Adding upstream version 1:7.0.4.upstream/1%7.0.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 493 insertions, 0 deletions

diff --git a/compilerplugins/clang/passstuffbyref.cxx b/compilerplugins/clang/passstuffbyref.cxx
new file mode 100644
index 000000000..cff1e7814
--- /dev/null
+++ b/compilerplugins/clang/passstuffbyref.cxx
@@ -0,0 +1,493 @@
+/* -*- 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 <iostream>
+
+#include "check.hxx"
+#include "plugin.hxx"
+
+// Find places where various things are passed by value.
+// It's not very efficient, because we generally end up copying it twice - once into the parameter and
+// again into the destination.
+// They should rather be passed by reference.
+//
+// Generally recommending lambda capture by-ref rather than by-copy is even more
+// problematic than with function parameters, as a lambda instance can easily
+// outlive a referenced variable. So once lambdas start to get used in more
+// sophisticated ways than passing them into standard algorithms, this plugin's
+// advice, at least for explicit captures, will need to be revisited.
+
+namespace {
+
+class PassStuffByRef:
+    public loplugin::FilteringPlugin<PassStuffByRef>
+{
+public:
+    explicit PassStuffByRef(loplugin::InstantiationData const & data): FilteringPlugin(data), mbInsideFunctionDecl(false), mbFoundReturnValueDisqualifier(false) {}
+
+    virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+    // When warning about function params of primitive type that could be passed
+    // by value instead of by reference, make sure not to warn if the parameter
+    // is ever bound to a reference; on the one hand, this needs scaffolding in
+    // all Traverse*Decl functions (indirectly) derived from FunctionDecl; and
+    // on the other hand, use a hack of ignoring just the DeclRefExprs nested in
+    // LValueToRValue ImplicitCastExprs when determining whether a param is
+    // bound to a reference:
+    bool TraverseFunctionDecl(FunctionDecl * decl);
+    bool TraverseCXXMethodDecl(CXXMethodDecl * decl);
+    bool TraverseCXXConstructorDecl(CXXConstructorDecl * decl);
+    bool TraverseCXXDestructorDecl(CXXDestructorDecl * decl);
+    bool TraverseCXXConversionDecl(CXXConversionDecl * decl);
+    bool VisitFunctionDecl(const FunctionDecl * decl);
+    bool TraverseImplicitCastExpr(ImplicitCastExpr * expr);
+    bool VisitDeclRefExpr(const DeclRefExpr * expr);
+
+    bool VisitReturnStmt(const ReturnStmt * );
+    bool VisitVarDecl(const VarDecl * );
+
+private:
+    template<typename T> bool traverseAnyFunctionDecl(
+        T * decl, bool (RecursiveASTVisitor::* fn)(T *));
+    void checkParams(const FunctionDecl * functionDecl);
+    void checkReturnValue(const FunctionDecl * functionDecl, const CXXMethodDecl * methodDecl);
+    bool isPrimitiveConstRef(QualType type);
+    bool isReturnExprDisqualified(const Expr* expr);
+
+    bool mbInsideFunctionDecl;
+    bool mbFoundReturnValueDisqualifier;
+
+    struct FDecl {
+        std::set<ParmVarDecl const *> parms;
+        bool check = false;
+    };
+    std::vector<FDecl> functionDecls_;
+};
+
+bool PassStuffByRef::TraverseFunctionDecl(FunctionDecl * decl) {
+    return traverseAnyFunctionDecl(
+        decl, &RecursiveASTVisitor::TraverseFunctionDecl);
+}
+
+bool PassStuffByRef::TraverseCXXMethodDecl(CXXMethodDecl * decl) {
+    return traverseAnyFunctionDecl(
+        decl, &RecursiveASTVisitor::TraverseCXXMethodDecl);
+}
+
+bool PassStuffByRef::TraverseCXXConstructorDecl(CXXConstructorDecl * decl) {
+    return traverseAnyFunctionDecl(
+        decl, &RecursiveASTVisitor::TraverseCXXConstructorDecl);
+}
+
+bool PassStuffByRef::TraverseCXXDestructorDecl(CXXDestructorDecl * decl) {
+    return traverseAnyFunctionDecl(
+        decl, &RecursiveASTVisitor::TraverseCXXDestructorDecl);
+}
+
+bool PassStuffByRef::TraverseCXXConversionDecl(CXXConversionDecl * decl) {
+    return traverseAnyFunctionDecl(
+        decl, &RecursiveASTVisitor::TraverseCXXConversionDecl);
+}
+
+template<typename T> bool PassStuffByRef::traverseAnyFunctionDecl(
+    T * decl, bool (RecursiveASTVisitor::* fn)(T *))
+{
+    if (ignoreLocation(decl)) {
+        return true;
+    }
+    if (decl->doesThisDeclarationHaveABody()) {
+        functionDecls_.emplace_back();
+    }
+    bool ret = (this->*fn)(decl);
+    if (decl->doesThisDeclarationHaveABody()) {
+        assert(!functionDecls_.empty());
+        if (functionDecls_.back().check) {
+            for (auto d: functionDecls_.back().parms) {
+                report(
+                    DiagnosticsEngine::Warning,
+                    ("passing primitive type param %0 by const &, rather pass"
+                     " by value"),
+                    d->getLocation())
+                    << d->getType() << d->getSourceRange();
+                auto can = decl->getCanonicalDecl();
+                if (can->getLocation() != decl->getLocation()) {
+                    report(
+                        DiagnosticsEngine::Note, "function is declared here:",
+                        can->getLocation())
+                        << can->getSourceRange();
+                }
+            }
+        }
+        functionDecls_.pop_back();
+    }
+    return ret;
+}
+
+bool PassStuffByRef::VisitFunctionDecl(const FunctionDecl * functionDecl) {
+    if (ignoreLocation(functionDecl)) {
+        return true;
+    }
+    if (functionDecl->isDeleted()
+        || functionDecl->isFunctionTemplateSpecialization())
+    {
+        return true;
+    }
+    // only consider base declarations, not overridden ones, or we warn on methods that
+    // are overriding stuff from external libraries
+    const CXXMethodDecl * methodDecl = dyn_cast<CXXMethodDecl>(functionDecl);
+    if (methodDecl && methodDecl->size_overridden_methods() > 0) {
+            return true;
+    }
+
+    checkParams(functionDecl);
+    checkReturnValue(functionDecl, methodDecl);
+    return true;
+}
+
+bool PassStuffByRef::TraverseImplicitCastExpr(ImplicitCastExpr * expr) {
+    if (ignoreLocation(expr)) {
+        return true;
+    }
+    return
+        (expr->getCastKind() == CK_LValueToRValue
+         && (dyn_cast<DeclRefExpr>(expr->getSubExpr()->IgnoreParenImpCasts())
+             != nullptr))
+        || RecursiveASTVisitor::TraverseImplicitCastExpr(expr);
+}
+
+bool PassStuffByRef::VisitDeclRefExpr(const DeclRefExpr * expr) {
+    if (ignoreLocation(expr)) {
+        return true;
+    }
+    auto d = dyn_cast<ParmVarDecl>(expr->getDecl());
+    if (d == nullptr) {
+        return true;
+    }
+    for (auto & fd: functionDecls_) {
+        if (fd.parms.erase(d) == 1) {
+            break;
+        }
+    }
+    return true;
+}
+
+void PassStuffByRef::checkParams(const FunctionDecl * functionDecl) {
+    // Only warn on the definition of the function:
+    if (!functionDecl->doesThisDeclarationHaveABody()) {
+        return;
+    }
+    // ignore stuff that forms part of the stable URE interface
+    if (isInUnoIncludeFile(functionDecl)) {
+        return;
+    }
+    // these functions are passed as parameters to another function
+    if (loplugin::DeclCheck(functionDecl).MemberFunction()
+        .Class("ShapeAttributeLayer").Namespace("internal")
+        .Namespace("slideshow").GlobalNamespace())
+    {
+        return;
+    }
+    unsigned n = functionDecl->getNumParams();
+    assert(!functionDecls_.empty());
+    functionDecls_.back().check = true;
+    for (unsigned i = 0; i != n; ++i) {
+        const ParmVarDecl * pvDecl = functionDecl->getParamDecl(i);
+        auto const t = pvDecl->getType();
+        if (isPrimitiveConstRef(t)) {
+            functionDecls_.back().parms.insert(pvDecl);
+        }
+    }
+}
+
+static bool startswith(const std::string& rStr, const char* pSubStr) {
+    return rStr.compare(0, strlen(pSubStr), pSubStr) == 0;
+}
+
+void PassStuffByRef::checkReturnValue(const FunctionDecl * functionDecl, const CXXMethodDecl * methodDecl) {
+    if (methodDecl && (methodDecl->isVirtual() || methodDecl->hasAttr<OverrideAttr>())) {
+        return;
+    }
+    if( !functionDecl->doesThisDeclarationHaveABody()
+        || functionDecl->isLateTemplateParsed())
+    {
+        return;
+    }
+
+    const QualType type = functionDecl->getReturnType().getDesugaredType(compiler.getASTContext());
+    if (type->isReferenceType() || type->isIntegralOrEnumerationType() || type->isPointerType()
+        || type->isTemplateTypeParmType() || type->isDependentType() || type->isBuiltinType()
+        || type->isScalarType())
+    {
+        return;
+    }
+
+    // not sure if it's possible to modify these
+    if (isa<CXXConversionDecl>(functionDecl))
+        return;
+
+    // ignore stuff that forms part of the stable URE interface
+    if (isInUnoIncludeFile(functionDecl)) {
+        return;
+    }
+
+    loplugin::DeclCheck dc(functionDecl);
+    // function is passed as parameter to another function
+    if (dc.Function("ImplColMonoFnc").Class("GDIMetaFile").GlobalNamespace()
+        || (dc.Function("darkColor").Class("SvxBorderLine").Namespace("editeng")
+            .GlobalNamespace())
+        || (dc.MemberFunction().Class("Binding").Namespace("xforms")
+            .GlobalNamespace())
+        || (dc.MemberFunction().Class("Model").Namespace("xforms")
+            .GlobalNamespace())
+        || (dc.MemberFunction().Class("Submission").Namespace("xforms")
+            .GlobalNamespace())
+        || (dc.Function("TopLeft").Class("SwRect").GlobalNamespace())
+        || (dc.Function("ConvDicList_CreateInstance").GlobalNamespace())
+        || (dc.Function("Create").Class("OUnoAutoPilot").Namespace("dbp").GlobalNamespace())
+        || (dc.Function("Size_").Class("SwRect").GlobalNamespace()))
+    {
+        return;
+    }
+    // not sure how to exclude this yet, returns copy of one of it's params
+    if (dc.Function("sameDistColor").GlobalNamespace()
+        || dc.Function("sameColor").GlobalNamespace()
+        || (dc.Operator(OO_Call).Struct("StringIdentity").AnonymousNamespace()
+            .Namespace("pcr").GlobalNamespace())
+        || (dc.Function("accumulate").Namespace("internal")
+            .Namespace("slideshow").GlobalNamespace())
+        || (dc.Function("lerp").Namespace("internal").Namespace("slideshow")
+            .GlobalNamespace()))
+        return;
+    // depends on a define
+    if (dc.Function("GetSharedFileURL").Class("SfxObjectShell")
+        .GlobalNamespace()) {
+        return;
+    }
+    // hides a constructor
+    if (dc.Function("createNonOwningCopy").Class("SortedAutoCompleteStrings").Namespace("editeng")
+        .GlobalNamespace()) {
+        return;
+    }
+    // template function
+    if (dc.Function("convertItems").Class("ValueParser").Namespace("configmgr").GlobalNamespace()
+        || dc.Function("parseListValue").AnonymousNamespace().Namespace("configmgr").GlobalNamespace()
+        || dc.Function("parseSingleValue").AnonymousNamespace().Namespace("configmgr").GlobalNamespace()
+        || dc.Function("Create").Class("HandlerComponentBase").Namespace("pcr").GlobalNamespace()) {
+        return;
+    }
+    if (startswith(type.getAsString(), "struct o3tl::strong_int")) {
+        return;
+    }
+    // extremely simple class, might as well pass by value
+    if (loplugin::TypeCheck(functionDecl->getReturnType()).Class("Color")) {
+        return;
+    }
+
+    // functionDecl->dump();
+
+    mbInsideFunctionDecl = true;
+    mbFoundReturnValueDisqualifier = false;
+    TraverseStmt(functionDecl->getBody());
+    mbInsideFunctionDecl = false;
+
+    if (mbFoundReturnValueDisqualifier)
+        return;
+
+    report( DiagnosticsEngine::Warning,
+            "rather return %0 by const& than by value, to avoid unnecessary copying",
+            functionDecl->getSourceRange().getBegin())
+        << type.getAsString() << functionDecl->getSourceRange();
+
+    // display the location of the class member declaration so I don't have to search for it by hand
+    auto canonicalDecl = functionDecl->getCanonicalDecl();
+    if (functionDecl != canonicalDecl)
+    {
+        report( DiagnosticsEngine::Note,
+                "decl here",
+                canonicalDecl->getSourceRange().getBegin())
+            << canonicalDecl->getSourceRange();
+    }
+
+    //functionDecl->dump();
+}
+
+bool PassStuffByRef::VisitReturnStmt(const ReturnStmt * returnStmt)
+{
+    if (!mbInsideFunctionDecl)
+        return true;
+    const Expr* expr = dyn_cast<Expr>(*returnStmt->child_begin())->IgnoreParenCasts();
+
+    if (isReturnExprDisqualified(expr))
+        mbFoundReturnValueDisqualifier = true;
+
+    return true;
+}
+
+/**
+ * Does a return expression disqualify this method from doing return by const & ?
+ */
+bool PassStuffByRef::isReturnExprDisqualified(const Expr* expr)
+{
+    while (true)
+    {
+        expr = expr->IgnoreParens();
+        if (auto implicitCast = dyn_cast<ImplicitCastExpr>(expr)) {
+            expr = implicitCast->getSubExpr();
+            continue;
+        }
+        if (auto exprWithCleanups = dyn_cast<ExprWithCleanups>(expr)) {
+            expr = exprWithCleanups->getSubExpr();
+            continue;
+        }
+        if (auto constructExpr = dyn_cast<CXXConstructExpr>(expr))
+        {
+            if (constructExpr->getNumArgs()==1
+                && constructExpr->getConstructor()->isCopyOrMoveConstructor())
+            {
+                expr = constructExpr->getArg(0);
+                continue;
+            }
+            else
+                return true;
+        }
+        if (isa<CXXFunctionalCastExpr>(expr)) {
+            return true;
+        }
+        if (isa<MaterializeTemporaryExpr>(expr)) {
+            return true;
+        }
+        if (isa<CXXBindTemporaryExpr>(expr)) {
+            return true;
+        }
+        if (isa<InitListExpr>(expr)) {
+            return true;
+        }
+        expr = expr->IgnoreParenCasts();
+        if (auto childExpr = dyn_cast<ArraySubscriptExpr>(expr)) {
+            expr = childExpr->getLHS();
+            continue;
+        }
+        if (auto memberExpr = dyn_cast<MemberExpr>(expr)) {
+            expr = memberExpr->getBase();
+            continue;
+        }
+        if (auto declRef = dyn_cast<DeclRefExpr>(expr)) {
+            // a param might be a temporary
+            if (isa<ParmVarDecl>(declRef->getDecl()))
+                return true;
+            const VarDecl* varDecl = dyn_cast<VarDecl>(declRef->getDecl());
+            if (varDecl) {
+                if (varDecl->getStorageDuration() == SD_Thread
+                    || varDecl->getStorageDuration() == SD_Static ) {
+                    return false;
+                }
+                return true;
+            }
+        }
+        if (auto condOper = dyn_cast<ConditionalOperator>(expr)) {
+            return isReturnExprDisqualified(condOper->getTrueExpr())
+                || isReturnExprDisqualified(condOper->getFalseExpr());
+        }
+        if (auto unaryOp = dyn_cast<UnaryOperator>(expr)) {
+            expr = unaryOp->getSubExpr();
+            continue;
+        }
+        if (auto operatorCallExpr = dyn_cast<CXXOperatorCallExpr>(expr)) {
+            // TODO could improve this, but sometimes it means we're returning a copy of a temporary.
+            // Same logic as CXXOperatorCallExpr::isAssignmentOp(), which our supported clang
+            // doesn't have yet.
+            auto Opc = operatorCallExpr->getOperator();
+            if (Opc == OO_Equal || Opc == OO_StarEqual ||
+                Opc == OO_SlashEqual || Opc == OO_PercentEqual ||
+                Opc == OO_PlusEqual || Opc == OO_MinusEqual ||
+                Opc == OO_LessLessEqual || Opc == OO_GreaterGreaterEqual ||
+                Opc == OO_AmpEqual || Opc == OO_CaretEqual ||
+                Opc == OO_PipeEqual)
+                return true;
+            if (Opc == OO_Subscript)
+            {
+                if (isReturnExprDisqualified(operatorCallExpr->getArg(0)))
+                    return true;
+                // otherwise fall through to the checking below
+            }
+        }
+        if (auto memberCallExpr = dyn_cast<CXXMemberCallExpr>(expr)) {
+            if (isReturnExprDisqualified(memberCallExpr->getImplicitObjectArgument()))
+                return true;
+            // otherwise fall through to the checking in CallExpr
+        }
+        if (auto callExpr = dyn_cast<CallExpr>(expr)) {
+            FunctionDecl const * calleeFunctionDecl = callExpr->getDirectCallee();
+            if (!calleeFunctionDecl)
+                return true;
+            // TODO anything takes a non-integral param is suspect because it might return the param by ref.
+            // we could tighten this to only reject functions that have a param of the same type
+            // as the return type. Or we could check for such functions and disallow them.
+            // Or we could force such functions to be annotated somehow.
+            for (unsigned i = 0; i != calleeFunctionDecl->getNumParams(); ++i) {
+                if (!calleeFunctionDecl->getParamDecl(i)->getType()->isIntegralOrEnumerationType())
+                    return true;
+            }
+            auto tc = loplugin::TypeCheck(calleeFunctionDecl->getReturnType());
+            if (!tc.LvalueReference() && !tc.Pointer())
+                return true;
+        }
+        return false;
+    }
+}
+
+bool PassStuffByRef::VisitVarDecl(const VarDecl * varDecl)
+{
+    if (!mbInsideFunctionDecl)
+        return true;
+    // things guarded by locking are probably best left alone
+    loplugin::TypeCheck dc(varDecl->getType());
+    if (dc.Class("Guard").Namespace("osl").GlobalNamespace())
+        mbFoundReturnValueDisqualifier = true;
+    if (dc.Class("ClearableGuard").Namespace("osl").GlobalNamespace())
+        mbFoundReturnValueDisqualifier = true;
+    if (dc.Class("ResettableGuard").Namespace("osl").GlobalNamespace())
+        mbFoundReturnValueDisqualifier = true;
+    else if (dc.Class("SolarMutexGuard").GlobalNamespace())
+        mbFoundReturnValueDisqualifier = true;
+    else if (dc.Class("SfxModelGuard").GlobalNamespace())
+        mbFoundReturnValueDisqualifier = true;
+    else if (dc.Class("ReadWriteGuard").Namespace("utl").GlobalNamespace())
+        mbFoundReturnValueDisqualifier = true;
+    return true;
+}
+
+bool PassStuffByRef::isPrimitiveConstRef(QualType type) {
+    if (type->isIncompleteType()) {
+        return false;
+    }
+    const clang::ReferenceType* referenceType = type->getAs<ReferenceType>();
+    if (referenceType == nullptr) {
+        return false;
+    }
+    QualType pointeeQT = referenceType->getPointeeType();
+    if (!pointeeQT.isConstQualified()) {
+        return false;
+    }
+    if (!pointeeQT->isFundamentalType()) {
+        return false;
+    }
+    // ignore double for now, some of our code seems to believe it is cheaper to pass by ref
+    const BuiltinType* builtinType = pointeeQT->getAs<BuiltinType>();
+    return builtinType->getKind() != BuiltinType::Kind::Double;
+}
+
+
+loplugin::Plugin::Registration< PassStuffByRef > X("passstuffbyref", false);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */