make the Color constructors explicitly specify transparency

to reduce the churn, we leave the existing constructor in place,
and add a clang plugin to detect when the value passed to the
existing constructor may contain transparency/alpha data.

i.e. we leave expressions like Color(0xffffff) alone, but
warn about any non-constant expression, and any expression
like Color(0xff000000)

Change-Id: Id2ce58e08882d9b7bd0b9f88eca97359dcdbcc8c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/109362
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 95 insertions, 0 deletions

diff --git a/compilerplugins/clang/colorcheck.cxx b/compilerplugins/clang/colorcheck.cxx
new file mode 100644
index 000000000000..83f9a9688381
--- /dev/null
+++ b/compilerplugins/clang/colorcheck.cxx
@@ -0,0 +1,95 @@
+/* -*- 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/.
+ */
+#ifndef LO_CLANG_SHARED_PLUGINS
+
+#include <memory>
+#include <cassert>
+#include <string>
+#include <iostream>
+#include <fstream>
+#include <set>
+
+#include "check.hxx"
+#include "plugin.hxx"
+
+/**
+*/
+
+namespace
+{
+class ColorCheck : public loplugin::FilteringPlugin<ColorCheck>
+{
+public:
+    explicit ColorCheck(loplugin::InstantiationData const& data)
+        : FilteringPlugin(data)
+    {
+    }
+
+    virtual void run() override
+    {
+        if (preRun())
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+    }
+
+    bool VisitCXXConstructExpr(const CXXConstructExpr*);
+};
+
+bool ColorCheck::VisitCXXConstructExpr(const CXXConstructExpr* constructExpr)
+{
+    if (ignoreLocation(constructExpr))
+        return true;
+
+    if (constructExpr->getNumArgs() != 1)
+        return true;
+
+    auto tc = loplugin::TypeCheck(constructExpr->getType());
+    if (!tc.Class("Color").GlobalNamespace())
+        return true;
+
+    StringRef aFileName = getFilenameOfLocation(
+        compiler.getSourceManager().getSpellingLoc(compat::getBeginLoc(constructExpr)));
+    if (loplugin::isSamePathname(aFileName, SRCDIR "/include/tools/color.hxx"))
+        return true;
+
+    const CXXConstructorDecl* constructorDecl = constructExpr->getConstructor();
+    constructorDecl = constructorDecl->getCanonicalDecl();
+
+    if (!loplugin::TypeCheck(constructorDecl->getParamDecl(0)->getType())
+             .Typedef("sal_uInt32")
+             .GlobalNamespace())
+        return true;
+
+    auto arg0 = constructExpr->getArg(0);
+    if (arg0->isCXX11ConstantExpr(compiler.getASTContext()))
+    {
+        if (!arg0->isValueDependent())
+        {
+            llvm::Optional<llvm::APSInt> xVal
+                = compat::getIntegerConstantExpr(arg0, compiler.getASTContext());
+            if (xVal && *xVal > 0xffffff)
+                report(DiagnosticsEngine::Warning,
+                       "Rather use the ColorTransparency or ColorAlpha version of this constructor",
+                       arg0->getExprLoc());
+            return true;
+        }
+    }
+    report(DiagnosticsEngine::Warning,
+           "Rather use the ColorTransparency or ColorAlpha version of this constructor",
+           arg0->getExprLoc());
+
+    return true;
+}
+
+loplugin::Plugin::Registration<ColorCheck> colorcheck("colorcheck");
+
+} // namespace
+
+#endif // LO_CLANG_SHARED_PLUGINS
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */