Is it a user error to declare a generic inline function `const` for shortstring, or is this a compiler bug?

The compiler generates incorrect code for shortstring when using the function

function TTestObject<T>.Compare(const Left, Right: T): integer; inline;

It mangles the parameters.

The following sample program demonstrates the concept:

program ShortStringsAndConst;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils;

type
  TStr100 = string[100];

  TTestObject<T> = class
  private
    Bag1, Bag2: T;
    procedure RandomBags;
    procedure TestCompare;
    function CompareFail(const Left, Right: T): integer; inline;
    function CompareWin(const [ref] Left, Right: T): integer; inline;
  end;

var
  TestStr100: TTestObject<TStr100>;

  procedure Test;
  begin
    TestStr100:= TTestObject<TStr100>.Create;
    TestStr100.RandomBags;
    TestStr100.TestCompare;
  end;

{ TTestObject<T> }

procedure TTestObject<T>.RandomBags;
var
  a: integer;
begin
  PByteArray(@Bag1)^[0]:= SizeOf(T)- 1;
  for a:= 1 to SizeOf(T)- 1 do begin
    PByteArray(@Bag1)^[a]:= byte('a');
  end;
  Bag2:= Bag1;
end;

function TTestObject<T>.CompareFail(const Left, Right: T): integer;
var
  L,R: shortstring;
begin
  L:= PShortstring(@Left)^;
  R:= PShortstring(@Right)^;
  WriteLn(Format('Fail!! @Left = %p, @Right = %p, Left = %s, Right = %s',[@Left, @Right, L, R]));
end;

function TTestObject<T>.CompareWin(const [ref] Left, Right: T): integer;
var
  L,R: shortstring;
begin
  L:= PShortstring(@Left)^;
  R:= PShortstring(@Right)^;
  WriteLn(Format('Win:  @Left = %p, @Right = %p, Left = %s, Right = %s',[@Left, @Right, L, R]));
end;

procedure TTestObject<T>.TestCompare;
begin
  CompareFail(Bag1,Bag2);
  WriteLn;
  CompareWin(Bag1,Bag2);
  ReadLn;
end;

begin
  Test;
end.

Question
Is it an error on my part to assume I can get away with using normal const in generic functions, or is this a compiler bug?

Bonus question
Besides Shortstring, are there other types which cause CompareFail to generate non-working code?

Background
I don't feel a strong need to work with shortstring, but I'm writing some generic library code and need to support all types.

Update This is a compiler bug which has been fixed in 10.1 Berlin.

Is it an error on my part to assume I can get away with using normal const in generic functions, or is this a compiler bug?

Assuming that what you say is true, then this is a compiler bug. You need to report the bug and block the use of short strings.