatcher(
binaryOperator(
allOf(binaryEqualityOperator(),
hasLHS(has(ignoringParenImpCasts(
declRefExpr(hasType(qualType((isFloat())))).bind("lhs")))),
hasRHS(has(ignoringParenImpCasts(
declRefExpr(hasType(qualType((isFloat())))).bind("rhs")))),
unless(anyOf(isInSystemHeader(), isInWhitelistForNaNExpr()))))
.bind("node"),
this);
}
void NaNExprChecker::check(const MatchFinder::MatchResult &Result) {
if (!Result.Context->getLangOpts().CPlusPlus) {
// mozilla::IsNaN is not usable in C, so there is no point in issuing these
// warnings.
return;
}
const BinaryOperator *Expression =
Result.Nodes.getNodeAs<BinaryOperator>("node");
const DeclRefExpr *LHS = Result.Nodes.getNodeAs<DeclRefExpr>("lhs");
const DeclRefExpr *RHS = Result.Nodes.getNodeAs<DeclRefExpr>("rhs");
const ImplicitCastExpr *LHSExpr =
dyn_cast<ImplicitCastExpr>(Expression->getLHS());
const ImplicitCastExpr *RHSExpr =
dyn_cast<ImplicitCastExpr>(Expression->getRHS());
// The AST subtree that we are looking for will look like this:
// -BinaryOperator ==/!=
// |-ImplicitCastExpr LValueToRValue
// | |-DeclRefExpr
// |-ImplicitCastExpr LValueToRValue
// |-DeclRefExpr
// The check below ensures that we are dealing with the correct AST subtree
// shape, and
// also that both of the found DeclRefExpr's point to the same declaration.
if (LHS->getFoundDecl() == RHS->getFoundDecl() && LHSExpr && RHSExpr &&
std::distance(LHSExpr->child_begin(), LHSExpr->child_end()) == 1 &&
std::distance(RHSExpr->child_begin(), RHSExpr->child_end()) == 1 &&
*LHSExpr->child_begin() == LHS && *RHSExpr->child_begin() == RHS) {
diag(Expression->getBeginLoc(),
"comparing a floating point value to itself for "
"NaN checking can lead to incorrect results",
DiagnosticIDs::Error);
diag(Expression->getBeginLoc(), "consider using mozilla::IsNaN instead",
DiagnosticIDs::Note);
}
}
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