Adding upstream version 4:24.2.0.upstream/4%24.2.0

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

1 files changed, 234 insertions, 0 deletions

diff --git a/compilerplugins/clang/passparamsbyref.cxx b/compilerplugins/clang/passparamsbyref.cxx
new file mode 100644
index 0000000000..9a3562752c
--- /dev/null
+++ b/compilerplugins/clang/passparamsbyref.cxx
@@ -0,0 +1,234 @@
+/* -*- 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/.
+ */
+#ifndef LO_CLANG_SHARED_PLUGINS
+
+#include <string>
+#include <unordered_set>
+
+#include "check.hxx"
+#include "compat.hxx"
+#include "plugin.hxx"
+
+// Find places where parameters 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 PassParamsByRef:
+    public loplugin::FilteringPlugin<PassParamsByRef>
+{
+public:
+    explicit PassParamsByRef(loplugin::InstantiationData const & data): FilteringPlugin(data), mbInsideFunctionDecl(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 PreTraverseFunctionDecl(FunctionDecl *);
+    bool PostTraverseFunctionDecl(FunctionDecl *, bool);
+    bool TraverseFunctionDecl(FunctionDecl *);
+    bool PreTraverseImplicitCastExpr(ImplicitCastExpr *);
+    bool TraverseImplicitCastExpr(ImplicitCastExpr *);
+
+    bool VisitBinaryOperator(BinaryOperator const *);
+    bool VisitCXXOperatorCallExpr(const CXXOperatorCallExpr *);
+
+private:
+    bool isFat(QualType type);
+
+    bool mbInsideFunctionDecl;
+    std::unordered_set<ParmVarDecl const *> mParamExclusions;
+};
+
+bool PassParamsByRef::PreTraverseFunctionDecl(FunctionDecl* functionDecl)
+{
+    if (ignoreLocation(functionDecl))
+        return false;
+    if (functionDecl->isDeleted()
+        || functionDecl->isFunctionTemplateSpecialization())
+    {
+        return false;
+    }
+    // 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 false;
+
+    // Only warn on the definition of the function:
+    if (!functionDecl->doesThisDeclarationHaveABody())
+        return false;
+
+    mbInsideFunctionDecl = true;
+    mParamExclusions.clear();
+    return true;
+}
+
+bool PassParamsByRef::PostTraverseFunctionDecl(FunctionDecl* functionDecl, bool)
+{
+    mbInsideFunctionDecl = false;
+
+    auto cxxConstructorDecl = dyn_cast<CXXConstructorDecl>(functionDecl);
+    unsigned n = functionDecl->getNumParams();
+    for (unsigned i = 0; i != n; ++i) {
+        const ParmVarDecl * pvDecl = functionDecl->getParamDecl(i);
+        auto const t = pvDecl->getType();
+        if (!isFat(t))
+            continue;
+        if (mParamExclusions.find(pvDecl) != mParamExclusions.end())
+            continue;
+        // Ignore cases where the parameter is std::move'd.
+        // This is a fairly simple check, might need some more complexity if the parameter is std::move'd
+        // somewhere else in the constructor.
+        bool bFoundMove = false;
+        if (cxxConstructorDecl) {
+            for (CXXCtorInitializer const * cxxCtorInitializer : cxxConstructorDecl->inits()) {
+                if (cxxCtorInitializer->isMemberInitializer())
+                {
+                    auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(cxxCtorInitializer->getInit()->IgnoreParenImpCasts());
+                    if (cxxConstructExpr && cxxConstructExpr->getNumArgs() == 1)
+                    {
+                        if (auto callExpr = dyn_cast<CallExpr>(cxxConstructExpr->getArg(0)->IgnoreParenImpCasts())) {
+                            if (loplugin::DeclCheck(callExpr->getCalleeDecl()).Function("move").StdNamespace()) {
+                                bFoundMove = true;
+                                break;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        if (bFoundMove)
+            continue;
+        report(
+            DiagnosticsEngine::Warning,
+            ("passing %0 by value, rather pass by const lvalue reference"),
+            pvDecl->getLocation())
+            << t << pvDecl->getSourceRange();
+        auto can = functionDecl->getCanonicalDecl();
+        if (can->getLocation() != functionDecl->getLocation()) {
+            report(
+                DiagnosticsEngine::Note, "function is declared here:",
+                can->getLocation())
+                << can->getSourceRange();
+        }
+    }
+    return true;
+}
+
+bool PassParamsByRef::TraverseFunctionDecl(FunctionDecl* functionDecl)
+{
+    bool ret = true;
+    if (PreTraverseFunctionDecl(functionDecl))
+    {
+        ret = RecursiveASTVisitor::TraverseFunctionDecl(functionDecl);
+        PostTraverseFunctionDecl(functionDecl, ret);
+    }
+    return ret;
+}
+
+bool PassParamsByRef::PreTraverseImplicitCastExpr(ImplicitCastExpr * expr)
+{
+    if (ignoreLocation(expr))
+        return false;
+    if (expr->getCastKind() == CK_LValueToRValue
+         && isa<DeclRefExpr>(expr->getSubExpr()->IgnoreParenImpCasts()))
+        return false;
+    return true;
+}
+
+bool PassParamsByRef::TraverseImplicitCastExpr(ImplicitCastExpr * expr)
+{
+    bool ret = true;
+    if (PreTraverseImplicitCastExpr(expr))
+    {
+        ret = RecursiveASTVisitor::TraverseImplicitCastExpr(expr);
+    }
+    return ret;
+}
+
+bool PassParamsByRef::VisitBinaryOperator(const BinaryOperator * binaryOperator)
+{
+    if (binaryOperator->getOpcode() != BO_Assign) {
+        return true;
+    }
+    if (!mbInsideFunctionDecl)
+        return true;
+    // if we are assigning to a parameter, it can be inconvenient to make the param pass-by-ref
+    if (auto declRefExpr = dyn_cast<DeclRefExpr>(binaryOperator->getLHS()))
+    {
+        if (auto parmVarDecl = dyn_cast<ParmVarDecl>(declRefExpr->getDecl()))
+            mParamExclusions.emplace(parmVarDecl);
+    }
+    return true;
+}
+
+bool PassParamsByRef::VisitCXXOperatorCallExpr(const CXXOperatorCallExpr * cxxOperatorCallExpr )
+{
+    if (!mbInsideFunctionDecl)
+        return true;
+    // if we are assigning to a parameter, it can be inconvenient to make the param pass-by-ref
+    auto op = cxxOperatorCallExpr->getOperator();
+    if ( op != clang::OverloadedOperatorKind::OO_Equal
+         && op != clang::OverloadedOperatorKind::OO_SlashEqual
+         && op != clang::OverloadedOperatorKind::OO_StarEqual
+         && op != clang::OverloadedOperatorKind::OO_MinusEqual
+         && op != clang::OverloadedOperatorKind::OO_PlusEqual)
+        return true;
+    auto declRefExpr = dyn_cast<DeclRefExpr>(cxxOperatorCallExpr->getArg(0));
+    if (!declRefExpr)
+        return true;
+    if (auto parmVarDecl = dyn_cast<ParmVarDecl>(declRefExpr->getDecl()))
+        mParamExclusions.emplace(parmVarDecl);
+    return true;
+}
+
+bool PassParamsByRef::isFat(QualType type) {
+    if (!type->isRecordType()) {
+        return false;
+    }
+    loplugin::TypeCheck tc(type);
+    if ((tc.Class("Reference").Namespace("uno").Namespace("star")
+            .Namespace("sun").Namespace("com").GlobalNamespace())
+        || (tc.Class("Sequence").Namespace("uno").Namespace("star")
+            .Namespace("sun").Namespace("com").GlobalNamespace())
+        || tc.Class("OString").Namespace("rtl").GlobalNamespace()
+        || tc.Class("OUString").Namespace("rtl").GlobalNamespace()
+        || tc.Class("Reference").Namespace("rtl").GlobalNamespace())
+    {
+        return true;
+    }
+    if (type->isIncompleteType()) {
+        return false;
+    }
+    clang::Type const * t2 = type.getTypePtrOrNull();
+    return t2 != nullptr
+        && compiler.getASTContext().getTypeSizeInChars(t2).getQuantity() > 64;
+}
+
+loplugin::Plugin::Registration< PassParamsByRef > passparamsbyref("passparamsbyref");
+
+} // namespace
+
+#endif // LO_CLANG_SHARED_PLUGINS
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */