New loplugin:unicodetochar

Change-Id: I279fe1dec196b6e1e551b4f6aba77f24e3f76ab7

1 files changed, 91 insertions, 0 deletions

diff --git a/compilerplugins/clang/unicodetochar.cxx b/compilerplugins/clang/unicodetochar.cxx
new file mode 100644
index 000000000000..cfcb5b5d7549
--- /dev/null
+++ b/compilerplugins/clang/unicodetochar.cxx
@@ -0,0 +1,91 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * 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 <stack>
+
+#include "check.hxx"
+#include "plugin.hxx"
+
+// In C++, find implicit conversions from char16_t (aka sal_Unicode) to char.
+// Such places are probably meant to properly work on char16_t instead.
+
+// (This does not work for clang-cl/MSVC yet, where sal_Unicode is still a
+// typedef for wchar_t, but that is intended to be changed eventually.)
+
+namespace {
+
+class Visitor final:
+    public RecursiveASTVisitor<Visitor>, public loplugin::Plugin
+{
+public:
+    explicit Visitor(InstantiationData const & data): Plugin(data) {}
+
+    bool TraverseCStyleCastExpr(CStyleCastExpr * expr) {
+        subExprs_.push(expr->getSubExpr());
+        bool ret = RecursiveASTVisitor::TraverseCStyleCastExpr(expr);
+        subExprs_.pop();
+        return ret;
+    }
+
+    bool TraverseCXXStaticCastExpr(CXXStaticCastExpr * expr) {
+        subExprs_.push(expr->getSubExpr());
+        bool ret = RecursiveASTVisitor::TraverseCXXStaticCastExpr(expr);
+        subExprs_.pop();
+        return ret;
+    }
+
+    bool TraverseCXXFunctionalCastExpr(CXXFunctionalCastExpr * expr) {
+        subExprs_.push(expr->getSubExpr());
+        bool ret = RecursiveASTVisitor::TraverseCXXFunctionalCastExpr(expr);
+        subExprs_.pop();
+        return ret;
+    }
+
+    bool VisitImplicitCastExpr(ImplicitCastExpr const * expr) {
+        if ((!subExprs_.empty() && expr == subExprs_.top())
+            || ignoreLocation(expr))
+        {
+            return true;
+        }
+        if (!(loplugin::TypeCheck(expr->getType()).Char()
+              && expr->getSubExpr()->getType()->isSpecificBuiltinType(
+                  clang::BuiltinType::Char16)))
+        {
+            return true;
+        }
+        APSInt res;
+        if (expr->getSubExpr()->EvaluateAsInt(res, compiler.getASTContext())
+            && res >= 0 && res <= 0x7F)
+        {
+            return true;
+        }
+        report(
+            DiagnosticsEngine::Warning,
+            "suspicious implicit cast from %0 to %1",
+            expr->getExprLoc())
+            << expr->getSubExpr()->getType() << expr->getType()
+            << expr->getSourceRange();
+        return true;
+    }
+
+private:
+    void run() override {
+        if (compiler.getLangOpts().CPlusPlus) {
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+        }
+    }
+
+    std::stack<Expr const *> subExprs_;
+};
+
+static loplugin::Plugin::Registration<Visitor> reg("unicodetochar");
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */