[Ada] Extended syntax for Check_Policy

[Arnaud Charlet <charlet at adacore dot com>]

With this patch, Check_Policy can optionally use the same syntax as
Assertion_Policy (the old syntax is still allowed).

This test shows error detection

     1. package BadCpol is
     2.    pragma Check_Policy
     3.      (Junk, Ignore);                        -- OK
     4.    pragma Check_Policy
     5.      (Junk => Ignore);                      -- OK
     6.    pragma Check_Policy
     7.      (Name => Junk, Policy => Ignore);      -- OK
     8.    pragma Check_Policy
     9.      (Name => Name, Policy => Policy);      -- Error
                      |
        >>> pragma "Check_Policy" does not allow "Name" as check name

    10.    pragma Check_Policy
    11.      (Name => Name1, Policy => Ignore);     -- OK
    12.    pragma Check_Policy
    13.      (Policy, Ignore);                      -- Error
              |
        >>> pragma "Check_Policy" does not allow "Policy" as check name

    14.    pragma Check_Policy
    15.      (Policy => Ignore);                    -- Error
              |
        >>> pragma "Check_Policy" does not allow "Policy" as check name

    16.    pragma Check_Policy
    17.      (Pre'Class, Ignore);                   -- OK
    18.    pragma Check_Policy
    19.      (Pre'Class => Check);                  -- OK
    20.    pragma Check_Policy
    21.      (Pre => Check, Post);                  -- Error
                            |
        >>> pragma argument identifier required here
        >>> since previous argument had identifier (RM 2.8(4))
        >>> missing assertion kind for pragma "Check_Policy"

    22. end;

The following test compiled and run without -gnata generates
the output:

OK 1
OK 2
OK 3

     1. with Text_IO; use Text_IO;
     2. with System.Assertions;
     3. use System.Assertions;
     4.
     5. procedure GoodCpol is
     6.    X, Y : Integer;
     7.
     8. begin
     9.    X := 23;
    10.    Y := 24;
    11.
    12.    declare
    13.       pragma Check_Policy (Grumble, Check);
    14.    begin
    15.       pragma Check (Grumble, Y < X);
              |
        >>> warning: check will fail at run time

    16.       Put_Line ("Not OK 1");
    17.    exception
    18.       when Assert_Failure =>
    19.          Put_Line ("OK 1");
    20.    end;
    21.
    22.    declare
    23.       pragma Check_Policy (Mumble => Ignore, Grumble => Check);
    24.    begin
    25.       pragma Check (Mumble, Y = 100, "Not OK 2");
    26.       pragma Check (Grumble, Y < X);
    27.       Put_Line ("Not OK 3");
    28.    exception
    29.       when Assert_Failure =>
    30.          Put_Line ("OK 2");
    31.
    32.    end;
    33.    declare
    34.       pragma Check_Policy (Mumble => Disable);
    35.    begin
    36.       pragma Check (Mumble, "Not OK 4");
    37.       Put_Line ("OK 3");
    38.    exception
    39.       when Assert_Failure =>
    40.          Put_Line ("Not OK 5");
    41.    end;
    42. end GoodCpol;

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

2013-04-12  Robert Dewar  <dewar@adacore.com>

	* exp_util.adb (Make_Invariant_Call): Use Check_Kind instead
	of Check_Enabled.
	* gnat_rm.texi (Check_Policy): Update documentation for new
	Check_Policy syntax.
	* sem_prag.adb (Check_Kind): Replaces Check_Enabled
	(Analyze_Pragma, case Check_Policy): Rework to accomodate new
	syntax (like Assertion_Policy).
	* sem_prag.ads (Check_Kind): Replaces Check_Enabled.

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