1 files changed, 343 insertions, 0 deletions
diff --git a/compilerplugins/clang/unusedvariablemore.cxx b/compilerplugins/clang/unusedvariablemore.cxx
new file mode 100644
index 000000000..38e3bbe81
--- /dev/null
+++ b/compilerplugins/clang/unusedvariablemore.cxx
@@ -0,0 +1,343 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * Based on LLVM/Clang.
+ *
+ * This file is distributed under the University of Illinois Open Source
+ * License. See LICENSE.TXT for details.
+ *
+ */
+
+#include "config_clang.h"
+#include <config_global.h>
+#include "plugin.hxx"
+#include "compat.hxx"
+#include "check.hxx"
+#include <unordered_set>
+#include <unordered_map>
+
+#if CLANG_VERSION >= 110000
+#include "clang/AST/ParentMapContext.h"
+#endif
+
+namespace loplugin
+{
+/*
+  This is a compile check. The results of this plugin need to be checked by hand, since it is a collection of heuristics.
+
+  Check for unused variable where
+  (*) we never call methods that return information from the variable.
+  (*) we never pass the variable to anything else
+
+  Classes which are safe to be warned about need to be marked using
+  SAL_WARN_UNUSED (see e.g. OUString). For external classes such as std::vector
+  that cannot be edited there is a manual list.
+
+  This is an expensive plugin, since it walks up the parent tree,
+  so it is off by default.
+*/
+
+class UnusedVariableMore : public loplugin::FilteringPlugin<UnusedVariableMore>
+{
+public:
+    explicit UnusedVariableMore(const InstantiationData& data);
+    virtual void run() override;
+    bool VisitVarDecl(VarDecl const*);
+    bool VisitDeclRefExpr(DeclRefExpr const*);
+    bool VisitFunctionDecl(FunctionDecl const*);
+
+private:
+    bool checkifUnused(Stmt const*, VarDecl const*);
+    bool isOkForParameter(const QualType&);
+
+    std::unordered_set<VarDecl const*> interestingSet;
+    // used to dump the last place that said the usage was unused, for debug purposes
+    std::unordered_map<VarDecl const*, Stmt const*> interestingDebugMap;
+};
+
+UnusedVariableMore::UnusedVariableMore(const InstantiationData& data)
+    : FilteringPlugin(data)
+{
+}
+
+void UnusedVariableMore::run()
+{
+    std::string fn(handler.getMainFileName());
+    loplugin::normalizeDotDotInFilePath(fn);
+
+    // ignore QA folders
+    if (loplugin::hasPathnamePrefix(fn, SRCDIR "/sal/qa/"))
+        return;
+    if (loplugin::hasPathnamePrefix(fn, SRCDIR "/i18npool/qa/"))
+        return;
+    if (loplugin::hasPathnamePrefix(fn, SRCDIR "/sc/qa/"))
+        return;
+
+    // vector of shared_ptr used to delay destruction
+    if (fn == SRCDIR "/cppuhelper/source/servicemanager.cxx")
+        return;
+    if (fn == SRCDIR "/i18nlangtag/source/languagetag/languagetag.cxx")
+        return;
+    // unordered_set of Reference to delay destruction
+    if (fn == SRCDIR "/stoc/source/servicemanager/servicemanager.cxx")
+        return;
+    // TODO "operator >>" fooling me here
+    if (fn == SRCDIR "/editeng/source/accessibility/AccessibleEditableTextPara.cxx")
+        return;
+    // some weird stuff
+    if (fn == SRCDIR "/sfx2/source/dialog/dinfdlg.cxx")
+        return;
+    // std::vector< Reference< XInterface > > keep alive
+    if (fn == SRCDIR "/dbaccess/source/core/dataaccess/databasedocument.cxx")
+        return;
+    // template magic
+    if (fn == SRCDIR "/sc/source/core/tool/scmatrix.cxx")
+        return;
+    // storing local copy of Link<>
+    if (fn == SRCDIR "/sc/source/ui/miscdlgs/simpref.cxx")
+        return;
+    // Using an SwPaM to do stuff
+    if (fn == SRCDIR "/sw/source/core/crsr/bookmrk.cxx")
+        return;
+    // index variable in for loop?
+    if (fn == SRCDIR "/sw/source/uibase/docvw/edtwin.cxx")
+        return;
+    // TODO "operator >>" fooling me here
+    if (fn == SRCDIR "/sw/source/filter/ww8/ww8par.cxx")
+        return;
+    // TODO "operator >>" fooling me here
+    if (fn == SRCDIR "/sc/source/filter/excel/xistream.cxx")
+        return;
+
+    TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+
+    for (VarDecl const* varDecl : interestingSet)
+    {
+        report(DiagnosticsEngine::Warning, "unused variable %0", varDecl->getLocation())
+            << varDecl->getDeclName();
+        //auto it = interestingDebugMap.find(varDecl);
+        //if (it != interestingDebugMap.end())
+        //    it->second->dump();
+    }
+}
+
+bool isWarnUnusedType(QualType type)
+{
+    if (auto const t = type->getAs<TypedefType>())
+    {
+        if (t->getDecl()->hasAttr<WarnUnusedAttr>())
+        {
+            return true;
+        }
+    }
+    if (auto const t = type->getAs<RecordType>())
+    {
+        if (t->getDecl()->hasAttr<WarnUnusedAttr>())
+        {
+            return true;
+        }
+    }
+    return loplugin::isExtraWarnUnusedType(type);
+}
+
+bool UnusedVariableMore::VisitVarDecl(VarDecl const* var)
+{
+    if (ignoreLocation(var))
+        return true;
+    if (var->isDefinedOutsideFunctionOrMethod())
+        return true;
+    if (isa<ParmVarDecl>(var))
+        return true;
+    if (!isWarnUnusedType(var->getType()))
+        return true;
+
+    // some false +
+    auto dc = loplugin::TypeCheck(var->getType());
+    if (dc.Class("ZCodec").GlobalNamespace())
+        return true;
+    if (dc.Class("ScopedVclPtrInstance").GlobalNamespace())
+        return true;
+    if (dc.Class("VclPtrInstance").GlobalNamespace())
+        return true;
+    if (dc.Class("Config").GlobalNamespace())
+        return true;
+    // I think these classes modify global state somehow
+    if (dc.Class("SvtHistoryOptions").GlobalNamespace())
+        return true;
+    if (dc.Class("SvtSecurityOptions").GlobalNamespace())
+        return true;
+    if (dc.Class("SvtViewOptions").GlobalNamespace())
+        return true;
+    if (dc.Class("SvtUserOptions").GlobalNamespace())
+        return true;
+    if (dc.Class("SvtFontOptions").GlobalNamespace())
+        return true;
+    if (dc.Class("SvtMenuOptions").GlobalNamespace())
+        return true;
+    if (dc.Class("SvtPathOptions").GlobalNamespace())
+        return true;
+    if (dc.Class("SvtPrintWarningOptions").GlobalNamespace())
+        return true;
+    if (dc.Class("SvtSysLocaleOptions").GlobalNamespace())
+        return true;
+
+    interestingSet.insert(var);
+    return true;
+}
+
+bool UnusedVariableMore::VisitDeclRefExpr(DeclRefExpr const* declRefExpr)
+{
+    if (ignoreLocation(declRefExpr))
+        return true;
+    auto varDecl = dyn_cast<VarDecl>(declRefExpr->getDecl());
+    if (!varDecl)
+        return true;
+    if (interestingSet.find(varDecl) == interestingSet.end())
+        return true;
+    if (!checkifUnused(declRefExpr, varDecl))
+        interestingSet.erase(varDecl);
+    return true;
+}
+
+// Walk up from a statement that contains a DeclRefExpr, checking if the usage means that the
+// related VarDecl is unused.
