new loplugin overrideparam

verify that parameters on override methods have the same set of default
values for their params as their parent/super-methods do.

Change-Id: Ibdbc1c6e417fbaa680ea025a6bbf5ba9c2e5bcd2
Reviewed-on: https://gerrit.libreoffice.org/27437
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>

1 files changed, 179 insertions, 0 deletions

diff --git a/compilerplugins/clang/overrideparam.cxx b/compilerplugins/clang/overrideparam.cxx
new file mode 100644
index 000000000000..c04165bbd8c2
--- /dev/null
+++ b/compilerplugins/clang/overrideparam.cxx
@@ -0,0 +1,179 @@
+/* -*- 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"
+#include "compat.hxx"
+#include "check.hxx"
+
+/*
+  Find overriden methods that :
+  (a) declare default params in different palces to their super-method(s)
+
+  Still TODO
+  (b) Find places where the values of the default parameters are different
+  (c) Find places where the names of the parameters differ
+*/
+
+namespace {
+
+class OverrideParam:
+    public RecursiveASTVisitor<OverrideParam>, public loplugin::Plugin
+{
+public:
+    explicit OverrideParam(InstantiationData const & data): Plugin(data) {}
+
+    virtual void run() override;
+
+    bool VisitCXXMethodDecl(const CXXMethodDecl *);
+
+private:
+    bool hasSameDefaultParams(const ParmVarDecl * parmVarDecl, const ParmVarDecl * superParmVarDecl);
+};
+
+void OverrideParam::run()
+{
+    /*
+    StringRef fn( compiler.getSourceManager().getFileEntryForID(
+                      compiler.getSourceManager().getMainFileID())->getName() );
+    if (fn == SRCDIR "/include/svx/checklbx.hxx")
+         return;
+*/
+    TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+}
+
+bool OverrideParam::VisitCXXMethodDecl(const CXXMethodDecl * methodDecl) {
+    if (ignoreLocation(methodDecl)) {
+        return true;
+    }
+    if (methodDecl->isThisDeclarationADefinition() || methodDecl->size_overridden_methods() == 0) {
+        return true;
+    }
+    loplugin::DeclCheck dc(methodDecl);
+    // there is an InsertEntry override here which causes trouble if I modify it
+    if (dc.Function("InsertEntry").Class("SvxCheckListBox").GlobalNamespace()) {
+        return true;
+    }
+    // This class is overriding ShowCursor(bool) AND declaring a ShowCursor() method.
+    // Adding a default param causes 'ambiguous override'.
+    if (dc.Function("ShowCursor").Class("ScTabViewShell").GlobalNamespace()) {
+        return true;
+    }
+
+    for(auto superMethodIt = methodDecl->begin_overridden_methods();
+        superMethodIt != methodDecl->end_overridden_methods(); ++superMethodIt)
+    {
+        const CXXMethodDecl * superMethodDecl = *superMethodIt;
+        if (ignoreLocation(superMethodDecl)) {
+            continue;
+        }
+        int i = 0;
+        for (const ParmVarDecl *superParmVarDecl : compat::parameters(*superMethodDecl)) {
+            const ParmVarDecl *parmVarDecl = methodDecl->getParamDecl(i);
+            if (parmVarDecl->hasDefaultArg() && !superParmVarDecl->hasDefaultArg()) {
+                report(
+                    DiagnosticsEngine::Warning,
+                    "overridden method declaration has default arg, but super-method does not",
+                    parmVarDecl->getSourceRange().getBegin())
+                    << parmVarDecl->getSourceRange();
+                report(
+                    DiagnosticsEngine::Note,
+                    "original param here",
+                    superParmVarDecl->getSourceRange().getBegin())
+                    << superParmVarDecl->getSourceRange();
+            }
+            else if (!parmVarDecl->hasDefaultArg() && superParmVarDecl->hasDefaultArg()) {
+                report(
+                    DiagnosticsEngine::Warning,
+                    "overridden method declaration has no default arg, but super-method does",
+                    parmVarDecl->getSourceRange().getBegin())
+                    << parmVarDecl->getSourceRange();
+                report(
+                    DiagnosticsEngine::Note,
+                    "original param here",
+                    superParmVarDecl->getSourceRange().getBegin())
+                    << superParmVarDecl->getSourceRange();
+            }
+            else if (parmVarDecl->hasDefaultArg() && superParmVarDecl->hasDefaultArg()
+                && !hasSameDefaultParams(parmVarDecl, superParmVarDecl)) {
+                /* do nothing for now, will enable this in a later commit
+                report(
+                    DiagnosticsEngine::Warning,
+                    "overridden method declaration has different default param to super-method",
+                    parmVarDecl->getSourceRange().getBegin())
+                    << parmVarDecl->getSourceRange();
+                report(
+                    DiagnosticsEngine::Note,
+                    "original param here",
+                    superParmVarDecl->getSourceRange().getBegin())
+                    << superParmVarDecl->getSourceRange();
+                */
+            }
+            /* do nothing for now, will enable this in a later commit
+            if (methodDecl->isThisDeclarationADefinition() && parmVarDecl->getName().empty()) {
+                // ignore this - means the param is unused
+            }
+            else if (superParmVarDecl->getName().empty()) {
+                // ignore, nothing reasonable I can do
+            }
+            else if (superParmVarDecl->getName() != parmVarDecl->getName()) {
+                report(
+                    DiagnosticsEngine::Warning,
+                    "overridden method declaration uses different name for parameter",
+                    parmVarDecl->getSourceRange().getBegin())
+                    << parmVarDecl->getSourceRange();
+                report(
+                    DiagnosticsEngine::Note,
+                    "original param here",
+                    superParmVarDecl->getSourceRange().getBegin())
+                    << superParmVarDecl->getSourceRange();
+            }*/
+            ++i;
+        }
+    }
+    return true;
+}
+
+bool OverrideParam::hasSameDefaultParams(const ParmVarDecl * parmVarDecl, const ParmVarDecl * superParmVarDecl)
+{
+    // don't know what this means, but it prevents a clang crash
+    if (parmVarDecl->hasUninstantiatedDefaultArg() || superParmVarDecl->hasUninstantiatedDefaultArg()) {
+        return false;
+    }
+    const Expr* defaultArgExpr = parmVarDecl->getDefaultArg();
+    const Expr* superDefaultArgExpr = superParmVarDecl->getDefaultArg();
+
+    if (defaultArgExpr->isNullPointerConstant(compiler.getASTContext(), Expr::NPC_NeverValueDependent)
+        && superDefaultArgExpr->isNullPointerConstant(compiler.getASTContext(), Expr::NPC_NeverValueDependent))
+    {
+        return true;
+    }
+    APSInt x1, x2;
+    if (defaultArgExpr->EvaluateAsInt(x1, compiler.getASTContext())
+        && superDefaultArgExpr->EvaluateAsInt(x2, compiler.getASTContext()))
+    {
+        return x1 == x2;
+    }
+    // catch params with defaults like "= OUString()"
+    if (isa<MaterializeTemporaryExpr>(defaultArgExpr)
+        && isa<MaterializeTemporaryExpr>(superDefaultArgExpr))
+    {
+        return true;
+    }
+    return false;
+}
+
+
+loplugin::Plugin::Registration< OverrideParam > X("overrideparam");
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */