[Ada] Handle compilation unit specific restrictions for subunits

[Arnaud Charlet <charlet at adacore dot com>]

This patch corrects two problems introduced by the previous patch
to handle compilation unit specific restrictions. First if a subunit
is compiled on its own, it does not pick up compilation unit specific
restrictions from a configuration pragma file.

Seccond, if such restrictions appear in the parent unit, they were
improperly applied to subunits.

The following two tests test both these cases

with the following configuration pragmas file:

     1. pragma Restrictions (No_Implementation_Attributes);
     2. pragma Restrictions (SPARK);

and the following sources:

     1. procedure P is
     2.    procedure Q is separate;
     3. begin
     4.    Q;
     5. end;

     1. separate (P)
     2. procedure Q is
     3.    X : constant Integer := 0;
     4.    S : String := X'Img;
     5. begin
     6.    null;
     7. end Q;

Then if we compile p.adb we get messages for both units:

p.adb:5:04: violation of restriction "SPARK" at p.adc:2
             "end P" required
p-q.adb:4:04: violation of restriction "SPARK" at p.adc:2
               declaration of object of unconstrained type
              not allowed
p-q.adb:4:19: violation of restriction
              "No_Implementation_Attributes" at p.adc:1

If we compile the subunit on its own we get messages
only for the subunit:

p-q.adb:4:04: violation of restriction "SPARK" at p.adc:2
               declaration of object of unconstrained type
              not allowed
p-q.adb:4:19: violation of restriction
              "No_Implementation_Attributes" at p.adc:1

The second test tests the case of pragmas in the file:

     1. pragma Restrictions (No_Implementation_Attributes);
     2. pragma Restrictions (SPARK);
     3. procedure R is
     4.    procedure Q is separate;
     5. begin
     6.    Q;
     7. end;

     1. separate (R)
     2. procedure Q is
     3.    X : constant Integer := 0;
     4.    S : String := X'Img;
     5. begin
     6.    null;
     7. end Q;

If we compile the parent unit, we get only messages
for the parent unit:

     1. pragma Restrictions (No_Implementation_Attributes);
     2. pragma Restrictions (SPARK);
     3. procedure R is
     4.    procedure Q is separate;
     5. begin
     6.    Q;
     7. end;
           |
        >>> violation of restriction "SPARK" at line 2
        >>>  "end R" required

If we compile the subunit, we still get messages only
for the parent unit:

Compiling: r-q.adb

     1. separate (R)
     2. procedure Q is
     3.    X : constant Integer := 0;
     4.    S : String := X'Img;
     5. begin
     6.    null;
     7. end Q;

Compiling: r.adb

     1. pragma Restrictions (No_Implementation_Attributes);
     2. pragma Restrictions (SPARK);
     3. procedure R is
     4.    procedure Q is separate;
     5. begin
     6.    Q;
     7. end;
           |
        >>> violation of restriction "SPARK" at line 2
        >>>  "end R" required

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

2012-01-23  Robert Dewar  <dewar@adacore.com>

	* sem_ch10.adb (Analyze_Subunit): Properly save/restore cunit
	restrictions.

Attachment: difs
Description: Text document