1 files changed, 119 insertions, 0 deletions
diff --git a/compilerplugins/clang/unnecessaryvirtual.cxx b/compilerplugins/clang/unnecessaryvirtual.cxx
new file mode 100644
index 000000000000..0ead077473de
--- /dev/null
+++ b/compilerplugins/clang/unnecessaryvirtual.cxx
@@ -0,0 +1,119 @@
+/* -*- 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 "plugin.hxx"
+#include "compat.hxx"
+
+/**
+Dump a list of virtual methods and a list of methods overriding virtual methods.
+Then we will post-process the 2 lists and find the set of virtual methods which don't need to be virtual.
+
+The process goes something like this:
+  $ make check
+  $ make FORCE_COMPILE_ALL=1 COMPILER_PLUGIN_TOOL='unnecessaryvirtual' check > log.txt
+  $ grep 'definition' log.txt | cut -f 2 | sort -u > definition.txt
+  $ grep 'overriding' log.txt | cut -f 2 | sort -u > overriding.txt
+  $ cat definition.txt overriding.txt | sort | uniq -u > result.txt
+  $ echo "\n" >> result.txt
+  $ for dir in *; do make  FORCE_COMPILE_ALL=1 UPDATE_FILES=$dir COMPILER_PLUGIN_TOOL='removevirtuals' $dir; done
+
+Note that the actual process may involve a fair amount of undoing, hand editing, and general messing around
+to get it to work :-)
+Notably templates tend to confuse it into removing stuff that is still needed.
+*/
+
+namespace {
+
+class UnnecessaryVirtual:
+    public RecursiveASTVisitor<UnnecessaryVirtual>, public loplugin::Plugin
+{
+public:
+    explicit UnnecessaryVirtual(InstantiationData const & data): Plugin(data) {}
+
+    virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+    bool VisitCXXMethodDecl( const CXXMethodDecl* var );
+
+};
+
+static std::string niceName(const CXXMethodDecl* functionDecl)
+{
+    std::string s =
+           functionDecl->getParent()->getQualifiedNameAsString() + "::"
+           + compat::getReturnType(*functionDecl).getAsString() + "-"
+           + functionDecl->getNameAsString() + "(";
+    for (const ParmVarDecl *pParmVarDecl : functionDecl->params()) {
+        s += pParmVarDecl->getType().getAsString();
+        s += ",";
+    }
+    s += ")";
+    if (functionDecl->isConst()) {
+        s += "const";
+    }
+    return s;
+}
+
+bool UnnecessaryVirtual::VisitCXXMethodDecl( const CXXMethodDecl* functionDecl )
+{
+    if (ignoreLocation(functionDecl)) {
+        return true;
+    }
+    functionDecl = functionDecl->getCanonicalDecl();
+    // ignore stuff that forms part of the stable URE interface
+    if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(
+                              functionDecl->getNameInfo().getLoc()))) {
+        return true;
+    }
+    if (!functionDecl->isVirtual()) {
+        return true;
+    }
+    // ignore UNO interface definitions, cannot change those
+    static const char cssPrefix[] = "com::sun::star";
+    if (functionDecl->getParent()->getQualifiedNameAsString().compare(0, strlen(cssPrefix), cssPrefix) == 0) {
+        return true;
+    }
+    std::string aNiceName = niceName(functionDecl);
+    // Ignore virtual destructors for now.
+    // I cannot currently detect the case where we are overriding a pure virtual destructor.
+    if (dyn_cast<CXXDestructorDecl>(functionDecl)) {
+        return true;
+    }
+    if (functionDecl->size_overridden_methods() == 0) {
+        // ignore definition of virtual functions in templates
+//        if (functionDecl->getTemplatedKind() != FunctionDecl::TK_NonTemplate
+//           && functionDecl->getParent()->getDescribedClassTemplate() == nullptr)
+//        {
+           cout << "definition\t" << aNiceName << endl;
+//        }
+    } else {
+       for (CXXMethodDecl::method_iterator iter = functionDecl->begin_overridden_methods(); iter != functionDecl->end_overridden_methods(); ++iter) {
+           const CXXMethodDecl *pOverriddenMethod = *iter;
+           // we only care about the first level override to establish that a virtual qualifier was useful.
+           if (pOverriddenMethod->size_overridden_methods() == 0) {
+               // ignore UNO interface definitions, cannot change those
+               if (pOverriddenMethod->getParent()->getQualifiedNameAsString().compare(0, strlen(cssPrefix), cssPrefix) != 0) {
+                   std::string aOverriddenNiceName = niceName(pOverriddenMethod);
+                   cout << "overriding\t" << aOverriddenNiceName << endl;
+               }
+           }
+      }
+    }
+    return true;
+}
+
+
+
+loplugin::Plugin::Registration< UnnecessaryVirtual > X("unnecessaryvirtual", false);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */