1 files changed, 128 insertions, 0 deletions
diff --git a/compilerplugins/clang/store/defaultparams.cxx b/compilerplugins/clang/store/defaultparams.cxx
new file mode 100644
index 000000000..cb533cb19
--- /dev/null
+++ b/compilerplugins/clang/store/defaultparams.cxx
@@ -0,0 +1,128 @@
+/* -*- 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 <string>
+#include <set>
+
+#include "plugin.hxx"
+
+// Find places where we call a method with values == the values specified in the parameter defaults.
+// i.e. where the code might as well not specify anything.
+
+namespace {
+
+class DefaultParams:
+    public loplugin::FilteringPlugin<DefaultParams>
+{
+public:
+    explicit DefaultParams(InstantiationData const & data): FilteringPlugin(data) {}
+
+    virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+    bool VisitCallExpr(CallExpr * callExpr);
+private:
+    bool evaluate(const Expr* expr, APSInt& x);
+};
+
+bool DefaultParams::VisitCallExpr(CallExpr * callExpr) {
+    if (ignoreLocation(callExpr)) {
+        return true;
+    }
+    if (callExpr->getDirectCallee() == nullptr) {
+        return true;
+    }
+    const FunctionDecl* functionDecl = callExpr->getDirectCallee()->getCanonicalDecl();
+    auto n = functionDecl->getNumParams();
+    if (n == 0 || !functionDecl->getParamDecl(n - 1)->hasDefaultArg()) {
+        return true;
+    }
+    assert(callExpr->getNumArgs() <= n); // can be < in template code
+    for (unsigned i = callExpr->getNumArgs(); i != 0;) {
+        --i;
+        Expr* arg = callExpr->getArg(i);
+        if (arg->isDefaultArgument()) {
+            continue;
+        }
+        // ignore this, it seems to trigger an infinite recursion
+        if (isa<UnaryExprOrTypeTraitExpr>(arg))
+            break;
+        const ParmVarDecl* parmVarDecl = functionDecl->getParamDecl(i);
+        if (!parmVarDecl->hasDefaultArg()
+            || parmVarDecl->hasUninstantiatedDefaultArg())
+        {
+            break;
+        }
+        const Expr* defaultArgExpr = parmVarDecl->getDefaultArg();
+        if (!defaultArgExpr) {
+            break;
+        }
+        bool found = false;
+        if (defaultArgExpr->isNullPointerConstant(compiler.getASTContext(), Expr::NPC_NeverValueDependent)
+            && arg->isNullPointerConstant(compiler.getASTContext(), Expr::NPC_NeverValueDependent))
+        {
+            found = true;
+        }
+        if (!found)
+        {
+            APSInt x1, x2;
+            if (evaluate(defaultArgExpr, x1) && evaluate(arg, x2) && x1 == x2)
+            {
+                found = true;
+            }
+        }
+        // catch params with defaults like "= OUString()"
+        if (!found
+            && isa<MaterializeTemporaryExpr>(arg)
+            && isa<MaterializeTemporaryExpr>(defaultArgExpr))
+        {
+            const CXXBindTemporaryExpr* strippedArg = dyn_cast_or_null<CXXBindTemporaryExpr>(arg->IgnoreParenCasts());
+            if (strippedArg && isa<CXXTemporaryObjectExpr>(strippedArg->getSubExpr())
+                && dyn_cast<CXXTemporaryObjectExpr>(strippedArg->getSubExpr())->getNumArgs() == 0)
+            {
+                found = true;
+            }
+        }
+        if (!found)
+            break;
+        // Ignore CPPUNIT, it's macros contain some stuff that triggers us
+        StringRef aFileName = getFilenameOfLocation(compiler.getSourceManager().getSpellingLoc(parmVarDecl->getLocStart()));
+        if (aFileName.find("include/cppunit") != std::string::npos)
+            break;
+        report(
+            DiagnosticsEngine::Warning,
+            "not necessary to pass this argument, it defaults to the same value",
+            arg->getSourceRange().getBegin())
+            << arg->getSourceRange();
+        report(
+            DiagnosticsEngine::Note,
+            "default method parameter declaration here",
+            parmVarDecl->getSourceRange().getBegin())
+            << parmVarDecl->getSourceRange();
+    }
+    return true;
+}
+
+bool DefaultParams::evaluate(const Expr* expr, APSInt& x)
+{
+    if (isa<CXXNullPtrLiteralExpr>(expr)) {
+        x = 0;
+        return true;
+    }
+    if (expr->EvaluateAsInt(x, compiler.getASTContext()))
+    {
+        return true;
+    }
+    return false;
+}
+
+loplugin::Plugin::Registration< DefaultParams > X("defaultparams");
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */