1 files changed, 123 insertions, 0 deletions
diff --git a/compilerplugins/clang/commaoperator.cxx b/compilerplugins/clang/commaoperator.cxx
new file mode 100644
index 000000000..e619d3794
--- /dev/null
+++ b/compilerplugins/clang/commaoperator.cxx
@@ -0,0 +1,123 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * 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 <cassert>
+#include <string>
+#include <iostream>
+#include <fstream>
+#include <set>
+#include "plugin.hxx"
+
+/**
+the comma operator is best used sparingly
+*/
+
+namespace {
+
+Stmt const * lookThroughExprWithCleanups(Stmt const * stmt) {
+    if (auto const e = dyn_cast_or_null<ExprWithCleanups>(stmt)) {
+        return e->getSubExpr();
+    }
+    return stmt;
+}
+
+class CommaOperator:
+    public loplugin::FilteringPlugin<CommaOperator>
+{
+public:
+    explicit CommaOperator(loplugin::InstantiationData const & data):
+        FilteringPlugin(data) {}
+
+    virtual void run() override
+    {
+        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+    }
+
+    bool TraverseForStmt(ForStmt * stmt) {
+        auto const saved1 = ignore1_;
+        ignore1_ = lookThroughExprWithCleanups(stmt->getInit());
+        auto const saved2 = ignore2_;
+        ignore2_ = lookThroughExprWithCleanups(stmt->getInc());
+        auto const ret = RecursiveASTVisitor::TraverseForStmt(stmt);
+        ignore1_ = saved1;
+        ignore2_ = saved2;
+        return ret;
+    }
+
+    bool TraverseWhileStmt(WhileStmt * stmt) {
+        auto const saved1 = ignore1_;
+        ignore1_ = lookThroughExprWithCleanups(stmt->getCond());
+        auto const ret = RecursiveASTVisitor::TraverseWhileStmt(stmt);
+        ignore1_ = saved1;
+        return ret;
+    }
+
+    bool TraverseParenExpr(ParenExpr * expr) {
+        auto const saved1 = ignore1_;
+        ignore1_ = expr->getSubExpr();
+        auto const ret = RecursiveASTVisitor::TraverseParenExpr(expr);
+        ignore1_ = saved1;
+        return ret;
+    }
+
+    bool TraverseBinComma(BinaryOperator * expr) {
+        if (!WalkUpFromBinComma(expr)) {
+            return false;
+        }
+        auto const saved1 = ignore1_;
+        ignore1_ = expr->getLHS();
+        auto const ret = TraverseStmt(expr->getLHS())
+            && TraverseStmt(expr->getRHS());
+        ignore1_ = saved1;
+        return ret;
+    }
+
+    bool VisitBinComma(const BinaryOperator* );
+
+private:
+    Stmt const * ignore1_ = nullptr;
+    Stmt const * ignore2_ = nullptr;
+};
+
+bool CommaOperator::VisitBinComma(const BinaryOperator* binaryOp)
+{
+    if (binaryOp == ignore1_ || binaryOp == ignore2_) {
+        return true;
+    }
+    if (ignoreLocation(binaryOp)) {
+        return true;
+    }
+    // Ignore FD_SET expanding to "...} while(0, 0)" in some Microsoft
+    // winsock2.h (TODO: improve heuristic of determining that the whole
+    // binaryOp is part of a single macro body expansion):
+    if (compiler.getSourceManager().isMacroBodyExpansion(
+            compat::getBeginLoc(binaryOp))
+        && compiler.getSourceManager().isMacroBodyExpansion(
+            binaryOp->getOperatorLoc())
+        && compiler.getSourceManager().isMacroBodyExpansion(
+            compat::getEndLoc(binaryOp))
+        && ignoreLocation(
+            compiler.getSourceManager().getSpellingLoc(
+                binaryOp->getOperatorLoc())))
+    {
+        return true;
+    }
+    report(
+        DiagnosticsEngine::Warning, "comma operator hides code",
+        binaryOp->getOperatorLoc())
+      << binaryOp->getSourceRange();
+    return true;
+}
+
+
+loplugin::Plugin::Registration< CommaOperator > X("commaoperator", true);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */