new loplugin mergeclasses

Idea from Norbert (shm_get) - look for classes that are
(a) not instantiated
(b) have zero or one subclasses
and warn about them - would allow us to remove a bunch of abstract
classes that can be merged into one class and simplified

Change-Id: I4e43fdd2f549b5cbe25dcb7cee5e9dd3c1df8ba0

2 files changed, 272 insertions, 0 deletions

diff --git a/compilerplugins/clang/mergeclasses.cxx b/compilerplugins/clang/mergeclasses.cxx
new file mode 100644
index 000000000000..b6fccfe9418f
--- /dev/null
+++ b/compilerplugins/clang/mergeclasses.cxx
@@ -0,0 +1,199 @@
+/* -*- 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"
+#include <fstream>
+
+/**
+
+Idea from Norbert (shm_get) - look for classes that are
+(a) not instantiated
+(b) have zero or one subclasses
+and warn about them - would allow us to remove a bunch of abstract classes
+that can be merged into one class and simplified.
+
+Dump a list of
+- unique classes that exist (A)
+- unique classes that are instantiated (B)
+- unique class-subclass relationships (C)
+Then
+   let D = A minus B
+   for each class in D, look in C and count the entries, then dump it if no-entries == 1
+
+The process goes something like this:
+  $ make check
+  $ make FORCE_COMPILE_ALL=1 COMPILER_PLUGIN_TOOL='mergeclasses' check
+  $ ./compilerplugins/clang/mergeclasses.py > mergeclasses.results
+
+FIXME exclude 'static-only' classes, which some people may use/have used instead of a namespace to tie together a bunch of functions
+
+*/
+
+namespace {
+
+// try to limit the voluminous output a little
+static std::set<std::string> instantiatedSet;
+static std::set<std::pair<std::string,std::string> > childToParentClassSet; // childClassName -> parentClassName
+static std::map<std::string,std::string> definitionMap;  // className -> filename
+
+class MergeClasses:
+    public RecursiveASTVisitor<MergeClasses>, public loplugin::Plugin
+{
+public:
+    explicit MergeClasses(InstantiationData const & data): Plugin(data) {}
+
+    virtual void run() override
+    {
+        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+
+        // dump all our output in one write call - this is to try and limit IO "crosstalk" between multiple processes
+        // writing to the same logfile
+        std::string output;
+        for (const std::string & s : instantiatedSet)
+            output += "instantiated:\t" + s + "\n";
+        for (const std::pair<std::string,std::string> & s : childToParentClassSet)
+            output += "has-subclass:\t" + s.first + "\t" + s.second + "\n";
+        for (const std::pair<std::string,std::string> & s : definitionMap)
+            output += "definition:\t" + s.first + "\t" + s.second + "\n";
+        ofstream myfile;
+        myfile.open( SRCDIR "/mergeclasses.log", ios::app | ios::out);
+        myfile << output;
+        myfile.close();
+    }
+
+    bool VisitVarDecl(const VarDecl *);
+    bool VisitFieldDecl(const FieldDecl *);
+    bool VisitCXXConstructExpr( const CXXConstructExpr* var );
+    bool VisitCXXRecordDecl( const CXXRecordDecl* decl);
+    bool VisitFunctionDecl( const FunctionDecl* decl);
+    bool VisitCallExpr(const CallExpr* decl);
+};
+
+static bool startsWith(const std::string& rStr, const char* pSubStr) {
+    return rStr.compare(0, strlen(pSubStr), pSubStr) == 0;
+}
+
+static void addToInstantiatedSet(const std::string& s)
+{
+    // ignore stuff in the standard library, and UNO stuff we can't touch.
+    if (startsWith(s, "rtl::") || startsWith(s, "sal::") || startsWith(s, "com::sun::")
+        || startsWith(s, "std::") || startsWith(s, "boost::")
+        || s == "OString" || s == "OUString" || s == "bad_alloc")
+    {
+        return;
+    }
+    instantiatedSet.insert(s);
+}
+
+// check for implicit construction
+bool MergeClasses::VisitVarDecl( const VarDecl* pVarDecl )
+{
+    if (ignoreLocation(pVarDecl)) {
+        return true;
+    }
+    addToInstantiatedSet(pVarDecl->getType().getAsString());
+    return true;
+}
+
+// check for implicit construction
+bool MergeClasses::VisitFieldDecl( const FieldDecl* pFieldDecl )
+{
+    if (ignoreLocation(pFieldDecl)) {
+        return true;
+    }
+    addToInstantiatedSet(pFieldDecl->getType().getAsString());
+    return true;
+}
+
+bool MergeClasses::VisitCXXConstructExpr( const CXXConstructExpr* pCXXConstructExpr )
+{
+    if (ignoreLocation(pCXXConstructExpr)) {
+        return true;
+    }
+    const CXXConstructorDecl* pCXXConstructorDecl = pCXXConstructExpr->getConstructor();
+    const CXXRecordDecl* pParentCXXRecordDecl = pCXXConstructorDecl->getParent();
+    if (ignoreLocation(pParentCXXRecordDecl)) {
+        return true;
+    }
+    std::string s = pParentCXXRecordDecl->getQualifiedNameAsString();
+    addToInstantiatedSet(s);
+    return true;
+}
+
+bool MergeClasses::VisitCXXRecordDecl(const CXXRecordDecl* decl)
+{
+    if (ignoreLocation(decl)) {
+        return true;
+    }
+    if (decl->hasDefinition())
+    {
+        SourceLocation spellingLocation = compiler.getSourceManager().getSpellingLoc(decl->getCanonicalDecl()->getLocStart());
+        std::string filename = compiler.getSourceManager().getFilename(spellingLocation);
+        filename = filename.substr(strlen(SRCDIR));
+        definitionMap.insert( std::pair<std::string,std::string>(decl->getQualifiedNameAsString(), filename) );
+        for (auto it = decl->bases_begin(); it != decl->bases_end(); ++it)
+        {
+            const CXXBaseSpecifier spec = *it;
+            // need to look through typedefs, hence the getUnqualifiedDesugaredType
+            QualType baseType = spec.getType().getDesugaredType(compiler.getASTContext());
+            childToParentClassSet.insert( std::pair<std::string,std::string>(decl->getQualifiedNameAsString(),  baseType.getAsString()) );
+        }
+    }
+    return true;
+}
+
+bool MergeClasses::VisitFunctionDecl(const FunctionDecl* decl)
+{
+    if (ignoreLocation(decl)) {
+        return true;
+    }
+    return true;
+}
+
+static bool startswith(const std::string& s, const std::string& prefix)
+{
+    return s.rfind(prefix,0) == 0;
+}
+
+static bool endswith(const std::string& s, const std::string& suffix)
+{
+    return s.rfind(suffix) == (s.size()-suffix.size());
+}
+
+bool MergeClasses::VisitCallExpr(const CallExpr* decl)
+{
+    if (ignoreLocation(decl)) {
+        return true;
+    }
+    // VclPtr<T>::Create using a forwarding constructor, so we need to handle it differently in order
+    // to pick up the instantiation via it.
+    if (decl->getCalleeDecl() && isa<CXXMethodDecl>(decl->getCalleeDecl()))
+    {
+        const CXXMethodDecl * pMethod = dyn_cast<CXXMethodDecl>(decl->getCalleeDecl());
+        std::string s = pMethod->getQualifiedNameAsString();
+        if (startswith(s, "VclPtr<") && endswith(s, ">::Create"))
+        {
+            const ClassTemplateSpecializationDecl *pTemplateDecl = dyn_cast<ClassTemplateSpecializationDecl>(pMethod->getParent());
+            QualType windowType = pTemplateDecl->getTemplateArgs()[0].getAsType();
+            instantiatedSet.insert(windowType.getAsString());
+        }
+    }
+    return true;
+}
+
+
+loplugin::Plugin::Registration< MergeClasses > X("mergeclasses", false);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/compilerplugins/clang/mergeclasses.py b/compilerplugins/clang/mergeclasses.py
new file mode 100755
index 000000000000..07b68f320f28
--- /dev/null
+++ b/compilerplugins/clang/mergeclasses.py
@@ -0,0 +1,73 @@
+#!/usr/bin/python
+
+import sys
+
+instantiatedSet = set()
+definitionSet = set()
+parentChildDict = {}
+definitionToFileDict = {}
+
+with open("mergeclasses.log") as txt:
+    for line in txt:
+    
+        if line.startswith("instantiated:\t"):
+            idx1 = line.find("\t")
+            clazzName = line[idx1+1 : len(line)-1]
+            if (clazzName.startswith("const ")):
+                clazzName = clazzName[6:]
+            if (clazzName.startswith("class ")):
+                clazzName = clazzName[6:]
+            if (clazzName.endswith(" &")):
+                clazzName = clazzName[:len(clazzName)-3]
+            instantiatedSet.add(clazzName)
+            
+        elif line.startswith("definition:\t"):
+            idx1 = line.find("\t")
+            idx2 = line.find("\t", idx1+1)
+            clazzName = line[idx1+1 : idx2]
+            fileName  = line[idx2+1 : len(line)-1]
+            definitionSet.add(clazzName)
+            definitionToFileDict[clazzName] = fileName
+            
+        elif line.startswith("has-subclass:\t"):
+            idx1 = line.find("\t")
+            idx2 = line.find("\t", idx1+1)
+            child  = line[idx1+1 : idx2]
+            parent = line[idx2+1 : len(line)-1]
+            if (parent.startswith("class ")):
+                parent = parent[6:]
+            elif (parent.startswith("struct ")):
+                parent = parent[7:]
+            if (child.startswith("class ")):
+                child = child[6:]
+            elif (child.startswith("struct ")):
+                child = child[7:]
+            if (parent not in parentChildDict):
+                parentChildDict[parent] = set()
+            parentChildDict[parent].add(child)
+            
+def extractModuleName(clazz):
+    filename = definitionToFileDict[clazz]
+    if filename.startswith("include/"):
+        filename = filename[8:]
+    idx = filename.find("/")
+    return filename[:idx]
+
+for clazz in sorted(definitionSet - instantiatedSet):
+    # find uninstantiated classes without any subclasses
+    if (not(clazz in parentChildDict)) or (len(parentChildDict[clazz]) != 1):
+        continue
+    # exclude some common false positives
+    a = ['Dialog', 'Dlg', 'com::sun', 'Base']
+    if any(x in clazz for x in a):
+        continue
+    # ignore base class that contain the word "mutex", they are normally there to
+    # help with the WeakComponentImpl template magic
+    if clazz.find("mutex") != -1 or clazz.find("Mutex") != -1:
+        continue
+    otherclazz = next(iter(parentChildDict[clazz]))
+   # exclude combinations that span modules because we often use those to make cross-module dependencies more manageable.
+    if extractModuleName(clazz) != extractModuleName(otherclazz):
+        continue
+    print "merge", clazz, "with", otherclazz
+