diff --git a/components/codetools/ccodeparsertool.pas b/components/codetools/ccodeparsertool.pas
index 33ed7874bd..e29dab5ae8 100644
--- a/components/codetools/ccodeparsertool.pas
+++ b/components/codetools/ccodeparsertool.pas
@@ -635,6 +635,7 @@ procedure TCCodeParserTool.ReadStruct;
     struct hidp_connadd_req {
       int ctrl_sock;
     }
+    struct SwsContext; // no content
 
   As variable:
     struct hidp_conninfo *ci;
@@ -693,6 +694,8 @@ begin
     // using another struct
     CreateChildNode(ccnStructAlias);
     EndChildNode;
+  end else if AtomIsChar(';') then begin
+    // struct without content
   end else
     RaiseExpectedButAtomFound('{');
 
diff --git a/components/codetools/codetoolsstructs.pas b/components/codetools/codetoolsstructs.pas
index b666faa048..0165737d36 100644
--- a/components/codetools/codetoolsstructs.pas
+++ b/components/codetools/codetoolsstructs.pas
@@ -35,7 +35,7 @@ unit CodeToolsStructs;
 interface
 
 uses
-  Classes, SysUtils, AVL_Tree, CodeCache, CodeAtom;
+  Classes, SysUtils, FileProcs, AVL_Tree, CodeCache, CodeAtom;
   
 type
   TResourcestringInsertPolicy = (
@@ -124,6 +124,7 @@ type
     property Strings[const s: string]: string read GetStrings write SetStrings; default;
     property CaseSensitive: boolean read FCaseSensitive;
     property Tree: TAVLTree read FTree;
+    procedure WriteDebugReport;
   end;
   
 function CompareStringToStringItems(Data1, Data2: Pointer): integer;
@@ -426,5 +427,19 @@ begin
   end;
 end;
 
+procedure TStringToStringTree.WriteDebugReport;
+var
+  Node: TAVLTreeNode;
+  Item: PStringToStringTreeItem;
+begin
+  DebugLn(['TStringToStringTree.WriteDebugReport ',Tree.Count]);
+  Node:=Tree.FindLowest;
+  while Node<>nil do begin
+    Item:=PStringToStringTreeItem(Node.Data);
+    DebugLn([Item^.Name,'=',Item^.Value]);
+    Node:=Tree.FindSuccessor(Node);
+  end;
+end;
+
 end.
 
diff --git a/components/codetools/examples/h2pastest.lpr b/components/codetools/examples/h2pastest.lpr
index 409b2b6206..87444f8069 100644
--- a/components/codetools/examples/h2pastest.lpr
+++ b/components/codetools/examples/h2pastest.lpr
@@ -87,7 +87,6 @@ begin
         Src:=Src+LineEnding;
       Src:=Src+CCode.Source;
     end;
-    Halt;
 
     // Step 2: create a temporary file
     Filename:='h2pasoutput.pas';
diff --git a/components/codetools/examples/scanexamples/test.h b/components/codetools/examples/scanexamples/test.h
index 0bc9c47d1b..4a68bd231f 100644
--- a/components/codetools/examples/scanexamples/test.h
+++ b/components/codetools/examples/scanexamples/test.h
@@ -170,6 +170,8 @@ const char* (*item_name)(void* ctx);
 const struct AVOption *option;
 #if LIBAVUTIL_VERSION_INT < (50<<16)
 void av_log(void*, int level, const char *fmt, ...) __attribute__ ((__format__ (__printf__, 3, 4)));
+struct SwsContext; // SwsContext = record end;
+
 
 #ifdef __cplusplus
 }
diff --git a/components/codetools/h2pastool.pas b/components/codetools/h2pastool.pas
index 65935fa470..edbd7e1edc 100644
--- a/components/codetools/h2pastool.pas
+++ b/components/codetools/h2pastool.pas
@@ -225,7 +225,7 @@ type
     procedure SimplifyDefineDirective(Node: TH2PDirectiveNode;
                                       var NextNode: TH2PDirectiveNode;
                                       var Changed: boolean);
-    procedure SimplifyIfDirective(Node: TH2PDirectiveNode; const Expression: string;
+    procedure SimplifyIfDirective(Node: TH2PDirectiveNode; Expression: string;
                                   var NextNode: TH2PDirectiveNode;
                                   var Changed: boolean);
     function SimplifyIfDirectiveExpression(var Expression: string): boolean;
@@ -1604,7 +1604,7 @@ begin
 end;
 
 procedure TH2PasTool.SimplifyIfDirective(Node: TH2PDirectiveNode;
-  const Expression: string; var NextNode: TH2PDirectiveNode;
+  Expression: string; var NextNode: TH2PDirectiveNode;
   var Changed: boolean);
 begin
   if Node.H2PNode=nil then exit;
@@ -1616,18 +1616,35 @@ begin
   then begin
     // no content
     DebugLn(['TH2PasTool.SimplifyIfDirective REMOVING empty if directive: ',Node.DescAsString(CTool)]);
-    if (NextNode=Node.NextBrother) and (NextNode.Desc=h2pdnEndIf) then
+    if NextNode.HasAsParent(Node)
+    or ((NextNode=Node.NextBrother) and (NextNode.Desc=h2pdnEndIf)) then
       NextNode:=TH2PDirectiveNode(NextNode.NextSkipChilds);
     DeleteDirectiveNode(Node,true,true);
     Changed:=true;
-  end else begin
-  
+    exit;
+  end;
+
+  Changed:=SimplifyIfDirectiveExpression(Expression);
+  if Expression='0' then begin
+    // always false
+    DebugLn(['TH2PasTool.SimplifyIfDirective REMOVING directive, because always false: ',Node.DescAsString(CTool)]);
+    if NextNode.HasAsParent(Node)
+    or ((NextNode=Node.NextBrother) and (NextNode.Desc=h2pdnEndIf)) then
+      NextNode:=TH2PDirectiveNode(NextNode.NextSkipChilds);
+    DeleteDirectiveNode(Node,true,true);
+    Changed:=true;
+    exit;
+  end;
+
+  if Changed and ((Node.Desc=h2pdnIf) or (Node.Desc=h2pdnElseIf)) then begin
+    Node.Expression:=Expression;
   end;
 end;
 
 function TH2PasTool.SimplifyIfDirectiveExpression(var Expression: string
   ): boolean;
 // returns true, if changed
+// uses current Undefines and Defines
 var
   p: Integer;
   AtomStart: integer;
@@ -1639,9 +1656,7 @@ begin
     ReadRawNextCAtom(Expression,p,AtomStart);
     if AtomStart>length(Expression) then break;
     CurAtom:=copy(Expression,AtomStart,p-AtomStart);
-    if (CurAtom='not') then begin
-
-    end;
+    if CurAtom='' then ;
   until false;
 end;
 
@@ -2040,6 +2055,7 @@ begin
   if Node=nil then exit;
   MacroName:=CTool.ExtractDirectiveFirstAtom(Node);
   if MacroName='' then exit;
+  //DebugLn(['TH2PasTool.UndefineEnclosingIFNDEF UNDEFINE ',MacroName]);
   Undefines.Add(MacroName,'');
 end;
 
@@ -2068,6 +2084,7 @@ var
   Changed: Boolean;
   H2PNode: TH2PNode;
 begin
+  // Undefines.WriteDebugReport;
   repeat
     Changed:=false;
     InitMacros;
@@ -2679,7 +2696,8 @@ end;
 
 procedure TH2PasTool.AddCommonCDefines;
 begin
-  Undefines['__cplusplus']:='1';
+  Undefines['__cplusplus']:='1';// avoid C++ and use the easier c part
+  Defines['__GNUC__']:='1';// assume the GNUC compiler
 end;
 
 procedure TH2PasTool.ResetMacros;