helpers: key distinct type aliases by their own identity (fixes upstream#41564)

compiler/symtable.pas

@@ -3243,7 +3243,8 @@         if defowner.typ=recorddef then
             assigned(tstoreddef(def).genericdef) and
             assigned(def.typesym) then
           result:=make_mangledname('',tstoreddef(def).genericdef.owner,def.typesym.name)
-        else if def.typ in [recorddef,objectdef] then
+        else if (def.typ in [recorddef,objectdef]) and
+           not (df_unique in def.defoptions) then
           result:=make_mangledname('',tabstractrecorddef(def).symtable,'')
         else
           result:=make_mangledname('',def.owner,def.typesym.name);

tests/webtbs/tw41564.pp

@@ -0,0 +1,80 @@
+program tw41564;
+
+{$mode delphi}
+
+type
+  TBase = record
+    Value: Integer;
+  end;
+  TAlias = TBase;
+  TFirst = type TBase;
+  TSecond = type TBase;
+
+  TBaseHelper = record helper for TBase
+    function Marker: Integer;
+    class function StaticMarker: Integer; static;
+  end;
+
+  TFirstHelper = record helper for TFirst
+    function Marker: Integer;
+    class function StaticMarker: Integer; static;
+  end;
+
+  TSecondHelper = record helper for TSecond
+    function Marker: Integer;
+    class function StaticMarker: Integer; static;
+  end;
+
+function TBaseHelper.Marker: Integer;
+begin
+  Result := 10;
+end;
+
+class function TBaseHelper.StaticMarker: Integer;
+begin
+  Result := 20;
+end;
+
+function TFirstHelper.Marker: Integer;
+begin
+  Result := 11;
+end;
+
+class function TFirstHelper.StaticMarker: Integer;
+begin
+  Result := 21;
+end;
+
+function TSecondHelper.Marker: Integer;
+begin
+  Result := 12;
+end;
+
+class function TSecondHelper.StaticMarker: Integer;
+begin
+  Result := 22;
+end;
+
+var
+  Base: TBase;
+  AliasValue: TAlias;
+  First: TFirst;
+  Second: TSecond;
+begin
+  if Base.Marker <> 10 then
+    Halt(1);
+  if AliasValue.Marker <> 10 then
+    Halt(2);
+  if First.Marker <> 11 then
+    Halt(3);
+  if Second.Marker <> 12 then
+    Halt(4);
+  if TBase.StaticMarker <> 20 then
+    Halt(5);
+  if TAlias.StaticMarker <> 20 then
+    Halt(6);
+  if TFirst.StaticMarker <> 21 then
+    Halt(7);
+  if TSecond.StaticMarker <> 22 then
+    Halt(8);
+end.