+bool UnusedVariableMore::checkifUnused(Stmt const* stmt, VarDecl const* varDecl)
+{
+    const Stmt* parent = getParentStmt(stmt);
+    if (!parent)
+    {
+        // check if we're inside a CXXCtorInitializer
+        auto parentsRange = getParents(*stmt);
+        if (parentsRange.begin() != parentsRange.end())
+        {
+            auto parentDecl = parentsRange.begin()->get<Decl>();
+            if (parentDecl && (isa<CXXConstructorDecl>(parentDecl) || isa<VarDecl>(parentDecl)))
+                return false;
+        }
+        interestingDebugMap[varDecl] = stmt;
+        return true;
+    }
+
+    if (isa<ReturnStmt>(parent))
+        return false;
+    if (isa<IfStmt>(parent))
+        return false;
+    if (isa<SwitchStmt>(parent))
+        return false;
+    if (isa<InitListExpr>(parent))
+        return false;
+    if (isa<CXXConstructExpr>(parent))
+        return false;
+    if (isa<BinaryOperator>(parent))
+        return false;
+    if (isa<UnaryOperator>(parent))
+        return false;
+    if (isa<ConditionalOperator>(parent))
+        return false;
+    if (isa<ArraySubscriptExpr>(parent))
+        return false;
+    if (isa<CXXBindTemporaryExpr>(parent))
+        return checkifUnused(parent, varDecl);
+    if (isa<MaterializeTemporaryExpr>(parent))
+        return checkifUnused(parent, varDecl);
+
+    if (isa<CompoundStmt>(parent))
+    {
+        interestingDebugMap[varDecl] = parent;
+        return true;
+    }
+
+    // check for cast to void
+    if (auto explicitCastExpr = dyn_cast<ExplicitCastExpr>(parent))
+    {
+        if (loplugin::TypeCheck(explicitCastExpr->getTypeAsWritten()).Void())
+            return false;
+    }
+
+    if (isa<MemberExpr>(parent))
+        return checkifUnused(parent, varDecl);
+    if (isa<ExprWithCleanups>(parent))
+        return checkifUnused(parent, varDecl);
+    if (isa<CastExpr>(parent))
+        return checkifUnused(parent, varDecl);
+    if (isa<ParenExpr>(parent))
+        return checkifUnused(parent, varDecl);
+
+    if (auto operatorCallExpr = dyn_cast<CXXOperatorCallExpr>(parent))
+    {
+        const CXXMethodDecl* calleeMethodDecl
+            = dyn_cast_or_null<CXXMethodDecl>(operatorCallExpr->getDirectCallee());
+        if (calleeMethodDecl)
+        {
+            if (calleeMethodDecl->getNumParams() == 0)
+                return checkifUnused(parent, varDecl);
+            if (operatorCallExpr->getArg(0) == stmt)
+                return checkifUnused(parent, varDecl);
+        }
+    }
+    if (auto memberCallExpr = dyn_cast<CXXMemberCallExpr>(parent))
+    {
+        const MemberExpr* memberExpr = dyn_cast<MemberExpr>(stmt);
+        if (memberExpr && memberCallExpr->getImplicitObjectArgument() == memberExpr->getBase())
+        {
+            // if we are calling a method on the varDecl, walk up
+            if (!checkifUnused(parent, varDecl))
+                return false;
+            // check if we are passing something to the var by non-const ref, in which case it is updating something else for us
+            const FunctionDecl* calleeFunctionDecl = memberCallExpr->getDirectCallee();
+            if (calleeFunctionDecl)
+            {
+                if (calleeFunctionDecl->isVariadic())
+                    return false;
+                for (unsigned i = 0; i < memberCallExpr->getNumArgs(); ++i)
+                {
+                    if (i >= calleeFunctionDecl->getNumParams()) // can happen in template code
+                    {
+                        interestingDebugMap[varDecl] = parent;
+                        return true;
+                    }
+                    if (!isOkForParameter(calleeFunctionDecl->getParamDecl(i)->getType()))
+                        return false;
+                }
+            }
+            interestingDebugMap[varDecl] = parent;
+            return true;
+        }
+    }
+    if (isa<CallExpr>(parent))
+        return false;
+
+    interestingDebugMap[varDecl] = parent;
+    return true;
+}
+
+bool UnusedVariableMore::isOkForParameter(const QualType& qt)
+{
+    if (qt->isIntegralOrEnumerationType())
+        return true;
+    auto const type = loplugin::TypeCheck(qt);
+    if (type.Pointer())
+    {
+        return bool(type.Pointer().Const());
+    }
+    else if (type.LvalueReference())
+    {
+        return bool(type.LvalueReference().Const());
+    }
+    return false;
+}
+
+bool UnusedVariableMore::VisitFunctionDecl(FunctionDecl const* functionDecl)
+{
+    if (ignoreLocation(functionDecl))
+        return true;
+    //functionDecl->dump();
+    return true;
+}
+
+static Plugin::Registration<UnusedVariableMore> X("unusedvariablemore", false);
+
+} // namespace
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */