diff --git a/.gitattributes b/.gitattributes
index 81d508e2b5..d56b96a776 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -2578,6 +2578,7 @@ packages/fcl-passrc/src/pasresolver.pp svneol=native#text/plain
 packages/fcl-passrc/src/passrcutil.pp svneol=native#text/plain
 packages/fcl-passrc/src/pastounittest.pp svneol=native#text/plain
 packages/fcl-passrc/src/pastree.pp svneol=native#text/plain
+packages/fcl-passrc/src/pasuseanalyzer.pas svneol=native#text/plain
 packages/fcl-passrc/src/paswrite.pp svneol=native#text/plain
 packages/fcl-passrc/src/pparser.pp svneol=native#text/plain
 packages/fcl-passrc/src/pscanner.pp svneol=native#text/plain
@@ -2594,6 +2595,7 @@ packages/fcl-passrc/tests/tcresolver.pas svneol=native#text/plain
 packages/fcl-passrc/tests/tcscanner.pas svneol=native#text/plain
 packages/fcl-passrc/tests/tcstatements.pas svneol=native#text/plain
 packages/fcl-passrc/tests/tctypeparser.pas svneol=native#text/plain
+packages/fcl-passrc/tests/tcuseanalyzer.pas svneol=native#text/plain
 packages/fcl-passrc/tests/tcvarparser.pas svneol=native#text/plain
 packages/fcl-passrc/tests/testpassrc.lpi svneol=native#text/plain
 packages/fcl-passrc/tests/testpassrc.lpr svneol=native#text/plain
diff --git a/packages/fcl-passrc/src/pasuseanalyzer.pas b/packages/fcl-passrc/src/pasuseanalyzer.pas
new file mode 100644
index 0000000000..9f15b5d7a3
--- /dev/null
+++ b/packages/fcl-passrc/src/pasuseanalyzer.pas
@@ -0,0 +1,1402 @@
+{
+    This file is part of the Free Component Library
+
+    Pascal parse tree classes
+    Copyright (c) 2017  Mattias Gaertner, mattias@freepascal.org
+
+    See the file COPYING.FPC, included in this distribution,
+    for details about the copyright.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+ **********************************************************************}
+{
+Abstract:
+  After running TPasResolver, run this to
+  - create a list of used declararion, either in a module or a whole program.
+  - emit hints about unused declarations
+  - and warnings about uninitialized variables.
+
+Working:
+- mark used elements of a module, starting from all accessible elements
+
+ToDo:
+- unary
+- Note: (5025) Local variable "i" not used
+- hint: local proc not used
+- hint: private member not used
+- check program/library: method for whole program checking
+- Call Override: e.g. A.Proc, mark only overrides of descendants of A
+- TPasArgument: compute the effective Access
+- calls: use the effective Access of arguments
+}
+unit PasUseAnalyzer;
+
+{$mode objfpc}{$H+}{$inline on}
+
+interface
+
+uses
+  Classes, SysUtils, AVL_Tree, PasResolver, PasTree, PScanner;
+
+const
+  nPAUnitNotUsed = 5023;
+  sPAUnitNotUsed = 'Unit "%s" not used in %s';
+  nPAParameterNotUsed = 5024;
+  sPAParameterNotUsed = 'Parameter "%s" not used';
+  nPALocalVariableNotUsed = 5025;
+  sPALocalVariableNotUsed = 'Local variable "%s" not used';
+  nPAValueParameterIsAssignedButNeverUsed = 5026;
+  sPAValueParameterIsAssignedButNeverUsed = 'Value parameter "$1" is assigned but never used';
+  nPALocalVariableIsAssignedButNeverUsed = 5027;
+  sPALocalVariableIsAssignedButNeverUsed = 'Local variable "$1" is assigned but never used';
+  nPALocalXYNotUsed = 5028;
+  sPALocalXYNotUsed = 'Local %s "%s" not used';
+  nPAPrivateFieldIsNeverUsed = 5029;
+  sPAPrivateFieldIsNeverUsed = 'Private field "$1" is never used';
+  nPAPrivateFieldIsAssignedButNeverUsed = 5030;
+  sPAPrivateFieldIsAssignedButNeverUsed = 'Private field "$1" is assigned but never used';
+  nPAPrivateMethodIsNeverUsed = 5031;
+  sPAPrivateMethodIsNeverUsed = 'Private method "$1" is never used';
+  //nPAFunctionResultDoesNotSeemToBeSet = 5033;
+  //sPAFunctionResultDoesNotSeemToBeSet  = 'Function result does not seem to be set';
+  nPAPrivateTypeXNeverUsed = 5071;
+  sPAPrivateTypeXNeverUsed = 'Private type "$1" never used';
+  nPAPrivateConstXNeverUsed = 5072;
+  sPAPrivateConstXNeverUsed = 'Private const "$1" never used';
+  nPAPrivatePropertyXNeverUsed = 5073;
+  sPAPrivatePropertyXNeverUsed = 'Private property "$1" never used';
+  //nPAUnreachableCode = 6018;
+  //sPAUnreachableCode = 'unreachable code';
+
+type
+  EPasAnalysis = class(EPasResolve);
+
+  TPAMessage = class
+  public
+    Id: int64;
+    MsgType: TMessageType;
+    MsgNumber: integer;
+    Fmt: String;
+    Args: TMessageArgs;
+    PosEl: TPasElement;
+    Filename: string;
+    Row, Col: integer;
+  end;
+
+  TPAMessageEvent = procedure(Sender: TObject; Msg: TPAMessage) of object;
+
+  TPAIdentifierAccess = (
+    paiaNone,
+    paiaRead,
+    paiaWrite,
+    paiaReadWrite,
+    paiaWriteRead
+    );
+
+  { TPAElement }
+
+  TPAElement = class
+  private
+    FElement: TPasElement;
+    procedure SetElement(AValue: TPasElement);
+  public
+    Access: TPAIdentifierAccess;
+    destructor Destroy; override;
+    property Element: TPasElement read FElement write SetElement;
+  end;
+  TPAElementClass = class of TPAElement;
+
+  { TPAOverrideList }
+
+  TPAOverrideList = class
+  private
+    FElement: TPasElement;
+    FOverrides: TFPList; // list of TPasElement
+    function GetOverrides(Index: integer): TPasElement; inline;
+    procedure SetElement(AValue: TPasElement);
+  public
+    constructor Create;
+    destructor Destroy; override;
+    procedure Add(OverrideEl: TPasElement);
+    property Element: TPasElement read FElement write SetElement;
+    function Count: integer;
+    function IndexOf(OverrideEl: TPasElement): integer; inline;
+    property Overrides[Index: integer]: TPasElement read GetOverrides; default;
+  end;
+
+  TPasAnalyzerOption = (
+    paoAlwaysUsePublished, // when a class is used, use all published members as well
+    paoOnlyExports // default: use all class members accessible from outside (protected, but not private)
+    );
+  TPasAnalyzerOptions = set of TPasAnalyzerOption;
+
+  { TPasAnalyzer }
+
+  TPasAnalyzer = class
+  private
+    FOnMessage: TPAMessageEvent;
+    FOptions: TPasAnalyzerOptions;
+    FOverrideLists: TAVLTree; // tree of TPAOverrideList sorted for Element
+    FResolver: TPasResolver;
+    FScopeModule: TPasModule;
+    FUsedElements: TAVLTree; // tree of TPAElement sorted for Element
+    function AddOverride(OverriddenEl, OverrideEl: TPasElement): boolean;
+    function FindOverrideNode(El: TPasElement): TAVLTreeNode;
+    function FindOverrideList(El: TPasElement): TPAOverrideList;
+    procedure SetOptions(AValue: TPasAnalyzerOptions);
+    procedure UpdateAccess(IsWrite: Boolean; IsRead: Boolean; Usage: TPAElement);
+  protected
+    procedure RaiseInconsistency(const Id: int64; Msg: string);
+    procedure RaiseNotSupported(const Id: int64; El: TPasElement; const Msg: string = '');
+    // mark used elements
+    function Add(El: TPasElement; CheckDuplicate: boolean = true;
+      aClass: TPAElementClass = nil): TPAElement;
+    function FindNode(El: TPasElement): TAVLTreeNode; inline;
+    function FindPAElement(El: TPasElement): TPAElement; inline;
+    procedure CreateTree; virtual;
+    function MarkElement(El: TPasElement; aClass: TPAElementClass = nil): boolean; // true if new
+    procedure UseElement(El: TPasElement; Access: TResolvedRefAccess;
+      UseFull: boolean); virtual;
+    procedure UseSection(Section: TPasSection); virtual;
+    procedure UseDeclarations(El: TPasDeclarations; OnlyExports: boolean); virtual;
+    procedure UseImplBlock(Block: TPasImplBlock; Mark: boolean); virtual;
+    procedure UseImplElement(El: TPasImplElement); virtual;
+    procedure UseExpr(El: TPasExpr); virtual;
+    procedure UseProcedure(Proc: TPasProcedure); virtual;
+    procedure UseProcedureType(ProcType: TPasProcedureType); virtual;
+    procedure UseType(El: TPasType); virtual;
+    procedure UseArrayType(El: TPasArrayType; Mark: boolean); virtual;
+    procedure UseRecordType(El: TPasRecordType; Mark: boolean); virtual;
+    procedure UseClassType(El: TPasClassType; Mark: boolean); virtual;
+    procedure UseVariable(El: TPasVariable; Access: TResolvedRefAccess;
+      UseFull: boolean); virtual;
+    procedure UseArgument(El: TPasArgument; Access: TResolvedRefAccess); virtual;
+    procedure UseResultElement(El: TPasResultElement; Access: TResolvedRefAccess); virtual;
+    // create hints for a unit, program or library
+    procedure EmitElementHints(El: TPasElement); virtual;
+    procedure EmitModuleHints(aModule: TPasModule); virtual;
+    procedure EmitSectionHints(Section: TPasSection); virtual;
+    procedure EmitDeclarationsHints(El: TPasDeclarations); virtual;
+    procedure EmitTypeHints(El: TPasType); virtual;
+    procedure EmitVariableHints(El: TPasVariable); virtual;
+    procedure EmitProcedureHints(El: TPasProcedure); virtual;
+    // utility
+    function IsModuleInternal(El: TPasElement): boolean;
+    function IsExport(El: TPasElement): boolean;
+    procedure EmitMessage(const Id: int64; const MsgType: TMessageType;
+      MsgNumber: integer; Fmt: String; const Args: array of const; PosEl: TPasElement);
+    procedure EmitMessage(Msg: TPAMessage);
+  public
+    constructor Create;
+    destructor Destroy; override;
+    procedure Clear;
+    procedure AnalyzeModule(aModule: TPasModule);
+    function FindElement(El: TPasElement): TPAElement;
+    property OnMessage: TPAMessageEvent read FOnMessage write FOnMessage;
+    property Options: TPasAnalyzerOptions read FOptions write SetOptions;
+    property Resolver: TPasResolver read FResolver write FResolver;
+    property ScopeModule: TPasModule read FScopeModule write FScopeModule;
+  end;
+
+function ComparePAElements(Identifier1, Identifier2: Pointer): integer;
+function CompareElementWithPAElement(El, Id: Pointer): integer;
+function ComparePAOverrideLists(List1, List2: Pointer): integer;
+function CompareElementWithPAOverrideList(El, List: Pointer): integer;
+
+implementation
+
+function ComparePointer(Data1, Data2: Pointer): integer;
+begin
+  if Data1>Data2 then Result:=-1
+  else if Data1<Data2 then Result:=1
+  else Result:=0;
+end;
+
+function ComparePAElements(Identifier1, Identifier2: Pointer): integer;
+var
+  Item1: TPAElement absolute Identifier1;
+  Item2: TPAElement absolute Identifier2;
+begin
+  Result:=ComparePointer(Item1.Element,Item2.Element);
+end;
+
+function CompareElementWithPAElement(El, Id: Pointer): integer;
+var
+  Identifier: TPAElement absolute Id;
+begin
+  Result:=ComparePointer(El,Identifier.Element);
+end;
+
+function ComparePAOverrideLists(List1, List2: Pointer): integer;
+var
+  Item1: TPAOverrideList absolute List1;
+  Item2: TPAOverrideList absolute List2;
+begin
+  Result:=ComparePointer(Item1.Element,Item2.Element);
+end;
+
+function CompareElementWithPAOverrideList(El, List: Pointer): integer;
+var
+  OvList: TPAOverrideList absolute List;
+begin
+  Result:=ComparePointer(El,OvList.Element);
+end;
+
+{ TPAOverrideList }
+
+// inline
+function TPAOverrideList.GetOverrides(Index: integer): TPasElement;
+begin
+  Result:=TPasElement(FOverrides[Index]);
+end;
+
+// inline
+function TPAOverrideList.IndexOf(OverrideEl: TPasElement): integer;
+begin
+  Result:=FOverrides.IndexOf(OverrideEl);
+end;
+
+procedure TPAOverrideList.SetElement(AValue: TPasElement);
+begin
+  if FElement=AValue then Exit;
+  if FElement<>nil then
+    FElement.Release;
+  FElement:=AValue;
+  if FElement<>nil then
+    FElement.AddRef;
+end;
+
+constructor TPAOverrideList.Create;
+begin
+  FOverrides:=TFPList.Create;
+end;
+
+destructor TPAOverrideList.Destroy;
+var
+  i: Integer;
+begin
+  for i:=0 to FOverrides.Count-1 do
+    TPasElement(FOverrides[i]).Release;
+  FreeAndNil(FOverrides);
+  inherited Destroy;
+end;
+
+procedure TPAOverrideList.Add(OverrideEl: TPasElement);
+begin
+  FOverrides.Add(OverrideEl);
+  OverrideEl.AddRef;
+end;
+
+function TPAOverrideList.Count: integer;
+begin
+  Result:=FOverrides.Count;
+end;
+
+{ TPAElement }
+
+procedure TPAElement.SetElement(AValue: TPasElement);
+begin
+  if FElement=AValue then Exit;
+  if FElement<>nil then
+    FElement.Release;
+  FElement:=AValue;
+  if FElement<>nil then
+    FElement.AddRef;
+end;
+
+destructor TPAElement.Destroy;
+begin
+  Element:=nil;
+  inherited Destroy;
+end;
+
+{ TPasAnalyzer }
+
+// inline
+function TPasAnalyzer.FindNode(El: TPasElement): TAVLTreeNode;
+begin
+  Result:=FUsedElements.FindKey(El,@CompareElementWithPAElement);
+end;
+
+// inline
+function TPasAnalyzer.FindPAElement(El: TPasElement): TPAElement;
+var
+  Node: TAVLTreeNode;
+begin
+  Node:=FindNode(El);
+  if Node=nil then
+    Result:=nil
+  else
+    Result:=TPAElement(Node.Data);
+end;
+
+procedure TPasAnalyzer.SetOptions(AValue: TPasAnalyzerOptions);
+begin
+  if FOptions=AValue then Exit;
+  FOptions:=AValue;
+end;
+
+function TPasAnalyzer.FindOverrideNode(El: TPasElement): TAVLTreeNode;
+begin
+  Result:=FOverrideLists.FindKey(El,@CompareElementWithPAOverrideList);
+end;
+
+function TPasAnalyzer.FindOverrideList(El: TPasElement): TPAOverrideList;
+var
+  Node: TAVLTreeNode;
+begin
+  Node:=FindOverrideNode(El);
+  if Node=nil then
+    Result:=nil
+  else
+    Result:=TPAOverrideList(Node.Data);
+end;
+
+function TPasAnalyzer.AddOverride(OverriddenEl, OverrideEl: TPasElement): boolean;
+// OverrideEl overrides OverriddenEl
+// returns true if new override
+var
+  Node: TAVLTreeNode;
+  Item: TPAOverrideList;
+  OverriddenPAEl: TPAElement;
+begin
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.AddOverride OverriddenEl=',GetObjName(OverriddenEl),' OverrideEl=',GetObjName(OverrideEl));
+  {$ENDIF}
+  Node:=FindOverrideNode(OverriddenEl);
+  if Node=nil then
+    begin
+    Item:=TPAOverrideList.Create;
+    Item.Element:=OverriddenEl;
+    FOverrideLists.Add(Item);
+    end
+  else
+    begin
+    Item:=TPAOverrideList(Node.Data);
+    if Item.IndexOf(OverrideEl)>=0 then
+      exit(false);
+    end;
+  // new override
+  Item.Add(OverrideEl);
+  Result:=true;
+
+  OverriddenPAEl:=FindPAElement(OverriddenEl);
+  if OverriddenPAEl<>nil then
+    UseElement(OverrideEl,rraNone,true);
+end;
+
+procedure TPasAnalyzer.UpdateAccess(IsWrite: Boolean; IsRead: Boolean;
+  Usage: TPAElement);
+begin
+  if IsRead then
+    case Usage.Access of
+      paiaNone: Usage.Access:=paiaRead;
+      paiaRead: ;
+      paiaWrite: Usage.Access:=paiaWriteRead;
+      paiaReadWrite: ;
+      paiaWriteRead: ;
+      else RaiseInconsistency(20170311183122, '');
+    end;
+  if IsWrite then
+    case Usage.Access of
+      paiaNone: Usage.Access:=paiaWrite;
+      paiaRead: Usage.Access:=paiaReadWrite;
+      paiaWrite: ;
+      paiaReadWrite: ;
+      paiaWriteRead: ;
+      else RaiseInconsistency(20170311183127, '');
+    end;
+end;
+
+procedure TPasAnalyzer.RaiseInconsistency(const Id: int64; Msg: string);
+begin
+  raise EPasAnalysis.Create('['+IntToStr(Id)+']: '+Msg);
+end;
+
+procedure TPasAnalyzer.RaiseNotSupported(const Id: int64; El: TPasElement;
+  const Msg: string);
+var
+  s: String;
+  E: EPasAnalysis;
+begin
+  s:='['+IntToStr(Id)+']: Element='+GetObjName(El);
+  if Msg<>'' then S:=S+' '+Msg;
+  E:=EPasAnalysis.Create(s);
+  E.PasElement:=El;
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.RaiseNotSupported ',E.Message);
+  {$ENDIF}
+  raise E;
+end;
+
+function TPasAnalyzer.Add(El: TPasElement; CheckDuplicate: boolean;
+  aClass: TPAElementClass): TPAElement;
+begin
+  if El=nil then
+    RaiseInconsistency(20170308093407,'');
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.Add ',GetObjName(El),' New=',FindNode(El)=nil);
+  {$ENDIF}
+  if CheckDuplicate and (FindNode(El)<>nil) then
+    RaiseInconsistency(20170304201318,'');
+  if aClass=nil then
+    aClass:=TPAElement;
+  Result:=aClass.Create;
+  Result.Element:=El;
+  FUsedElements.Add(Result);
+end;
+
+procedure TPasAnalyzer.CreateTree;
+begin
+  FUsedElements:=TAVLTree.Create(@ComparePAElements);
+end;
+
+function TPasAnalyzer.MarkElement(El: TPasElement; aClass: TPAElementClass
+  ): boolean;
+var
+  CurModule: TPasModule;
+begin
+  if El=nil then exit(false);
+  if ScopeModule<>nil then
+    begin
+    CurModule:=El.GetModule;
+    if CurModule=nil then
+      begin
+      if El.ClassType=TPasUnresolvedSymbolRef then
+        exit(false);
+      {$IFDEF VerbosePasAnalyzer}
+      writeln('TPasAnalyzer.MarkElement GetModule failed for El=',GetObjName(El),' El.Parent=',GetObjName(El.Parent));
+      {$ENDIF}
+      RaiseInconsistency(20170308093540,GetObjName(El));
+      end;
+    if CurModule<>ScopeModule then
+      begin
+      // element from another unit -> mark unit as needed
+      if FindNode(CurModule)=nil then
+        Add(CurModule);
+      exit(false);
+      end;
+    end;
+  if FindNode(El)<>nil then exit(false);
+  Add(El,false,aClass);
+  Result:=true;
+end;
+
+procedure TPasAnalyzer.UseElement(El: TPasElement; Access: TResolvedRefAccess;
+  UseFull: boolean);
+begin
+  if El=nil then exit;
+  if El is TPasType then
+    UseType(TPasType(El))
+  else if El is TPasVariable then
+    UseVariable(TPasVariable(El),Access,UseFull)
+  else if El.ClassType=TPasArgument then
+    UseArgument(TPasArgument(El),Access)
+  else if El.ClassType=TPasResultElement then
+    UseResultElement(TPasResultElement(El),Access)
+  else if El is TPasProcedure then
+    UseProcedure(TPasProcedure(El))
+  else if El is TPasExpr then
+    UseExpr(TPasExpr(El))
+  else
+    RaiseNotSupported(20170307090947,El);
+end;
+
+procedure TPasAnalyzer.UseSection(Section: TPasSection);
+var
+  i: Integer;
+  UsesList: TFPList;
+  UsedModule: TPasModule;
+  InitSection: TInitializationSection;
+begin
+  if not MarkElement(Section) then exit;
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.UseSection ',GetObjName(Section),' New=',FindNode(Section)=nil);
+  {$ENDIF}
+  // initialization, program or library sections
+  UsesList:=Section.UsesList;
+  for i:=0 to UsesList.Count-1 do
+    begin
+    if TObject(UsesList[i]) is TPasModule then
+      begin
+      UsedModule:=TPasModule(UsesList[i]);
+      InitSection:=UsedModule.InitializationSection;
+      if (InitSection=nil) or (InitSection.Elements.Count=0) then continue;
+      // has initialization section
+      Add(UsedModule);
+      if ScopeModule=nil then
+        UseImplBlock(InitSection,true);
+      end;
+    end;
+  UseDeclarations(Section,paoOnlyExports in Options);
+end;
+
+procedure TPasAnalyzer.UseDeclarations(El: TPasDeclarations;
+  OnlyExports: boolean);
+var
+  i: Integer;
+  Decl: TPasElement;
+begin
+  for i:=0 to El.Declarations.Count-1 do
+    begin
+    Decl:=TPasElement(El.Declarations[i]);
+    if Decl is TPasProcedure then
+      begin
+      if OnlyExports and (TPasProcedure(Decl).PublicName=nil) then continue;
+      UseProcedure(TPasProcedure(Decl))
+      end
+    else if Decl is TPasType then
+      UseType(TPasType(Decl))
+    else if Decl is TPasVariable then
+      begin
+      if OnlyExports and ([vmExport,vmPublic]*TPasVariable(Decl).VarModifiers=[]) then
+        continue;
+      UseVariable(TPasVariable(Decl),rraNone,true);
+      end
+    else
+      RaiseNotSupported(20170306165213,Decl);
+    end;
+end;
+
+procedure TPasAnalyzer.UseImplBlock(Block: TPasImplBlock; Mark: boolean);
+var
+  i: Integer;
+  El: TPasElement;
+begin
+  if Block=nil then exit;
+  if Mark and not MarkElement(Block) then exit;
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.UseImplBlock ',GetObjName(Block),' Elements=',Block.Elements.Count);
+  {$ENDIF}
+  for i:=0 to Block.Elements.Count-1 do
+    begin
+    El:=TPasElement(Block.Elements[i]);
+    if El is TPasImplElement then
+      UseImplElement(TPasImplElement(El))
+    else
+      RaiseNotSupported(20170306195110,El);
+    end;
+end;
+
+procedure TPasAnalyzer.UseImplElement(El: TPasImplElement);
+var
+  C: TClass;
+  ForLoop: TPasImplForLoop;
+  CaseOf: TPasImplCaseOf;
+  i, j: Integer;
+  CaseSt: TPasImplCaseStatement;
+  WithDo: TPasImplWithDo;
+  SubEl: TPasElement;
+begin
+  // do not mark
+  if El=nil then exit;
+  C:=El.ClassType;
+  if C=TPasImplBlock then
+    // impl block
+    UseImplBlock(TPasImplBlock(El),false)
+  else if C=TPasImplSimple then
+    // simple expression
+    UseExpr(TPasImplSimple(El).expr)
+  else if C=TPasImplAssign then
+    // a:=b
+    begin
+    UseExpr(TPasImplAssign(El).left);
+    UseExpr(TPasImplAssign(El).right);
+    end
+  else if C=TPasImplAsmStatement then
+    // asm..end
+  else if C=TPasImplBeginBlock then
+    // begin..end
+    UseImplBlock(TPasImplBeginBlock(El),false)
+  else if C=TPasImplCaseOf then
+    begin
+    // case-of
+    CaseOf:=TPasImplCaseOf(El);
+    UseExpr(CaseOf.CaseExpr);
+    for i:=0 to CaseOf.Elements.Count-1 do
+      begin
+      SubEl:=TPasElement(CaseOf.Elements[i]);
+      if SubEl.ClassType=TPasImplCaseStatement then
+        begin
+        CaseSt:=TPasImplCaseStatement(SubEl);
+        for j:=0 to CaseSt.Expressions.Count-1 do
+          UseExpr(TObject(CaseSt.Expressions[j]) as TPasExpr);
+        UseImplElement(CaseSt.Body);
+        end
+      else if SubEl.ClassType=TPasImplCaseElse then
+        UseImplBlock(TPasImplCaseElse(SubEl),false)
+      else
+        RaiseNotSupported(20170307195329,SubEl);
+      end;
+    end
+  else if C=TPasImplForLoop then
+    begin
+    // for-loop
+    ForLoop:=TPasImplForLoop(El);
+    UseExpr(ForLoop.VariableName);
+    UseExpr(ForLoop.StartExpr);
+    UseExpr(ForLoop.EndExpr);
+    UseImplElement(ForLoop.Body);
+    end
+  else if C=TPasImplExceptOn then
+    begin
+    // except-on
+    UseType(TPasImplExceptOn(El).TypeEl);
+    UseImplElement(TPasImplExceptOn(El).Body);
+    end
+  else if C=TPasImplIfElse then
+    begin
+    // if-then-else
+    UseExpr(TPasImplIfElse(El).ConditionExpr);
+    UseImplElement(TPasImplIfElse(El).IfBranch);
+    UseImplElement(TPasImplIfElse(El).ElseBranch);
+    end
+  else if C=TPasImplLabelMark then
+    // label mark
+  else if C=TPasImplRepeatUntil then
+    begin
+    // repeat-until
+    UseImplBlock(TPasImplRepeatUntil(El),false);
+    UseExpr(TPasImplRepeatUntil(El).ConditionExpr);
+    end
+  else if C=TPasImplWhileDo then
+    begin
+    // while-do
+    UseExpr(TPasImplWhileDo(El).ConditionExpr);
+    UseImplBlock(TPasImplWhileDo(El),false);
+    end
+  else if C=TPasImplWithDo then
+    begin
+    // with-do
+    WithDo:=TPasImplWithDo(El);
+    for i:=0 to WithDo.Expressions.Count-1 do
+      UseExpr(TObject(WithDo.Expressions[i]) as TPasExpr);
+    UseImplBlock(WithDo,false);
+    end
+  else if C=TPasImplRaise then
+    begin
+    // raise
+    UseExpr(TPasImplRaise(El).ExceptObject);
+    UseExpr(TPasImplRaise(El).ExceptAddr);
+    end
+  else if C=TPasImplTry then
+    begin
+    // try..finally/except..else..end
+    UseImplBlock(TPasImplTry(El),false);
+    UseImplBlock(TPasImplTry(El).FinallyExcept,false);
+    UseImplBlock(TPasImplTry(El).ElseBranch,false);
+    end
+  else
+    RaiseNotSupported(20170307162715,El);
+end;
+
+procedure TPasAnalyzer.UseExpr(El: TPasExpr);
+var
+  Ref: TResolvedReference;
+  C: TClass;
+  Params: TPasExprArray;
+  i: Integer;
+begin
+  if El=nil then exit;
+  // expression are not marked
+  if El.CustomData is TResolvedReference then
+    begin
+    Ref:=TResolvedReference(El.CustomData);
+    UseElement(Ref.Declaration,Ref.Access,false);
+    end;
+  UseExpr(El.format1);
+  UseExpr(El.format2);
+  C:=El.ClassType;
+  if (C=TPrimitiveExpr)
+      or (C=TSelfExpr)
+      or (C=TBoolConstExpr)
+      or (C=TInheritedExpr)
+      or (C=TNilExpr) then
+  else if C=TBinaryExpr then
+    begin
+    UseExpr(TBinaryExpr(El).left);
+    UseExpr(TBinaryExpr(El).right);
+    end
+  else if C=TParamsExpr then
+    begin
+    UseExpr(TParamsExpr(El).Value);
+    Params:=TParamsExpr(El).Params;
+    for i:=0 to length(Params)-1 do
+      UseExpr(Params[i]);
+    end
+  else
+    RaiseNotSupported(20170307085444,El);
+end;
+
+procedure TPasAnalyzer.UseProcedure(Proc: TPasProcedure);
+
+  procedure UseOverrides(CurProc: TPasProcedure);
+  var
+    OverrideList: TPAOverrideList;
+    i: Integer;
+    OverrideProc: TPasProcedure;
+  begin
+    OverrideList:=FindOverrideList(CurProc);
+    if OverrideList=nil then exit;
+    // Note: while traversing the OverrideList it may grow
+    i:=0;
+    while i<OverrideList.Count do
+      begin
+      OverrideProc:=TObject(OverrideList.Overrides[i]) as TPasProcedure;
+      UseProcedure(OverrideProc);
+      inc(i);
+      end;
+  end;
+
+var
+  ProcScope: TPasProcedureScope;
+  ImplProc: TPasProcedure;
+begin
+  // use declaration, not implementation
+  ProcScope:=Proc.CustomData as TPasProcedureScope;
+  if ProcScope.DeclarationProc<>nil then
+    exit; // skip implementation, Note:PasResolver always refers the declaration
+
+  if not MarkElement(Proc) then exit;
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.UseProcedure ',GetObjName(Proc));
+  {$ENDIF}
+  UseProcedureType(Proc.ProcType);
+
+  ImplProc:=Proc;
+  if ProcScope.ImplProc<>nil then
+    ImplProc:=ProcScope.ImplProc;
+  if ImplProc.Body<>nil then
+    UseImplBlock(ImplProc.Body.Body,false);
+
+  if ProcScope.OverriddenProc<>nil then
+    AddOverride(ProcScope.OverriddenProc,Proc);
+
+  // mark overrides
+  if [pmOverride,pmVirtual]*Proc.Modifiers<>[] then
+    UseOverrides(Proc);
+end;
+
+procedure TPasAnalyzer.UseProcedureType(ProcType: TPasProcedureType);
+var
+  i: Integer;
+  Arg: TPasArgument;
+begin
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.UseProcedureType ',GetObjName(ProcType));
+  {$ENDIF}
+  // proc types are marked
+  for i:=0 to ProcType.Args.Count-1 do
+    begin
+    Arg:=TPasArgument(ProcType.Args[i]);
+    // Note: argument are marked when used in code
+    // mark argument type
+    UseType(Arg.ArgType);
+    end;
+  if ProcType is TPasFunctionType then
+    UseType(TPasFunctionType(ProcType).ResultEl.ResultType);
+end;
+
+procedure TPasAnalyzer.UseType(El: TPasType);
+var
+  C: TClass;
+begin
+  {$IFDEF VerbosePasAnalyzer}
+  if El=nil then exit;
+  writeln('TPasAnalyzer.UseType ',GetObjName(El));
+  {$ENDIF}
+  if not MarkElement(El) then exit;
+  C:=El.ClassType;
+  if C=TPasUnresolvedSymbolRef then
+    begin
+    if El.CustomData is TResElDataBaseType then
+    else
+      RaiseNotSupported(20170307101353,El);
+    end
+  else if (C=TPasAliasType) or (C=TPasTypeAliasType) then
+    UseType(TPasAliasType(El).DestType)
+  else if C=TPasArrayType then
+    UseArrayType(TPasArrayType(El),false)
+  else if C=TPasRecordType then
+    UseRecordType(TPasRecordType(El),false)
+  else if C=TPasClassType then
+    UseClassType(TPasClassType(El),false)
+  else
+    RaiseNotSupported(20170306170315,El);
+end;
+
+procedure TPasAnalyzer.UseArrayType(El: TPasArrayType; Mark: boolean);
+var
+  i: Integer;
+begin
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.UseArrayType ',GetObjName(El),' ElType=',GetObjName(El.ElType),' Ranges=',length(El.Ranges));
+  {$ENDIF}
+  if Mark and not MarkElement(El) then exit;
+  for i:=0 to length(El.Ranges)-1 do
+    UseExpr(El.Ranges[i]);
+  UseType(El.ElType);
+end;
+
+procedure TPasAnalyzer.UseRecordType(El: TPasRecordType; Mark: boolean);
+var
+  i: Integer;
+begin
+  if Mark and not MarkElement(El) then exit;
+  if (paoOnlyExports in Options) or IsModuleInternal(El) then exit;
+  for i:=0 to El.Members.Count-1 do
+    UseVariable(TObject(El.Members) as TPasVariable,rraNone,true);
+end;
+
+procedure TPasAnalyzer.UseClassType(El: TPasClassType; Mark: boolean);
+var
+  i: Integer;
+  Member: TPasElement;
+  UsePublished, OnlyExports: Boolean;
+  ProcScope: TPasProcedureScope;
+begin
+  if Mark and not MarkElement(El) then exit;
+  UseType(El.AncestorType);
+  UseType(El.HelperForType);
+  UseExpr(El.GUIDExpr);
+  for i:=0 to El.Interfaces.Count-1 do
+    UseType(TPasType(El.Interfaces[i]));
+  // members
+  UsePublished:=paoAlwaysUsePublished in Options;
+  OnlyExports:=(paoOnlyExports in Options) or IsModuleInternal(El);
+  // Note: OnlyExports means to use only explicitely exported members
+  //       and directly used members
+  for i:=0 to El.Members.Count-1 do
+    begin
+    Member:=TPasElement(El.Members[i]);
+    if (Member is TPasProcedure) then
+      begin
+      ProcScope:=Member.CustomData as TPasProcedureScope;
+      if ProcScope.OverriddenProc<>nil then
+        AddOverride(ProcScope.OverriddenProc,Member);
+      end;
+    if UsePublished and (Member.Visibility=visPublished) then
+      // always include published
+    else if OnlyExports then
+      begin
+      if not IsExport(Member) then continue;
+      end
+    else if IsModuleInternal(Member) then
+      continue
+    else
+      ; // else: class is in unit interface, mark all non private members
+    UseElement(Member,rraNone,true);
+    end;
+end;
+
+procedure TPasAnalyzer.UseVariable(El: TPasVariable;
+  Access: TResolvedRefAccess; UseFull: boolean);
+var
+  Usage: TPAElement;
+  UseRead, UseWrite: boolean;
+
+  procedure UpdateVarAccess(IsRead, IsWrite: boolean);
+  begin
+    if IsRead then
+      case Usage.Access of
+        paiaNone: begin Usage.Access:=paiaRead; UseRead:=true; end;
+        paiaRead: ;
+        paiaWrite: begin Usage.Access:=paiaWriteRead; UseRead:=true; end;
+        paiaReadWrite: ;
+        paiaWriteRead: ;
+        else RaiseInconsistency(20170311182420,'');
+      end;
+    if IsWrite then
+      case Usage.Access of
+        paiaNone: begin Usage.Access:=paiaWrite; UseWrite:=true; end;
+        paiaRead: begin Usage.Access:=paiaReadWrite; UseWrite:=true; end;
+        paiaWrite: ;
+        paiaReadWrite: ;
+        paiaWriteRead: ;
+        else RaiseInconsistency(20170311182536,'');
+      end;
+  end;
+
+var
+  Prop: TPasProperty;
+  i: Integer;
+  IsRead, IsWrite, CanRead, CanWrite: Boolean;
+begin
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.UseVariable ',GetObjName(El),' ',Access,' Full=',UseFull);
+  {$ENDIF}
+  if El.ClassType=TPasProperty then
+    Prop:=TPasProperty(El)
+  else
+    Prop:=nil;
+
+  IsRead:=false;
+  IsWrite:=false;
+  if UseFull and (Prop<>nil) then
+    begin
+    CanRead:=Resolver.GetPasPropertyGetter(Prop)<>nil;
+    CanWrite:=Resolver.GetPasPropertySetter(Prop)<>nil;
+    if CanRead then
+      begin
+      if CanWrite then
+        Access:=rraReadAndAssign
+      else
+        Access:=rraRead;
+      end
+    else
+      if CanWrite then
+        Access:=rraAssign
+      else
+        Access:=rraNone;
+    end;
+  case Access of
+    rraNone: ;
+    rraRead: IsRead:=true;
+    rraAssign: IsWrite:=true;
+    rraReadAndAssign,
+    rraVarParam,
+    rraOutParam: begin IsRead:=true; IsWrite:=true; end;
+    rraParamToUnknownProc: RaiseInconsistency(20170307153439,'');
+  else
+    RaiseInconsistency(20170308120949,'');
+  end;
+
+  UseRead:=false;
+  UseWrite:=false;
+  if MarkElement(El) then
+    begin
+    // first access of this variable
+    Usage:=FindElement(El);
+    // first set flags
+    if El.Expr<>nil then
+      Usage.Access:=paiaWrite;
+    UpdateVarAccess(IsRead,IsWrite);
+    // then use recursively
+    UseType(El.VarType);
+    UseExpr(El.Expr);
+    UseExpr(El.LibraryName);
+    UseExpr(El.ExportName);
+    if Prop<>nil then
+      begin
+      for i:=0 to Prop.Args.Count-1 do
+        UseType(TPasArgument(Prop.Args[i]).ArgType);
+      UseExpr(Prop.IndexExpr);
+      // ToDo: Prop.ImplementsFunc
+      // ToDo: Prop.DispIDExpr
+      // ToDo: Prop.StoredAccessor;
+      // ToDo: Prop.DefaultExpr;
+      end;
+    end
+  else
+    begin
+    Usage:=FindElement(El);
+    if Usage=nil then
+      exit; // element outside of scope
+    // var is accessed another time
+
+    // first update flags
+    UpdateVarAccess(IsRead,IsWrite);
+    end;
+  // then use recursively
+  if Prop<>nil then
+    begin
+    {$IFDEF VerbosePasAnalyzer}
+    writeln('TPasAnalyzer.UseVariable Property=',Prop.FullName,
+      ' Ancestor=',GetObjName(Resolver.GetPasPropertyAncestor(Prop)),
+      ' UseRead=',UseRead,',Acc=',GetObjName(Resolver.GetPasPropertyGetter(Prop)),
+      ' UseWrite=',UseWrite,',Acc=',GetObjName(Resolver.GetPasPropertySetter(Prop)),
+      '');
+    {$ENDIF}
+    if UseRead then
+      UseElement(Resolver.GetPasPropertyGetter(Prop),rraRead,false);
+    if UseWrite then
+      UseElement(Resolver.GetPasPropertySetter(Prop),rraAssign,false);
+    end;
+end;
+
+procedure TPasAnalyzer.UseArgument(El: TPasArgument; Access: TResolvedRefAccess
+  );
+var
+  Usage: TPAElement;
+  IsRead, IsWrite: Boolean;
+begin
+  IsRead:=false;
+  IsWrite:=false;
+  case Access of
+    rraNone: ;
+    rraRead: IsRead:=true;
+    rraAssign: IsWrite:=true;
+    rraReadAndAssign,
+    rraVarParam,
+    rraOutParam: begin IsRead:=true; IsWrite:=true; end;
+    rraParamToUnknownProc: RaiseInconsistency(20170308121031,'');
+  else
+    RaiseInconsistency(20170308121037,'');
+  end;
+  if MarkElement(El) then
+    begin
+    // first time
+    Usage:=FindElement(El);
+    end
+  else
+    begin
+    // used again
+    Usage:=FindElement(El);
+    if Usage=nil then
+      RaiseNotSupported(20170308121928,El);
+    end;
+  UpdateAccess(IsWrite, IsRead, Usage);
+end;
+
+procedure TPasAnalyzer.UseResultElement(El: TPasResultElement;
+  Access: TResolvedRefAccess);
+var
+  IsRead, IsWrite: Boolean;
+  Usage: TPAElement;
+begin
+  IsRead:=false;
+  IsWrite:=false;
+  case Access of
+    rraNone: ;
+    rraRead: IsRead:=true;
+    rraAssign: IsWrite:=true;
+    rraReadAndAssign,
+    rraVarParam,
+    rraOutParam: begin IsRead:=true; IsWrite:=true; end;
+    rraParamToUnknownProc: RaiseInconsistency(20170308122319,'');
+  else
+    RaiseInconsistency(20170308122324,'');
+  end;
+  if MarkElement(El) then
+    begin
+    // first time
+    Usage:=FindElement(El);
+    end
+  else
+    begin
+    // used again
+    Usage:=FindElement(El);
+    if Usage=nil then
+      RaiseNotSupported(20170308122333,El);
+    end;
+  UpdateAccess(IsWrite, IsRead, Usage);
+end;
+
+procedure TPasAnalyzer.EmitElementHints(El: TPasElement);
+begin
+  if El=nil then exit;
+  if El is TPasVariable then
+    EmitVariableHints(TPasVariable(El))
+  else if El is TPasType then
+    EmitTypeHints(TPasType(El))
+  else if El is TPasProcedure then
+    EmitProcedureHints(TPasProcedure(El))
+  else
+    RaiseInconsistency(20170312093126,'');
+end;
+
+procedure TPasAnalyzer.EmitModuleHints(aModule: TPasModule);
+begin
+  if aModule.ClassType=TPasProgram then
+    EmitSectionHints(TPasProgram(aModule).ProgramSection)
+  else if aModule.ClassType=TPasLibrary then
+    EmitSectionHints(TPasLibrary(aModule).LibrarySection)
+  else
+    begin
+    // unit
+    EmitSectionHints(aModule.InterfaceSection);
+    EmitSectionHints(aModule.ImplementationSection);
+    end;
+  //EmitBlockHints(aModule.InitializationSection);
+  //EmitBlockHints(aModule.FinalizationSection);
+end;
+
+procedure TPasAnalyzer.EmitSectionHints(Section: TPasSection);
+var
+  UsesList: TFPList;
+  i: Integer;
+  UsedModule, aModule: TPasModule;
+begin
+  {$IFDEF VerbosePasAnalyzer}
+  writeln('TPasAnalyzer.EmitSectionHints ',GetObjName(Section));
+  {$ENDIF}
+  // initialization, program or library sections
+  aModule:=Section.GetModule;
+  UsesList:=Section.UsesList;
+  for i:=0 to UsesList.Count-1 do
+    begin
+    if TObject(UsesList[i]) is TPasModule then
+      begin
+      UsedModule:=TPasModule(UsesList[i]);
+      if FindNode(UsedModule)=nil then
+        EmitMessage(20170311191725,mtHint,nPAUnitNotUsed,sPAUnitNotUsed,
+          [UsedModule.Name,aModule.Name],aModule);
+      end;
+    end;
+  EmitDeclarationsHints(Section);
+end;
+
+procedure TPasAnalyzer.EmitDeclarationsHints(El: TPasDeclarations);
+var
+  i: Integer;
+  Decl: TPasElement;
+  Usage: TPAElement;
+begin
+  for i:=0 to El.Declarations.Count-1 do
+    begin
+    Decl:=TPasElement(El.Declarations[i]);
+    if Decl is TPasVariable then
+      EmitVariableHints(TPasVariable(Decl))
+    else if Decl is TPasType then
+      EmitTypeHints(TPasType(Decl))
+    else if Decl is TPasProcedure then
+      EmitProcedureHints(TPasProcedure(Decl))
+    else
+      begin
+      Usage:=FindPAElement(Decl);
+      if Usage=nil then
+        begin
+        // declaration was never used
+        EmitMessage(20170311231734,mtHint,nPALocalXYNotUsed,
+          sPALocalXYNotUsed,[Decl.ElementTypeName,Decl.Name],Decl);
+        end;
+      end;
+    end;
+end;
+
+procedure TPasAnalyzer.EmitTypeHints(El: TPasType);
+var
+  C: TClass;
+  Usage: TPAElement;
+  i: Integer;
+  Member: TPasElement;
+begin
+  Usage:=FindPAElement(El);
+  if Usage=nil then
+    begin
+    // the whole type was never used
+    if (El.Visibility in [visPrivate,visStrictPrivate]) then
+      EmitMessage(20170312000020,mtHint,nPAPrivateTypeXNeverUsed,
+        sPAPrivateTypeXNeverUsed,[El.FullName],El)
+    else
+      EmitMessage(20170312000025,mtHint,nPALocalXYNotUsed,
+        sPALocalXYNotUsed,[El.ElementTypeName,El.Name],El);
+    exit;
+    end;
+  // emit hints for sub elements
+  C:=El.ClassType;
+  if C=TPasRecordType then
+    begin
+    for i:=0 to TPasRecordType(El).Members.Count-1 do
+      EmitVariableHints(TObject(TPasRecordType(El).Members) as TPasVariable);
+    end
+  else if C=TPasClassType then
+    begin
+    for i:=0 to TPasClassType(El).Members.Count-1 do
+      begin
+      Member:=TPasElement(TPasClassType(El).Members[i]);
+      EmitElementHints(Member);
+      end;
+    end;
+end;
+
+procedure TPasAnalyzer.EmitVariableHints(El: TPasVariable);
+var
+  Usage: TPAElement;
+begin
+  Usage:=FindPAElement(El);
+  if Usage=nil then
+    begin
+    // not used
+    if El.Visibility in [visPrivate,visStrictPrivate] then
+      begin
+      if El.ClassType=TPasConst then
+        EmitMessage(20170311234602,mtHint,nPAPrivateConstXNeverUsed,
+          sPAPrivateConstXNeverUsed,[El.FullName],El)
+      else if El.ClassType=TPasProperty then
+        EmitMessage(20170311234634,mtHint,nPAPrivatePropertyXNeverUsed,
+          sPAPrivatePropertyXNeverUsed,[El.FullName],El)
+      else
+        EmitMessage(20170311231412,mtHint,nPAPrivateFieldIsNeverUsed,
+          sPAPrivateFieldIsNeverUsed,[El.FullName],El);
+      end
+    else
+      EmitMessage(20170311234201,mtHint,nPALocalVariableNotUsed,
+        sPALocalVariableNotUsed,[El.Name],El);
+    end
+  else if Usage.Access=paiaWrite then
+    begin
+    // write without read
+    if El.Visibility in [visPrivate,visStrictPrivate] then
+      EmitMessage(20170311234159,mtHint,nPAPrivateFieldIsAssignedButNeverUsed,
+        sPAPrivateFieldIsAssignedButNeverUsed,[El.FullName],El)
+    else
+      EmitMessage(20170311233825,mtHint,nPALocalVariableIsAssignedButNeverUsed,
+        sPALocalVariableIsAssignedButNeverUsed,[El.Name],El);
+    end;
+end;
+
+procedure TPasAnalyzer.EmitProcedureHints(El: TPasProcedure);
+var
+  Args: TFPList;
+  i: Integer;
+  Arg: TPasArgument;
+  Usage: TPAElement;
+  ProcScope: TPasProcedureScope;
+  WasNeverUsed: Boolean;
+begin
+  ProcScope:=El.CustomData as TPasProcedureScope;
+  if ProcScope.DeclarationProc<>nil then
+    WasNeverUsed:=FindNode(ProcScope.DeclarationProc)=nil
+  else
+    WasNeverUsed:=FindNode(El)=nil;
+  if WasNeverUsed then
+    begin
+    // procedure never used
+    if El.Visibility in [visPrivate,visStrictPrivate] then
+      EmitMessage(20170312093348,mtHint,nPAPrivateMethodIsNeverUsed,
+        sPAPrivateMethodIsNeverUsed,[El.FullName],El)
+    else
+      EmitMessage(20170312093418,mtHint,nPALocalXYNotUsed,
+        sPALocalXYNotUsed,[El.ElementTypeName,El.Name],El);
+    exit;
+    end;
+
+  // procedure was used
+
+  if pmAssembler in El.Modifiers then exit;
+
+  if ProcScope.DeclarationProc=nil then
+    begin
+    // check parameters
+    Args:=El.ProcType.Args;
+    for i:=0 to Args.Count-1 do
+      begin
+      Arg:=TPasArgument(Args[i]);
+      Usage:=FindPAElement(Arg);
+      if (Usage=nil) or (Usage.Access=paiaNone) then
+        // parameter was never used
+        EmitMessage(20170312094401,mtHint,nPAParameterNotUsed,
+          sPAParameterNotUsed,[Arg.Name],Arg)
+      else
+        begin
+        // parameter was used
+        if Usage.Access=paiaWrite then
+          EmitMessage(20170312095348,mtHint,nPAValueParameterIsAssignedButNeverUsed,
+            sPAValueParameterIsAssignedButNeverUsed,[El.Name],El);
+        end;
+      end;
+    end;
+  if El.Body<>nil then
+    begin
+    // check declarations
+    EmitDeclarationsHints(El.Body);
+    // ToDo: emit hints for statements
+    end;
+end;
+
+function TPasAnalyzer.IsModuleInternal(El: TPasElement): boolean;
+begin
+  if El=nil then
+    exit(true);
+  if El.ClassType=TInterfaceSection then
+    exit(false);
+  if IsExport(El) then exit(false);
+  case El.Visibility of
+  visPrivate,visStrictPrivate: exit(true);
+  visPublished: if paoAlwaysUsePublished in Options then exit(false);
+  end;
+  Result:=IsModuleInternal(El.Parent);
+end;
+
+function TPasAnalyzer.IsExport(El: TPasElement): boolean;
+begin
+  if El is TPasVariable then
+    Result:=[vmExport,vmPublic]*TPasVariable(El).VarModifiers<>[]
+  else if El is TPasProcedure then
+    Result:=[pmExport,pmPublic]*TPasProcedure(El).Modifiers<>[]
+  else
+    Result:=false;
+end;
+
+procedure TPasAnalyzer.EmitMessage(const Id: int64;
+  const MsgType: TMessageType; MsgNumber: integer; Fmt: String;
+  const Args: array of const; PosEl: TPasElement);
+var
+  Msg: TPAMessage;
+begin
+  Msg:=TPAMessage.Create;
+  Msg.Id:=Id;
+  Msg.MsgType:=MsgType;
+  Msg.MsgNumber:=MsgNumber;
+  Msg.Fmt:=Fmt;
+  CreateMsgArgs(Msg.Args,Args);
+  Msg.PosEl:=PosEl;
+  Msg.Filename:=PosEl.SourceFilename;
+  Resolver.UnmangleSourceLineNumber(PosEl.SourceLinenumber,Msg.Row,Msg.Col);
+  EmitMessage(Msg);
+end;
+
+procedure TPasAnalyzer.EmitMessage(Msg: TPAMessage);
+begin
+  try
+    OnMessage(Self,Msg);
+  finally
+    Msg.Free;
+  end;
+end;
+
+constructor TPasAnalyzer.Create;
+begin
+  CreateTree;
+  FOverrideLists:=TAVLTree.Create(@ComparePAOverrideLists);
+end;
+
+destructor TPasAnalyzer.Destroy;
+begin
+  Clear;
+  FreeAndNil(FOverrideLists);
+  FreeAndNil(FUsedElements);
+  inherited Destroy;
+end;
+
+procedure TPasAnalyzer.Clear;
+begin
+  FOverrideLists.FreeAndClear;
+  FUsedElements.FreeAndClear;
+end;
+
+procedure TPasAnalyzer.AnalyzeModule(aModule: TPasModule);
+begin
+  ScopeModule:=aModule;
+  Add(aModule);
+  if aModule is TPasProgram then
+    UseSection(TPasProgram(aModule).ProgramSection)
+  else if aModule is TPasLibrary then
+    UseSection(TPasLibrary(aModule).LibrarySection)
+  else
+    begin
+    // unit
+    UseSection(aModule.InterfaceSection);
+    end;
+  UseImplBlock(aModule.InitializationSection,true);
+  if Assigned(OnMessage) then
+    EmitModuleHints(aModule);
+end;
+
+function TPasAnalyzer.FindElement(El: TPasElement): TPAElement;
+var
+  Node: TAVLTreeNode;
+begin
+  Node:=FindNode(El);
+  if Node=nil then
+    Result:=nil
+  else
+    Result:=TPAElement(Node.Data);
+end;
+
+end.
+
diff --git a/packages/fcl-passrc/tests/tcuseanalyzer.pas b/packages/fcl-passrc/tests/tcuseanalyzer.pas
new file mode 100644
index 0000000000..2bc7bc0e3d
--- /dev/null
+++ b/packages/fcl-passrc/tests/tcuseanalyzer.pas
@@ -0,0 +1,497 @@
+{
+  Examples:
+    ./testpassrc --suite=TTestResolver.TestEmpty
+}
+unit tcuseanalyzer;
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, fpcunit,
+  PasTree, PScanner, PasResolver,
+  tcbaseparser, testregistry, strutils, tcresolver, PasUseAnalyzer;
+
+type
+
+  { TCustomTestUseAnalyzer }
+
+  TCustomTestUseAnalyzer = Class(TCustomTestResolver)
+  private
+    FAnalyzer: TPasAnalyzer;
+  protected
+    procedure SetUp; override;
+    procedure TearDown; override;
+    procedure AnalyzeProgram; virtual;
+    procedure ParseProgram; override;
+    procedure CheckUsedMarkers; virtual;
+  public
+    property Analyzer: TPasAnalyzer read FAnalyzer;
+  end;
+
+  TTestUseAnalyzer = Class(TCustomTestUseAnalyzer)
+  published
+    // single module
+    procedure TestM_ProgramLocalVar;
+    procedure TestM_AssignStatement;
+    procedure TestM_ForLoopStatement;
+    procedure TestM_AsmStatement;
+    procedure TestM_CaseOfStatement;
+    procedure TestM_IfThenElseStatement;
+    procedure TestM_WhileDoStatement;
+    procedure TestM_RepeatUntilStatement;
+    procedure TestM_TryFinallyStatement;
+    procedure TestM_TypeAlias;
+    // ToDo: unary
+    procedure TestM_Record;
+    procedure TestM_Array;
+    procedure TestM_NestedFuncResult;
+    procedure TestM_Class;
+    procedure TestM_Class_Property;
+    procedure TestM_Class_PropertyOverride;
+    procedure TestM_Class_MethodOverride;
+    procedure TestM_Class_MethodOverride2;
+    procedure TestM_HintLocalVarNotUsed;
+
+    // whole program optimization
+  end;
+
+implementation
+
+{ TCustomTestUseAnalyzer }
+
+procedure TCustomTestUseAnalyzer.SetUp;
+begin
+  inherited SetUp;
+  FAnalyzer:=TPasAnalyzer.Create;
+  FAnalyzer.Resolver:=ResolverEngine;
+end;
+
+procedure TCustomTestUseAnalyzer.TearDown;
+begin
+  FreeAndNil(FAnalyzer);
+  inherited TearDown;
+end;
+
+procedure TCustomTestUseAnalyzer.AnalyzeProgram;
+begin
+  ParseProgram;
+  Analyzer.AnalyzeModule(Module);
+  CheckUsedMarkers;
+end;
+
+procedure TCustomTestUseAnalyzer.ParseProgram;
+begin
+  try
+    inherited ParseProgram;
+  except
+    on E: EPasAnalysis do
+      begin
+      raise E;
+      end;
+  end;
+end;
+
+procedure TCustomTestUseAnalyzer.CheckUsedMarkers;
+var
+  aMarker: PSrcMarker;
+  p: SizeInt;
+  Postfix: String;
+  Elements: TFPList;
+  i: Integer;
+  El: TPasElement;
+  ExpectedUsed: Boolean;
+  FoundEl: TPAElement;
+begin
+  aMarker:=FirstSrcMarker;
+  while aMarker<>nil do
+    begin
+    writeln('TCustomTestUseAnalyzer.CheckUsedMarkers ',aMarker^.Identifier,' ',aMarker^.StartCol,' ',aMarker^.EndCol);
+    p:=RPos('_',aMarker^.Identifier);
+    if p>1 then
+      begin
+      Postfix:=copy(aMarker^.Identifier,p+1);
+
+      if Postfix='used' then
+        ExpectedUsed:=true
+      else if Postfix='notused' then
+        ExpectedUsed:=false
+      else
+        RaiseErrorAtSrcMarker('TCustomTestUseAnalyzer.CheckUsedMarkers unknown postfix "'+Postfix+'"',aMarker);
+
+      Elements:=FindElementsAt(aMarker);
+      try
+        FoundEl:=nil;
+        for i:=0 to Elements.Count-1 do
+          begin
+          El:=TPasElement(Elements[i]);
+          writeln('TCustomTestUseAnalyzer.CheckUsedMarkers ',aMarker^.Identifier,' ',i,'/',Elements.Count,' El=',GetObjName(El),' ',GetObjName(El.CustomData));
+          FoundEl:=Analyzer.FindElement(El);
+          if FoundEl<>nil then break;
+          end;
+        if FoundEl<>nil then
+          begin
+          if not ExpectedUsed then
+            RaiseErrorAtSrcMarker('expected element to be *not* used, but it is marked',aMarker);
+          end
+        else
+          begin
+          if ExpectedUsed then
+            RaiseErrorAtSrcMarker('expected element to be used, but it is not marked',aMarker);
+          end;
+      finally
+        Elements.Free;
+      end;
+      end;
+    aMarker:=aMarker^.Next;
+    end;
+
+end;
+
+{ TTestUseAnalyzer }
+
+procedure TTestUseAnalyzer.TestM_ProgramLocalVar;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('var {#l_notused}l: longint;');
+  Add('begin');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_AssignStatement;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('var');
+  Add('  {#a_notused}a: longint;');
+  Add('  {#b_used}b: longint;');
+  Add('  {#c_used}c: longint;');
+  Add('begin');
+  Add('  b:=c;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_ForLoopStatement;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('var');
+  Add('  {#a_used}a: longint;');
+  Add('  {#b_used}b: longint;');
+  Add('  {#c_used}c: longint;');
+  Add('  {#d_used}d: longint;');
+  Add('begin');
+  Add('  for a:=b to c do d:=a;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_AsmStatement;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('begin');
+  Add('  asm end;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_CaseOfStatement;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('const');
+  Add('  {#a_used}a = 1;');
+  Add('  {#b_used}b = 2;');
+  Add('var');
+  Add('  {#c_used}c: longint;');
+  Add('  {#d_used}d: longint;');
+  Add('begin');
+  Add('  case a of');
+  Add('    b: c:=1;');
+  Add('  else');
+  Add('    d:=2;');
+  Add('  end;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_IfThenElseStatement;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('var');
+  Add('  {#a_used}a: longint;');
+  Add('  {#b_used}b: longint;');
+  Add('  {#c_used}c: longint;');
+  Add('begin');
+  Add('  if a=0 then b:=1 else c:=2;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_WhileDoStatement;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('var');
+  Add('  {#a_used}a: longint;');
+  Add('  {#b_used}b: longint;');
+  Add('begin');
+  Add('  while a>0 do b:=1;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_RepeatUntilStatement;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('var');
+  Add('  {#a_used}a: longint;');
+  Add('  {#b_used}b: longint;');
+  Add('begin');
+  Add('  repeat a:=1; until b>1;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_TryFinallyStatement;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('var');
+  Add('  {#a_used}a: longint;');
+  Add('  {#b_used}b: longint;');
+  Add('begin');
+  Add('  try');
+  Add('    a:=1;');
+  Add('  finally');
+  Add('    b:=2;');
+  Add('  end;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_TypeAlias;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('var');
+  Add('  {#a_used}a: integer;');
+  Add('  {#b_used}b: integer;');
+  Add('  {#c_notused}c: integer;');
+  Add('begin');
+  Add('  a:=b;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_Record;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('  {#trec_used}TRec = record');
+  Add('    {#a_used}a: integer;');
+  Add('    {#b_notused}b: integer;');
+  Add('    {#c_used}c: integer;');
+  Add('  end;');
+  Add('var');
+  Add('  {#r_used}r: TRec;');
+  Add('begin');
+  Add('  r.a:=3;');
+  Add('  with r do c:=4;');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_Array;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('  {#tarrayint_used}TArrayInt = array of integer;');
+  Add('var');
+  Add('  {#a_used}a: TArrayInt;');
+  Add('  {#b_used}b: integer;');
+  Add('  {#c_used}c: TArrayInt;');
+  Add('  {#d_used}d: integer;');
+  Add('  {#e_used}e: TArrayInt;');
+  Add('  {#f_used}f: integer;');
+  Add('  {#g_used}g: TArrayInt;');
+  Add('  {#h_used}h: TArrayInt;');
+  Add('  {#i_used}i: TArrayInt;');
+  Add('begin');
+  Add('  a[b]:=c[d];');
+  Add('  SetLength(e,f)');
+  Add('  if low(g)=high(h)+length(i) then');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_NestedFuncResult;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('  {#tarrayint_used}TArrayInt = array of integer;');
+  Add('  function {#nestedfunc_used}NestedFunc({#b_notused}b: longint): TArrayInt;');
+  Add('  begin');
+  Add('  end;');
+  Add('var');
+  Add('  {#d_used}d: longint;');
+  Add('begin');
+  Add('  NestedFunc(d);');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_Class;
+begin
+  StartProgram(false);
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('  {tobject_used}TObject = class');
+  Add('    {#a_used}a: integer;');
+  Add('  end;');
+  Add('var Obj: TObject;');
+  Add('begin');
+  Add('  Obj.a:=3;');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_Class_Property;
+begin
+  StartProgram(false);
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('  {tobject_used}TObject = class');
+  Add('    {#fa_used}Fa: integer;');
+  Add('    {#fb_used}Fb: integer;');
+  Add('    {#fc_used}Fc: integer;');
+  Add('    {#fd_used}Fd: integer;');
+  Add('    {#fe_notused}Fe: integer;');
+  Add('    function {#getfc_used}GetFC: integer;');
+  Add('    procedure {#setfd_used}SetFD({#setfd_value_used}Value: integer);');
+  Add('    property {#A_used}A: integer read Fa write Fb;');
+  Add('    property {#C_used}C: integer read GetFC write SetFD;');
+  Add('  end;');
+  Add('function TObject.GetFC: integer;');
+  Add('begin');
+  Add('  Result:=Fc;');
+  Add('end;');
+  Add('procedure TObject.SetFD({#setfd_value_impl_notused}Value: integer);');
+  Add('begin');
+  Add('  Fd:=Value;');
+  Add('end;');
+  Add('var Obj: TObject;');
+  Add('begin');
+  Add('  Obj.A:=Obj.A;');
+  Add('  Obj.C:=Obj.C;');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_Class_PropertyOverride;
+begin
+  StartProgram(false);
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('  {tobject_used}TObject = class');
+  Add('    {#fa_used}FA: integer;');
+  Add('    {#fb_notused}FB: integer;');
+  Add('    property {#obj_a_notused}A: integer read FA write FB;');
+  Add('  end;');
+  Add('  {tmobile_used}TMobile = class(TObject)');
+  Add('    {#fc_used}FC: integer;');
+  Add('    property {#mob_a_used}A write FC;');
+  Add('  end;');
+  Add('var {#m_used}M: TMobile;');
+  Add('begin');
+  Add('  M.A:=M.A;');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_Class_MethodOverride;
+begin
+  StartProgram(false);
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('  {tobject_used}TObject = class');
+  Add('    procedure {#obj_doa_used}DoA; virtual; abstract;');
+  Add('    procedure {#obj_dob_notused}DoB; virtual; abstract;');
+  Add('  end;');
+  Add('  {tmobile_used}TMobile = class(TObject)');
+  Add('    constructor {#mob_create_used}Create;');
+  Add('    procedure {#mob_doa_used}DoA; override;');
+  Add('    procedure {#mob_dob_notused}DoB; override;');
+  Add('  end;');
+  Add('constructor TMobile.Create; begin end;');
+  Add('procedure TMobile.DoA; begin end;');
+  Add('procedure TMobile.DoB; begin end;');
+  Add('var {#o_used}o: TObject;');
+  Add('begin');
+  Add('  o:=TMobile.Create;'); // use TMobile before o.DoA
+  Add('  o.DoA;');
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_Class_MethodOverride2;
+begin
+  StartProgram(false);
+  Add('type');
+  Add('  {#integer_used}integer = longint;');
+  Add('  {tobject_used}TObject = class');
+  Add('    procedure {#obj_doa_used}DoA; virtual; abstract;');
+  Add('  end;');
+  Add('  {tmobile_used}TMobile = class(TObject)');
+  Add('    constructor {#mob_create_used}Create;');
+  Add('    procedure {#mob_doa_used}DoA; override;');
+  Add('  end;');
+  Add('constructor TMobile.Create; begin end;');
+  Add('procedure TMobile.DoA; begin end;');
+  Add('var {#o_used}o: TObject;');
+  Add('begin');
+  Add('  o.DoA;');
+  Add('  o:=TMobile.Create;'); // use TMobile after o.DoA
+  AnalyzeProgram;
+end;
+
+procedure TTestUseAnalyzer.TestM_HintLocalVarNotUsed;
+begin
+  StartProgram(false);
+  Add('procedure {#DoIt_used}DoIt;');
+  Add('var {#l_notused}l: longint;');
+  Add('begin');
+  Add('end;');
+  Add('begin');
+  AnalyzeProgram;
+end;
+
+initialization
+  RegisterTests([TTestUseAnalyzer]);
+
+end.
+
diff --git a/packages/fcl-passrc/tests/testpassrc.lpi b/packages/fcl-passrc/tests/testpassrc.lpi
index c5c74182ae..4ee3cab3d9 100644
--- a/packages/fcl-passrc/tests/testpassrc.lpi
+++ b/packages/fcl-passrc/tests/testpassrc.lpi
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <CONFIG>
   <ProjectOptions>
-    <Version Value="9"/>
+    <Version Value="10"/>
     <General>
       <Flags>
         <SaveOnlyProjectUnits Value="True"/>
@@ -16,9 +16,6 @@
     <i18n>
       <EnableI18N LFM="False"/>
     </i18n>
-    <VersionInfo>
-      <StringTable ProductVersion=""/>
-    </VersionInfo>
     <BuildModes Count="1">
       <Item1 Name="Default" Default="True"/>
     </BuildModes>
@@ -38,7 +35,7 @@
         <PackageName Value="FCL"/>
       </Item1>
     </RequiredPackages>
-    <Units Count="14">
+    <Units Count="15">
       <Unit0>
         <Filename Value="testpassrc.lpr"/>
         <IsPartOfProject Value="True"/>
@@ -95,6 +92,10 @@
         <Filename Value="tcgenerics.pp"/>
         <IsPartOfProject Value="True"/>
       </Unit13>
+      <Unit14>
+        <Filename Value="tcuseanalyzer.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit14>
     </Units>
   </ProjectOptions>
   <CompilerOptions>
@@ -106,6 +107,20 @@
       <IncludeFiles Value="$(ProjOutDir)"/>
       <OtherUnitFiles Value="../src"/>
     </SearchPaths>
+    <Parsing>
+      <SyntaxOptions>
+        <AllowLabel Value="False"/>
+      </SyntaxOptions>
+    </Parsing>
+    <CodeGeneration>
+      <Checks>
+        <IOChecks Value="True"/>
+        <RangeChecks Value="True"/>
+        <OverflowChecks Value="True"/>
+        <StackChecks Value="True"/>
+      </Checks>
+      <VerifyObjMethodCallValidity Value="True"/>
+    </CodeGeneration>
   </CompilerOptions>
   <Debugging>
     <Exceptions Count="3">
diff --git a/packages/fcl-passrc/tests/testpassrc.lpr b/packages/fcl-passrc/tests/testpassrc.lpr
index 322bb01a3d..204c4ca3b9 100644
--- a/packages/fcl-passrc/tests/testpassrc.lpr
+++ b/packages/fcl-passrc/tests/testpassrc.lpr
@@ -5,7 +5,8 @@ program testpassrc;
 uses
   Classes, consoletestrunner, tcscanner, tctypeparser, tcstatements,
   tcbaseparser, tcmoduleparser, tconstparser, tcvarparser, tcclasstype,
-  tcexprparser, tcprocfunc, tcpassrcutil, tcresolver, tcgenerics;
+  tcexprparser, tcprocfunc, tcpassrcutil, tcresolver, tcgenerics,
+  tcuseanalyzer;
 
 type