new loplugin:trivialconstructor

Change-Id: Iaaf63c49ce94987ab9c4ebc68e963cc3054a3c34
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/131342
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

15 files changed, 146 insertions, 23 deletions

diff --git a/basic/inc/sbxfac.hxx b/basic/inc/sbxfac.hxx
index bbdbcb018f0b..5493a6687e00 100644
--- a/basic/inc/sbxfac.hxx
+++ b/basic/inc/sbxfac.hxx
@@ -26,7 +26,6 @@ class SbxFactory
 {
 public:
     virtual ~SbxFactory();
-    SbxFactory() {}
     virtual SbxBaseRef Create(sal_uInt16 nSbxId, sal_uInt32);
     virtual SbxObjectRef CreateObject(const OUString&);
 };
diff --git a/compilerplugins/clang/trivialconstructor.cxx b/compilerplugins/clang/trivialconstructor.cxx
new file mode 100644
index 000000000000..6f5bb640b760
--- /dev/null
+++ b/compilerplugins/clang/trivialconstructor.cxx
@@ -0,0 +1,146 @@
+/* -*- 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 <unordered_map>
+#include <unordered_set>
+
+#include "plugin.hxx"
+#include "check.hxx"
+#include "config_clang.h"
+#include "clang/AST/CXXInheritance.h"
+#include "clang/AST/StmtVisitor.h"
+
+// Look for declared constructors that can be trivial (and therefore don't need to be declared)
+
+namespace
+{
+class TrivialConstructor : public loplugin::FilteringPlugin<TrivialConstructor>
+{
+public:
+    explicit TrivialConstructor(loplugin::InstantiationData const& data)
+        : FilteringPlugin(data)
+    {
+    }
+
+    virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+
+    bool VisitCXXConstructorDecl(CXXConstructorDecl const*);
+
+private:
+    bool HasTrivialConstructorBody(const CXXRecordDecl* BaseClassDecl,
+                                   const CXXRecordDecl* MostDerivedClassDecl);
+    bool FieldHasTrivialConstructorBody(const FieldDecl* Field);
+};
+
+bool TrivialConstructor::VisitCXXConstructorDecl(CXXConstructorDecl const* constructorDecl)
+{
+    if (ignoreLocation(constructorDecl))
+        return true;
+    if (!constructorDecl->hasTrivialBody())
+        return true;
+    if (constructorDecl->isExplicit())
+        return true;
+    if (!constructorDecl->isDefaultConstructor())
+        return true;
+    if (!constructorDecl->inits().empty())
+        return true;
+    if (constructorDecl->getExceptionSpecType() != EST_None)
+        return true;
+    if (constructorDecl->getAccess() != AS_public)
+        return true;
+    if (!constructorDecl->isThisDeclarationADefinition())
+        return true;
+    if (isInUnoIncludeFile(
+            compiler.getSourceManager().getSpellingLoc(constructorDecl->getLocation())))
+        return true;
+    const CXXRecordDecl* recordDecl = constructorDecl->getParent();
+    if (std::distance(recordDecl->ctor_begin(), recordDecl->ctor_end()) != 1)
+        return true;
+    if (!HasTrivialConstructorBody(recordDecl, recordDecl))
+        return true;
+
+    // template magic in sc/inc/stlalgorithm.hxx
+    if (recordDecl->getIdentifier() && recordDecl->getName() == "AlignedAllocator")
+        return true;
+
+    report(DiagnosticsEngine::Warning, "no need for explicit constructor decl",
+           constructorDecl->getLocation())
+        << constructorDecl->getSourceRange();
+    if (constructorDecl->getCanonicalDecl() != constructorDecl)
+    {
+        constructorDecl = constructorDecl->getCanonicalDecl();
+        report(DiagnosticsEngine::Warning, "no need for explicit constructor decl",
+               constructorDecl->getLocation())
+            << constructorDecl->getSourceRange();
+    }
+    return true;
+}
+
+bool TrivialConstructor::HasTrivialConstructorBody(const CXXRecordDecl* BaseClassDecl,
+                                                   const CXXRecordDecl* MostDerivedClassDecl)
+{
+    if (BaseClassDecl != MostDerivedClassDecl && !BaseClassDecl->hasTrivialDefaultConstructor())
+        return false;
+
+    // Check fields.
+    for (const auto* field : BaseClassDecl->fields())
+        if (!FieldHasTrivialConstructorBody(field))
+            return false;
+
+    // Check non-virtual bases.
+    for (const auto& I : BaseClassDecl->bases())
+    {
+        if (I.isVirtual())
+            continue;
+        if (!I.getType()->isRecordType())
+            continue;
+        const CXXRecordDecl* NonVirtualBase = I.getType()->getAsCXXRecordDecl();
+        if (NonVirtualBase && !HasTrivialConstructorBody(NonVirtualBase, MostDerivedClassDecl))
+            return false;
+    }
+
+    if (BaseClassDecl == MostDerivedClassDecl)
+    {
+        // Check virtual bases.
+        for (const auto& I : BaseClassDecl->vbases())
+        {
+            if (!I.getType()->isRecordType())
+                continue;
+            const CXXRecordDecl* VirtualBase = I.getType()->getAsCXXRecordDecl();
+            if (VirtualBase && !HasTrivialConstructorBody(VirtualBase, MostDerivedClassDecl))
+                return false;
+        }
+    }
+    return true;
+}
+
+bool TrivialConstructor::FieldHasTrivialConstructorBody(const FieldDecl* Field)
+{
+    QualType FieldBaseElementType = compiler.getASTContext().getBaseElementType(Field->getType());
+
+    const RecordType* RT = FieldBaseElementType->getAs<RecordType>();
+    if (!RT)
+        return true;
+
+    CXXRecordDecl* FieldClassDecl = cast<CXXRecordDecl>(RT->getDecl());
+
+    // The constructor for an implicit anonymous union member is never invoked.
+    if (FieldClassDecl->isUnion() && FieldClassDecl->isAnonymousStructOrUnion())
+        return false;
+
+    return FieldClassDecl->hasTrivialDefaultConstructor();
+}
+
+loplugin::Plugin::Registration<TrivialConstructor> X("trivialconstructor", true);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/forms/source/xforms/namedcollection.hxx b/forms/source/xforms/namedcollection.hxx
index 10eeafcfd65b..f5fed0c09572 100644
--- a/forms/source/xforms/namedcollection.hxx
+++ b/forms/source/xforms/namedcollection.hxx
@@ -37,7 +37,6 @@ class NamedCollection : public cppu::ImplInheritanceHelper<
     using Collection<T>::hasItem;
 
 public:
-    NamedCollection() {}
 
     const T& getItem( const OUString& rName ) const
     {
diff --git a/include/comphelper/SelectionMultiplex.hxx b/include/comphelper/SelectionMultiplex.hxx
index 00ba7f955b09..c1a1842f2ee0 100644
--- a/include/comphelper/SelectionMultiplex.hxx
+++ b/include/comphelper/SelectionMultiplex.hxx
@@ -42,7 +42,6 @@ namespace comphelper
         friend class OSelectionChangeMultiplexer;
 
     public:
-        OSelectionChangeListener() {}
         virtual ~OSelectionChangeListener();
 
         /// @throws css::uno::RuntimeException
diff --git a/include/editeng/editview.hxx b/include/editeng/editview.hxx
index 6d3a09664767..4f312b578a62 100644
--- a/include/editeng/editview.hxx
+++ b/include/editeng/editview.hxx
@@ -95,7 +95,6 @@ enum class ScrollRangeCheck
 class EDITENG_DLLPUBLIC EditViewCallbacks
 {
 public:
-    EditViewCallbacks() {}
     virtual ~EditViewCallbacks();
 
     // call this when text visualization changed in any way. It
diff --git a/include/editeng/svxacorr.hxx b/include/editeng/svxacorr.hxx
index e45cec1279eb..4197b456214c 100644
--- a/include/editeng/svxacorr.hxx
+++ b/include/editeng/svxacorr.hxx
@@ -98,7 +98,6 @@ enum class ACQuotes
 class EDITENG_DLLPUBLIC SvxAutoCorrDoc
 {
 public:
-    SvxAutoCorrDoc() {}
     virtual ~SvxAutoCorrDoc();
 
     virtual bool Delete( sal_Int32 nStt, sal_Int32 nEnd ) = 0;
diff --git a/include/filter/msfilter/escherex.hxx b/include/filter/msfilter/escherex.hxx
index b4fdad459da9..dd13b5c72cf1 100644
--- a/include/filter/msfilter/escherex.hxx
+++ b/include/filter/msfilter/escherex.hxx
@@ -885,7 +885,6 @@ class EscherEx;
 class MSFILTER_DLLPUBLIC EscherExClientRecord_Base
 {
 public:
-                                EscherExClientRecord_Base() {}
     virtual                     ~EscherExClientRecord_Base();
 
                                 /// Application writes the record header
@@ -899,7 +898,6 @@ public:
 class MSFILTER_DLLPUBLIC EscherExClientAnchor_Base
 {
 public:
-                                EscherExClientAnchor_Base() {}
     virtual                     ~EscherExClientAnchor_Base();
 
                                 /// Application writes the record header
diff --git a/include/formula/IFunctionDescription.hxx b/include/formula/IFunctionDescription.hxx
index b27907fedca5..28f293704364 100644
--- a/include/formula/IFunctionDescription.hxx
+++ b/include/formula/IFunctionDescription.hxx
@@ -48,7 +48,6 @@ namespace formula
     class SAL_NO_VTABLE IFunctionManager
     {
     public:
-        IFunctionManager(){}
         enum EToken
         {
             eOk,
@@ -70,7 +69,6 @@ namespace formula
     class SAL_NO_VTABLE IFunctionCategory
     {
     public:
-        IFunctionCategory(){}
         virtual sal_uInt32                  getCount() const = 0;
         virtual const IFunctionDescription* getFunction(sal_uInt32 _nPos) const = 0;
         virtual sal_uInt32                  getNumber() const = 0;
@@ -83,7 +81,6 @@ namespace formula
     class SAL_NO_VTABLE IFunctionDescription
     {
     public:
-        IFunctionDescription(){}
         virtual OUString getFunctionName() const = 0;
         virtual const IFunctionCategory* getCategory() const = 0;
         virtual OUString getDescription() const = 0;
@@ -113,7 +110,6 @@ namespace formula
     class SAL_NO_VTABLE IFormulaEditorHelper
     {
     public:
-        IFormulaEditorHelper(){}
         virtual void notifyChange() = 0;
         virtual void fill() = 0;
 
diff --git a/include/oox/drawingml/chart/modelbase.hxx b/include/oox/drawingml/chart/modelbase.hxx
index a167077753e0..581713bbc9e1 100644
--- a/include/oox/drawingml/chart/modelbase.hxx
+++ b/include/oox/drawingml/chart/modelbase.hxx
@@ -58,8 +58,6 @@ public:
     typedef typename RefVector< ModelType >::value_type value_type;
     typedef typename RefVector< ModelType >::size_type  size_type;
 
-                 ModelVector() {}
-
     ModelType&   create() { return append( std::make_shared<ModelType>() ); }
     template< typename Param1Type >
     ModelType&   create( const Param1Type& rParam1 ) { return append( std::make_shared<ModelType>( rParam1 ) ); }
@@ -84,8 +82,6 @@ public:
     typedef typename RefMap< KeyType, ModelType >::mapped_type  mapped_type;
     typedef typename RefMap< KeyType, ModelType >::value_type   value_type;
 
-                 ModelMap() {}
-
     ModelType&   create( KeyType eKey ) { return insert( eKey, new ModelType ); }
 
 private:
diff --git a/include/svx/gridctrl.hxx b/include/svx/gridctrl.hxx
index 9551afcbb8da..e029b8e23f8a 100644
--- a/include/svx/gridctrl.hxx
+++ b/include/svx/gridctrl.hxx
@@ -517,7 +517,6 @@ public:
     {
         friend class DbCellControl;
         friend class RowSetEventListener;
-        GrantControlAccess() { }
     };
 
     /// called when a controller needs to be re-initialized
diff --git a/starmath/inc/parsebase.hxx b/starmath/inc/parsebase.hxx
index c5618525626f..ffa9b538a2b0 100644
--- a/starmath/inc/parsebase.hxx
+++ b/starmath/inc/parsebase.hxx
@@ -93,7 +93,6 @@ OUString getParseErrorDesc(SmParseError err);
 class AbstractSmParser
 {
 public:
-    AbstractSmParser() {}
     virtual ~AbstractSmParser() {}
 
     /** Parse rBuffer to formula tree */
diff --git a/sw/inc/IDocumentExternalData.hxx b/sw/inc/IDocumentExternalData.hxx
index 7ed3dfafb279..50ab4f2d2189 100644
--- a/sw/inc/IDocumentExternalData.hxx
+++ b/sw/inc/IDocumentExternalData.hxx
@@ -35,7 +35,6 @@ struct ExternalDataTypeHash
 class ExternalData
 {
 public:
-    ExternalData() {}
     virtual ~ExternalData() {}
 };
 
diff --git a/sw/source/core/inc/SwPortionHandler.hxx b/sw/source/core/inc/SwPortionHandler.hxx
index 2036b0a66d5f..c183781d8fea 100644
--- a/sw/source/core/inc/SwPortionHandler.hxx
+++ b/sw/source/core/inc/SwPortionHandler.hxx
@@ -46,8 +46,6 @@ class SW_DLLPUBLIC SwPortionHandler
 {
 public:
 
-    SwPortionHandler() {}           /// (empty) constructor
-
     virtual ~SwPortionHandler() {}  /// (empty) destructor
 
     /** text portion. A run of nLength characters from the view
diff --git a/vcl/inc/salmenu.hxx b/vcl/inc/salmenu.hxx
index c696503549e6..79254d9f5fd5 100644
--- a/vcl/inc/salmenu.hxx
+++ b/vcl/inc/salmenu.hxx
@@ -51,14 +51,12 @@ struct SalMenuButtonItem
 class VCL_PLUGIN_PUBLIC SalMenuItem
 {
 public:
-    SalMenuItem() {}
     virtual ~SalMenuItem();
 };
 
 class VCL_PLUGIN_PUBLIC SalMenu
 {
 public:
-    SalMenu() {}
     virtual ~SalMenu();
 
     virtual bool VisibleMenuBar() = 0;  // must return true to actually DISPLAY native menu bars
diff --git a/vcl/inc/salsys.hxx b/vcl/inc/salsys.hxx
index cf89bff59259..dff65b2f35cd 100644
--- a/vcl/inc/salsys.hxx
+++ b/vcl/inc/salsys.hxx
@@ -30,7 +30,6 @@ const int SALSYSTEM_SHOWNATIVEMSGBOX_BTN_OK = 1;
 class VCL_PLUGIN_PUBLIC SalSystem
 {
 public:
-    SalSystem() {}
     virtual ~SalSystem();
 
     // get info about the display