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-rw-r--r--build/clang-plugin/NaNExprChecker.cpp54
1 files changed, 54 insertions, 0 deletions
diff --git a/build/clang-plugin/NaNExprChecker.cpp b/build/clang-plugin/NaNExprChecker.cpp
new file mode 100644
index 0000000000..bacebc9155
--- /dev/null
+++ b/build/clang-plugin/NaNExprChecker.cpp
@@ -0,0 +1,54 @@
+/* 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) {
+ 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 std::isnan instead",
+ DiagnosticIDs::Note);
+ }
+}