[Ada] Missing error on T'Enum_Rep with no parameter

[Arnaud Charlet <charlet at adacore dot com>]

This patch fixes a bug in which the compiler fails to give an error on
T'Enum_Rep, where T is a type. If X is an object of enumeration type T,
then X'Enum_Rep and T'Enum_Rep(X) are allowed, but not T'Enum_Rep.

The following test must get an error.

enum_val_test.adb:4:21: prefix of "Enum_Rep" attribute must be discrete object

procedure Enum_Val_Test is
   type Color is (Red, Orange, Yellow);
   Current_Index : Color := Orange;
   Rep : Integer := Color'Enum_Rep; -- Illegal!
begin
   null;
end Enum_Val_Test;

Tested on x86_64-pc-linux-gnu, committed on trunk

2017-05-02  Bob Duff  <duff@adacore.com>

	* sem_attr.adb (Attribute_Enum_Rep): Disallow T'Enum_Rep.

Attachment: difs
Description: Text document